Hydration of copper(II): new insights from density functional theory and the COSMO solvation model.

PubMed

Bryantsev, Vyacheslav S; Diallo, Mamadou S; van Duin, Adri C T; Goddard, William A

2008-09-25

The hydrated structure of the Cu(II) ion has been a subject of ongoing debate in the literature. In this article, we use density functional theory (B3LYP) and the COSMO continuum solvent model to characterize the structure and stability of [Cu(H2O)n](2+) clusters as a function of coordination number (4, 5, and 6) and cluster size (n = 4-18). We find that the most thermodynamically favored Cu(II) complexes in the gas phase have a very open four-coordinate structure. They are formed from a stable square-planar [Cu(H2O)8](2+) core stabilized by an unpaired electron in the Cu(II) ion d(x(2)-y(2)) orbital. This is consistent with cluster geometries suggested by recent mass-spectrometric experiments. In the aqueous phase, we find that the more compact five-coordinate square-pyramidal geometry is more stable than either the four-coordinate or six-coordinate clusters in agreement with recent combined EXAFS and XANES studies of aqueous solutions of Cu(II). However, a small energetic difference (approximately 1.4 kcal/mol) between the five- and six-coordinate models with two full hydration shells around the metal ion suggests that both forms may coexist in solution.

(N-Benzyl-N-isopropyl­dithio­carbamato)chloridodiphenyl­tin(IV)

PubMed Central

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Ng, Seik Weng; Tiekink, Edward R. T.

2010-01-01

The SnIV atom in the title organotin dithio­carbamate, [Sn(C6H5)2(C11H14NS2)Cl], is penta-coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two ispo-C atoms of the Sn-bound phenyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square-pyramidal and trigonal-bipyramidal with a slight tendency towards the latter. The formation of close intra­molecular C–H⋯Cl and C–H⋯S contacts precludes the Cl and S atoms from forming significant inter­molecular contacts. The presence of C–H⋯π contacts leads to the formation of supra­molecular arrays that stack along the b axis. PMID:21588504

X-ray crystal structure and theoretical study of a new dinuclear Cu(II) complex with two different geometry centers bridged with an oxo group

NASA Astrophysics Data System (ADS)

Golbedaghi, Reza; Azimi, Saeid; Molaei, Atefeh; Hatami, Masoud; Notash, Behrouz

2017-10-01

A new Schiff base ligand HL, 1,3-bis(2-((Z)-(2-aminoethylimino)methyl)phenoxy)ethylene di amine, has been synthesized from the reaction of a new aldehyde and ethylenediamine. After preparation the Schiff base, a new dinuclear Cu(II) complex with two different geometry for each metal ion was synthesized. Single crystal X-ray structure analysis of the complex Cu(II) showed that the complex is binuclear and all nitrogen and oxygen atoms of ligand (N4O3) are coordinated to two Cu(II) center ions. The crystal structure studying shows, a perchlorate ion has been coordinated to the two Cu(II) metal centers as bridged and another perchlorate coordinated to the one of Cu(II) ion as terminal. However, two interesting structures square pyramidal and distorted octahedral Cu(II) ions are bridged asymmetrically by a perchlorate ion and oxygen of hydroxyl group of Schiff base ligand. In addition, we had a theoretical study to have a comparison of experimental and theoretical results we determined the HOMO and LUMO orbitals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jing-Yun, E-mail: jyunwu@ncnu.edu.tw; Tsai, Chi-Jou; Chang, Ching-Yun

A Zn(II)−salicylaldimine complex [Zn(L{sup salpyca})(H{sub 2}O)]{sub n} (1, where H{sub 2}L{sup salpyca}=4-hydroxy-3-(((pyridin-2-yl)methylimino)methyl)benzoic acid), with a one-dimensional (1D) chain structure, has been successfully converted to a discrete Ni(II)−salicylaldimine complex [Ni(L{sup salpyca})(H{sub 2}O){sub 3}] (2) and an infinite Cu(II)−salicylaldimine complex ([Cu(L{sup salpyca})]·3H{sub 2}O){sub n} (3) through a metal-ion exchange induced structural transformation process. However, such processes do not worked by Mn(II) and Co(II) ions. Solid-state structure analyses reveal that complexes 1–3 form comparable coordinative or supramolecular zigzag chains running along the crystallographic [201] direction. In addition, replacing Zn(II) ion by Ni(II) and Cu(II) ions caused changes in coordination environment and sphere ofmore » metal centers, from a 5-coordinate intermediate geometry of square pyramidal and trigonal bipyramidal in 1 to a 6-coordinate octahedral geometry in 2, and to a 4-coordiante square planar geometry in 3. This study shows that metal-ion exchange serves as a very efficient way of forming new coordination complexes that may not be obtained through direct synthesis. - Graphical abstract: A Zn(II)−salicylaldimine zigzag chain has been successfully converted to a Ni(II)−salicylaldimine supramolecular zigzag chain and a Cu(II)−salicylaldimine coordinative zigzag chain through metal-ion exchange induced structural transformations, which is not achieved by Mn(II) and Co(II) ions.« less

Mononuclear nickel (II) and copper (II) coordination complexes supported by bispicen ligand derivatives: Experimental and computational studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Nirupama; Niklas, Jens; Poluektov, Oleg

2017-01-01

The synthesis, characterization and density functional theory calculations of mononuclear Ni and Cu complexes supported by the N,N’-Dimethyl-N,N’-bis-(pyridine-2-ylmethyl)-1,2-diaminoethane ligand and its derivatives are reported. The complexes were characterized by X-ray crystallography as well as by UV-visible absorption spectroscopy and EPR spectroscopy. The solid state structure of these coordination complexes revealed that the geometry of the complex depended on the identity of the metal center. Solution phase characterization data are in accord with the solid phase structure, indicating minimal structural changes in solution. Optical spectroscopy revealed that all of the complexes exhibit color owing to d-d transition bands in the visiblemore » region. Magnetic parameters obtained from EPR spectroscopy with other structural data suggest that the Ni(II) complexes are in pseudo-octahedral geometry and Cu(II) complexes are in a distorted square pyramidal geometry. In order to understand in detail how ligand sterics and electronics affect complex topology detailed computational studies were performed. The series of complexes reported in this article will add significant value in the field of coordination chemistry as Ni(II) and Cu(II) complexes supported by tetradentate pyridyl based ligands are rather scarce.« less

Crystallographic studies on complexes of potassium iodide and copper perchlorate with N, Nʹ-dicyclohexylurea tethered to a benzo-12-crown-4

NASA Astrophysics Data System (ADS)

Tripathi, Garima; Ramanathan, Gurunath

2018-03-01

The N, N‧-dicyclohexylurea-capped benzo-12-crown-4 (compound 1) has been synthesized. The coordination behaviour of this compound (1) has been studied by crystallizing it with KI (2) and Cu(ClO4)2 (3) salts. The crystallographic studies were performed with all three compounds. The presence of metal ions significantly affects the crystal packing of the compound 1. The crystal lattice of compound 1 was stabilized by Csbnd H⋯π and Cdbnd O⋯Hsbnd N hydrogen bonding. The presence of KI in compound 2 results in a dimer structure in which iodide anion behaves as a bridging ligand. The K+ forms a perching structure with the crown ring. In the compound 3, Cu2+ ion and ligand molecule (1) crystallized independently. They were connected through hydrogen bonding. Interestingly, Cu2+ adopts two different geometries with the coordination number 5 and 6. The centre Cu2+ (Cu1) adopted an octahedral geometry whereas the terminal Cu2+ (Cu2) acquired square pyramidal geometry. The coordination sphere of Cu2+ contains ClO4- anion and water molecules. Cu2+ ion forms a chain structure through ClO4- anion and water molecules involve in hydrogen bonding with the ligand molecule.

Investigation of the Great Pyramid of Giza.

ERIC Educational Resources Information Center

Peace, Nigel; And Others

1997-01-01

Describes an activity in which geometry and trigonometry are studied using pyramids. Identical model pyramids are constructed from card stock, along with pyramids of different proportions and cuboids to use as controls. Also includes an investigation of some apparently non-scientific claims. (DDR)

Glycine and metformin as new counter ions for mono and dinuclear vanadium(V)-dipicolinic acid complexes based on the insulin-enhancing anions: Synthesis, spectroscopic characterization and crystal structure

NASA Astrophysics Data System (ADS)

Ghasemi, Fatemeh; Rezvani, Ali Reza; Ghasemi, Khaled; Graiff, Claudia

2018-02-01

Complexes [VO(dipic) (H2O)2]·2H2O (1), [H2Met][V2O4(dipic)2] (2) and [HGly][VO2(dipic)] (3), where H2dipic = 2,6-pyridinedicarboxylic acid, Met = Metformin (N,N-dimethylbiguanide) and Gly = glycine, were synthesized. The three complexes were characterized by elemental analysis, FTIR, 1H and 13C NMR, and UV-Vis spectroscopy. Solid-state structures of (2) and (3) were determined by single-crystal X-ray diffraction analysis. The coordination geometry around the vanadium atoms in 2 is octahedral, while the coordination geometry in 3 is between trigonal bipyramidal and squared pyramidal. In the binuclear complex 2 and mononuclear complex 3, metformin and glycine are diprotonated and monoprotonated respectively, and act as a counter ion. The redox behavior of the complexes was also investigated by cyclic voltammetry.

First-principles study of amorphous Ga4Sb6Te3 phase-change alloys

NASA Astrophysics Data System (ADS)

Bouzid, Assil; Gabardi, Silvia; Massobrio, Carlo; Boero, Mauro; Bernasconi, Marco

2015-05-01

First-principles molecular dynamics simulations within the density functional theory framework were performed to generate amorphous models of the Ga4Sb6Te3 phase change alloy by quenching from the melt. We find that Ga-Sb and Ga-Te are the most abundant bonds with only a minor amount of Sb-Te bonds participating to the alloy network. Ga and four-coordinated Sb atoms present a tetrahedral-like geometry, whereas three-coordinated Sb atoms are in a pyramidal configuration. The tetrahedral-like geometries are similar to those of the crystalline phase of the two binary compounds GaTe and GaSb. A sizable fraction of Sb-Sb bonds is also present, indicating a partial nanoscale segregation of Sb. Despite the fact that the composition Ga4Sb6Te3 lies on the pseudobinary Ga Sb -Sb2Te3 tie line, the amorphous network can be seen as a mixture of the two binary compounds GaTe and GaSb with intertwined elemental Sb.

Revisiting the polytopal rearrangements in penta-coordinate d7-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization.

PubMed

Asatryan, Rubik; Ruckenstein, Eli; Hachmann, Johannes

2017-08-01

This paper provides a first-principles theoretical investigation of the polytopal rearrangements and fluxional behavior of five-coordinate d 7 -transition metal complexes. Our work is primarily based on a potential energy surface analysis of the iron tetracarbonyl hydride radical HFe˙(CO) 4 . We demonstrate the existence of distorted coordination geometries in this prototypical system and, for the first time, introduce three general rearrangement mechanisms, which account for the non-ideal coordination. The first of these mechanisms constitutes a modified version of the Berry pseudorotation via a square-based pyramidal C 4v transition state that connects two chemically identical edge-bridged tetrahedral stereoisomers of C 2v symmetry. It differs from the classical Berry mechanism, which involves two regular D 3h equilibrium structures and a C 4v transition state. The second mechanism is related to the famous "tetrahedral jump" hypothesis, postulated by Muetterties for a number of d 6 HML 4 and H 2 ML 4 complexes. Here, our study suggests two fluxional rearrangement pathways via distinct types of C 2v transition states. Both pathways of this mechanism can be described as a single-ligand migration to a vacant position of an "octahedron", thus interchanging (switching) the apical and basal ligands of the initial quasi-square pyramidal isomer, which is considered as an idealized octahedron with a vacancy. Accordingly, we call this mechanism "octahedral switch". The third mechanism follows a butterfly-type isomerization featuring a key-angle deformation, and we thus call it "butterfly isomerization". It connects the quasi-square pyramidal and edge-bridged tetrahedral isomers of HFe˙(CO) 4 through a distorted edge-bridged tetrahedral transition state of C s symmetry. Our paper discusses the overall features of the isomers and rearrangement mechanisms as well as their implications. We rationalize the existence of each stationary point through an electronic structure analysis and argue their relevance for isolobal analogues of HFe˙(CO) 4 .

Picolinic acid based Cu(II) complexes with heterocyclic bases--crystal structure, DNA binding and cleavage studies.

PubMed

Pulimamidi, Rabindra Reddy; Nomula, Raju; Pallepogu, Raghavaiah; Shaik, Hussain

2014-05-22

In view of the importance of picolinic acid (PA) in preventing cell growth and arresting cell cycle, new PA based metallonucleases were designed with a view to study their DNA binding and cleavage abilities. Three new Cu(II) complexes [Cu(II)(DPPA)].4H2O (1),[Cu(II)(DPPA)(bpy)].5H2O (2) and [Cu(II)(DPPA)(phen)].5H2O (3), were synthesized using a picolinic acid based bifunctional ligand (DPPA) and heterocyclic bases (where DPPA: Pyridine-2-carboxylic acid {2-phenyl-1-[(pyridin-2-ylmethyl)-carbonyl]-ethyl}-amide; bpy: 2, 2'-bipyridine and phen: 1, 10-phenanthroline). DPPA was obtained by coupling 2-picolinic acid and 2-picolyl amine with l-phenylalanine through amide bond‌‌. Complexes were structurally characterized by a single crystal X-ray crystallography. The molecular structure of 1 shows Cu(II) center essentially in a square planar coordination geometry, while complex 2 shows an approximate five coordinated square-pyramidal geometry. Eventhough we could not isolate single crystal for complex (3), its structure was established based on other techniques. The complex (3) also exhibits five coordinate square pyramidal geometry. The complexes show good binding affinity towards CT-DNA. The binding constants (Kb) decrease in the order 1.35 ± 0.01 × 10(5) (3) > 1.23 ± 0.01 × 10(5) (2) > 8.3 ± 0.01 × 10(4) (1) M(-1). They also exhibit efficient nuclease activity towards supercoiled pUC19 DNA both in the absence and presence of external agent (H2O2). The kinetic studies reveal that the hydrolytic cleavage reactions follow the pseudo first-order rate constant and the hydrolysis rates are in the range of (5.8-8.0) × 10(7) fold rate enhancement compared to non-catalyzed double stranded DNA (3.6 × 10(-8) h(-1)). Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Syntheses and structural characterization of iron(II) and copper(II) coordination compounds with the neutral flexible bidentate N-donor ligands

NASA Astrophysics Data System (ADS)

Beheshti, Azizolla; Lalegani, Arash; Bruno, Giuseppe; Rudbari, Hadi Amiri

2014-08-01

Two new coordination compounds [Fe(bib)2(N3)2]n(1) and [Cu2(bpp)2(N3)4] (2) with azide and flexible ligands 1,4-bis(imidazolyl)butane (bib) and 1,3-bis(3,5-dimethylpyrazolyl)propane (bpp) were prepared and structurally characterized. In the 2D network structure of 1, the iron(II) ion lies on an inversion center and exhibits an FeN6 octahedral arrangement while in the dinuclear structure of 2, the copper(II) ion adopts an FeN5 distorted square pyramid geometry. In the complex 1, each μ2-bib acts as bridging ligand connecting two adjacent iron(II) ions while in the complex 2, the bpp ligand is coordinated to copper(II) ion in a cyclic-bidentate fashion forming an eight-membered metallocyclic ring. Coordination compounds 1 and 2 have been characterized by infrared spectroscopy, elemental analyses and single-crystal X-ray diffraction. Thermal analysis of polymer 1 was also studied.

Three VO2+ complexes of the pyridoxal-derived Schiff bases: Synthesis, experimental and theoretical characterizations, and catalytic activity in a cyclocondensation reaction

NASA Astrophysics Data System (ADS)

Jafari-Moghaddam, Faezeh; Beyramabadi, S. Ali; Khashi, Maryam; Morsali, Ali

2018-02-01

Three oxovanadium(IV) complexes of the pyridoxal Schiff bases have been newly synthesized and characterized. The used Schiff bases were N,N‧-dipyridoxyl(ethylenediamine), N,N‧-dipyridoxyl(1,3-propanediamine) and N,N‧-dipyridoxyl(1,2-benzenediamine). Also, the optimized geometry, assignment of the IR bands and the Natural Bond Orbital (NBO) analysis of the complexes have been computed using the density functional theory (DFT) methods. Dianionic form of the Schiff bases (L2-) acts as a tetradentate N2O2 ligand. The coordinating atoms of the Schiff base are the phenolate oxygens and imine nitrogens, which occupy four base positions of the square-pyramidal geometry of the complexes. The oxo ligand occupies the apical position of the [VO(L)] complexes. In the optimized geometry of the complexes, the coordinated Schiff bases have more planar structure than their free form. Due to the high-energy gaps, all of the complexes are predicted to be stable. Good agreement between the experimental values and the DFT-computed results supports suitability of the optimized geometries for the complexes. The investigated complexes show high catalytic activities in synthesis of the tetrahydrobenzo[b]pyrans through a three-component cyclocondensation reaction of dimedone, malononitrile and some aromatic aldehydes. The complexes catalyzed the reaction in solvent free conditions and the catalysts were found to be reusable.

Enhancement of thermoelectric characteristics in AlGaN/GaN films deposited on inverted pyramidal Si surfaces

NASA Astrophysics Data System (ADS)

Yalamarthy, Ananth Saran; So, Hongyun; Senesky, Debbie G.

2017-07-01

In this letter, we demonstrate an engineering strategy to boost thermoelectric power factor via geometry-induced properties of the pyramid structure. Aluminum gallium nitride (AlGaN)/GaN heterostructured films grown on inverted pyramidal silicon (Si) demonstrate higher power factor as compared to those grown on conventional flat Si substrates. We found that the magnitude of the Seebeck coefficient at room temperature increased from approximately 297 μVK-1 for the flat film to approximately 849 μVK-1 for the film on inverted pyramidal Si. In addition, the "effective" electrical conductivity of the AlGaN/GaN on the inverted pyramidal structure increased compared to the flat structure, generating an enhancement of thermoelectric power factor. The results demonstrate how manipulation of geometry can be used to achieve better thermoelectric characteristics in a manner that could be scaled to a variety of different material platforms.

Near-IR MCD of the nonheme ferrous active site in naphthalene 1,2-dioxygenase: correlation to crystallography and structural insight into the mechanism of Rieske dioxygenases.

PubMed

Ohta, Takehiro; Chakrabarty, Sarmistha; Lipscomb, John D; Solomon, Edward I

2008-02-06

Near-IR MCD and variable temperature, variable field (VTVH) MCD have been applied to naphthalene 1,2-dioxygenase (NDO) to describe the coordination geometry and electronic structure of the mononuclear nonheme ferrous catalytic site in the resting and substrate-bound forms with the Rieske 2Fe2S cluster oxidized and reduced. The structural results are correlated with the crystallographic studies of NDO and other related Rieske nonheme iron oxygenases to develop molecular level insights into the structure/function correlation for this class of enzymes. The MCD data for resting NDO with the Rieske center oxidized indicate the presence of a six-coordinate high-spin ferrous site with a weak axial ligand which becomes more tightly coordinated when the Rieske center is reduced. Binding of naphthalene to resting NDO (Rieske oxidized and reduced) converts the six-coordinate sites into five-coordinate (5c) sites with elimination of a water ligand. In the Rieske oxidized form the 5c sites are square pyramidal but transform to a 1:2 mixture of trigonal bipyramial/square pyramidal sites when the Rieske center is reduced. Thus the geometric and electronic structure of the catalytic site in the presence of substrate can be significantly affected by the redox state of the Rieske center. The catalytic ferrous site is primed for the O2 reaction when substrate is bound in the active site in the presence of the reduced Rieske site. These structural changes ensure that two electrons and the substrate are present before the binding and activation of O2, which avoids the uncontrolled formation and release of reactive oxygen species.

Low-spin manganese(II) and high-spin manganese(III) complexes derived from disalicylaldehyde oxaloyldihydrazone: Synthesis, spectral characterization and electrochemical studies

NASA Astrophysics Data System (ADS)

Syiemlieh, Ibanphylla; Kumar, Arvind; Kurbah, Sunshine D.; De, Arjune K.; Lal, Ram A.

2018-01-01

Low-spin manganese(II) complexes [MnII(H2slox)].H2O (1), [MnII(H2slox)(SL)] (where SL (secondary ligand) = pyridine (py, 2), 2-picoline (2-pic, 3), 3-picoline (3-pic, 4), and 4-picoline (4-pic, 5) and high-spin manganese(III) complex Na(H2O)4[MnIII(slox)(H2O)2].2.5H2O have been synthesized from disalicyaldehyde oxaloyldihydrazone in methanolic - water medium. The composition of complexes has been established by elemental analyses and thermoanalytical data. The structures of the complexes have been discussed on the basis of data obtained from molar conductance, UV visible, 1H NMR, infrared spectra, magnetic moment and electron paramagnetic resonance spectroscopic studies. Conductivity measurements in DMF suggest that the complexes (1-5) are non-electrolyte while the complex (6) is 1:1 electrolyte. The electronic spectral studies and magnetic moment data suggest five - coordinate square pyramidal structure for the complexes (2-5) and square planar geometry for manganese(II) in complex (1). In complex (6), both sodium and manganese(III) have six coordinate octahedral geometry. IR spectral studies reveal that the dihydrazone coordinates to the manganese centre in keto form in complexes (1-5) and in enol form in complex (6). In all complexes, the ligand is present in anti-cis configuration. Magnetic moment and EPR studies indicate manganese in +2 oxidation state in complexes (1-5), with low-spin square planar complex (1) and square pyramidal stereochemistries complexes (2-5) while in +3 oxidation state in high-spin distorted octahedral stereochemistry in complex (6). The complex (1) involves significant metal - metal interaction in the solid state. All of the complexes show only one metal centred electron transfer reaction in DMF solution in cyclic voltammetric studies. The complexes (1-5) involve MnII→MnI redox reaction while the complex (6) involves MnIII→MnII redox reaction, respectively.

The force pyramid: a spatial analysis of force application during virtual reality brain tumor resection.

PubMed

Azarnoush, Hamed; Siar, Samaneh; Sawaya, Robin; Zhrani, Gmaan Al; Winkler-Schwartz, Alexander; Alotaibi, Fahad Eid; Bugdadi, Abdulgadir; Bajunaid, Khalid; Marwa, Ibrahim; Sabbagh, Abdulrahman Jafar; Del Maestro, Rolando F

2017-07-01

OBJECTIVE Virtual reality simulators allow development of novel methods to analyze neurosurgical performance. The concept of a force pyramid is introduced as a Tier 3 metric with the ability to provide visual and spatial analysis of 3D force application by any instrument used during simulated tumor resection. This study was designed to answer 3 questions: 1) Do study groups have distinct force pyramids? 2) Do handedness and ergonomics influence force pyramid structure? 3) Are force pyramids dependent on the visual and haptic characteristics of simulated tumors? METHODS Using a virtual reality simulator, NeuroVR (formerly NeuroTouch), ultrasonic aspirator force application was continually assessed during resection of simulated brain tumors by neurosurgeons, residents, and medical students. The participants performed simulated resections of 18 simulated brain tumors with different visual and haptic characteristics. The raw data, namely, coordinates of the instrument tip as well as contact force values, were collected by the simulator. To provide a visual and qualitative spatial analysis of forces, the authors created a graph, called a force pyramid, representing force sum along the z-coordinate for different xy coordinates of the tool tip. RESULTS Sixteen neurosurgeons, 15 residents, and 84 medical students participated in the study. Neurosurgeon, resident and medical student groups displayed easily distinguishable 3D "force pyramid fingerprints." Neurosurgeons had the lowest force pyramids, indicating application of the lowest forces, followed by resident and medical student groups. Handedness, ergonomics, and visual and haptic tumor characteristics resulted in distinct well-defined 3D force pyramid patterns. CONCLUSIONS Force pyramid fingerprints provide 3D spatial assessment displays of instrument force application during simulated tumor resection. Neurosurgeon force utilization and ergonomic data form a basis for understanding and modulating resident force application and improving patient safety during tumor resection.

Colorimetric detection of hydrogen peroxide by dioxido-vanadium(V) complex containing hydrazone ligand: synthesis and crystal structure

NASA Astrophysics Data System (ADS)

Kurbah, Sunshine D.; Syiemlieh, Ibanphylla; Lal, Ram A.

2018-03-01

Dioxido-vanadium(V) complex has been synthesized in good yield, the complex was characterized by IR, UV-visible and 1H NMR spectroscopy. Single crystal X-ray crystallography techniques were used to assign the structure of the complex. Complex crystallized with monoclinic P21/c space group with cell parameters a (Å) = 39.516(5), b (Å) = 6.2571(11), c (Å) = 17.424(2), α (°) = 90, β (°) = 102.668(12) and γ (°) = 90. The hydrazone ligand is coordinate to metal ion in tridentate fashion through -ONO- donor atoms forming a distorted square pyramidal geometry around the metal ion.

Unusual saccharin-N,O (carbonyl) coordination in mixed-ligand copper(II) complexes: Synthesis, X-ray crystallography and biological activity

NASA Astrophysics Data System (ADS)

Mokhtaruddin, Nur Shuhada Mohd; Yusof, Enis Nadia Md; Ravoof, Thahira B. S. A.; Tiekink, Edward R. T.; Veerakumarasivam, Abhi; Tahir, Mohamed Ibrahim Mohamed

2017-07-01

Three tridentate Schiff bases containing N and S donor atoms were synthesized via the condensation reaction between S-2-methylbenzyldithiocarbazate with 2-acetyl-4-methylpyridine (S2APH); 4-methyl-3-thiosemicarbazide with 2-acetylpyridine (MT2APH) and 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine (ET2APH). Three new, binuclear and mixed-ligand copper(II) complexes with the general formula, [Cu(sac)(L)]2 (sac = saccharinate anion; L = anion of the Schiff base) were then synthesized, and subsequently characterized by IR and UV/Vis spectroscopy as well as by molar conductivity and magnetic susceptibility measurements. The Schiff bases were also spectroscopically characterized using NMR and MS to further confirm their structures. The spectroscopic data indicated that the Schiff bases behaved as a tridentate NNS donor ligands coordinating via the pyridyl-nitrogen, azomethine-nitrogen and thiolate-sulphur atoms. Magnetic data indicated a square pyramidal environment for the complexes and the conductivity values showed that the complexes were essentially non-electrolytes in DMSO. The X-ray crystallographic analysis of one complex, [Cu(sac)(S2AP)]2 showed that the Cu(II) atom was coordinated to the thiolate-S, azomethine-N and pyridyl-N donors of the S2AP Schiff base and to the saccharinate-N from one anion, as well as to the carbonyl-O atom from a symmetry related saccharinate anion yielding a centrosymmetric binuclear complex with a penta-coordinate, square pyramidal geometry. All the copper(II) saccharinate complexes were found to display strong cytotoxic activity against the MCF-7 and MDA-MB-231 human breast cancer cell lines.

Geometric isomerism in pentacoordinate Cu2+ complexes: equilibrium, kinetic, and density functional theory studies reveal the existence of equilibrium between square pyramidal and trigonal bipyramidal forms for a tren-derived ligand.

PubMed

Algarra, Andrés G; Basallote, Manuel G; Castillo, Carmen E; Clares, M Paz; Ferrer, Armando; García-España, Enrique; Llinares, José M; Máñez, M Angeles; Soriano, Conxa

2009-02-02

A ligand (L1) (bis(aminoethyl)[2-(4-quinolylmethyl)aminoethyl]amine) containing a 4-quinolylmethyl group attached to one of the terminal amino groups of tris(2-aminoethyl)amine (tren) has been prepared, and its protonation constants and stability constants for the formation of Cu(2+) complexes have been determined. Kinetic studies on the formation of Cu(2+) complexes in slightly acidic solutions and on the acid-promoted complex decomposition strongly suggest that the Cu(2+)-L1 complex exists in solution as a mixture of two species, one of them showing a trigonal bipyramidal (tbp) coordination environment with an absorption maximum at 890 nm in the electronic spectrum, and the other one being square pyramidal (sp) with a maximum at 660 nm. In acidic solution only a species with tbp geometry is formed, whereas in neutral and basic solutions a mixture of species with tbp and sp geometries is formed. The results of density functional theory (DFT) calculations indicate that these results can be rationalized by invoking the existence of an equilibrium of hydrolysis of the Cu-N bond with the amino group supporting the quinoline ring so that CuL1(2+) would be actually a mixture of tbp [CuL1(H(2)O)](2+) and sp [CuL1(H(2)O)(2)](2+). As there are many Cu(2+)-polyamine complexes with electronic spectra that show two overlapping bands at wavelengths close to those observed for the Cu(2+)-L1 complex, the existence of this kind of equilibrium between species with two different geometries can be quite common in the chemistry of these compounds. A correlation found between the position of the absorption maximum and the tau parameter measuring the distortion from the idealized tbp and sp geometries can be used to estimate the actual geometry in solution of this kind of complex.

Comparison of solid shapes geometry derived by a laser scanner and a total station

NASA Astrophysics Data System (ADS)

Sidiropoulos, Andreas; Lakakis, Konstantinos

2016-08-01

The laser scanning technology has become a common method for the daily applications of a large variety of scientists and professionals. Even for more sophisticated projects, laser scanners have been proved a very useful tool at researchers' and engineers' disposal. In this paper, we investigated the ability of a laser scanner compared to the ability of a total station to provide the geometry of solids. The tests were made in the laboratory facilities of the Aristotle University of Thessaloniki, in a variety of distances between the measuring instrument and the object. The solids that were used differ in shape, material and color. The objects are a wooden cube, a metal cube and a wooden pyramid. The absolute dimensions of the solid shapes were provided by the use of a caliper and were compared to the dimensions that were calculated by the coordinates produced by the total station and laser scanner measurements.

SERS encoded silver pyramids for attomolar detection of multiplexed disease biomarkers.

PubMed

Xu, Liguang; Yan, Wenjing; Ma, Wei; Kuang, Hua; Wu, Xiaoling; Liu, Liqaing; Zhao, Yuan; Wang, Libing; Xu, Chuanlai

2015-03-11

Three disease biomarkers can simultaneously be detected at the attomolar level because of a novel surface-enhanced Raman scattering (SERS) encoded silver pyramid sensing system. This newly designed pyramidal sensor with well-controlled geometry exhibits highly sensitive, selective, and reproducible SERS signals, and holds promising potential for biodetection applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural, electrochemical characterization and SOD mimic activities of 1D chain or 3D network encouraged by unique μ2-bridging by adipate ion in mixed ligand complexes containing α-diimine as auxiliary ligand

NASA Astrophysics Data System (ADS)

Siddiqi, Zafar A.; Sharma, Prashant K.; Shahid, M.; Kumar, Sarvendra; Anjuli; Siddique, Armeen

The present ternary complexes [Cu(ada)(phen)(H2O)]·2H2O (1), [Co2(ada)2(phen)2(H2O)2] (2) and [{Cu(ada)3(bipy)}n·3nH2O] (3) (H2ada = adipic acid, phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine) obtained under varying experimental conditions were characterized by spectral, electrochemical and thermal studies. The bonding modes and the spatial arrangements of the carboxylate dianion around the metal ions have been investigated employing FTIR, EPR and X-ray crystallographic studies. Present data revealed a six coordinate distorted octahedral geometry for 2 with a = 8.068, b = 9.788, c = 11.788 Å, α = 70.464, β = 75.109, γ = 72.063° and a five coordinate square pyramidal geometry for 3 with a = 9.509, b = 9.912, c = 12.656 Å, α = 70.486, β = 73.604, γ = 75.162°. The superoxide dismutase (SOD) mimic activities of the complexes are in the order 1 > 3 > 2.

Structural influence in the interaction of cysteine with five coordinated copper complexes: Theoretical and experimental studies

NASA Astrophysics Data System (ADS)

Huerta-Aguilar, Carlos Alberto; Thangarasu, Pandiyan; Mora, Jesús Gracia

2018-04-01

Copper complexes of N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,2-diaminoethane (L1) and N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,3-diaminopropane (L2) prepared were characterized completely by different analytical methods. The X-structure of the complexes shows that Cu(II) presents in trigonal bi-pyramidal (TBP) geometry, consisting with the electronic spectra where two visible bands corresponding to five coordinated structure were observed. Thus TD-DFT was used to analyze the orbital contribution to the electronic transitions for the visible bands. Furthermore, the interaction of cysteine with the complexes was spectrally studied, and the results were explained through DFT analysis, observing that the geometrical parameters and oxidation state of metal ions play a vital role in the binding of cysteine with copper ion. It appears that the TBP structure is being changed into octahedral geometry during the addition of cysteine to the complexes as two bands (from complex) is turned to a broad band in visible region, signifying the occupation of cysteine molecule at sixth position of octahedral geometry. In the molecular orbital analysis, the existence of a strong overlapping of HOMOs (from cysteine) with LUMOs of Cu ion was observed. The total energy of the systems calculated by DFT shows that cysteine binds favorably with copper (I) than that with Cu(II).

Novel Route to Transition Metal Isothiocyanate Complexes Using Metal Powders and Thiourea

NASA Technical Reports Server (NTRS)

Harris, Jerry D.; Eckles, William E.; Hepp, Aloysius F.; Duraj, Stan A.; Hehemann, David G.; Fanwick, Phillip E.; Richardson, John

2003-01-01

A new synthetic route to isothiocyanate-containing materials is presented. Eight isothiocyanate- 4-methylpyridine (y-picoline) compounds were prepared by refluxing metal powders (Mn, Fe, Co, Ni, and Cu) with thiourea in y-picoline. With the exception of compound 5,prepared with Co, the isothiocyanate ligand was generated in situ by the isomerization of thiourea to NH4+SCN- at reflux temperatures. The complexes were characterized by x-ray crystallography. Compounds 1,2, and 8 are the first isothiocyanate- 4-methylpyridine anionic compounds ever prepared and structurally characterized. Compounds 1 and 2 are isostructural with four equatorially bound isothiocyanate ligands and two axially bound y-picoline molecules. Compound 8 is a five-coordinate copper(II) molecule with a distorted square-pyramidal geometry. Coordinated picoline and two isothiocyanates form the basal plane and the remaining isothiocyanate is bound at the apex. Structural data are presented for all compounds.

Synthesis, characterization, X-ray crystal structure and conductometry studying of a number of new Schiff base complexes; a new example of binuclear square pyramidal geometry of Cu(II) complex bridged with an oxo group

NASA Astrophysics Data System (ADS)

Golbedaghi, Reza; Alavipour, Ehsan

2015-11-01

Three new binuclear Cu(II), Mn(II), Co(II) complexes [Cu2(L) (ClO4)](ClO4)2 (1), [Mn2(L) (ClO4)](ClO4)2 (2), and [Co2(L) (ClO4)](ClO4)2 (3), {L = 1,3-bis(2-((Z)-(2-aminopropylimino)methyl)phenoxy)propan-2-ol} have been synthesized. Single crystal X-ray structure analysis of complex 1 showed that the complex is binuclear and all nitrogen and oxygen atoms of ligand (N4O3) are coordinated to two Cu(II) center ions. In addition, the crystal structure studying shows, a perchlorate ion has been bridged to the Cu(II) metal centers. However, two distorted square pyramidal Cu(II) ions are bridged asymmetrically by a perchlorate ion and oxygen of hydroxyl group of Schiff base ligand. In addition, the conductometry behaviors of all complexes were studied in acetonitrile solution.

[μ-10,21-Dimethyl-3,6,14,17-tetra-za-tricyclo-[17.3.1.1]tetra-cosa-1(23),2,6,8,10,12 (24),13,17,19,21-deca-ene-23,24-diolato-κN,N,O,O:κN,N,O,O]bis-(perchlorato-κO)dimanganese(II).

PubMed

Liu, Jing; Pan, Zhi-Quan; Zhou, Hong; Li, Yi-Zhi

2008-11-08

In the centrosymmetric and dinuclear title complex, [Mn(2)(C(22)H(22)N(4)O(2))(ClO(4))(2)], the two Mn atoms are bridged by two phenolate O atoms of the N(4)O(2) macrocycle with an Mn⋯Mn distance of 2.9228 (11) Å. The distorted square-pyramidal N(2)O(3) coordination geometry is completed by an O atom derived from a perchlorate anion.

Budding Architects: Exploring the Designs of Pyramids and Prisms

ERIC Educational Resources Information Center

Leavy, Aisling; Hourigan, Mairéad

2015-01-01

The context of students as architects is used to examine the similarities and differences between prisms and pyramids. Leavy and Hourigan use the Van Hiele Model as a tool to support teachers to develop expectations for differentiating geometry in the classroom using practical examples.

Practical Geometry Problems: The Case of the Ritzville Pyradmids.

ERIC Educational Resources Information Center

Nowlin, Donald

1993-01-01

Ritzville Pyramids are cone-shaped piles of wheat found near the community of Ritzville, Washington. Presents the practical problem of determining the volume and surface area of a Ritzville pyramid to help farmers solve cost-effectiveness questions related to selling the wheat. (MDH)

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas.

PubMed

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-08-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas.

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas

PubMed Central

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-01-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas. PMID:25081193

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-01

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, 1H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand.

Clipping polygon faces through a polyhedron of vision

NASA Technical Reports Server (NTRS)

Florence, Judit K. (Inventor); Rohner, Michel A. (Inventor)

1980-01-01

A flight simulator combines flight data and polygon face terrain data to provide a CRT display at each window of the simulated aircraft. The data base specifies the relative position of each vertex of each polygon face therein. Only those terrain faces currently appearing within the pyramid of vision defined by the pilots eye and the edges of the pilots window need be displayed at any given time. As the orientation of the pyramid of vision changes in response to flight data, the displayed faces are correspondingly displaced, eventually moving out of the pyramid of vision. Faces which are currently not visible (outside the pyramid of vision) are clipped from the data flow. In addition, faces which are only partially outside of pyramid of vision are reconstructed to eliminate the outside portion. Window coordinates are generated defining the distance between each vertex and each of the boundary planes forming the pyramid of vision. The sign bit of each window coordinate indicates whether the vertex is on the pyramid of vision side of the associated boundary panel (positive), or on the other side thereof (negative). The set of sign bits accompanying each vertex constitute the outcode of that vertex. The outcodes (O.C.) are systematically processed and examined to determine which faces are completely inside the pyramid of vision (Case A--all signs positive), which faces are completely outside (Case C--All signs negative) and which faces must be reconstructed (Case B--both positive and negative signs).

Bromidotetra-kis-(1H-2-ethyl-5-methyl-imidazole-κN)copper(II) bromide.

PubMed

Godlewska, Sylwia; Baranowska, Katarzyna; Socha, Joanna; Dołęga, Anna

2011-12-01

The Cu(II) ion in the title compound, [CuBr(C(6)H(10)N(2))(4)]Br, is coordinated in a square-based-pyramidal geometry by the N atoms of four imidazole ligands and a bromide anion in the apical site. Both the Cu(II) and Br(-) atoms lie on a crystallographic fourfold axis. In the crystal, the [CuBr(C(6)H(10)N(2))(4)](+) complex cations are linked to the uncoordinated Br(-) anions (site symmetry [Formula: see text]) by N-H⋯Br hydrogen bonds, generating a three-dimensional network. The ethyl group of the imidazole ligand was modelled as disordered over two orientations with occupancies of 0.620 (8) and 0.380 (8).

Temporal redistribution of inhibition over neuronal subcellular domains underlies state-dependent rhythmic change of excitability in the hippocampus

PubMed Central

Somogyi, Peter; Katona, Linda; Klausberger, Thomas; Lasztóczi, Bálint; Viney, Tim J.

2014-01-01

The behaviour-contingent rhythmic synchronization of neuronal activity is reported by local field potential oscillations in the theta, gamma and sharp wave-related ripple (SWR) frequency ranges. In the hippocampus, pyramidal cell assemblies representing temporal sequences are coordinated by GABAergic interneurons selectively innervating specific postsynaptic domains, and discharging phase locked to network oscillations. We compare the cellular network dynamics in the CA1 and CA3 areas recorded with or without anaesthesia. All parts of pyramidal cells, except the axon initial segment, receive GABA from multiple interneuron types, each with distinct firing dynamics. The axon initial segment is exclusively innervated by axo-axonic cells, preferentially firing after the peak of the pyramidal layer theta cycle, when pyramidal cells are least active. Axo-axonic cells are inhibited during SWRs, when many pyramidal cells fire synchronously. This dual inverse correlation demonstrates the key inhibitory role of axo-axonic cells. Parvalbumin-expressing basket cells fire phase locked to field gamma activity in both CA1 and CA3, and also strongly increase firing during SWRs, together with dendrite-innervating bistratified cells, phasing pyramidal cell discharge. Subcellular domain-specific GABAergic innervation probably developed for the coordination of multiple glutamatergic inputs on different parts of pyramidal cells through the temporally distinct activity of GABAergic interneurons, which differentially change their firing during different network states. PMID:24366131

Synthesis and molecular structure of [Cu(NH3)4][Ni(CN)4]: A missing piece in the [Cu(NH3)n][Ni(CN)4] story

NASA Astrophysics Data System (ADS)

Solanki, Dina; Hogarth, Graeme

2015-11-01

Reaction of CuCl2·2H2O and K2[Ni(CN)4]·2H2O in aqueous ammonia gave blue rod-like crystals of [Cu(NH3)4][Ni(CN)4]. An X-ray crystallographic reveals that square-planar anions and cations are weakly associated through coordination of a cis pair of cyanide ligands to copper, with one short and one long contact and thus the copper centre is best described as a square-based pyramid. Crystals lose ammonia readily upon removal from the solvent and this has been probed by TGA and DSC measurements. For comparison we have also re-determined the structure of the related ethylenediamine (en) complex [Cu(en)2][Ni(CN)4] at 150 K. This consists of a 1D chain in which a trans pair of cyanide ligands bind to copper such that the latter has an overall tetragonally distorted octahedral coordination geometry.

Poly[[di-μ-aqua-(μ-4-formyl-2-meth­oxy­phenol­ato)disodium] 4-formyl-2-meth­oxy­phenolate

PubMed Central

Asghar, Muhammad Nadeem; Şahin, Onur; Arshad, Muhammad Nadeem; Mazhar, Uzma; Khan, Islam Ullah; Büyükgüngör, Orhan

2010-01-01

In the title coordination polymer, {[Na2(C8H7O3)(H2O)4](C8H7O3)}n, all the non-H atoms except the water O atoms lie on a crystallographic mirror plane. One sodium cation is bonded to four water O atoms and one vanillinate O atom in a distorted square-based pyramidal arrangement; the other Na+ ion is six-coordinated by four water O atoms and two vanillinate O atoms in an irregular geometry. One of the vanillinate anions is directly bonded to two sodium ions, whilst the other only inter­acts with the polymeric network by way of hydrogen bonds. In the crystal, a two-dimensional polymeric array is formed; this is reinforced by O—H⋯O hydrogen bonds, which generate R 2 1(6) and R 2 2(20) loops. PMID:21579628

Some biologically active oxovanadium(IV) complexes of triazole derived Schiff bases: their synthesis, characterization and biological properties.

PubMed

Chohan, Zahid H; Sumrra, Sajjad H

2010-10-01

A series of biologically active oxovanadium(IV) complexes of triazole derived Schiff bases L(1)-L(5) have been synthesized and characterized by their physical, analytical, and spectral data. The synthesized ligands potentially act as bidentate, in which the oxygen of furfural and nitrogen of azomethine coordinate with the oxovanadium atom to give a stoichiometry of vanadyl complexes 1:2 (M:L) in a square-pyramidal geometry. In vitro antibacterial and antifungal activities on different species of pathogenic bacteria (E. coli, S. flexneri, P. aeruginosa, S. typhi, S. aureus, and B. subtilis) and fungi (T. longifusus, C. albicans, A. flavus, M. canis, F. solani, and C. glabrata) have been studied. All compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against most of the fungal strains. The brine shrimp bioassay was also carried out to check the cytotoxicity of coordinated and uncoordinated synthesized compounds.

Synthesis,and structural characterization of [(CH3(C5H4N))Ga(SCH2(CO)O)]-[(4-MepyH)]+, a novel Ga(III) five coordinate complex.

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Duraj, Stan A.; Fanwic, Phillp E.; Hepp, Aloysius F.; Martuch, Robert A.

2003-01-01

The synthesis and structural characterization of a novel ionic Ga(III) five coordinate complex [{CH3(C5H4N)}Ga(SCH2(CO)O)2]-[(4-MepyH)]+, (4-Mepy = CH3(C5H5N)) from the reaction between Ga2Cl4 with sodium mercapto-acetic acid in 4-methylpyridine is described. Under basic reaction conditions the mercapto ligand is found to behave as a 2e- bidentate ligand. Single crystal X-ray diffraction studies show the complex to have a distorted square pyramidal geometry with the [(-SCH2(CO)CO-)] ligands in a trans conformation. The compound crystallizes in the P2(sub 1)/c (No. 14) space group with a = 7.7413(6) A, b = 16.744(2) A, c = 14.459(2) A, V = 1987.1(6) A(sup 3), R(F) = 0.032 and R(sub w) = 0.038.

UTSA-74: A MOF-74 Isomer with Two Accessible Binding Sites per Metal Center for Highly Selective Gas Separation.

PubMed

Luo, Feng; Yan, Changsheng; Dang, Lilong; Krishna, Rajamani; Zhou, Wei; Wu, Hui; Dong, Xinglong; Han, Yu; Hu, Tong-Liang; O'Keeffe, Michael; Wang, Lingling; Luo, Mingbiao; Lin, Rui-Biao; Chen, Banglin

2016-05-04

A new metal-organic framework Zn2(H2O)(dobdc)·0.5(H2O) (UTSA-74, H4dobdc = 2,5-dioxido-1,4-benzenedicarboxylic acid), Zn-MOF-74/CPO-27-Zn isomer, has been synthesized and structurally characterized. It has a novel four coordinated fgl topology with one-dimensional channels of about 8.0 Å. Unlike metal sites in the well-established MOF-74 with a rod-packing structure in which each of them is in a five coordinate square pyramidal coordination geometry, there are two different Zn(2+) sites within the binuclear secondary building units in UTSA-74 in which one of them (Zn1) is in a tetrahedral while another (Zn2) in an octahedral coordination geometry. After activation, the two axial water molecules on Zn2 sites can be removed, generating UTSA-74a with two accessible gas binding sites per Zn2 ion. Accordingly, UTSA-74a takes up a moderately high and comparable amount of acetylene (145 cm(3)/cm(3)) to Zn-MOF-74. Interestingly, the accessible Zn(2+) sites in UTSA-74a are bridged by carbon dioxide molecules instead of being terminally bound in Zn-MOF-74, so UTSA-74a adsorbs a much smaller amount of carbon dioxide (90 cm(3)/cm(3)) than Zn-MOF-74 (146 cm(3)/cm(3)) at room temperature and 1 bar, leading to a superior MOF material for highly selective C2H2/CO2 separation. X-ray crystal structures, gas sorption isotherms, molecular modeling, and simulated and experimental breakthroughs comprehensively support this result.

Ab initio calculations of ionic hydrocarbon compounds with heptacoordinate carbon.

PubMed

Wang, George; Rahman, A K Fazlur; Wang, Bin

2018-04-25

Ionic hydrocarbon compounds that contain hypercarbon atoms, which bond to five or more atoms, are important intermediates in chemical synthesis and may also find applications in hydrogen storage. Extensive investigations have identified hydrocarbon compounds that contain a five- or six-coordinated hypercarbon atom, such as the pentagonal-pyramidal hexamethylbenzene, C 6 (CH 3 ) 6 2+ , in which a hexacoordinate carbon atom is involved. It remains challenging to search for further higher-coordinated carbon in ionic hydrocarbon compounds, such as seven- and eight-coordinated carbon. Here, we report ab initio density functional calculations that show a stable 3D hexagonal-pyramidal configuration of tropylium trication, (C 7 H 7 ) 3+ , in which a heptacoordinate carbon atom is involved. We show that this tropylium trication is stable against deprotonation, dissociation, and structural deformation. In contrast, the pyramidal configurations of ionic C 8 H 8 compounds, which would contain an octacoordinate carbon atom, are unstable. These results provide insights for developing new molecular structures containing hypercarbon atoms, which may have potential applications in chemical synthesis and in hydrogen storage. Graphical abstract Possible structural transformations of stable configurations of (C 7 H 7 ) 3+ , which may result in the formation of the pyramidal structure that involves a heptacoordinate hypercarbon atom.

Bromidotetra­kis­(1H-2-ethyl-5-methyl­imidazole-κN 3)copper(II) bromide

PubMed Central

Godlewska, Sylwia; Baranowska, Katarzyna; Socha, Joanna; Dołęga, Anna

2011-01-01

The CuII ion in the title compound, [CuBr(C6H10N2)4]Br, is coordinated in a square-based-pyramidal geometry by the N atoms of four imidazole ligands and a bromide anion in the apical site. Both the CuII and Br− atoms lie on a crystallographic fourfold axis. In the crystal, the [CuBr(C6H10N2)4]+ complex cations are linked to the uncoordinated Br− anions (site symmetry ) by N—H⋯Br hydrogen bonds, generating a three-dimensional network. The ethyl group of the imidazole ligand was modelled as disordered over two orientations with occupancies of 0.620 (8) and 0.380 (8). PMID:22199662

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes.

PubMed

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-25

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, (1)H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand. Copyright © 2014 Elsevier B.V. All rights reserved.

Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

PubMed

Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

2013-03-04

Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

Red/near-infrared luminescence tuning of group-14 element complexes of dipyrrins based on a central atom.

PubMed

Yamamura, Masaki; Albrecht, Marcel; Albrecht, Markus; Nishimura, Yoshinobu; Arai, Tatsuo; Nabeshima, Tatsuya

2014-02-03

A dipyrrin complex has been one of the most utilized fluorescent dyes, and a variety of dipyrrin complexes show intriguing functions based on the various coordination structures of the central element. We now report the synthesis, structure, and photophysical properties of germanium and stannane complexes of the N2O2-type tetradentate dipyrrin, L·Ge and L·Sn, which are heavier analogues of the previously reported dipyrrin silicon complex, L·Si. The central group-14 atoms of the monomeric complexes have geometries close to trigonal bipyramidal (TBP), in which the contribution of the square-pyramidal (SP) character becomes higher as the central atom is heavier. Interestingly, L·Sn formed a dimeric structure in the crystal. All complexes L·Si, L·Ge, and L·Sn showed a fluorescence in the red/NIR region. Fluorescence quantum yields of L·Ge and L·Sn are higher than that of L·Si. These results indicated that the central atom on the dipyrrin complexes contributes not only to the geometry difference but also to tuning the fluorescence properties.

Coordination behavior of tetraaza [N4] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: Synthesis, spectroscopic characterization and anticancer activity

NASA Astrophysics Data System (ADS)

El-Boraey, Hanaa A.

2012-11-01

Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N4] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate dx2-y2 ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC50 = 25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

[15]aneN4S: synthesis, thermodynamic studies and potential applications in chelation therapy.

PubMed

Torres, Nuno; Gonçalves, Sandrina; Fernandes, Ana S; Machado, J Franco; de Brito, Maria J Villa; Oliveira, Nuno G; Castro, Matilde; Costa, Judite; Cabral, Maria F

2014-01-03

The purpose of this work was to synthesize and characterize the thiatetraaza macrocycle 1-thia-4,7,10,13-tetraazacyclopentadecane ([15]aneN4S). Its acid-base behaviour was studied by potentiometry at 25 °C and ionic strength 0.10 M in KNO3. The protonation sequence of this ligand was investigated by 1H-NMR titration that also allowed the determination of protonation constants in D2O. Binding studies of [15]aneN4S with Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ metal ions were further performed under the same experimental conditions. The results demonstrated that this compound has a higher selectivity and thermodynamic stability for Hg2+ and Cu2+, followed by Ni2+. The UV-visible-near IR spectroscopies and magnetic moment data for the Co(II) and Ni(II) complexes indicated a tetragonal distorted coordination geometry for both metal centres. The value of magnetic moment and the X-band EPR spectra of the Cu(II) complex are consistent with a distorted square pyramidal geometry.

Coordination polyhedron and chemical vapor deposition of Cu(hfacac)2(t-BuNH2).

PubMed

Woo, Kyoungja; Paek, Hojeong; Lee, Wan In

2003-10-06

A new pentacoordinate Cu(II) complex, Cu(hfacac)(2)(t-BuNH(2)) [hfacac = CF(3)C(O)CHC(O)CF(3)(-), t-BuNH(2) = tert-butylamine], has been synthesized and structurally characterized. Interestingly, the structure of a single crystal occurred as square pyramidal with one O atom at the apical position and one N and three O atoms at the basal positions, showing a serious degree of distortion. This contrasts with the square-pyramidal structure of Cu(hfacac)(2)L (L = H(2)O and pyrazine), which has the L ligand at the axial position. In the Cu(hfacac)(2)(t-BuNH(2)) complex, the t-BuNH(2) ligand is placed at an equatorial position with a lowered angle by 19.9(2) degrees from the basal plane. This distortion seems to reduce sigma influence and steric hindrance and so stabilizes the square-pyramidal geometry. This precursor has a lower melting point and superior stability to air, moisture, and heat than the Cu(hfacac)(2)(xH(2)O) precursor. The deposition rate of copper oxide film on a Pt layer above 450 degrees C was nearly constant with increasing temperature, indicating a mass transport limited reaction. Therefore it would be a useful metal organic chemical vapor deposition precursor for the fabrication of copper oxide film or superconducting materials. Crystal data for Cu(hfacac)(2)(t-BuNH(2)): 293(2) K, a = 9.6699(4) A, b = 18.0831(10) A, c = 12.8864(11) A, beta = 111.839(5) degrees, monoclinic, space group P2(1)/c, Z = 4.

Dendritic branching angles of pyramidal cells across layers of the juvenile rat somatosensory cortex.

PubMed

Leguey, Ignacio; Bielza, Concha; Larrañaga, Pedro; Kastanauskaite, Asta; Rojo, Concepción; Benavides-Piccione, Ruth; DeFelipe, Javier

2016-09-01

The characterization of the structural design of cortical microcircuits is essential for understanding how they contribute to function in both health and disease. Since pyramidal neurons represent the most abundant neuronal type and their dendritic spines constitute the major postsynaptic elements of cortical excitatory synapses, our understanding of the synaptic organization of the neocortex largely depends on the available knowledge regarding the structure of pyramidal cells. Previous studies have identified several apparently common rules in dendritic geometry. We study the dendritic branching angles of pyramidal cells across layers to further shed light on the principles that determine the geometric shapes of these cells. We find that the dendritic branching angles of pyramidal cells from layers II-VI of the juvenile rat somatosensory cortex suggest common design principles, despite the particular morphological and functional features that are characteristic of pyramidal cells in each cortical layer. J. Comp. Neurol. 524:2567-2576, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Terminal Field and Firing Selectivity of Cholecystokinin-Expressing Interneurons in the Hippocampal CA3 Area

PubMed Central

Lasztóczi, Bálint; Tukker, John J.; Somogyi, Peter; Klausberger, Thomas

2015-01-01

Hippocampal oscillations reflect coordinated neuronal activity on many timescales. Distinct types of GABAergic interneuron participate in the coordination of pyramidal cells over different oscillatory cycle phases. In the CA3 area, which generates sharp waves and gamma oscillations, the contribution of identified GABAergic neurons remains to be defined. We have examined the firing of a family of cholecystokinin-expressing interneurons during network oscillations in urethane-anesthetized rats and compared them with firing of CA3 pyramidal cells. The position of the terminals of individual visualized interneurons was highly diverse, selective, and often spatially coaligned with either the entorhinal or the associational inputs to area CA3. The spike timing in relation to theta and gamma oscillations and sharp waves was correlated with the innervated pyramidal cell domain. Basket and dendritic-layer-innervating interneurons receive entorhinal and associational inputs and preferentially fire on the ascending theta phase, when pyramidal cell assemblies emerge. Perforant-path-associated cells, driven by recurrent collaterals of pyramidal cells fire on theta troughs, when established pyramidal cell assemblies are most active. In the CA3 area, slow and fast gamma oscillations occurred on opposite theta oscillation phases. Perforant-path-associated and some COUP-TFII-positive interneurons are strongly coupled to both fast and slow gamma oscillations, but basket and dendritic-layer-innervating cells are weakly coupled to fast gamma oscillations only. During sharp waves, different interneuron types are activated, inhibited, or remain unaffected. We suggest that specialization in pyramidal cell domain and glutamatergic input-specific operations, reflected in the position of GABAergic terminals, is the evolutionary drive underlying the diversity of cholecystokinin-expressing interneurons. PMID:22159120

Antibacterial activity and spectral studies of trivalent chromium, manganese, iron macrocyclic complexes derived from oxalyldihydrazide and glyoxal.

PubMed

Singh, D P; Kumar, Ramesh; Singh, Jitender

2009-06-01

A new series of complexes is synthesized by template condensation of oxalyldihydrazide and glyoxal in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type: [M(C(8)H(8)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(-1)(3), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry for these complexes has been proposed. The biological activities of the metal complexes were tested in vitro against a number of pathogenic bacteria and some of the complexes exhibited remarkable antibacterial activities.

Syntheses, crystal structures and Hirshfeld surface analysis of a coordination polymer of Cu(II) chlorido and a tris-octahedral complex of Ni(II) containing isonicotinoylhydrazone blockers

NASA Astrophysics Data System (ADS)

Mahmoudi, Ghodrat; Chowdhury, Habibar; Ghosh, Barindra K.; Lofland, Samuel E.; Maniukiewicz, Waldemar

2018-05-01

One-pot reactions of pre-assigned molar ratios of appropriate metal (II) salts and HL1 (2-acetylpyridine nicotinoylhydrazone) or HL2 (2-acetylpyridine isonicotinoylhydrazone) in MeOH solutions at room temperature afford 1D coordination polymeric chain [Cu(μ-L1) (Cl)]n (1) and a mononuclear complex [Ni(L2)2] (2). The compounds (1) and (2) were characterized using elemental analyses, spectral and other physicochemical methods. Single crystal X-ray diffraction measurements for (1) and (2) have been made to define the molecular aggregates and crystalline architectures. In (1), each copper (II) center adopts a distorted square pyramidal geometry with a CuN3OCl chromophore linked through μ-L1 to form the 1D polymeric chain. While in (2) each Ni(II) cation is six-coordinate with octahedral structure having NiN4O2 chromophore containing two L2 units each functioning as a classical tridentate (N,N,O) chelator. Different weak non-covalent interactions promote dimensionalities in the compounds. A Hirshfeld surface analysis was employed to gain additional insight into interactions responsible for packing of (1) and (2). Magnetic susceptibility measurement of (1) in the 4-300 K range reveals simple paramagnetism.

Activity of pyramidal I and II < c + a > slip in Mg alloys as revealed by texture development

NASA Astrophysics Data System (ADS)

Zecevic, Miroslav; Beyerlein, Irene J.; Knezevic, Marko

2018-02-01

Due to the geometry of the hexagonal close-packed (HCP) lattice, there are two types of pyramidal slip modes: { 10 1 bar 1 } 〈 11 2 bar 3 bar 〉 or type I and { 1 bar 1 bar 22 } 〈 11 2 bar 3 〉 or type II in HCP crystalline materials. Here we use crystal plasticity to examine the importance of crystallographic slip by pyramidal type I and type II on texture evolution. The study is applied to an Mg-4%Li alloy. An elastic-plastic polycrystal model is employed to elucidate the reorientation tendencies of these two slip modes in rolling of a textured polycrystal. Comparisons with experimental texture measurements indicate that both pyramidal I and II type slip were active during rolling deformation, with pyramidal I being the dominant mode. A single-slip-mode analysis is used to identify the orientations that prefer pyramidal I vs. II type slip when acting alone in a crystal. The analysis applies not only to Mg-4%Li, but identifies the key texture components in HCP crystals that would help distinguish the activity of pyramidal I from pyramidal II slip in rolling deformation.

Digital pyramid wavefront sensor with tunable modulation.

PubMed

Akondi, Vyas; Castillo, Sara; Vohnsen, Brian

2013-07-29

The pyramid wavefront sensor is known for its high sensitivity and dynamic range that can be tuned by mechanically altering its modulation amplitude. Here, a novel modulating digital scheme employing a reflecting phase only spatial light modulator is demonstrated. The use of the modulator allows an easy reconfigurable pyramid with digital control of the apex angle and modulation geometry without the need of any mechanically moving parts. Aberrations introduced by a 140-actuator deformable mirror were simultaneously sensed with the help of a commercial Hartmann-Shack wavefront sensor. The wavefronts reconstructed using the digital pyramid wavefront sensor matched very closely with those sensed by the Hartmann-Shack. It is noted that a tunable modulation is necessary to operate the wavefront sensor in the linear regime and to accurately sense aberrations. Through simulations, it is shown that the wavefront sensor can be extended to astronomical applications as well. This novel digital pyramid wavefront sensor has the potential to become an attractive option in both open and closed loop adaptive optics systems.

Molecular modelling, spectroscopic characterization and biological studies of tetraazamacrocyclic metal complexes

NASA Astrophysics Data System (ADS)

Rathi, Parveen; Sharma, Kavita; Singh, Dharam Pal

2014-09-01

Macrocyclic complexes of the type [MLX]X2; where L is (C30H28N4), a macrocyclic ligand, M = Cr(III) and Fe(III) and X = Cl-, CH3COO- or NO3-, have been synthesized by template condensation reaction of 1,8-diaminonaphthalene and acetylacetone in the presence of trivalent metal salts in a methanolic medium. The complexes have been formulated as [MLX]X2 due to 1:2 electrolytic nature of these complexes. The complexes have been characterized with the help of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, electronic, infrared, far infrared, Mass spectral studies and molecular modelling. Molecular weight of these complexes indicates their monomeric nature. On the basis of all these studies, a five coordinated square pyramidal geometry has been proposed for all these complexes. These metal complexes have also been screened for their in vitro antimicrobial activities.

Synthesis and spectroscopic studies of biologically active compounds derived from oxalyldihydrazide and benzil, and their Cr(III), Fe(III) and Mn(III) complexes.

PubMed

Singh, D P; Kumar, Ramesh; Singh, Jitender

2009-04-01

A new series of complexes have been synthesized by template condensation of oxalyldihydrazide and benzil in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type [M(C(32)H(24)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(3)(-1), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry has been proposed for all these complexes. The biological activities of the metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Some of these complexes have been found to exhibit remarkable antibacterial activities.

Tris(O-cyclo-hexyl dithio-carbonato-κS)anti-mony(III).

PubMed

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2008-12-10

In the mol-ecule of the title compound, [Sb(C(7)H(11)OS(2))(3)], the anti-mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination.

3D morphology-based clustering and simulation of human pyramidal cell dendritic spines.

PubMed

Luengo-Sanchez, Sergio; Fernaud-Espinosa, Isabel; Bielza, Concha; Benavides-Piccione, Ruth; Larrañaga, Pedro; DeFelipe, Javier

2018-06-13

The dendritic spines of pyramidal neurons are the targets of most excitatory synapses in the cerebral cortex. They have a wide variety of morphologies, and their morphology appears to be critical from the functional point of view. To further characterize dendritic spine geometry, we used in this paper over 7,000 individually 3D reconstructed dendritic spines from human cortical pyramidal neurons to group dendritic spines using model-based clustering. This approach uncovered six separate groups of human dendritic spines. To better understand the differences between these groups, the discriminative characteristics of each group were identified as a set of rules. Model-based clustering was also useful for simulating accurate 3D virtual representations of spines that matched the morphological definitions of each cluster. This mathematical approach could provide a useful tool for theoretical predictions on the functional features of human pyramidal neurons based on the morphology of dendritic spines.

DNA interaction studies of new nano metal based anticancer agent: validation by spectroscopic methods

NASA Astrophysics Data System (ADS)

Tabassum, Sartaj; Sharma, Girish Chandra; Arjmand, Farukh; Azam, Ameer

2010-05-01

A new nano dimensional heterobimetallic Cu-Sn containing complex as a potential drug candidate was designed, synthesized and characterized by analytical and spectral methods. The electronic absorption and electron paramagnetic resonance parameters of the complex revealed that the Cu(II) ion exhibits a square pyramidal geometry with the two pyrazole nitrogen atoms, the amine nitrogen atom and the carboxylate oxygen of the phenyl glycine chloride ligand located at the equatorial sites and the coordinated chloride ion occupying an apical position. 119Sn NMR spectral data showed a hexa-coordinated environment around the Sn(IV) metal ion. TEM, AFM and XRD measurements illustrate that the complex could induce the condensation of CT-DNA to a particulate nanostructure. The interaction of the Cu-Sn complex with CT-DNA was investigated by UV-vis absorption and emission spectroscopy, as well as cyclic voltammetric measurements. The results indicated that the complex interacts with DNA through an electrostatic mode of binding with an intrinsic binding constant Kb = 8.42 × 104 M - 1. The Cu-Sn complex exhibits effective cleavage of pBR322 plasmid DNA by an oxidative cleavage mechanism, monitored at different concentrations both in the absence and in the presence of reducing agents.

Synthesis, spectroscopic, and antibacterial activity of tetraazamacrocyclic complexes of trivalent chromium, manganese, and iron.

PubMed

Singh, D P; Malik, Vandna; Kumar, Ramesh; Singh, Jitender

2009-10-01

A new series of macrocyclic complexes of type [M(TML)X]X(2), where M = Cr(III), Mn(III), or Fe(III), TML is tetradentate macrocyclic ligand, and X = Cl(-), NO(3)(-), CH(3)COO(-) for Cr(III), Fe(III) and X = CH(3)COO(-) for Mn (III), has been synthesized by condensation of benzil and succinyldihydrazide in the presence of metal salt. The complexes have been so formulated due to the 1:2 electrolytic nature of these complexes as shown by conductivity measurements. The complexes have been characterized with the help of various physicochemical techniques such as elemental analysis, molar conductance, electronic and infrared spectral studies, and magnetic susceptibility. On the basis of these studies, a five-coordinate distorted square pyramidal geometry, in which two nitrogens and two carbonyl oxygen atoms are suitably placed for coordination toward the metal ion, has been proposed for all the complexes. The complexes have been tested for their in vitro antibacterial activity. Some of the complexes show remarkable antibacterial activities against some selected bacterial strains. The minimum inhibitory concentrations shown by these complexes have been compared with those shown by some standard antibiotics such as linezolid and cefaclor.

Synthesis, characterization, single crystal X-ray determination, fluorescence and electrochemical studies of new dinuclear nickel(II) and oxovanadium(IV) complexes containing double Schiff base ligands

NASA Astrophysics Data System (ADS)

Shafaatian, Bita; Ozbakzaei, Zahra; Notash, Behrouz; Rezvani, S. Ahmad

2015-04-01

A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s-1 scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction.

Molecular structure, supramolecular association and anion sensing by chlorodiorganotin(IV) methylferrocenyldithiocarbamates

NASA Astrophysics Data System (ADS)

Yadav, Reena; Awasthi, Mahendra Kumar; Singh, Amita; Kociok-Köhn, Gabriele; Trivedi, Manoj; Prasad, Rajendra; Shahid, Mohammad; Kumar, Abhinav

2017-10-01

Three new chlorodiorganotin(IV) methylferrocenyl dithiocarbamate complexes viz. [(FcCH2)(CH2CH2OH)NCS2SnMe2(Cl)] (1), [(FcCH2)(CH2CH2OH)NCS2SnnBu2(Cl)] (2) and [(FcCH2)(CH2CH2OH)NCS2SnPh2(Cl)] (3) have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H, 13C and 119Sn NMR spectroscopy and X-ray crystallography. The crystal structure of 1 indicates that the coordination geometries around the tin(IV) center is intermediate between ideal trigonal-bipyramidal and square pyramidal coordination polyhedra bonded through two sulfur atoms of the dithiocarbamate ligand in an isobidentate mode, two CH3 groups and one chlorine atom. Since, in 2 and 3 only alkyl and aryl fragments have been changed we infer that both 2 and 3 would also have the same behaviors in the solution state as observed in 1. Ionic interactions abilities of 1-3 are examined in acetonitrile through UV-vis absorption spectroscopy which offers reasonably good selectivity and sensitivity towards the detection of the acetate ion. Compounds 1-3 exhibit a bathochromic shift with the acetate ion with a moderate association constant.

Crystal structure of bis-[(phenyl-methanamine-κN)(phthalocyaninato-κ(4) N)zinc] phenyl-methan-amine tris-olvate.

PubMed

Shamsudin, Norzianah; Tan, Ai Ling; Wimmer, Franz L; Young, David J; Tiekink, Edward R T

2015-09-01

The asymmetric unit of the title compound, 2[Zn(C32H16N8)(C7H9N)]·3C7H9N, comprises two independent complex mol-ecules and three benzyl-amine solvent mol-ecules. Each complex mol-ecule features a penta-coordinated Zn(2+) ion within a square-pyramidal geometry, whereby the N5 donor set is defined by four atoms of the phthalocyaninate dianion (PC) and an N-bound benzyl-amine mol-ecule; it is the relative orientations of the latter that differentiate between the independent complex mol-ecules. The uncoordinated benzyl-amine mol-ecules display different conformations in the structure, with syn-Car-Car-Cm-N (ar = aromatic, m = methyl-ene) torsion angles spanning the range -28.7 (10) to 35.1 (14)°. In the crystal, N-H⋯N and N-H⋯π inter-actions lead to supra-molecular layers in the ab plane. The layers have a zigzag topology, have the coordinating and non-coordinating benzyl-amine mol-ecules directed to the inside, and present the essentially flat PC resides to the outside. This arrangement enables adjacent layers to associate via π-π inter-actions [inter-centroid distance between pyrrolyl and fused-benzene rings = 3.593 (2) Å] so that a three-dimensional architecture is formed.

Binuclear Pt-Tl bonded complex with square pyramidal coordination around Pt: a combined multinuclear NMR, EXAFS, UV-Vis, and DFT/TDDFT study in dimethylsulfoxide solution.

PubMed

Purgel, Mihály; Maliarik, Mikhail; Glaser, Julius; Platas-Iglesias, Carlos; Persson, Ingmar; Tóth, Imre

2011-07-04

The structure and bonding of a new Pt-Tl bonded complex formed in dimethylsulfoxide (dmso), (CN)(4)Pt-Tl(dmso)(5)(+), have been studied by multinuclear NMR and UV-vis spectroscopies, and EXAFS measurements in combination with density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. This complex is formed following the equilibrium reaction Pt(CN)(4)(2-) + Tl(dmso)(6)(3+) ⇆ (CN)(4)Pt-Tl(dmso)(5)(+) + dmso. The stability constant of the Pt-Tl bonded species, as determined using (13)C NMR spectroscopy, amounts to log K = 2.9 ± 0.2. The (NC)(4)Pt-Tl(dmso)(5)(+) species constitutes the first example of a Pt-Tl bonded cyanide complex in which the sixth coordination position around Pt (in trans with respect to the Tl atom) is not occupied. The spectral parameters confirm the formation of the metal-metal bond, but differ substantially from those measured earlier in aqueous solution for complexes (CN)(5)Pt-Tl(CN)(n)(H(2)O)(x)(n-) (n = 0-3). The (205) Tl NMR chemical shift, δ = 75 ppm, is at extraordinary high field, while spin-spin coupling constant, (1)J(Pt-Tl) = 93 kHz, is the largest measured to date for a Pt-Tl bond in the absence of supporting bridging ligands. The absorption spectrum is dominated by two strong absorption bands in the UV region that are assigned to MMCT (Pt → Tl) and LMCT (dmso → Tl) bands, respectively, on the basis of MO and TDDFT calculations. The solution of the complex has a bright yellow color as a result of a shoulder present on the low energy side of the band at 355 nm. The geometry of the (CN)(4)Pt-Tl core can be elucidated from NMR data, but the particular stoichiometry and structure involving the dmso ligands are established by using Tl and Pt L(III)-edge EXAFS measurements. The Pt-Tl bond distance is 2.67(1) Å, the Tl-O bond distance is 2.282(6) Å, and the Pt-C-N entity is linear with Pt-C and Pt···N distances amounting to 1.969(6) and 3.096(6) Å, respectively. Geometry optimizations on the (CN)(4)Pt-Tl(dmso)(5)(+) system by using DFT calculations (B3LYP model) provide bond distances in excellent agreement with the EXAFS data. The four cyanide ligands are located in a square around the Pt atom, while the Tl atom is coordinated in a distorted octahedral fashion with the metal being located 0.40 Å above the equatorial plane described by four oxygen atoms of dmso ligands. The four equatorial Tl-O bonds and the four cyano ligands around the Pt atom are arranged in an alternate geometry. The coordination environment around Pt may be considered as being square pyramidal, where the apical position is occupied by the Tl atom. The optimized geometry of (CN)(4)Pt-Tl(dmso)(5)(+) is asymmetrical (C(1) point group). This low symmetry might be responsible for the unusually large NMR linewidths observed due to intramolecular chemical exchange processes. The nature of the Pt-Tl bond has been studied by MO analysis. The metal-metal bond formation in (CN)(4)Pt-Tl(dmso)(5)(+) can be simply interpreted as the result of a Pt(5d(z(2)))(2) → Tl(6s)(0) donation. This bonding scheme may rationalize the smaller thermodynamic stability of this adduct compared to the related complexes with (CN)(5)Pt-Tl entity, where the linear C-Pt-Tl unit constitutes a very stable bonding system. © 2011 American Chemical Society

Tris(O-cyclo­hexyl dithio­carbonato-κS)anti­mony(III)

PubMed Central

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2009-01-01

In the mol­ecule of the title compound, [Sb(C7H11OS2)3], the anti­mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination. PMID:21581504

Insight into inhibition of the human amyloid beta protein precursor (APP: PDB ID ) using (E)-N-(pyridin-2-ylmethylene)arylamine (LR) models: structure elucidation of a family of ZnX2-LR complexes.

PubMed

Basu Baul, Tushar S; Kundu, Sajal; Singh, Palwinder; Shaveta; Guedes da Silva, M Fátima C

2015-02-07

The amyloid beta precursor protein (APP) and its neurotoxic cleavage product amyloid beta (Aβ) are a cause of Alzheimer's disease and appear essential for neuronal development and cell homeostasis. Proteolytic processing of APP is influenced by metal ions and protein ligands, however the structural and functional mechanism of APP regulation is not known so far. In this context, molecular modeling studies were performed to understand the molecular behavior of (E)-N-(pyridin-2-ylmethylene)arylamines (LR) with an E2 domain of the APP in its complex with zinc (APP; PDB ID: ). Docking results indeed confirmed that the LR interacts with Zn in the binding site of the protein between two α-helical chains. In view of these findings, LR was further investigated for complexation reactions with Zn(2+) in order to establish the structural models in solution and in the solid state. Five new Zn(2+) complexes of compositions viz. [Zn(Br)2(L2-Me)] (), [Zn(Br)2(L2-OMe)] (), [Zn(i)2(L2-OMe)] (), [Zn(NO3)2(L2-OMe)(H2O)] () and [Zn(L4-Me)2(H2O)2](NO3)2 () were synthesized and their structures were ascertained by microanalysis, IR and (1)H NMR spectroscopy, and single-crystal X-ray diffraction. The zinc atom in complex exhibits a distorted tetrahedral geometry while the crystal structures of complexes and show distorted square pyramidal geometries. The zinc cation in and has an octahedral coordination environment, but in the zinc coordination geometry is less distorted. The Zn(ii) cations take part in one ( and ) or two () 5-membered metallacycles imposed by the NN or NNO chelation modes of LR. The significant intermolecular ππ interactions are also discussed.

Russia’s Contribution as a Partner in the War on Terrorism

DTIC Science & Technology

2014-07-01

pyramid ,” which sets out the relevant authority structure. The monograph first examines the roles of coordinating bodies such as the Security...Jordan, Egypt , and Saudi Arabia. Some of the Russian Islamic scholars were taught in the Middle East or North Africa.12 By 1999, in Dagestan alone...anti-terrorist operations (Article 22).18 THE RUSSIAN SECURITY PYRAMID The Russian president, in accordance with Article 5 of Nr 35-F3, defines the

Individual Template-Stripped Conductive Gold Pyramids for Tip-Enhanced Dielectrophoresis

PubMed Central

2015-01-01

Gradient fields of optical, magnetic, or electrical origin are widely used for the manipulation of micro- and nanoscale objects. Among various device geometries to generate gradient forces, sharp metallic tips are one of the most effective. Surface roughness and asperities present on traditionally produced tips reduce trapping efficiencies and limit plasmonic applications. Template-stripped, noble metal surfaces and structures have sub-nm roughness and can overcome these limits. We have developed a process using a mix of conductive and dielectric epoxies to mount template-stripped gold pyramids on tungsten wires that can be integrated with a movable stage. When coupled with a transparent indium tin oxide (ITO) electrode, the conductive pyramidal tip functions as a movable three-dimensional dielectrophoretic trap which can be used to manipulate submicrometer-scale particles. We experimentally demonstrate the electrically conductive functionality of the pyramidal tip by dielectrophoretic manipulation of fluorescent beads and concentration of single-walled carbon nanotubes, detected with fluorescent microscopy and Raman spectroscopy. PMID:25541619

Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

PubMed

Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

2013-11-01

Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

DFT Study of Optical Properties of Pt-based Complexes

NASA Astrophysics Data System (ADS)

Oprea, Corneliu I.; Dumbravǎ, Anca; Moscalu, Florin; Nicolaides, Atnanassios; Gîrţu, Mihai A.

2010-01-01

We report Density Functional Theory (DFT) calculations providing the geometrical and electronic structures, as well as the vibrational and optical properties of the homologous series of Pt-pyramidalized olefin complexes (CH2)n-(C8H10)Pt(PH3)2, where n = 0, 1, and 2, in their neutral and oxidized states. All complexes were geometry optimized for the singlet ground state in vacuum using DFT methods with B3LYP exchange-correlation functional and the Effective Core Potential LANL2DZ basis set, within the frame of Gaussian03 quantum chemistry package. We find the coordination geometry of Pt to be distorted square planar, with dihedral angles ranging from 0°, for n = 0 and 1, which have C2V symmetry to 3.4°, for n = 2 with C2 symmetry. The Mulliken charge analysis allows a discussion of the oxidation state of the Pt ion. Electronic transitions were calculated at the same level of theory by means of Time Dependant-DFT. For n = 2 the electronic absorption bands are located in the UV region of the spectrum, the transitions being assigned to metal to ligand charge transfers. The relevance of these Pt-based compounds as possible pigments for dye-sensitized solar cells is discussed.

Transition metal complexes of a new 15-membered [N5] penta-azamacrocyclic ligand with their spectral and anticancer studies

NASA Astrophysics Data System (ADS)

El-Boraey, Hanaa A.; Serag El-Din, Azza A.

2014-11-01

Novel penta-azamacrocyclic 15-membered [N5] ligand [L] i.e. 1,5,8,12-tetetraaza-3,4: 9,10-dibenzo-6-ethyl-7-methyl-1,12-(2,6-pyrido)cyclopentadecan-5,7 diene-2,11-dione and its transition metal complexes with Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) have been synthesized and structurally characterized by elemental analysis, spectral, thermal as well as magnetic and molar conductivity measurements. On basis of IR, MS, UV-Vis 1H NMR and EPR spectral studies an octahedral geometry has been proposed for all complexes except Co(II), Cu(II) nitrate complexes and Pd(II) chloride complex that adopt tetrahedral, square pyramidal and square planar geometries, respectively. The antitumor activity of the synthesized ligand and some complexes against human breast cancer cell lines (MCF-7) and human hepatocarcinoma cell lines (HepG2) has been studied. The complexes (IC50 = 2.04-9.7, 2.5-3.7 μg/mL) showed potent antitumor activity comparable with their ligand (IC50 = 11.7, 3.45 μg/mL) against the above mentioned cell lines, respectively. The results evidently show that the activity of the ligand becomes more pronounced and significant when coordinated to the metal ion.

Synthesis, X-ray crystal structure, photo luminescent property, antimicrobial activities and DFT computational study of Zn(II) coordination polymer derived from multisite N,O donor Schiff base ligand (H2L1)

NASA Astrophysics Data System (ADS)

Majumdar, Dhrubajyoti; Surendra Babu, M. S.; Das, Sourav; Biswas, Jayanta Kumar; Mondal, Monojit; Hazra, Suman

2017-06-01

A unique thiocyanato linked 1D chain of Zn(II) coordination polymer [Zn2L1(μ1,3-SCN)(η1SCN)]n (1) has been synthesized using potential multisite compartmental N,O donor Schiff base blocker ligand (L1H2) in presence of Zn(OAc)2 and KSCN. The Schiff base ligand [N, N‧-bis(3-methoxysalicylidenimino)-1,3-daminopropane] (L1H2) is 2:1 M ratio condensation product of O-vaniline and 1,3-diaminopropane in methanol medium. The characterization of Complex 1 was accomplished by means of different micro analytical techniques like elemental analyses, IR, UV-Vis, 1H NMR, emission spectroscopy and Single X-ray crystallographic study. Complex 1 crystallizes in Orthorhombic system, space group Pbca, with values a = 11.579(2), b = 18.538(3), and c = 22.160(4) Å; α = β = γ = 90.00°; V = 4756.6(14) and Z = 8. The single crystal X-ray revealed that the one dimensional chain system with the repeating unit [Zn2(μ1,3-SCN)(η1SCN)(L1)]n bridge by an end to end μ1,3 thiocyanate anion. Within each repeating unit two different types of Zn(II) ions are present. One of these is five-coordinate in a square pyramidal geometry while the other is six-coordinate in an octahedral geometry. A brief but lucid comparative approach has been demonstrated in between Schiff base (L1H2) and complex 1 with respect to their photoluminescence activities. Active luminescence behavior of complex 1 in presence of ligand (L1H2) is due to quenching of PET process which is mediated by 'chelating effect'. Complex 1 exhibits strong antimicrobial efficacy against some important Gram + ve and Gram -ve bacteria. Apart from antimicrobial potential, a combined experimental and theoretical investigation has been performed via DFT on molecular structure of complex 1 with respect to Hirshfeld surface analysis.

Reporting numeric values of complete crowns. Part 2: Retention and resistance theories.

PubMed

Tiu, Janine; Al-Amleh, Basil; Waddell, J Neil; Duncan, Warwick J

2015-07-01

Determining the retention and resistance of a tooth preparation for a complete crown has only existed in theory, and these theories have never been measured on tooth preparations performed in vivo. The purpose of this study was to measure the theoretical retention and resistance of clinically produced complete crown preparations by using an objective measuring method. Stone dies from 236 complete crown preparations were collected from dental laboratories. The dies were scanned and analyzed with the coordinate geometry method. Cross-sectional images were captured, and the surface area was measured with a cone frustum and right truncated pyramid formula. Two different theories of resistance form, the "on" or "off" theory (limiting taper) and the linear model (resistance length), were calculated for premolar and molar preparations. The mean surface areas ranged from 33.97 mm(2) to 105.44 mm(2) for the cone frustum formula and 41.75 mm(2) to 117.50 mm(2) for the right truncated pyramid formula. The facial side of maxillary premolars exhibited the highest percentage of resistance form with the limiting taper, at 58%, and the mesial side of the mandibular molars exhibited the lowest percentage of resistance form, at 6%. The objective method used in this study provides a way for retention and resistance theories to be tested and for further clinical implications to be investigated. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Thorium Copper Phosphides: More Diverse Metal-Phosphorus and Phosphorus-Phosphorus Interactions than U analogues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Geng Bang; Malliakas, Christos D.; Lin, Jian

To explore the chemical analogy between thorium and heavier actinides in soft anionic environments, three new thorium phosphides (ThCuP 2, beta-ThCu 2P 2, and ThCu 5P 3) have been prepared through solid-state reactions using CuI as a reaction promoter. The structure of ThCuP 2 can be described as a filled UTe 2-type with both dimeric P 2 4- and monomeric P 3- anions, in which Th is coordinated by eight P atoms in a bicapped trigonal prismatic arrangement and Cu is tetrahedrally coordinated by four P atoms. β-ThCu 2P 2 contains only P 3- anions and is isostructural with BaCumore » 2S 2. In this structure, Th is coordinated by seven P atoms in monocapped trigonal prismatic geometry and Cu is tetrahedrally coordinated by four P atoms. ThCu 5P 3 adopts the YCo 5P 3-type structure consisting of P 3- anions. This structure contains Th atoms coordinated by six P atoms in a trigonal prismatic arrangement and Cu atoms that are either tetrahedrally coordinated by four P atoms or square pyramidally coordinated by five P atoms. Electric resistivity measurements and electronic structure calculations on β-ThCu 2P 2 indicate a metal. These new compounds may be charge-balanced and formulated as Th 4+Cu +(P 2 4-) 1/2P 3-, Th 4+(Cu +) 2(P 3-) 2, and Th 4+(Cu +) 5(P 3-) 3, respectively. The structural, bonding, and property relationships between these Th compounds and related actinide and rare-earth phases are discussed. In conclusion, titled compounds display more diverse ion-ion interactions and different electronic structures from those in UCuP 2 and UCu 2P 2 that were synthesized under similar experimental conditions, suggesting divergence of thorium-phosphide chemistry from uranium-phosphide chemistry.« less

Thorium Copper Phosphides: More Diverse Metal-Phosphorus and Phosphorus-Phosphorus Interactions than U analogues

DOE PAGES

Jin, Geng Bang; Malliakas, Christos D.; Lin, Jian

2017-09-28

To explore the chemical analogy between thorium and heavier actinides in soft anionic environments, three new thorium phosphides (ThCuP 2, beta-ThCu 2P 2, and ThCu 5P 3) have been prepared through solid-state reactions using CuI as a reaction promoter. The structure of ThCuP 2 can be described as a filled UTe 2-type with both dimeric P 2 4- and monomeric P 3- anions, in which Th is coordinated by eight P atoms in a bicapped trigonal prismatic arrangement and Cu is tetrahedrally coordinated by four P atoms. β-ThCu 2P 2 contains only P 3- anions and is isostructural with BaCumore » 2S 2. In this structure, Th is coordinated by seven P atoms in monocapped trigonal prismatic geometry and Cu is tetrahedrally coordinated by four P atoms. ThCu 5P 3 adopts the YCo 5P 3-type structure consisting of P 3- anions. This structure contains Th atoms coordinated by six P atoms in a trigonal prismatic arrangement and Cu atoms that are either tetrahedrally coordinated by four P atoms or square pyramidally coordinated by five P atoms. Electric resistivity measurements and electronic structure calculations on β-ThCu 2P 2 indicate a metal. These new compounds may be charge-balanced and formulated as Th 4+Cu +(P 2 4-) 1/2P 3-, Th 4+(Cu +) 2(P 3-) 2, and Th 4+(Cu +) 5(P 3-) 3, respectively. The structural, bonding, and property relationships between these Th compounds and related actinide and rare-earth phases are discussed. In conclusion, titled compounds display more diverse ion-ion interactions and different electronic structures from those in UCuP 2 and UCu 2P 2 that were synthesized under similar experimental conditions, suggesting divergence of thorium-phosphide chemistry from uranium-phosphide chemistry.« less

Two-dimensional Zn(II) and one-dimensional Co(II) coordination polymers based on benzene-1,4-dicarboxylate and pyridine ligands.

PubMed

Zhou, Li-Juan; Han, Chang-Bao; Wang, Yu-Ling

2016-02-01

Coordination polymers constructed from metal ions and organic ligands have attracted considerable attention owing to their diverse structural topologies and potential applications. Ligands containing carboxylate groups are among the most extensively studied because of their versatile coordination modes. Reactions of benzene-1,4-dicarboxylic acid (H2BDC) and pyridine (py) with Zn(II) or Co(II) yielded two new coordination polymers, namely, poly[(μ4-benzene-1,4-dicarboxylato-κ(4)O:O':O'':O''')(pyridine-κN)zinc(II)], [Zn(C8H4O2)(C5H5N)]n, (I), and catena-poly[aqua(μ3-benzene-1,4-dicarboxylato-κ(3)O:O':O'')bis(pyridine-κN)cobalt(II)], [Co(C8H4O2)(C5H5N)2(H2O)]n, (II). In compound (I), the Zn(II) cation is five-coordinated by four carboxylate O atoms from four BDC(2-) ligands and one pyridine N atom in a distorted square-pyramidal coordination geometry. Four carboxylate groups bridge two Zn(II) ions to form centrosymmetric paddle-wheel-like Zn2(μ2-COO)4 units, which are linked by the benzene rings of the BDC(2-) ligands to generate a two-dimensional layered structure. The two-dimensional layer is extended into a three-dimensional supramolecular structure with the help of π-π stacking interactions between the aromatic rings. Compound (II) has a one-dimensional double-chain structure based on Co2(μ2-COO)2 units. The Co(II) cations are bridged by BDC(2-) ligands and are octahedrally coordinated by three carboxylate O atoms from three BDC(2-) ligands, one water O atom and two pyridine N atoms. Interchain O-H...O hydrogen-bonding interactions link these chains to form a three-dimensional supramolecular architecture.

Synthesis of Schiff base 24-membered trivalent transition metal derivatives with their anti-inflammation and antimicrobial evaluation

NASA Astrophysics Data System (ADS)

Kumar, Gajendra; Devi, Shoma; Kumar, Dharmendra

2016-03-01

The paper presents the synthesis of macrocyclic complexes [{M(C52H36N12O4)X}X2] of Cr(III), Mn(III) and Fe(III) with Schiff base ligand (C52H36N12O4) obtained through the condensation of 1,4-dicarbonyl phenyl dihydrazide with 1,2-di(1H-indol-1-yl)ethane-1,2-dione. The newly formed Schiff base and its complexes have been characterized with the help of elemental analysis, condensation measurements, magnetic measurements and their structure configuration have been determined by various spectroscopic (electronic, IR, 1H NMR, 13C NMR, GCMS) techniques. The electronic spectra of the complexes indicate a five coordinate square pyramidal geometry of the center metal ion. These metal complexes and ligand were tested for their anti-inflammation and antimicrobial inhibiting potential and compared with standard drugs Phenyl butazone (anti-inflammation), Imipenem (antibacterial) and Miconazole (antifungal).

Synthesis, antimicrobial, antioxidant and molecular docking studies of thiophene based macrocyclic Schiff base complexes

NASA Astrophysics Data System (ADS)

Rathi, Parveen; Singh, D. P.

2015-11-01

The macrocyclic complexes of pharmaceutical importance with trivalent transition metals have been synthesized by [1 + 1] condensation of succinyldihydrazide and thiophenedicarboxaldehyde, via template method, resulting in the formation of the complex [MLX] X2; where L is (C10H10N4O2S), a macrocyclic ligand, M = Cr (III) and Fe (III) and X = Cl-, CH3COO- or NO3- . These complexes have been characterized with the help of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, ultraviolet, infrared, far infrared, electron spin resonance, mass spectral studies and powder x-ray diffraction analysis. On the basis of all these studies, mononuclear complexes having 1:2 electrolytic nature with a five coordinated square pyramidal geometry have been proposed. Powder diffraction XRD indicates the presence of triclinic crystal system with p bravais lattice for the representative complex. All the metal complexes have also been explored for their in vitro antimicrobial and antioxidant activities.

Synthesis, characterization, electrical conductivity and luminescence properties of two copper(II) complexes with tridentate N2O chelating ligands containing imine bond

NASA Astrophysics Data System (ADS)

Gönül, İlyas; Ay, Burak; Karaca, Serkan; Şahin, Onur; Serin, Selahattin

2018-03-01

In the present study, we describe the synthesis and characterization of two tridentate N2O donor ligands, namely, (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL1) and (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL2), and their copper(II) complexes, [Cu(L1)(CH3COO)] (1), [Cu(L2)(CH3COO)] (2). They have been synthesized under conventional methods and characterized by elemental analysis, FTIR, 1H and 13C NMR, ICP-OES, TGA and GC/MS analysis. For the morphological analysis field emission scanning electron microscopy (FESEM) was used. The geometry of the copper(II) complexes was determined by single crystal X-ray diffraction analysis. The copper(II) ions are in distorted square-pyramidal coordination environments. Complexes crystallize in monoclinic space group, P21/c. The electrical conductivity and luminescence properties of 1-2 have been investigated.

Crystal structure of aqua-1κO-{μ-2-[(2-hydroxy-ethyl)methylamino]ethanolato-2:1κ(4) O (1),N,O (2):O (1)}[μ-2,2'-(methylimino)diethanolato-1:2κ(4) O,N,O':O]dithiocyanato-1κN,2κN-chromium(III)copper(II).

PubMed

Rusanova, Julia A; Semenaka, Valentina V; Dyakonenko, Viktoriya V; Shishkin, Oleg V

2015-09-01

The title compound, [CrCu(C5H11NO2)(C5H12NO2)(NCS)2(H2O)] or [Cr(μ-mdea)Cu(μ-Hmdea)(NCS)2H2O], (where mdeaH2 is N-methylethanolamine, C5H13NO2) is formed as a neutral heterometal Cu(II)/Cr(III) complex. The mol-ecular structure of the complex is based on a binuclear {CuCr(μ-O)2} core. The coordination environment of each metal atom involves the N,O,O atoms of the tridentate ligand, one bridging O atom of the ligand and the N atom of the thio-cyanato ligands. The Cu(II) ion adopts a distorted square-pyramidal coordination while the Cr(III) ion has a distorted octa-hedral coordination geometry completed by the aqua ligand. In the crystal, the binuclear complexes are linked via two pairs of O-H⋯O hydrogen bonds to form inversion dimers, which are arranged in columns parallel to the a axis. In the μ-mdea ligand two -CH2 groups and the methyl group were refined as disordered over two sets of sites with equal occupancies. The structure was refined as a two-component twin with a twin scale factor of 0.242 (1).

Versatile chelating behavior of benzil bis(thiosemicarbazone) in zinc, cadmium, and nickel complexes.

PubMed

López-Torres, Elena; Mendiola, Ma Antonia; Pastor, César J; Pérez, Beatriz Souto

2004-08-23

Reactions of benzil bis(thiosemicarbazone), LH(6), with M(NO(3))(2).nH(2)O (M = Zn, Cd, and Ni), in the presence of LiOH.H(2)O, show the versatile behavior of this molecule. The structure of the ligand, with the thiosemicarbazone moieties on opposite sides of the carbon backbone, changes to form complexes by acting as a chelating molecule. Complexes of these metal ions with empirical formula [MLH(4)] were obtained, although they show different molecular structures depending on their coordinating preferences. The zinc complex is the first example of a crystalline coordination polymer in which a bis(thiosemicarbazone) acts as bridging ligand, through a nitrogen atom, giving a 1D polymeric structure. The coordination sphere is formed by the imine nitrogen and sulfur atoms, and the remaining position, in a square-based pyramid, is occupied by an amine group of another ligand. The cadmium derivative shows the same geometry around the metal ion but consists of a dinuclear structure with sulfur atoms acting as a bridge between the metal ions. However, in the nickel complex LH(6) acts as a N(2)S(2) ligand yielding a planar structure for the nickel atom. The ligand and its complexes have been characterized by X-ray crystallography, microanalysis, mass spectrometry, IR, (1)H, and (13)C NMR spectroscopies and for the cadmium complex by (113)Cd NMR in solution and in the solid state.

Layer-specific optogenetic activation of pyramidal neurons causes beta–gamma entrainment of neonatal networks

PubMed Central

Bitzenhofer, Sebastian H; Ahlbeck, Joachim; Wolff, Amy; Wiegert, J. Simon; Gee, Christine E.; Oertner, Thomas G.; Hanganu-Opatz, Ileana L.

2017-01-01

Coordinated activity patterns in the developing brain may contribute to the wiring of neuronal circuits underlying future behavioural requirements. However, causal evidence for this hypothesis has been difficult to obtain owing to the absence of tools for selective manipulation of oscillations during early development. We established a protocol that combines optogenetics with electrophysiological recordings from neonatal mice in vivo to elucidate the substrate of early network oscillations in the prefrontal cortex. We show that light-induced activation of layer II/III pyramidal neurons that are transfected by in utero electroporation with a high-efficiency channelrhodopsin drives frequency-specific spiking and boosts network oscillations within beta–gamma frequency range. By contrast, activation of layer V/VI pyramidal neurons causes nonspecific network activation. Thus, entrainment of neonatal prefrontal networks in fast rhythms relies on the activation of layer II/III pyramidal neurons. This approach used here may be useful for further interrogation of developing circuits, and their behavioural readout. PMID:28216627

Optimization of wave-guided luminescence for higher efficiency of bifacial thin-film microscale GaAs solar cells

NASA Astrophysics Data System (ADS)

Shen, Ling; Shen, Yifeng; Li, Feng

2018-01-01

In pursuit of capturing more wave-guided luminescence for surface-printed bifacial GaAs μ-cells, the pyramid structure has been incorporated with specular back side reflector (BSR) to change the direction of photon propagation. Based on ray tracing model, the calculated photon capturing efficiency of GaAs μ-cells from back side via pyramid, dependent on the parameters of pyramid structure, achieve the largest 1.7× increase for dye absorption peak of 480 nm compared to the case without pyramid. More significantly, the short circuit current in experiment has been improved from original 16.5 mA/cm2 to 23.75 mA/cm2 for the AM 1.5G solar spectrum. Further experiment demonstrates that the optimized pyramid structure enables the integrated luminescent intensity to reach ∼3× increase in a smaller distance of optical transport, which means the advantages in photon capturing efficiency for cells with higher aspect ratio. The calculation further confirms that the cells with higher aspect ratio, among all cells with the same area, realize the higher concentration ratio for the same geometric gain. This provides a guideline for design of cell geometries to guarantee a higher power output in terms of cell modules.

Sweet-Tooth Geometry.

ERIC Educational Resources Information Center

Scanlon, Regina M.

2003-01-01

Describes an engaging project in which students have to design and construct a three-dimensional candy box that would appeal to children. Requires students to make the box out of prisms, pyramids, or cylinders, determine the surface area and volume of the solids, and write a persuasive business letter. (YDS)

GaN nanostructure design for optimal dislocation filtering

NASA Astrophysics Data System (ADS)

Liang, Zhiwen; Colby, Robert; Wildeson, Isaac H.; Ewoldt, David A.; Sands, Timothy D.; Stach, Eric A.; García, R. Edwin

2010-10-01

The effect of image forces in GaN pyramidal nanorod structures is investigated to develop dislocation-free light emitting diodes (LEDs). A model based on the eigenstrain method and nonlocal stress is developed to demonstrate that the pyramidal nanorod efficiently ejects dislocations out of the structure. Two possible regimes of filtering behavior are found: (1) cap-dominated and (2) base-dominated. The cap-dominated regime is shown to be the more effective filtering mechanism. Optimal ranges of fabrication parameters that favor a dislocation-free LED are predicted and corroborated by resorting to available experimental evidence. The filtering probability is summarized as a function of practical processing parameters: the nanorod radius and height. The results suggest an optimal nanorod geometry with a radius of ˜50b (26 nm) and a height of ˜125b (65 nm), in which b is the magnitude of the Burgers vector for the GaN system studied. A filtering probability of greater than 95% is predicted for the optimal geometry.

Low-resistance gateless high electron mobility transistors using three-dimensional inverted pyramidal AlGaN/GaN surfaces

NASA Astrophysics Data System (ADS)

So, Hongyun; Senesky, Debbie G.

2016-01-01

In this letter, three-dimensional gateless AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated with 54% reduction in electrical resistance and 73% increase in surface area compared with conventional gateless HEMTs on planar substrates. Inverted pyramidal AlGaN/GaN surfaces were microfabricated using potassium hydroxide etched silicon with exposed (111) surfaces and metal-organic chemical vapor deposition of coherent AlGaN/GaN thin films. In addition, electrical characterization of the devices showed that a combination of series and parallel connections of the highly conductive two-dimensional electron gas along the pyramidal geometry resulted in a significant reduction in electrical resistance at both room and high temperatures (up to 300 °C). This three-dimensional HEMT architecture can be leveraged to realize low-power and reliable power electronics, as well as harsh environment sensors with increased surface area.

Synthesis of Surface-Analogue Square-Planar Tetranuclear Nickel Hydride Clusters and Bonding to μ4-NR, -O and -BH Ligands.

PubMed

Shoshani, Manar M; Beck, Robert; Wang, Xiaoping; McLaughlin, Matthew J; Johnson, Samuel A

2018-03-05

Tetranuclear Ni complexes were synthesized with bonding to BH, NR, and O in atypical surface-like geometries. The previously reported electron-deficient cluster [( i Pr 3 P)Ni] 5 H 6 (1) reacts with N-methylmorpholine oxide to give [( i Pr 3 P)Ni] 4 H 4 (μ 4 -O) (2), which contains O coordinated in the center of a square-plane arrangement of Ni atoms. Reaction of 1 with benzonitrile gave the square-planar tetranuclear Ni cluster [( i Pr 3 P)Ni] 4 H 4 (μ 4 -NCH 2 Ph) (3), which contains an imido donor in a square-based-pyramidal geometry. This reaction also gives [( i Pr 3 P)Ni(N≡CPh)] 3 (4), with bridging benzonitrile ligands. Trimer 4 was independently synthesized from the reaction of Ni(COD) 2 , i Pr 3 P, and PhC≡N. The addition of dihydrogen to a 1:1 mixture of [( i Pr 3 P) 2 Ni] 2 (N 2 ) and ( i Pr 3 P) 2 NiCl 2 yielded [( i Pr 3 P)Ni] 4 (μ 3 -H) 4 (μ 2 -Cl) 2 (5), with a tetrahedral Ni core, in contrast to the square-planar geometries of 2 and 3. The solid-state structure of 5 was determined using both X-ray and neutron diffraction. Reaction of 5 with LiBH 4 gave [( i Pr 3 P)Ni] 4 H 4 (μ 4 -BH) 2 ] (6) via loss of LiCl and H 2 .

Structural, vibrational, and electronic properties of an uncoordinated pseudoephedrine derivative and its mononuclear and trinuclear copper(II)-coordinated compounds: A combined theoretical and experimental study

NASA Astrophysics Data System (ADS)

Valencia, Israel; Ávila-Torres, Yenny; Barba-Behrens, Norah; Garzón, Ignacio L.

2014-11-01

Multicopper oxidases are fundamental in a variety of biological processes in bacteria, fungi and vertebrates. The catalytic center in these enzymes is formed basically by three copper ions, bridged by oxygen bonds. In order to get insights into the reactivity of these complex systems, biomimetic compounds are usually synthesized. Accordingly, in this work, we studied structural, vibrational, and electronic properties of an uncoordinated pseudoephedrine derivative, as well as its corresponding mononuclear and trinuclear copper(II)-coordinated complexes by means of density functional theory. The calculations are compared with experimental results using measurements of the infrared spectra. It is obtained that the molecular configuration of the pseudoephedrine amino-alcohol derivative is stabilized by hydrogen bonding Osbnd H⋯N and by Csbnd H⋯π interactions that are not present in the mononuclear and trinuclear compounds. The coordination compounds show octahedral and square pyramid geometries, respectively, which are slightly distorted by Jahn-Teller effects. The analysis of their theoretical and experimental IR spectra reveals signals related with hydrogen bonding as well as metal-ligand vibrational modes. Regarding the electronic structure, the density of states was calculated in order to analyze the atomic orbital contributions present in these compounds. This analysis would provide useful insights about the optical behavior, for example, in the visible region of the spectrum of the coordinated compounds. At these energies, the optical absorption would be influenced by the orbital interaction of the Cu2+d orbitals with sp ones of the ligand, reflecting a decrease of the HOMO-LUMO gap of the organic ligand due to the presence of the copper(II) ions.

Metal-organophosphine and metal-organophosphonium frameworks with layered honeycomb-like structures.

PubMed

Humphrey, Simon M; Allan, Phoebe K; Oungoulian, Shaunt E; Ironside, Matthew S; Wise, Erica R

2009-04-07

Phosphanotriylbenzenecarboxylic acid (ptbcH(3); P(C(6)H(4)-p-CO(2)H)(3)) and its methyl phosphonium iodide derivative (mptbcH(3)I; {H(3)CP(C(6)H(4)-p-CO(2)H)(3)}I) have been used as organic building blocks in reaction with Zn(ii) salts to obtain a series of related two-dimensional coordination polymers with honeycomb-like networks. The variable coordination number and oxidation states available to phosphorus have been exploited to produce a family of related phosphine coordination materials (PCMs) using a single ligand precursor. The phosphine carboxylate trianion, ptbc(3-), reacted with Zn(ii) to form 3,3-connected undulating hexagonal sheets based on tetrahedral P and Zn nodes, where Zn-ptbc = 1 : 1. When hydroxide was used as an additional framework ligand, Zn(4)(OH)(2) clusters were obtained. The clusters support 6,3-connected bilayers that consist of pairs of fused hexagonal sheets (Zn-ptbc = 2 : 1) with intra-layer pore spaces. The Zn(4)(OH)(2) clusters are also coordinated by solvent, which was preferentially displaced when the bilayer material was synthesized in the presence of ethylene diamine. Treatment of ptbc(3-) with MeI resulted in methylation of the phosphine to give the P(v) phosphonium iodide salt derivative. The formally dianionic methylphosphonium tricarboxylate building block, mptbc(2-), has the same trigonal-pyramidal bridging geometry as the parent phosphine. However, mptbc(2-) reacted with Zn(ii) on a 1 : 1 stoichiometric ratio to give an unusual trilayer sheet polymer that is based exclusively on 3-connected nodes. Solid-state (31)P NMR studies confirmed that the phosphine ligands were resistant to oxidation upon solvothermal reaction under aerobic conditions.

Synthesis, characterization, and ligand exchange reactivity of a series of first row divalent metal 3-hydroxyflavonolate complexes.

PubMed

Grubel, Katarzyna; Rudzka, Katarzyna; Arif, Atta M; Klotz, Katie L; Halfen, Jason A; Berreau, Lisa M

2010-01-04

A series of divalent metal flavonolate complexes of the general formula [(6-Ph(2)TPA)M(3-Hfl)]X (1-5-X; X = OTf(-) or ClO(4)(-); 6-Ph(2)TPA = N,N-bis((6-phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II); 3-Hfl = 3-hydroxyflavonolate) were prepared and characterized by X-ray crystallography, elemental analysis, FTIR, UV-vis, (1)H NMR or EPR, and cyclic voltammetry. All of the complexes have a bidentate coordinated flavonolate ligand. The difference in M-O distances (Delta(M-O)) involving this ligand varies through the series, with the asymmetry of flavonolate coordination increasing in the order Mn(II) approximately Ni(II) < Cu(II) < Zn(II) < Co(II). The hypsochromic shift of the absorption band I (pi-->pi*) of the coordinated flavonolate ligand in 1-5-OTf (relative to that in free anion) increases in the order Ni(II) < Mn(II) < Cu(II) < Zn(II), Co(II). Previously reported 3-Hfl complexes of divalent metals fit well with this ordering. (1)H NMR studies indicate that the 3-Hfl complexes of Co(II), Ni(II), and Zn(II) exhibit a pseudo-octahedral geometry in solution. EPR studies suggest that the Mn(II) complex 1-OTf may form binuclear structures in solution. The mononuclear Cu(II) complex 4-OTf has a distorted square pyramidal geometry. The oxidation potential of the flavonolate ligand depends on the metal ion present and/or the solution structure of the complex, with the Mn(II) complex 1-OTf exhibiting the lowest potential, followed by the pseudo-octahedral Ni(II) and Zn(II) 3-Hfl complexes, and the distorted square pyramidal Cu(II) complex 4-OTf. The Mn(II) complex [(6-Ph(2)TPA)Mn(3-Hfl)]OTf (1-OTf) is unique in the series in undergoing ligand exchange reactions in the presence of M(ClO(4))(2).6H(2)O (M = Co, Ni, Zn) in CD(3)CN to produce [(6-Ph(2)TPA)M(CD(3)CN)(n)](X)(2), [Mn(3-Hfl)(2).0.5H(2)O], and MnX(2) (X = OTf(-) or ClO(4)(-)). Under similar conditions, the 3-Hfl complexes of Co(II), Ni(II), and Cu(II) undergo flavonolate ligand exchange to produce [(6-Ph(2)TPA)M(CD(3)CN)(n)](X)(2) (M = Co, Ni, Cu; n = 1 or 2) and [Zn(3-Hfl)(2).2H(2)O]. An Fe(II) complex of 3-Hfl, [(6-Ph(2)TPA)Fe(3-Hfl)]ClO(4) (8), was isolated and characterized by elemental analysis, FTIR, UV-vis, (1)H NMR, cyclic voltammetry, and a magnetic moment measurement. This complex reacts with O(2) to produce the diiron(III) mu-oxo compound [(6-Ph(2)TPAFe(3Hfl))(2)(mu-O)](ClO(4))(2) (6).

Unexpected ferromagnetic interaction in a new tetranuclear copper(II) complex: synthesis, crystal structure, magnetic properties, and theoretical studies.

PubMed

Fondo, Matilde; García-Deibe, Ana M; Corbella, Monstserrat; Ruiz, Eliseo; Tercero, Javier; Sanmartín, Jesús; Bermejo, Manuel R

2005-07-11

The new tetranuclear carbonate complex [Cu2L)2(CO3)] x 8H2O (1 x 8H2O) (H3L = (2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) has been obtained by two different synthetic routes and fully characterized. Recrystallization of 1 x 8H2O in methanol yields single crystals of {[(Cu2L)2(CO3)]}2 x 12H2O (1 x 6H2O), suitable for X-ray diffraction studies. The crystal structure of 1 x 6H2O shows two crystallographically different tetranuclear molecules in the asymmetric unit, 1a and 1b. Both molecules can be understood as self-assembled from two dinuclear [Cu2L]+ cations, joined by a mu4-eta(2):eta(1):eta(1) carbonate ligand. The copper atoms of each crystallographically different [(Cu2L)2(CO3)] molecule present miscellaneous coordination polyhedra: in both 1a and 1b, two metal centers are in square pyramidal environments, one displays a square planar chromophore and the other one has a geometry that can be considered as an intermediate between square pyramid and trigonal bipyramid. Magnetic studies reveal net intramolecular ferromagnetic coupling between the metal atoms. Density functional calculations allow the assignment of the different magnetic coupling constants and explain the unexpected ferromagnetic behavior, because of the presence of an unusual NCN bridging moiety and countercomplementarity of the phenoxo (or carbonate) and NCN bridges.

Mixed-ligand Cu II complexes with Me 5dien and heterocyclic acids. Synthesis, antioxidant and anti-inflammatory activity. Crystal structure of [Cu(Me 5dien)(tpaa)(H 2O)](ClO 4)

NASA Astrophysics Data System (ADS)

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

2008-01-01

The reaction of sodium salt of 2-thiophenecarboxylic acid (tpca), 2-thiopheneacetic acid (tpaa), 2-furoic acid (fa) and picolinic acid (pica), with [Cu(Me 5dien)(ClO 4) 2] ( 1) (Me 5dien = N, N, N', N″ N″-pentamethyldiethylenetriamine) in a 1:1 molar ratio, afforded new mixed-ligand compounds of the type [Cu(Me 5dien)(tpca)(H 2O)](ClO 4) ( 2), [Cu(Me 5dien)(tpaa)(H 2O)](ClO 4) ( 3), [Cu(Me 5dien)(fa)](BPh 4) ( 4) and [Cu(Me 5dien)(pica)](ClO 4) ( 5). The new mixed-ligand complexes are mononuclear, paramagnetic, conductive compounds with a distorted square pyramidal geometry. The square pyramidal stereochemistry proposed by spectroscopic (IR, UV-vis) data was further confirmed by the X-ray structure analysis of the compound ( 3) in which the Cu atom is coordinated by the three N atoms from the Me 5dien ligand, one O atom from the mono-carboxylate anion, lying on the equatorial square plane, and one O atom from the water molecule, occupying the axial position. The two Cu sbnd O bond distances are 1.955(2) and 2.212(2) Ǻ, respectively. The complexes were tested for antioxidant/anti-inflammatory activity. Complex 4 is the most active against soybean lipoxygenase with IC 50 = 100 μM. The presence of a furoic ring leads to higher lipoxygenase inhibition, whereas the picolinyl-ring supports scavenging activity.

Synthesis and spectral studies on metal complexes of s-triazine based ligand and non linear optical properties

NASA Astrophysics Data System (ADS)

Shanmugakala, R.; Tharmaraj, P.; Sheela, C. D.

2014-11-01

A series of transition metal complexes of type [ML] and [ML2]Cl2 (where M = Cu(II), Ni(II), Co(II) have synthesized from 2-phenylamino-4,6-dichloro-s-triazine and 3,5-dimethyl pyrazole; their characteristics have been investigated by means of elemental analyses, magnetic susceptibility, molar conductance, IR, UV-Vis, Mass, NMR and ESR spectra. The electrochemical behavior of copper(II) complexes we have studied, by using cyclic voltammetry. The ESR spectra of copper(II) complexes are recorded at 300 K and 77 K and their salient features are appropriately reported. Spectral datas, we found, show that the ligand acts as a neutral tridentate, and coordinates through the triazine ring nitrogen and pyrazolyl ring nitrogen atoms to the metal ion. Evident from our findings, the metal(II) complexes of [ML] type exhibit square pyramidal geometry, and that of [ML2]Cl2 exhibit octahedral geometry. The in vitro antimicrobial activities of the ligand and its complexes are evaluated against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus vulgaris, Cryptococcus neoformans, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Shigella flexneri, Vibrio cholera, Vibris parahaemolyticus, Aspergillus niger, Candida albicans and Penicillium oxalicum by well-diffusion method. The second harmonic generation efficiency of the ligand and its complexes are determined and compared with urea and KDP.

Schwarzschild-de Sitter spacetimes, McVittie coordinates, and trumpet geometries

NASA Astrophysics Data System (ADS)

Dennison, Kenneth A.; Baumgarte, Thomas W.

2017-12-01

Trumpet geometries play an important role in numerical simulations of black hole spacetimes, which are usually performed under the assumption of asymptotic flatness. Our Universe is not asymptotically flat, however, which has motivated numerical studies of black holes in asymptotically de Sitter spacetimes. We derive analytical expressions for trumpet geometries in Schwarzschild-de Sitter spacetimes by first generalizing the static maximal trumpet slicing of the Schwarzschild spacetime to static constant mean curvature trumpet slicings of Schwarzschild-de Sitter spacetimes. We then switch to a comoving isotropic radial coordinate which results in a coordinate system analogous to McVittie coordinates. At large distances from the black hole the resulting metric asymptotes to a Friedmann-Lemaître-Robertson-Walker metric with an exponentially-expanding scale factor. While McVittie coordinates have another asymptotically de Sitter end as the radial coordinate goes to zero, so that they generalize the notion of a "wormhole" geometry, our new coordinates approach a horizon-penetrating trumpet geometry in the same limit. Our analytical expressions clarify the role of time-dependence, boundary conditions and coordinate conditions for trumpet slices in a cosmological context, and provide a useful test for black hole simulations in asymptotically de Sitter spacetimes.

Crystal structure of aqua-1κO-{μ-2-[(2-hydroxy­ethyl)methylamino]ethanolato-2:1κ4 O 1,N,O 2:O 1}[μ-2,2′-(methylimino)diethanolato-1:2κ4 O,N,O′:O]dithiocyanato-1κN,2κN-chromium(III)copper(II)

PubMed Central

Rusanova, Julia A.; Semenaka, Valentina V.; Dyakonenko, Viktoriya V.; Shishkin, Oleg V.

2015-01-01

The title compound, [CrCu(C5H11NO2)(C5H12NO2)(NCS)2(H2O)] or [Cr(μ-mdea)Cu(μ-Hmdea)(NCS)2H2O], (where mdeaH2 is N-methylethanolamine, C5H13NO2) is formed as a neutral heterometal CuII/CrIII complex. The mol­ecular structure of the complex is based on a binuclear {CuCr(μ-O)2} core. The coordination environment of each metal atom involves the N,O,O atoms of the tridentate ligand, one bridging O atom of the ligand and the N atom of the thio­cyanato ligands. The CuII ion adopts a distorted square-pyramidal coordination while the CrIII ion has a distorted octa­hedral coordination geometry completed by the aqua ligand. In the crystal, the binuclear complexes are linked via two pairs of O—H⋯O hydrogen bonds to form inversion dimers, which are arranged in columns parallel to the a axis. In the μ-mdea ligand two –CH2 groups and the methyl group were refined as disordered over two sets of sites with equal occupancies. The structure was refined as a two-component twin with a twin scale factor of 0.242 (1). PMID:26396853

Probing the influence of the center atom coordination structure in iron phthalocyanine multi-walled carbon nanotube-based oxygen reduction reaction catalysts by X-ray absorption fine structure spectroscopy

NASA Astrophysics Data System (ADS)

Peng, Yingxiang; Li, Zhipan; Xia, Dingguo; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia

2015-09-01

Three different pentacoordinate iron phthalocyanine (FePc) electrocatalysts with an axial ligand (pyridyl group, Py) anchored to multi-walled carbon nanotubes (MWCNTs) are prepared by a microwave method as high performance composite electrocatalysts (FePc-Py/MWCNTs) for the oxygen reduction reaction (ORR). For comparison, tetracoordinate FePc electrocatalysts without an axial ligand anchored to MWCNTs (FePc/MWCNTs) are assembled in the same way. Ultraviolet-visible spectrophotometry (UV-Vis), Raman spectroscopy (RS), and high-resolution transmission electron microscopy (HRTEM) are used to characterize the obtained electrocatalysts. The electrocatalytic activity of the samples is measured by linear sweep voltammetry (LSV), and the onset potential of all of the FePc-Py/MWCNTs electrocatalysts is found to be more positive than that of their FePc/MWCNTs counterparts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy are employed to elucidate the relationship between molecular structure and electrocatalytic activity. XPS indicates that higher concentrations of Fe3+ and pyridine-type nitrogen play critical roles in determining the electrocatalytic ORR activity of the samples. XAFS spectroscopy reveals that the FePc-Py/MWCNTs electrocatalysts have a coordination geometry around Fe that is closer to the square pyramidal structure, a higher concentration of Fe3+, and a smaller phthalocyanine ring radius compared with those of FePc/MWCNTs.

Development of inhibitory synaptic inputs on layer 2/3 pyramidal neurons in the rat medial prefrontal cortex.

PubMed

Virtanen, Mari A; Lacoh, Claudia Marvine; Fiumelli, Hubert; Kosel, Markus; Tyagarajan, Shiva; de Roo, Mathias; Vutskits, Laszlo

2018-05-01

Inhibitory control of pyramidal neurons plays a major role in governing the excitability in the brain. While spatial mapping of inhibitory inputs onto pyramidal neurons would provide important structural data on neuronal signaling, studying their distribution at the single cell level is difficult due to the lack of easily identifiable anatomical proxies. Here, we describe an approach where in utero electroporation of a plasmid encoding for fluorescently tagged gephyrin into the precursors of pyramidal cells along with ionotophoretic injection of Lucifer Yellow can reliably and specifically detect GABAergic synapses on the dendritic arbour of single pyramidal neurons. Using this technique and focusing on the basal dendritic arbour of layer 2/3 pyramidal cells of the medial prefrontal cortex, we demonstrate an intense development of GABAergic inputs onto these cells between postnatal days 10 and 20. While the spatial distribution of gephyrin clusters was not affected by the distance from the cell body at postnatal day 10, we found that distal dendritic segments appeared to have a higher gephyrin density at later developmental stages. We also show a transient increase around postnatal day 20 in the percentage of spines that are carrying a gephyrin cluster, indicative of innervation by a GABAergic terminal. Since the precise spatial arrangement of synaptic inputs is an important determinant of neuronal responses, we believe that the method described in this work may allow a better understanding of how inhibition settles together with excitation, and serve as basics for further modelling studies focusing on the geometry of dendritic inhibition during development.

Compression asphyxia from a human pyramid.

PubMed

Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Biyabani, Naushad

2015-12-01

In compression asphyxia, respiration is stopped by external forces on the body. It is usually due to an external force compressing the trunk such as a heavy weight on the chest or abdomen and is associated with internal injuries. In present case, the victim was trapped and crushed under the falling persons from a human pyramid formation for a "Dahi Handi" festival. There was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The victim was unable to remove himself from the situation because his cognitive responses and coordination were impaired due to alcohol intake. The victim died from asphyxia due to compression of his chest and abdomen. Compression asphyxia resulting from the collapse of a human pyramid and the dynamics of its impact force in these circumstances is very rare and is not reported previously to the best of our knowledge. © The Author(s) 2015.

Ultrasound assisted synthesis, characterization and electrochemical study of a tetradentate oxovanadium diazomethine complex

NASA Astrophysics Data System (ADS)

Merzougui, Moufida; Ouari, Kamel; Weiss, Jean

2016-09-01

The oxovanadium (IV) complex ;VOL; of a tetradentate Schiff base ligand derived from the condensation of diaminoethane and 2-hydroxy-1-naphthaldehyde was efficiently prepared via ultrasound irradiation and the template effect of VO(acac)2. The resulting product was characterized by elemental analysis, infrared, electronic absorption and molar conductance measurement. Single X-ray structure analysis showed that the complex is a monomeric five-coordinate with a distorted square pyramidal geometry. It crystallizes in monoclinic system having unit cell parameters a = 8.3960 (5) Å; b = 12.5533 (8) Å and c = 18.7804 (11) Å; α = γ = 90°; β = 104.843°(2), with P 21/c space group. Cyclic voltammetry of the complex, carried out on a glassy carbon (GC) electrode in DMF, showed reversible cyclic voltammograms response in the potential range 0.15-0.60 V involving a single electron redox wave VV/VIV, the diffusion coefficient is determinedusing GC rotating disk electrode. The Levich plot Ilim = f(ω1/2), was used to calculate the diffusion-convection controlled currents.

Polyhedra in Poland

ERIC Educational Resources Information Center

Pawlikowski, Piotr

2007-01-01

Polish students learn about Platonic solids in the final year of secondary grammar school, but in such a way that few perceive the beauty of this branch of mathematics. An average student associates polyhedra with calculating lengths and angles in a cube, cuboid or pyramid. But for the author, 3-D geometry is the branch of mathematics that shows…

A logarithmic detection system suitable for a 4π array

NASA Astrophysics Data System (ADS)

Westfall, G. D.; Yurkon, J. E.; van der Plicht, J.; Koenig, Z. M.; Jacak, B. V.; Fox, R.; Crawley, G. M.; Maier, M. R.; Hasselquist, B. E.; Tickle, R. S.; Horn, D.

1985-08-01

A low pressure multiwire proportional counter, a Bragg curve counter, and an array of CaF2/plastic scintillator telescopes have been developed in a geometry suitable for close packing into a 4π detector designed to study nucleus-nucleus reactions at 100-200 MeV/nucleon. The multiwire counter is hexagonal in shape and gives X-Y position information using resistive charge division from nichrome-coated stretched polypropylene foils. The Bragg curve counter is a hexagonal pyramid with the charge taken from a Frisch gridded anode. A field shaping grid gives the Bragg curve counter a radial field. The scintillator telescopes are shaped as truncated triangular pyramids such that when stacked together they form a truncated hexagonal pyramid. The light signal of the CaF2-plastic combination is read with one phototube using a phoswich technique to separate the ΔE signal from the E signal. The entire system has been tested so far for particles with 1 <= Z <= 18 and gives good position, charge, and time resolution.

Design and fabrication of a 3D-structured gold film with nanopores for local electric field enhancement in the pore

NASA Astrophysics Data System (ADS)

Grant-Jacob, James A.; Zin Oo, Swe; Carpignano, Francesca; Boden, Stuart A.; Brocklesby, William S.; Charlton, Martin D. B.; Melvin, Tracy

2016-02-01

Three-dimensionally structured gold membrane films with nanopores of defined, periodic geometries are designed and fabricated to provide the spatially localised enhancement of electric fields by manipulation of the plasmons inside nanopores. Square nanopores of different size and orientation relative to the pyramid are considered for films in aqueous and air environments, which allow for control of the position of electric fields within the structure. Designs suitable for use with 780 nm light were created. Here, periodic pyramidal cavities produced by potassium hydroxide etching to the {111} planes of (100) silicon substrates are used as templates for creating a periodic, pyramidal structured, free-standing thin gold film. Consistent with the findings from the theoretical studies, a nano-sized hole of 50 nm square was milled through the gold film at a specific location in the cavity to provide electric field control which can subsequently used for enhancement of fluorescence or Raman scattering of molecules in the nanopore.

Design and fabrication of a 3D-structured gold film with nanopores for local electric field enhancement in the pore.

PubMed

Grant-Jacob, James A; Oo, Swe Zin; Carpignano, Francesca; Boden, Stuart A; Brocklesby, William S; Charlton, Martin D B; Melvin, Tracy

2016-02-12

Three-dimensionally structured gold membrane films with nanopores of defined, periodic geometries are designed and fabricated to provide the spatially localised enhancement of electric fields by manipulation of the plasmons inside nanopores. Square nanopores of different size and orientation relative to the pyramid are considered for films in aqueous and air environments, which allow for control of the position of electric fields within the structure. Designs suitable for use with 780 nm light were created. Here, periodic pyramidal cavities produced by potassium hydroxide etching to the {111} planes of (100) silicon substrates are used as templates for creating a periodic, pyramidal structured, free-standing thin gold film. Consistent with the findings from the theoretical studies, a nano-sized hole of 50 nm square was milled through the gold film at a specific location in the cavity to provide electric field control which can subsequently used for enhancement of fluorescence or Raman scattering of molecules in the nanopore.

New constraints on slip-rates, recurrence intervals, and strain partitioning beneath Pyramid Lake, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisses, Amy

A high-resolution CHIRP seismic survey of Pyramid Lake, Nevada, located within the northern Walker Lane Deformation Belt, was conducted in summer 2010. Seismic CHIRP data with submeter vertical accuracy, together with piston and gravity cores, were used to calculate Holocene vertical slip rates, relative earthquake timing, and produce the first complete fault map beneath the lake. More than 500 line-kilometers of CHIRP data imaged complex fault patterns throughout the basin. Fault architecture beneath Pyramid Lake highlights a polarity flip, where down-to-the west patterns of sedimentation near the dextral Pyramid Lake fault to the south give way to down-to-the-east geometries tomore » the north within a mostly normal (i.e., Lake Range fault) and transtensional environment. The Lake Range fault predominantly controls extensional deformation within the northern two-thirds of the basin and exhibits varying degrees of asymmetric tilting and divergence due to along-strike segmentation. This observation is likely a combination of fault segments splaying onshore moving the focus of extension away from the lake coupled with some true along-strike differences in slip-rate. The combination of normal and oblique-slip faults in the northern basin gives Pyramid Lake its distinctive “fanning open to the north” tectonic geometry. The dense network of oblique-slip faults in the northwestern region of the lake, in contrast to the well-defined Lake Range fault, are short and discontinuous in nature, and possible represent a nascent shear zone. Preliminary vertical slip-rates measured across the Lake Range and other faults provide new estimates on the extension across the Pyramid Lake basin. A minimum vertical slip rate of ~1.0 mm/yr is estimated along the Lake Range fault, which yields a potential earthquake magnitude range between M6.4 and M7.0. A rapid influx of sediment was deposited shortly after the end of the Tioga glaciation somewhere between 12.5 ka to 9.5 ka and provides a punctuated short-term record of little to no slip on the Lake Range fault. In contrast, for the past 9,500 years, the basin has experienced a decrease in sedimentation rate, but an escalation in earthquake activity on the Lake Range fault, with the potential of 3 or 4 major earthquakes assuming a characteristic offset of 2.5 m per event. Regionally, our CHIRP investigation helps to reveal how strain is partitioned along the boundary between the eastern edge of the Walker Lane Deformation Belt and the northwest Great Basin proper.« less

MATILDA: A Military Laser Range Safety Tool Based on Probabilistic Risk Assessment (PRA) Techniques

DTIC Science & Technology

2014-08-01

Figure 6: MATILDA Coordinate Transformations ....................................................... 22  Figure 7: Geocentric and MICS Coordinates...Target – Range Boundary Undershoot Geometry .............. 34  Figure 19: Geocentric Overshoot Geometry and Parameters...transformed into Geocentric coordinates, a Cartesian (x,y,z) coordinate system with origin at the center of the Earth and z-axis oriented towards the

The mammalian neocortex new pyramidal neuron: a new conception.

PubMed

Marín-Padilla, Miguel

2014-01-06

The new cerebral cortex (neocortex) and the new type of pyramidal neuron are mammalian innovations that have evolved for operating their increasing motor capabilities while essentially using analogous anatomical and neural makeups. The human neocortex starts to develop in 6-week-old embryos with the establishment of a primordial cortical organization, which resembles the primitive cortices of amphibian and reptiles. From the 8th to the 15th week of age, new pyramidal neurons, of ependymal origin, are progressively incorporated within this primordial cortex forming a cellular plate that divides its components into those above it (neocortex first layer) and those below it (neocortex subplate zone). From the 16th week of age to birth and postnatally, the new pyramidal neurons continue to elongate functionally their apical dendrite by adding synaptic membrane to incorporate the needed sensory information for operating its developing motor activities. The new pyramidal neuron' distinguishing feature is the capacity of elongating anatomically and functionally its apical dendrite (its main receptive surface) without losing its original attachment to first layer or the location of its soma and, hence, retaining its essential nature. The number of pyramidal cell functional strata established in the motor cortex increases and reflects each mammalian species motor capabilities: the hedgehog needs two pyramidal cell functional strata to carry out all its motor activities, the mouse 3, cat 4, primates 5 and humans 6. The presence of six pyramidal cell functional strata distinguish the human motor cortex from that of others primates. Homo sapiens represent a new evolutionary stage that have transformed his primate brain for operating his unique motor capabilities, such as speaking, writing, painting, sculpturing and thinking as a premotor activity. Words used in language are the motor expression of thoughts and represent sounds produced by maneuvering the column of expiratory air by coordinated motor quivering as it passes through the larynx, pharynx, mouth, tongue, and lips. Homo sapiens cerebrum has developed new motor centers to communicate mental thoughts (and/or intention) through motor actions.

Spectroscopic investigation of new water soluble Mn(II)(2) and Mg(II)(2) complexes for the substrate binding models of xylose/glucose isomerases.

PubMed

Patra, Ayan; Bera, Manindranath

2014-01-30

In methanol, the reaction of stoichiometric amounts of Mn(OAc)(2)·4H(2)O and the ligand H(3)hpnbpda [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in the presence of NaOH, afforded a new water soluble dinuclear manganese(II) complex, [Mn2(hpnbpda)(μ-OAc)] (1). Similarly, the reaction of Mg(OAc)(2)·4H(2)O and the ligand H3hpnbpda in the presence of NaOH, in methanol, yielded a new water soluble dinuclear magnesium(II) complex, [Mg2(hpnbpda)(μ-OAc)(H2O)2] (2). DFT calculations have been performed for the structural optimization of complexes 1 and 2. The DFT optimized structure of complex 1 shows that two manganese(II) centers are in a distorted square pyramidal geometry, whereas the DFT optimized structure of complex 2 reveals that two magnesium(II) centers adopt a six-coordinate distorted octahedral geometry. To understand the mode of substrate binding and the mechanistic details of the active site metals in xylose/glucose isomerases (XGI), we have investigated the binding interactions of biologically important monosaccharides d-glucose and d-xylose with complexes 1 and 2, in aqueous alkaline solution by a combined approach of FTIR, UV-vis, fluorescence, and (13)C NMR spectroscopic techniques. Fluorescence spectra show the binding-induced gradual decrease in emission of complexes 1 and 2 accompanied by a significant blue shift upon increasing the concentration of sugar substrates. The binding modes of d-glucose and d-xylose with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for C1 and C2 carbon atoms. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

NASA Astrophysics Data System (ADS)

Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

2016-06-01

Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort.

Image-guided preoperative prediction of pyramidal tract side effect in deep brain stimulation: proof of concept and application to the pyramidal tract side effect induced by pallidal stimulation.

PubMed

Baumgarten, Clement; Zhao, Yulong; Sauleau, Paul; Malrain, Cecile; Jannin, Pierre; Haegelen, Claire

2016-04-01

Deep brain stimulation of the medial globus pallidus (GPm) is a surgical procedure for treating patients suffering from Parkinson's disease. Its therapeutic effect may be limited by the presence of pyramidal tract side effect (PTSE). PTSE is a contraction time-locked to the stimulation when the current spreading reaches the motor fibers of the pyramidal tract within the internal capsule. The objective of the study was to propose a preoperative predictive model of PTSE. A machine learning-based method called PyMAN (PTSE model based on artificial neural network) accounting for the current used in stimulation, the three-dimensional electrode coordinates and the angle of the trajectory, was designed to predict the occurrence of PTSE. Ten patients implanted in the GPm have been tested by a clinician to create a labeled dataset of the stimulation parameters that trigger PTSE. The kappa index value between the data predicted by PyMAN and the labeled data was 0.78. Further evaluation studies are desirable to confirm whether PyMAN could be a reliable tool for assisting the surgeon to prevent PTSE during the preoperative planning.

Use of zerotree coding in a high-speed pyramid image multiresolution decomposition

NASA Astrophysics Data System (ADS)

Vega-Pineda, Javier; Cabrera, Sergio D.; Lucero, Aldo

1995-03-01

A Zerotree (ZT) coding scheme is applied as a post-processing stage to avoid transmitting zero data in the High-Speed Pyramid (HSP) image compression algorithm. This algorithm has features that increase the capability of the ZT coding to give very high compression rates. In this paper the impact of the ZT coding scheme is analyzed and quantified. The HSP algorithm creates a discrete-time multiresolution analysis based on a hierarchical decomposition technique that is a subsampling pyramid. The filters used to create the image residues and expansions can be related to wavelet representations. According to the pixel coordinates and the level in the pyramid, N2 different wavelet basis functions of various sizes and rotations are linearly combined. The HSP algorithm is computationally efficient because of the simplicity of the required operations, and as a consequence, it can be very easily implemented with VLSI hardware. This is the HSP's principal advantage over other compression schemes. The ZT coding technique transforms the different quantized image residual levels created by the HSP algorithm into a bit stream. The use of ZT's compresses even further the already compressed image taking advantage of parent-child relationships (trees) between the pixels of the residue images at different levels of the pyramid. Zerotree coding uses the links between zeros along the hierarchical structure of the pyramid, to avoid transmission of those that form branches of all zeros. Compression performance and algorithm complexity of the combined HSP-ZT method are compared with those of the JPEG standard technique.

A copper(II) paddle-wheel structure of tranexamic acid: di-chloro-tetra-kis-[μ-4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ato-O,O']dicopper(II) dichloride hexa-hydrate.

PubMed

Altaf, Muhammad; Stoeckli-Evans, Helen

2017-10-01

Tranexamic acid [systematic name: trans -4-(amino-meth-yl)cyclo-hexane-1-carb-oxy-lic acid], is an anti-fibrinolytic amino acid that exists as a zwitterion [ trans -4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ate] in the solid state. Its reaction with copper chloride leads to the formation of a compound with a copper(II) paddle-wheel structure that crystallizes as a hexa-hydrate, [Cu 2 Cl 2 (C 8 H 15 NO 2 ) 4 ] 2+ ·2Cl - ·6H 2 O. The asymmetric unit is composed of a copper(II) cation, two zwitterionic tranexamic acid units, a coordinating Cl - anion and a free Cl - anion, together with three water mol-ecules of crystallization. The whole structure is generated by inversion symmetry, with the Cu⋯Cu axle of the paddle-wheel dication being located about a center of symmetry. The cyclo-hexane rings of the zwitterionic tranexamic acid units have chair conformations. The carboxyl-ate groups that bridge the two copper(II) cations are inclined to one another by 88.4 (8)°. The copper(II) cation is ligated by four carboxyl-ate O atoms in the equatorial plane and by a Cl - ion in the axial position. Hence, it has a fivefold O 4 Cl coordination sphere with a perfect square-pyramidal geometry and a τ 5 index of zero. In the crystal, the paddle-wheel dications are linked by a series of N-H⋯Cl hydrogen bonds, involving the coordinating and free Cl - ions, forming a three-dimensional network. This network is strengthened by a series of N-H⋯O water , O water -H⋯Cl and O water -H⋯O hydrogen bonds.

Crystal structure of (4-cyano­pyridine-κN){5,10,15,20-tetrakis[4-(benzoyloxy)phenyl]porphyrinato-κ4 N}zinc–4-cyano­pyridine (1/1)

PubMed Central

Nasri, Soumaya; Amiri, Nesrine; Turowska-Tyrk, Ilona; Daran, Jean-Claude; Nasri, Habib

2016-01-01

In the title compound, [Zn(C72H44N4O8)(C6H4N2)]·C6H4N2 or [Zn(TPBP)(4-CNpy]·(4-CNpy) [where TPBP and 4-CNpy are 5,10,15,20-(tetra­phenyl­benzoate)porphyrinate and 4-cyano­pyridine, respectively], the ZnII cation is chelated by four pyrrole-N atoms of the porphyrinate anion and coordinated by a pyridyl-N atom of the 4-CNpy axial ligand in a distorted square-pyramidal geometry. The average Zn—N(pyrrole) bond length is 2.060 (6) Å and the Zn—N(4-CNpy) bond length is 2.159 (2) Å. The zinc cation is displaced by 0.319 (1) Å from the N4C20 mean plane of the porphyrinate anion toward the 4-cyano­pyridine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling and doming deformations. In the crystal, the [Zn(TPBP)(4-CNpy)] complex mol­ecules are linked together via weak C—H⋯N, C—H⋯O and C—H⋯π inter­actions, forming supra­molecular channels parallel to the c axis. The non-coordinating 4-cyano­pyridine mol­ecules are located in the channels and linked with the complex mol­ecules, via weak C—H⋯N inter­actions and π-π stacking or via weak C—H⋯O and C—H⋯π inter­actions. The non-coordinating 4-cyano­pyridine mol­ecule is disordered over two positions with an occupancy ratio of 0.666 (4):0.334 (4). PMID:26958379

Relationship between mathematical abstraction in learning parallel coordinates concept and performance in learning analytic geometry of pre-service mathematics teachers: an investigation

NASA Astrophysics Data System (ADS)

Nurhasanah, F.; Kusumah, Y. S.; Sabandar, J.; Suryadi, D.

2018-05-01

As one of the non-conventional mathematics concepts, Parallel Coordinates is potential to be learned by pre-service mathematics teachers in order to give them experiences in constructing richer schemes and doing abstraction process. Unfortunately, the study related to this issue is still limited. This study wants to answer a research question “to what extent the abstraction process of pre-service mathematics teachers in learning concept of Parallel Coordinates could indicate their performance in learning Analytic Geometry”. This is a case study that part of a larger study in examining mathematical abstraction of pre-service mathematics teachers in learning non-conventional mathematics concept. Descriptive statistics method is used in this study to analyze the scores from three different tests: Cartesian Coordinate, Parallel Coordinates, and Analytic Geometry. The participants in this study consist of 45 pre-service mathematics teachers. The result shows that there is a linear association between the score on Cartesian Coordinate and Parallel Coordinates. There also found that the higher levels of the abstraction process in learning Parallel Coordinates are linearly associated with higher student achievement in Analytic Geometry. The result of this study shows that the concept of Parallel Coordinates has a significant role for pre-service mathematics teachers in learning Analytic Geometry.

Foundations of Tensor Analysis for Students of Physics and Engineering With an Introduction to the Theory of Relativity

NASA Technical Reports Server (NTRS)

Kolecki, Joseph C.

2005-01-01

Tensor analysis is one of the more abstruse, even if one of the more useful, higher math subjects enjoined by students of physics and engineering. It is abstruse because of the intellectual gap that exists between where most physics and engineering mathematics leave off and where tensor analysis traditionally begins. It is useful because of its great generality, computational power, and compact, easy to use, notation. This paper bridges the intellectual gap. It is divided into three parts: algebra, calculus, and relativity. Algebra: In tensor analysis, coordinate independent quantities are sought for applications in physics and engineering. Coordinate independence means that the quantities have such coordinate transformations as to leave them invariant relative to a particular observer s coordinate system. Calculus: Non-zero base vector derivatives contribute terms to dynamical equations that correspond to pseudoaccelerations in accelerated coordinate systems and to curvature or gravity in relativity. These derivatives have a specific general form in tensor analysis. Relativity: Spacetime has an intrinsic geometry. Light is the tool for investigating that geometry. Since the observed geometry of spacetime cannot be made to match the classical geometry of Euclid, Einstein applied another more general geometry differential geometry. The merger of differential geometry and cosmology was accomplished in the theory of relativity. In relativity, gravity is equivalent to curvature.

(6-Acetyl-1,3,7-trimethyl­lumazine-κ3 O 4,N 5,O 6)bis­(triphenyl­phosphine-κP)copper(I) hexa­fluorido­phosphate

PubMed Central

Hueso-Ureña, Francisco; Illán-Cabeza, Nuria A.; Jiménez-Pulido, Sonia B.; Moreno-Carretero, Miguel N.

2010-01-01

The title compound, [Cu(C11H12N4O3)(C18H15P)2]PF6, is the third example reported in the literature of a five-coordinated CuIP2NO2 system. The metal is coordinated to both PPh3 mol­ecules through the P atoms and to the pyrazine ring of the lumazine mol­ecule through an N atom in a trigonal–planar arrangement; two additional coordinated O atoms, at Cu—O distances longer than 2.46 Å, complete the coordination. The coordination environment can be described as an inter­mediate square-pyramidal/trigonal–bipyramidal (SP/TBP) polyhedron. PMID:21579625

Initiatives (Part 3): Food Pyramid Juggle; Transportation Initiative Circuit.

ERIC Educational Resources Information Center

Kilty, Katie; Klag, Bill

2001-01-01

Presents two group activities for ages 10 and up; one instructs about food groups and reinforces healthy eating habits, while the other is a multitask physical activity stressing cooperation and coordination. Includes target group, group size, time and space needs, activity level, overview, goals, props, instructions, suggestions for framing and…

DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

PubMed Central

Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

2014-01-01

Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO 4] and [Cu. L. A] where “L” is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and “A” is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases

NASA Astrophysics Data System (ADS)

Abdel Aziz, Ayman A.; Badr, Ibrahim H. A.; El-Sayed, Ibrahim S. A.

2012-11-01

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)2·2H2O and anhydrous AlCl3 with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L1) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L2). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, 1H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the π-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi.

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

NASA Astrophysics Data System (ADS)

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.

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases.

PubMed

Abdel Aziz, Ayman A; Badr, Ibrahim H A; El-Sayed, Ibrahim S A

2012-11-01

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)(2).2H(2)O and anhydrous AlCl(3) with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, (1)H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the π-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi. Copyright © 2012 Elsevier B.V. All rights reserved.

Performance Analysis of Thermoelectric Modules Consisting of Square Truncated Pyramid Elements Under Constant Heat Flux

NASA Astrophysics Data System (ADS)

Oki, Sae; Natsui, Shungo; Suzuki, Ryosuke O.

2018-01-01

System design of a thermoelectric (TE) power generation module is pursued in order to improve the TE performance. Square truncated pyramid shaped P-N pairs of TE elements are connected electronically in series in the open space between two flat insulator boards. The performance of the TE module consisting of 2-paired elements is numerically simulated using commercial software and original TE programs. Assuming that the heat radiating into the hot surface is regulated, i.e., the amount of heat from the hot surface to the cold one is steadily constant, as it happens for solar radiation heating, the performance is significantly improved by changing the shape and the alignment pattern of the elements. When the angle θ between the edge and the base is smaller than 72°, and when the cold surface is kept at a constant temperature, two patterns in particular, amongst the 17 studied, show the largest TE power and efficiency. In comparison to other geometries, the smarter square truncated pyramid shape can provide higher performance using a large cold bath and constant heat transfer by heat radiation.

Performance Analysis of Thermoelectric Modules Consisting of Square Truncated Pyramid Elements Under Constant Heat Flux

NASA Astrophysics Data System (ADS)

Oki, Sae; Natsui, Shungo; Suzuki, Ryosuke O.

2018-06-01

System design of a thermoelectric (TE) power generation module is pursued in order to improve the TE performance. Square truncated pyramid shaped P-N pairs of TE elements are connected electronically in series in the open space between two flat insulator boards. The performance of the TE module consisting of 2-paired elements is numerically simulated using commercial software and original TE programs. Assuming that the heat radiating into the hot surface is regulated, i.e., the amount of heat from the hot surface to the cold one is steadily constant, as it happens for solar radiation heating, the performance is significantly improved by changing the shape and the alignment pattern of the elements. When the angle θ between the edge and the base is smaller than 72°, and when the cold surface is kept at a constant temperature, two patterns in particular, amongst the 17 studied, show the largest TE power and efficiency. In comparison to other geometries, the smarter square truncated pyramid shape can provide higher performance using a large cold bath and constant heat transfer by heat radiation.

Combined distribution functions: A powerful tool to identify cation coordination geometries in liquid systems

NASA Astrophysics Data System (ADS)

Sessa, Francesco; D'Angelo, Paola; Migliorati, Valentina

2018-01-01

In this work we have developed an analytical procedure to identify metal ion coordination geometries in liquid media based on the calculation of Combined Distribution Functions (CDFs) starting from Molecular Dynamics (MD) simulations. CDFs provide a fingerprint which can be easily and unambiguously assigned to a reference polyhedron. The CDF analysis has been tested on five systems and has proven to reliably identify the correct geometries of several ion coordination complexes. This tool is simple and general and can be efficiently applied to different MD simulations of liquid systems.

The R.I. Pimenov unified gravitation and electromagnetism field theory as semi-Riemannian geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gromov, N. A., E-mail: gromov@dm.komisc.r

2009-05-15

More than forty years ago R.I. Pimenov introduced a new geometry-semi-Riemannian one-as a set of geometrical objects consistent with a fibering pr: M{sub n} {yields} M{sub m}. He suggested the heuristic principle according to which the physically different quantities (meter, second, Coulomb, etc.) are geometrically modelled as space coordinates that are not superposed by automorphisms. As there is only one type of coordinates in Riemannian geometry and only three types of coordinates in pseudo-Riemannian one, a multiple-fibered semi-Riemannian geometry is the most appropriate one for the treatment of more than three different physical quantities as unified geometrical field theory. Semi-Euclideanmore » geometry {sup 3}R{sub 5}{sup 4} with 1-dimensional fiber x{sup 5} and 4-dimensional Minkowski space-time as a base is naturally interpreted as classical electrodynamics. Semi-Riemannian geometry {sup 3}V{sub 5}{sup 4} with the general relativity pseudo-Riemannian space-time {sup 3}V{sub 4}, and 1-dimensional fiber x{sup 5}, responsible for the electromagnetism, provides the unified field theory of gravitation and electromagnetism. Unlike Kaluza-Klein theories, where the fifth coordinate appears in nondegenerate Riemannian or pseudo-Riemannian geometry, the theory based on semi-Riemannian geometry is free from defects of the former. In particular, scalar field does not arise.« less

Cutting Solid Figures by Plane--Analytical Solution and Spreadsheet Implementation

ERIC Educational Resources Information Center

Benacka, Jan

2012-01-01

In some secondary mathematics curricula, there is a topic called Stereometry that deals with investigating the position and finding the intersection, angle, and distance of lines and planes defined within a prism or pyramid. Coordinate system is not used. The metric tasks are solved using Pythagoras' theorem, trigonometric functions, and sine and…

Image-guided preoperative prediction of pyramidal tract side effect in deep brain stimulation

NASA Astrophysics Data System (ADS)

Baumgarten, C.; Zhao, Y.; Sauleau, P.; Malrain, C.; Jannin, P.; Haegelen, C.

2016-03-01

Deep brain stimulation of the medial globus pallidus is a surgical procedure for treating patients suffering from Parkinson's disease. Its therapeutic effect may be limited by the presence of pyramidal tract side effect (PTSE). PTSE is a contraction time-locked to the stimulation when the current spreading reaches the motor fibers of the pyramidal tract within the internal capsule. The lack of side-effect predictive model leads the neurologist to secure an optimal electrode placement by iterating clinical testing on an awake patient during the surgical procedure. The objective of the study was to propose a preoperative predictive model of PTSE. A machine learning based method called PyMAN (for Pyramidal tract side effect Model based on Artificial Neural network) that accounted for the current of the stimulation, the 3D electrode coordinates and the angle of the trajectory, was designed to predict the occurrence of PTSE. Ten patients implanted in the medial globus pallidus have been tested by a clinician to create a labeled dataset of the stimulation parameters that trigger PTSE. The kappa index value between the data predicted by PyMAN and the labeled data was .78. Further evaluation studies are desirable to confirm whether PyMAN could be a reliable tool for assisting the surgeon to prevent PTSE during the preoperative planning.

Crystal structures and DFT calculations of mixed chloride-azide zinc(II) and chloride-isocyanate cadmium(II) complexes with the condensation product of 2-quinolinecarboxaldehyde and Girard's T reagent

NASA Astrophysics Data System (ADS)

Anđelković, Katarina; Pevec, Andrej; Grubišić, Sonja; Turel, Iztok; Čobeljić, Božidar; Milenković, Milica R.; Keškić, Tanja; Radanović, Dušanka

2018-06-01

The mixed chloride-azide [ZnL(N3)1.65Cl0.35] (1) and chloride-isocyanate [CdL(NCO)1.64Cl0.36] (2) complexes with the condensation product of 2-quinolinecarboxaldehyde and trimethylammonium acetohydrazide chloride (Girard's T reagent) (HLCl) have been prepared and characterized by X-ray crystallography. In complexes 1 and 2, Zn1 and Cd1 ions, respectively, are five-coordinated in a distorted square based pyramidal geometry with NNO set of donor atoms of deprotonated hydrazone ligand and two monodentate ligands N3- and/or N3- and Cl- in the case of 1 and OCN- and/or OCN- and Cl- in the case of 2. The structural parameters of 1 and 2 have been discussed in relation to those of previously reported M(II) complexes with the same hydrazone ligand. Density functional theory calculations have been employed to study the interaction between the Zn2+ and Cd2+ ions and ligands. High affinity of ligands towards the Zn2+ and Cd2+ ions are predicted for both complexes.

Synthesis, spectral and thermal studies of pyridyl adducts of Zn(II) and Cd(II) dithiocarbamates, and their use as single source precursors for ZnS and CdS nanoparticles.

PubMed

Onwudiwe, Damian C; Strydom, Christien A; Oluwafemi, Oluwatobi S; Hosten, Eric; Jordaan, Anine

2014-06-21

The synthesis, spectroscopic characterisation, and thermal studies of pyridyl adducts of Zn(II) and Cd(II) complexes of N-ethyl-N-phenyl dithiocarbamate, represented as [ZnL2py] and [CdL2py2], are reported. Single-crystal X-ray structural analysis of the Zn compound showed that it is five-coordinate with four sulphurs from dithiocarbamate and one nitrogen from pyridine in a distorted square pyramidal geometry. The thermogravimetric studies indicate that the zinc and cadmium compounds undergo fast weight loss, and the temperature at maximum rate of decomposition is at 277 °C and 265 °C respectively, to give the metal (Zn or Cd) sulphide residues. These compounds were used as single molecule precursors to produce nanocrystalline MS (M = Zn, Cd) after thermolysis in hexadecylamine. The morphological and optical properties of the resulting MS nanocrystallites were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-Vis absorption and photoluminescence (PL) spectroscopy, and powdered X-ray diffraction (XRD). By varying the growth time, the temporal evolution of the optical properties and morphology of the nanocrystals were investigated.

Identification of different coordination geometries by XAFS in copper(II) complexes with trimesic acid

NASA Astrophysics Data System (ADS)

Gaur, A.; Klysubun, W.; Soni, Balram; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

2016-10-01

X-ray absorption spectroscopy (XAS) is very useful in revealing the information about geometric and electronic structure of a transition-metal absorber and thus commonly used for determination of metal-ligand coordination. But XAFS analysis becomes difficult if differently coordinated metal centers are present in a system. In the present investigation, existence of distinct coordination geometries around metal centres have been studied by XAFS in a series of trimesic acid Cu(II) complexes. The complexes studied are: Cu3(tma)2(im)6 8H2O (1), Cu3(tma)2(mim)6 17H2O (2), Cu3(tma)2(tmen)3 8.5H2O (3), Cu3(tma) (pmd)3 6H2O (ClO4)3 (4) and Cu3(tma)2 3H2O (5). These complexes have not only Cu metal centres with different coordination but in complexes 1-3, there are multiple coordination geometries present around Cu centres. Using XANES spectra, different coordination geometries present in these complexes have been identified. The variation observed in the pre-edge features and edge features have been correlated with the distortion of the specific coordination environment around Cu centres in the complexes. XANES spectra have been calculated for the distinct metal centres present in the complexes by employing ab-initio calculations. These individual spectra have been used to resolve the spectral contribution of the Cu centres to the particular XANES features exhibited by the experimental spectra of the multinuclear complexes. Also, the variation in the 4p density of states have been calculated for the different Cu centres and then correlated with the features originated from corresponding coordination of Cu. Thus, these spectral features have been successfully utilized to detect the presence of the discrete metal centres in a system. The inferences about the coordination geometry have been supported by EXAFS analysis which has been used to determine the structural parameters for these complexes.

Lanthanide complex coordination polyhedron geometry prediction accuracies of ab initio effective core potential calculations.

PubMed

Freire, Ricardo O; Rocha, Gerd B; Simas, Alfredo M

2006-03-01

lanthanide coordination compounds efficiently and accurately is central for the design of new ligands capable of forming stable and highly luminescent complexes. Accordingly, we present in this paper a report on the capability of various ab initio effective core potential calculations in reproducing the coordination polyhedron geometries of lanthanide complexes. Starting with all combinations of HF, B3LYP and MP2(Full) with STO-3G, 3-21G, 6-31G, 6-31G* and 6-31+G basis sets for [Eu(H2O)9]3+ and closing with more manageable calculations for the larger complexes, we computed the fully predicted ab initio geometries for a total of 80 calculations on 52 complexes of Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III) and Tm(III), the largest containing 164 atoms. Our results indicate that RHF/STO-3G/ECP appears to be the most efficient model chemistry in terms of coordination polyhedron crystallographic geometry predictions from isolated lanthanide complex ion calculations. Moreover, both augmenting the basis set and/or including electron correlation generally enlarged the deviations and aggravated the quality of the predicted coordination polyhedron crystallographic geometry. Our results further indicate that Cosentino et al.'s suggestion of using RHF/3-21G/ECP geometries appears to be indeed a more robust, but not necessarily, more accurate recommendation to be adopted for the general lanthanide complex case. [Figure: see text].

Health Care Reform, Care Coordination, and Transformational Leadership.

PubMed

Steaban, Robin Lea

2016-01-01

This article is meant to spur debate on the role of the professional nurse in care coordination as well as the role of nursing leaders for defining and leading to a future state. This work highlights the opportunity and benefits associated with transformation of professional nursing practice in response to the mandates of the Affordable Care Act of 2010. An understanding of core concepts and the work of care coordination are used to propose a model of care coordination based on the population health pyramid. This maximizes the roles of nurses across the continuum as transformational leaders in the patient/family and nursing relationship. The author explores the role of the nurse in a transactional versus transformational relationship with patients, leading to actualization of the nurse in care coordination. Focusing on the role of the nurse leader, the challenges and necessary actions for optimization of the professional nurse role are explored, using principles of transformational leadership.

SFPQ associates to LSD1 and regulates the migration of newborn pyramidal neurons in the developing cerebral cortex.

PubMed

Saud, K; Cánovas, J; Lopez, C I; Berndt, F A; López, E; Maass, J C; Barriga, A; Kukuljan, M

2017-04-01

The development of the cerebral cortex requires the coordination of multiple processes ranging from the proliferation of progenitors to the migration and establishment of connectivity of the newborn neurons. Epigenetic regulation carried out by the COREST/LSD1 complex has been identified as a mechanism that regulates the development of pyramidal neurons of the cerebral cortex. We now identify the association of the multifunctional RNA-binding protein SFPQ to LSD1 during the development of the cerebral cortex. In vivo reduction of SFPQ dosage by in utero electroporation of a shRNA results in impaired radial migration of newborn pyramidal neurons, in a similar way to that observed when COREST or LSD1 expressions are decreased. Diminished SFPQ expression also associates to decreased proliferation of progenitor cells, while it does not affect the acquisition of neuronal fate. These results are compatible with the idea that SFPQ, plays an important role regulating proliferation and migration during the development of the cerebral cortex. Copyright © 2016 ISDN. Published by Elsevier Ltd. All rights reserved.

Synthesis, crystal structure and spectroscopic and electrochemical properties of bridged trisbenzoato copper-zinc heterobinuclear complex of 2,2‧-bipyridine

NASA Astrophysics Data System (ADS)

Koch, Angira; Kumar, Arvind; Singh, Suryabhan; Borthakur, Rosmita; Basumatary, Debajani; Lal, Ram A.; Shangpung, Sankey

2015-03-01

The synthesis of the heterobinuclear copper-zinc complex [CuZn(bz)3(bpy)2]ClO4 (bz = benzoate) from benzoic acid and bipyridine is described. Single crystal X-ray diffraction studies of the heterobinuclear complex reveals the geometry of the benzoato bridged Cu(II)-Zn(II) centre. The copper or zinc atom is pentacoordinate, with two oxygen atoms from bridging benzoato groups and two nitrogen atoms from one bipyridine forming an approximate plane and a bridging oxygen atom from a monodentate benzoate group. The Cu-Zn distance is 3.345 Å. The complex is normal paramagnetic having μeff value equal to 1.75 BM, ruling out the possibility of Cu-Cu interaction in the structural unit. The ESR spectrum of the complex in CH3CN at RT exhibit an isotropic four line spectrum centred at g = 2.142 and hyperfine coupling constants Aav = 63 × 10-4 cm-1, characteristic of a mononuclear square-pyramidal copper(II) complexes. At LNT, the complex shows an isotropic spectrum with g|| = 2.254 and g⊥ = 2.071 and A|| = 160 × 10-4 cm-1. The Hamiltonian parameters are characteristic of distorted square pyramidal geometry. Cyclic voltammetric studies of the complex have indicated quasi-reversible behaviour in acetonitrile solution.

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.

PubMed

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.

Coordinate Families for the Schwarzschild Geometry Based on Radial Timelike Geodesics

NASA Technical Reports Server (NTRS)

Finch, Tehani K.

2015-01-01

We explore the connections between various coordinate systems associated with observersmoving inwardly along radial geodesics in the Schwarzschild geometry. Painleve-Gullstrand (PG) time is adapted to freely falling observers dropped from rest from infinity; Lake-Martel-Poisson (LMP) time coordinates are adapted to observers who start at infinity with non-zero initial inward velocity; Gautreau-Hoffmann time coordinates are adapted to observers dropped from rest from a finite distance from the black hole horizon.We construct from these an LMP family and a proper-time family of time coordinates, the intersection of which is PG time. We demonstrate that these coordinate families are distinct, but related, one-parameter generalizations of PG time, and show linkage to Lemaître coordinates as well.

Painleve-gullstrand-type Coordinates for the Five-dimensional Myers-Perry Black Hole

NASA Technical Reports Server (NTRS)

Finch, Tehani Kahi

2013-01-01

The Painleve-Gullstrand coordinates provide a convenient framework for presenting the Schwarzschild geometry because of their flat constant-time hypersurfaces, and the fact that they are free of coordinate singularities outside r=0. Generalizations of Painlev´e-Gullstrand coordinates suitable for the Kerr geometry have been presented by Doran and Nat´ario. These coordinate systems feature a time coordinate identical to the proper time of zero-angular-momentum observers that are dropped from infinity. Here, the methods of Doran and Nat´ario are extended to the five-dimensional rotating black hole found by Myers and Perry. The result is a new formulation of the Myers-Perry metric. The properties and physical significance of these new coordinates are discussed.

EXAFS study of some coordination polymers of copper

NASA Astrophysics Data System (ADS)

Deshpande, A. P.

1995-02-01

The EXAFS spectra for (1) azelaic acid bis phenyl hydrazide, (2) azelaic acid bis 2,4 dinitro phenyl hydrazide and (3) sebacic acid bis phenyl hydrazide coordination polymers of copper were obtained using the EXAFS facility of the Daresbury Laboratory. The EXAFS analysis revealed that copper is surrounded by four nitrogen and two oxygen atoms in the first coordination shell, while the second coordination shell consists of two carbon atoms. This information suggests the octahedral geometry for the repeating units of polymeric complexes, in contrast to the square planar geometry previously proposed.

[Cu(aq)]2+ is structurally plastic and the axially elongated octahedron goes missing

NASA Astrophysics Data System (ADS)

Frank, Patrick; Benfatto, Maurizio; Qayyum, Munzarin

2018-05-01

High resolution (k = 18 Å-1 or k = 17 Å-1) copper K-edge EXAFS and MXAN (Minuit X-ray Absorption Near Edge) analyses have been used to investigate the structure of dissolved [Cu(aq)]2+ in 1,3-propanediol (1,3-P) or 1,5-pentanediol (1,5-P) aqueous frozen glasses. EXAFS analysis invariably found a single axially asymmetric 6-coordinate (CN6) site, with 4×Oeq = 1.97 Å, Oax1 = 2.22 Å, and Oax2 = 2.34 Å, plus a second-shell of 4×Owater = 3.6 Å. However, MXAN analysis revealed that [Cu(aq)]2+ occupies both square pyramidal (CN5) and axially asymmetric CN6 structures. The square pyramid included 4×H2O = 1.95 Å and 1×H2O = 2.23 Å. The CN6 sites included either a capped, near perfect, square pyramid with 5×H2O = 1.94 ± 0.04 Å and H2Oax = 2.22 Å (in 1,3-P) or a split axial configuration with 4×H2O = 1.94, H2Oax1 = 2.14 Å, and H2Oax2 = 2.28 Å (in 1,5-P). The CN6 sites also included an 8-H2O second-shell near 3.7 Å, which was undetectable about the strictly pyramidal sites. Equatorial angles averaging 94° ± 5° indicated significant departures from tetragonal planarity. MXAN assessment of the solution structure of [Cu(aq)]2+ in 1,5-P prior to freezing revealed the same structures as previously found in aqueous 1M HClO4, which have become axially compressed in the frozen glasses. [Cu(aq)]2+ in liquid and frozen solutions is dominated by a 5-coordinate square pyramid, but with split axial CN6 appearing in the frozen glasses. Among these phases, the Cu-O axial distances vary across 1 Å, and the equatorial angles depart significantly from the square plane. Although all these structures remove the dx2-y2, dz2 degeneracy, no structure can be described as a Jahn-Teller (JT) axially elongated octahedron. The JT-octahedral description for dissolved [Cu(aq)]2+ should thus be abandoned in favor of square pyramidal [Cu(H2O)5]2+. The revised ligand environments have bearing on questions of the Cu(i)/Cu(ii) self-exchange rate and on the mechanism for ligand exchange with bulk water. The plasticity of dissolved Cu(ii) complex ions falsifies the foundational assumption of the rack-induced bonding theory of blue copper proteins and obviates any need for a thermodynamically implausible protein constraint.

Trends Among the States in Governance and Coordination of Higher Education.

ERIC Educational Resources Information Center

Chambers, M. M.

There has been a trend in state government toward tighter and tighter centralization that, though done in the name of greater economy and efficiency, is in large part a reach for political power. Not all services of the state can be performed well if integrated into a single monolithic administrative pyramid with all other state services and…

Analyzing Group Coordination when Solving Geometry Problems with Dynamic Geometry Software

ERIC Educational Resources Information Center

Oner, Diler

2013-01-01

In CSCL research, collaborative activity is conceptualized along various yet intertwined dimensions. When functioning within these multiple dimensions, participants make use of several resources, which can be social or content-related (and sometimes temporal) in nature. It is the effective coordination of these resources that appears to…

Information Business: Applying Infometry (Informational Geometry) in Cognitive Coordination and Genetic Programming for Electronic Information Packaging and Marketing.

ERIC Educational Resources Information Center

Tsai, Bor-sheng

1994-01-01

Describes the use of infometry, or informational geometry, to meet the challenges of information service businesses. Highlights include theoretical models for cognitive coordination and genetic programming; electronic information packaging; marketing electronic information products, including cost-benefit analyses; and recapitalization, including…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimmermann, Iwan; Kremer, Reinhard K.; Johnsson, Mats, E-mail: mats.johnsson@mmk.su.se

The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) were synthesized by solid state reactions in sealed evacuated silica tubes. The compounds crystallize in the monoclinic space group P2{sub 1}/m with the unit cell parameters a=5.5463(3) Å (5.49434(7) Å), b=6.4893(4) Å (6.44184(9) Å), c=12.8709(7) Å (12.60451(18) Å), β=93.559(5)° (94.1590(12)°) and Z=2 for the respective Br and Cl analogues. Manganese adopts various distorted coordination polyhedra; [MnO{sub 6}] octahedra, [MnO{sub 5}] tetragonal pyramids and [MnO{sub 2}X{sub 2}] tetrahedra. Other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. The structure is made up from layers having no net chargemore » that are connected via weak Van der Waal interactions. The layers that are parallel to (1 1 0) consist of two manganese oxide sheets which are separated by [SiO{sub 4}] tetrahedra. On the outer sides of the sheets are the [MnO{sub 2}X{sub 2}] tetrahedra and the [TeO{sub 3}] trigonal pyramids connected so that the halide ions and the stereochemically active lone pairs on the tellurium atoms protrude from the layers. Magnetic susceptibility measurements reveal a Curie law with a Weiss temperature of θ=−153(3) K for temperatures ≥100 K and indicate antiferromagnetic ordering at T{sub N} ∼4 K. Possible structural origins of the large frustration parameter of f=38 are discussed. - Graphical abstract: Table of contents caption. The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) are layered with weak Van der Waal interactions in between the layers. Manganese adopts various distorted coordination polyhedral, other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. Magnetic susceptibility measurements indicate antiferromagnetic ordering at low temperatures and a large frustration parameter. - Highlights: • Two new isostructural oxohalide compounds are described. • The compounds are the first examples of oxohalides containing both Te{sup 4+} and Si{sup 4+}. • Both compounds display the unusual coordination polyhedron MnO{sub 2}X{sub 2} (X=Cl, Br). • The compounds are made up of charge neutral layers connected via weak interactions. • The compounds are antiferromagnetic and display a large frustration parameter.« less

Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl: A rare example of Ti(IV) in a square pyramidal oxygen coordination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batuk, Maria, E-mail: Maria.Batuk@uantwerpen.be; Batuk, Dmitry; Abakumov, Artem M.

A new oxychloride Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl has been synthesized using the solid state method. Its crystal and magnetic structure was investigated in the 1.5–550 K temperature range using electron diffraction, high angle annular dark field scanning transmission electron microscopy, atomic resolution energy dispersive X-ray spectroscopy, neutron and X-ray powder diffraction. At room temperature Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl crystallizes in the P4/mmm space group with the unit cell parameters a=3.91803(3) Å and c=19.3345(2) Å. Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is a new n=4 member of the oxychloride perovskite-based homologous series A{sub n+1}B{sub n}O{sub 3n−1}Cl. The structure is built of truncated Pb{submore » 3}Fe{sub 3}TiO{sub 11} quadruple perovskite blocks separated by CsCl-type Pb{sub 2}Cl slabs. The perovskite blocks consist of two layers of (Fe,Ti)O{sub 6} octahedra sandwiched between two layers of (Fe,Ti)O{sub 5} square pyramids. The Ti{sup 4+} cations are preferentially located in the octahedral layers, however, the presence of a noticeable amount of Ti{sup 4+} in a five-fold coordination environment has been undoubtedly proven using neutron powder diffraction and atomic resolution compositional mapping. Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is antiferromagnetically ordered below 450(10) K. The ordered Fe magnetic moments at 1.5 K are 4.06(4) μ{sub B} and 3.86(5) μ{sub B} on the octahedral and square-pyramidal sites, respectively. - Highlights: • Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl has been synthesized using the solid state method. • The structure has been refined using neutron powder diffraction data at 1.5–550 K. • It is a new n=4 member of the perovskite-related homologous series A{sub n+1}B{sub n}O{sub 3n−1}Cl. • Ti{sup 4+} cations have both octahedral and square-pyramidal coordination environment. • Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is antiferromagnetically ordered below T{sub N}≈450 K.« less

Coordinate Families for the Schwarzschild Geometry Based on Radial Timelike Geodesics

NASA Technical Reports Server (NTRS)

Finch, Tehani K.

2015-01-01

We explore the connections between various coordinate systems associated with observers moving inwardly along radial geodesics in the Schwarzschild geometry. Painleve-Gullstrand (PG) time is adapted to freely falling observers dropped from rest from in nity; Lake-Martel-Poisson (LMP) time coordinates are adapted to observers who start at in nity with non-zero initial inward velocity; Gautreau-Ho mann (GH) time coordinates are adapted to observers dropped from rest from a nite distance from the black hole horizon. We construct from these an LMP family and a propertime family of time coordinates, the intersection of which is PG time. We demonstrate that these coordinate families are distinct, but related, one-parameter generalizations of PG time, and show linkage to Lema^tre coordinates as well.

Bending nanofibers into nanospirals: coordination chemistry as a tool for shaping hydrophobic assemblies.

PubMed

Kossoy, Elizaveta; Weissman, Haim; Rybtchinski, Boris

2015-01-02

In the current work, we demonstrate how coordination chemistry can be employed to direct self-assembly based on strong hydrophobic interactions. To investigate the influence of coordination sphere geometry on aqueous self-assembly, we synthesized complexes of the amphiphilic perylene diimide terpyridine ligand with the first-row transition-metal centers (zinc, cobalt, and nickel). In aqueous medium, aggregation of these complexes is induced by hydrophobic interactions between the ligands. However, the final shapes of the resulting assemblies depend on the preferred geometry of the coordination spheres typical for the particular metal center. The self-assembly process was characterized by UV/Vis spectroscopy, zeta potential measurements, and cryogenic transmission electron microscopy (cryo-TEM). Coordination of zinc(II) and cobalt(II) leads to the formation of unique nanospiral assemblies, whereas complexation of nickel(II) leads to the formation of straight nanofibers. Notably, coordination bonds are utilized not as connectors between elementary building blocks, but as directing interactions, enabling control over supramolecular geometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Helicopter rotor wake geometry and its influence in forward flight. Volume 2: Wake geometry charts

NASA Technical Reports Server (NTRS)

Egolf, T. A.; Landgrebe, A. J.

1983-01-01

Isometric and projection view plots, inflow ratio nomographs, undistorted axial displacement nomographs, undistorted longitudinal and lateral coordinates, generalized axial distortion nomographs, blade/vortex passage charts, blade/vortex intersection angle nomographs, and fore and aft wake boundary charts are discussed. Example condition, in flow ratio, undistorted axial location, longitudinal and lateral coordinates, axial coordinates distortions, blade/tip vortex intersections, angle of intersection, and fore and aft wake boundaries are also discussed.

Growth and Electronic Structure Characterization of (SrCoOx)n :(SrTiO3)1 Superlattices

NASA Astrophysics Data System (ADS)

Cook, Say Young; Andersen, Tassie; Rosenberg, Richard; Hong, Hawoong; Marks, Laurence; Fong, Dillon

We report on the synthesis of a (SrCoOx)1 :(SrTiO3)1 superlattice by oxide molecular beam epitaxy and the characterization of its electronic structure by soft x-ray spectroscopy. X-ray photoelectron and absorption spectroscopy reveal that Ti remains octahedrally coordinated with a 4 + oxidation state, while the Co oxidation state is intermediate of 3 + and 4 +. Despite having the same half an oxygen vacancy per Co atom found in brownmillerite SrCoO2.5, which consists of alternating tetrahedral and octahedral layers of Co, the confinement of oxygen vacancies to isolated single atomic layers of SrCoOx stabilizes square pyramidal coordination of Co, as observed by the linear dichroism in the Co 2p-3d x-ray absorption. The corresponding stabilization of Co4+ along with Co3 + within the square pyramidal SrCoO2.5 layers gives rise to a Fermi-edge step observed at strong Co 2p-3d resonance in the resonant photoemission spectroscopy of the valence band, and reveals a band gap of 1.7 eV. Comparisons with a Sr(Co,Ti)Ox alloy and a (SrCoOx)2 :(SrTiO3)1 superlattice also will also be presented. The obtained results demonstrate artificial superlattices as effective means to defect engineer complex oxides by harnessing the confinement of oxygen vacancies to control the oxygen coordination environment of the transition metal.

The role of chloride in the mechanism of O(2) activation at the mononuclear nonheme Fe(II) center of the halogenase HctB.

PubMed

Pratter, Sarah M; Light, Kenneth M; Solomon, Edward I; Straganz, Grit D

2014-07-02

Mononuclear nonheme Fe(II) (MNH) and α-ketoglutarate (α-KG) dependent halogenases activate O2 to perform oxidative halogenations of activated and nonactivated carbon centers. While the mechanism of halide incorporation into a substrate has been investigated, the mechanism by which halogenases prevent oxidations in the absence of chloride is still obscure. Here, we characterize the impact of chloride on the metal center coordination and reactivity of the fatty acyl-halogenase HctB. Stopped-flow kinetic studies show that the oxidative transformation of the Fe(II)-α-KG-enzyme complex is >200-fold accelerated by saturating concentrations of chloride in both the absence and presence of a covalently bound substrate. By contrast, the presence of substrate, which generally brings about O2 activation at enzymatic MNH centers, only has an ∼10-fold effect in the absence of chloride. Circular dichroism (CD) and magnetic CD (MCD) studies demonstrate that chloride binding triggers changes in the metal center ligation: chloride binding induces the proper binding of the substrate as shown by variable-temperature, variable-field (VTVH) MCD studies of non-α-KG-containing forms and the conversion from six-coordinate (6C) to 5C/6C mixtures when α-KG is bound. In the presence of substrate, a site with square pyramidal five-coordinate (5C) geometry is observed, which is required for O2 activation at enzymatic MNH centers. In the absence of substrate an unusual trigonal bipyramidal site is formed, which accounts for the observed slow, uncoupled reactivity. Molecular dynamics simulations suggest that the binding of chloride to the metal center of HctB leads to a conformational change in the enzyme that makes the active site more accessible to the substrate and thus facilitates the formation of the catalytically competent enzyme-substrate complex. Results are discussed in relation to other MNH dependent halogenases.

Reactivity of dinuclear copper(II) complexes towards melanoma cells: Correlation with its stability, tyrosinase mimicking and nuclease activity.

PubMed

Nunes, Cléia Justino; Borges, Beatriz Essenfelder; Nakao, Lia Sumie; Peyroux, Eugénie; Hardré, Renaud; Faure, Bruno; Réglier, Marius; Giorgi, Michel; Prieto, Marcela Bach; Oliveira, Carla Columbano; Da Costa Ferreira, Ana M

2015-08-01

In this work, the influence of two new dinuclear copper(II) complexes in the viability of melanoma cells (B16F10 and TM1MNG3) was investigated, with the aim of verifying possible correlations between their cytotoxicity and their structure. One of the complexes had a polydentate dinucleating amine-imine ligand (complex 2), and the other a tridentate imine and a diamine-bridging ligand (complex 4). The analogous mononuclear copper(II) species (complexes 1 and 3, respectively) were also prepared for comparative studies. Crystal structure determination of complex 2 indicated a square-based pyramidal geometry around each copper, coordinated to three N atoms from the ligand and the remaining sites being occupied by either solvent molecules or counter-ions. Complex 4 has a tetragonal geometry. Interactions of these complexes with human albumin protein (HSA) allowed an estimation of their relative stabilities. Complementary studies of their reactivity towards DNA indicated that all of them are able of causing significant oxidative damage, with single and double strand cleavages, in the presence of hydrogen peroxide. However, nuclease activity of the dinuclear species was very similar and much higher than that of the corresponding mononuclear compounds. Although complex 2, with a more flexible structure, exhibits a much higher tyrosinase activity than complex 4, having a more rigid environment around the metal ion, both complexes showed comparable cytotoxicity towards melanoma cells. Corresponding mononuclear complexes showed to be remarkably less reactive as tyrosinase mimics as well as cytotoxic agents. Moreover, the dinuclear complexes showed higher cytotoxicity towards more melanogenic cells. The obtained results indicated that the structure of these species is decisive for its activity towards the malignant tumor cells tested. Copyright © 2015 Elsevier Inc. All rights reserved.

Syntheses, characterization and antioxidant activity studies of mixed-ligand copper(II) complexes of 2,2‧-bipyridine and glycine: The X-ray crystal structure of [Cu(BPy)(Gly)]ClO4

NASA Astrophysics Data System (ADS)

Ibrahim, Mohamed M.; Ramadan, Abd El-Motaleb M.; Shaban, Shaban Y.; Mersal, Gaber A. M.; El-Shazly, Samir A.; Al-Juaid, Salih

2017-04-01

A series of mixed-ligand complexes, viz., [CuLL'X]Y {L = bipyridine; L' = glycine; X = 0, Y = ClO4- (1); X = Cl, Y = 2H2O (2); X = H2O, Y = NO3- (3); X = CH3COO-, Y = H2O (4)} and {[Cu(Gly)(BPy)]2-μ-(SO4)}(5)} have been synthesized and characterized by means of elemental analysis, spectroscopic (FT-IR, UV-Vis and ESR), and thermal analysis, as well as magnetic moment measurements. Spectral and X-ray structural features led to the conclusion that complexes 2-5 have square-pyramidal environments around copper(II) center with coordination chromophores CuN3OCl and CuN3O2, respectively. Whereas complex 1 displays square planar geometry. The quasi-reversible CuII/CuI redox couple slightly improves its reversibility with considerable decrease in current intensity. Additionally, the antioxidant (superoxide dismutase and catalase) biomimetic catalytic activities of the obtained complexes have been tested and found to be promising candidates as dual functional mimic enzyme to serve for complete reactive oxygen species (ROS) detoxification, both with respect to the superoxide radicals and the related peroxides.

Excited state conformational dynamics in carotenoids: dark intermediates and excitation energy transfer.

PubMed

Beck, Warren F; Bishop, Michael M; Roscioli, Jerome D; Ghosh, Soumen; Frank, Harry A

2015-04-15

A consideration of the excited state potential energy surfaces of carotenoids develops a new hypothesis for the nature of the conformational motions that follow optical preparation of the S2 (1(1)Bu(+)) state. After an initial displacement from the Franck-Condon geometry along bond length alternation coordinates, it is suggested that carotenoids pass over a transition-state barrier leading to twisted conformations. This hypothesis leads to assignments for several dark intermediate states encountered in femtosecond spectroscopic studies. The Sx state is assigned to the structure reached upon the onset of torsional motions near the transition state barrier that divides planar and twisted structures on the S2 state potential energy surface. The X state, detected recently in two-dimensional electronic spectra, corresponds to a twisted structure well past the barrier and approaching the S2 state torsional minimum. Lastly, the S(∗) state is assigned to a low lying S1 state structure with intramolecular charge transfer character (ICT) and a pyramidal conformation. It follows that the bent and twisted structures of carotenoids that are found in photosynthetic light-harvesting proteins yield excited-state structures that favor the development of an ICT character and optimized energy transfer yields to (bacterio)chlorophyll acceptors. Copyright © 2015 Elsevier Inc. All rights reserved.

Synthesis, spectroscopy and biological investigations of manganese(III) Schiff base complexes derived from heterocyclic β-diketone with various primary amine and 2,2'-bipyridyl

NASA Astrophysics Data System (ADS)

Surati, Kiran R.

2011-06-01

The mixed ligand mononuclear complex [Mn(bipy)(HPMFP)(OAc)]ClO 4 was synthesized by reaction of Mn(OAc) 3·2H 2O with HPMFP and 2,2'-bipyridyl. The corresponding Schiff base complexes were prepared by condensation of [Mn(bipy)(HPMFP)(OAc)]ClO 4 with ethylenediamine, ethanolamine and glycine (where HPMFP = 1-phenyl-3methyl-4-formyl-2-pyrazolin-5one, bipy = 2,2'-bipyridyl). All the compounds have been characterized by elemental analysis, magnetic susceptibility, conductometry measurements and 1H and 13C NMR, FT-IR, mass spectrometry. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese(III) ion. The thermal stabilities, activation energy E*, entropy change Δ S*, enthalpy change Δ H* and heat capacity of thermal degradation for these complexes were determined by TGA and DSC. The in vitro antibacterial and antifungal activity of four coordination compounds and ligand HPMFP were investigated. In vitro activates of Bacillus subtillis (MTCC-619), Staphylococcus aureus (MTCC-96), Escherichia coli (MTCC-722) and Klebsiella pneumonia (MTCC-109) bacteria and the fungus Candida albicans (ATCC-90028) were determined. All the compounds showed good antimicrobial activity. The antimicrobial activities increased as formation of Schiff base.

Synthesis, spectroscopic, structural and thermal characterizations of vanadyl(IV) adenine complex prospective as antidiabetic drug agent

NASA Astrophysics Data System (ADS)

El-Megharbel, Samy M.; Hamza, Reham Z.; Refat, Moamen S.

2015-01-01

The vanadyl(IV) adenine complex; [VO(Adn)2]ṡSO4; was synthesized and characterized. The molar conductivity of this complex was measured in DMSO solution that showed an electrolyte nature. Spectroscopic investigation of the green solid complex studied here indicate that the adenine acts as a bidentate ligand, coordinated to vanadyl(IV) ions through the nitrogen atoms N7 and nitrogen atom of amino group. Thus, from the results presented the vanadyl(IV) complex has square pyramid geometry. Further characterizations using thermal analyses and scanning electron techniques was useful. The aim of this paper was to introduce a new drug model for the diabetic complications by synthesized a novel mononuclear vanadyl(IV) adenine complex to mimic insulin action and reducing blood sugar level. The antidiabetic ability of this complex was investigated in STZ-induced diabetic mice. The results suggested that VO(IV)/adenine complex has antidiabetic activity, it improved the lipid profile, it improved liver and kidney functions, also it ameliorated insulin hormone and blood glucose levels. The vanadyl(IV) complex possesses an antioxidant activity and this was clear through studying SOD, CAT, MDA, GSH and methionine synthase. The current results support the therapeutic potentiality of vanadyl(IV)/adenine complex for the management and treatment of diabetes.

Structure of thiocyanate hydrolase: a new nitrile hydratase family protein with a novel five-coordinate cobalt(III) center.

PubMed

Arakawa, Takatoshi; Kawano, Yoshiaki; Kataoka, Shingo; Katayama, Yoko; Kamiya, Nobuo; Yohda, Masafumi; Odaka, Masafumi

2007-03-09

Thiocyanate hydrolase (SCNase) of Thiobacillus thioparus THI115 is a cobalt(III)-containing enzyme catalyzing the degradation of thiocyanate to carbonyl sulfide and ammonia. We determined the crystal structures of the apo- and native SCNases at a resolution of 2.0 A. SCNases in both forms had a conserved hetero-dodecameric structure, (alphabetagamma)(4). Four alphabetagamma hetero-trimers were structurally equivalent. One alphabetagamma hetero-trimer was composed of the core domain and the betaN domain, which was located at the center of the molecule and linked the hetero-trimers with novel quaternary interfaces. In both the apo- and native SCNases, the core domain was structurally conserved between those of iron and cobalt-types of nitrile hydratase (NHase). Native SCNase possessed the post-translationally modified cysteine ligands, gammaCys131-SO(2)H and gammaCys133-SOH like NHases. However, the low-spin cobalt(III) was found to be in the distorted square-pyramidal geometry, which had not been reported before in any protein. The size as well as the electrostatic properties of the substrate-binding pocket was totally different from NHases with respect to the charge distribution and the substrate accessibility, which rationally explains the differences in the substrate preference between SCNase and NHase.

Geometry dependence of electron donating or accepting abilities of amine groups in 4,4‧-disulfanediylbis(methylene)dithiazol-2-amine: Pyramidal versus planar

NASA Astrophysics Data System (ADS)

Karabıyık, Hasan; Kırılmış, Cumhur; Karabıyık, Hande

2017-08-01

The molecular and crystal structure of the title compound in which two thiazole-2-amine rings are linked to each other by disulfide bridge (sbnd Csbnd Ssbnd Ssbnd Csbnd) were studied by single-crystal X-ray diffraction, FT-IR, NMR spectroscopy, quantum chemical calculations and topological analyses on the electron density. A novel synthesis route for the compounds having symmetrical disulfide bridge is reported. The most important result regarding the compound is about electron donating or accepting properties of the terminal amine groups. Planar amine group acts as an electron-donating group, while pyramidal amine behaves as electron-accepting group. This inference was confirmed by scrutiny of crystallographic geometry and quantum chemical studies. To ascertain underlying reasons for this fact, intermolecular interactions (Nsbnd H⋯N type H-bonds and Csbnd H···π interactions) were studied. These interactions involving aromatic thiazole rings are verified by topological electron density and Hirshfeld surface analyses. Intermolecular interactions do not have an effect on the differentiation in electron donating or accepting ability of amine groups, because both amine groups are involved in Nsbnd H⋯N type H-bonds. In methodological sense, it has been understood that Ehrenfest forces acting on electron density are useful theoretical probe to analyze intra-molecular charge transfer processes.

μ-Carbonato-bis­(bis­{2-[(diethyl­amino)­meth­yl]phen­yl}bis­muth(III))

PubMed Central

Soran, Albert P.; Nema, Mihai G.; Breunig, Hans J.; Silvestru, Cristian

2011-01-01

The mol­ecular structure of the title compound, [Bi2(C11H16N)4(CO3)], consists of a symmetrically bridging carbonato group which binds two [2-Et2NCH2C6H4]2Bi units that are crystallographically related via a twofold rotation axis bis­ecting the carbonate group. The two Bi atoms and two of the C atoms directly bonded to bis­muth are quasi-planar [deviations of 0.323 (1) and 0.330 (9)Å for the Bi and C atoms, respectively] with the carbonate group. The remaining two ligands are in a trans arrangement relative to the quasi-planar (CBi)2CO3 system. The metal atom is strongly coordinated by the N atom of one pendant arm [Bi—N = 2.739 (6) Å], almost trans to the O atom, while the N atom of the other pendant arm exhibits a weaker intra­molecular inter­action [Bi⋯N = 3.659 (7) Å] almost trans to a C atom. If both these intra­molecular N→Bi inter­actions per metal atom are considered, the overall coordination geometry at bis­muth becomes distorted square-pyramidal [(C,N)2BiO cores] and the compound can be described as a hypervalent 12-Bi-5 species. Additional quite short intra­molecular Bi⋯O inter­actions are also present [3.796 (8)–4.020 (9) Å]. Inter­molecular associations through weak η6⋯Bi inter­actions [Bi⋯centroid of benzene ring = 3.659 (1) Å] lead to a ribbon-like supra­molecular association. PMID:21522836

Metal based biologically active compounds: design, synthesis, and antibacterial/antifungal/cytotoxic properties of triazole-derived Schiff bases and their oxovanadium(IV) complexes.

PubMed

Chohan, Zahid H; Sumrra, Sajjad H; Youssoufi, Moulay H; Hadda, Taibi B

2010-07-01

A new series of oxovanadium(IV) complexes have been designed and synthesized with a new class of triazole Schiff bases derived from the reaction of 3,5-diamino-1,2,4-triazole with 2-hydroxy-1-naphthaldehyde, pyrrole-2-carboxaldehyde, pyridine-2-carboxaldehyde and acetyl pyridine-2-carboxaldehyde, respectively. Physical (magnetic susceptibility, molar conductance), spectral (IR, (1)H NMR, (13)C NMR, mass and electronic) and analytical data have established the structures of these synthesized Schiff bases and their oxovanadium(IV) complexes. The Schiff bases, predominantly act as bidentate and coordinate with the vanadium(IV) metal to give a stoichiometric ratio of 1:2 [M:L], forming a general formulae, [M(L-H)(2)] and [M(L)(2)]SO(4) where L = (L(1))-(L(4)) and M = VO(IV) of these complexes in a square-pyramidal geometry. In order to evaluate the biological activity of Schiff bases and to assess the role of vanadium(IV) metal on biological activity, the triazole Schiff bases and their oxovanadium(IV) complexes have been studied for in vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexenari, Pseudomonas aeruginosa, Salmonella typhi) and two Gram-positive (Staphylococcus aureus, Bacillus subtilis) bacterial strains, in vitro antifungal activity against Trichophyton longifucus, Candida albican, Aspergillus flavus, Microscopum canis, Fusarium solani and Candida glaberata. The simple Schiff bases showed weaker to significant activity against one or more bacterial and fungal strains. In most of the cases higher activity was exhibited upon coordination with vanadium(IV) metal. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. Copyright (c) 2010 Elsevier Masson SAS. All rights reserved.

Dihydroxo-bridged dimeric Cu(II) system containing sandwiched non-coordinating phenylacetate anion: Crystal structure, spectroscopic, anti-bacterial, anti-fungal and DNA-binding studies of [(phen)(H2O)Cu(OH)2Cu(H2O)(phen)]2L.6H2O: (HL = phenylacetic acid; phen = 1,10-phenanthroline)

NASA Astrophysics Data System (ADS)

Iqbal, Muhammad; Ali, Saqib; Tahir, Muhammad Nawaz; Shah, Naseer Ali

2017-09-01

This paper reports the synthesis, X-ray crystal structure, DNA-binding, antibacterial and antifungal studies of a rare dihydroxo-bridged dinuclear copper(II) complex including 1,10-phenanthroline (Phen) ligands and phenylacetate (L) anions, [Cu2(Phen)2(OH)2(H2O)2].2L.6H2O. Structural data revealed distorted square-pyramidal geometry for each copper(II) atom with the basal plane formed by the two nitrogen atoms of the phenantroline ligand and the oxygen atoms of two bridging hydroxyl groups. The apical positions are filled by the oxygen atom from a water molecule. This forms a centrosymmetric cationic dimer where the uncoordinated phenylacetate ligands serve to balance the electrical charge. The dimers interact by means of hydrogen bonds aided by the coordinated as well as uncoordinated water molecules and phenyl-acetate moieties in the crystal lattice. The binding ability of the complex with salmon sperm DNA was determined using cyclic voltammetry and absorption spectroscopy yielding binding constants 2.426 × 104 M-1 and 1.399 × 104 M-1, respectively. The complex was screened against two Gram-positive (Micrococcus luteus and Bacillus subtilis) and one Gram-negative (Escherichia coli) bacterial strains exhibiting significant activity against all the three strains. The complex exhibited significant, moderate and no activity against fungal strains Mucor piriformis, Helminthosporium solani and Aspergillus Niger, respectively. These preliminary tests indicate the competence of the complex towards the development of a potent biological drug.

μ-Carbonato-bis-(bis-{2-[(diethyl-amino)-meth-yl]phen-yl}bis-muth(III)).

PubMed

Soran, Albert P; Nema, Mihai G; Breunig, Hans J; Silvestru, Cristian

2011-01-12

The mol-ecular structure of the title compound, [Bi(2)(C(11)H(16)N)(4)(CO(3))], consists of a symmetrically bridging carbonato group which binds two [2-Et(2)NCH(2)C(6)H(4)](2)Bi units that are crystallographically related via a twofold rotation axis bis-ecting the carbonate group. The two Bi atoms and two of the C atoms directly bonded to bis-muth are quasi-planar [deviations of 0.323 (1) and 0.330 (9)Å for the Bi and C atoms, respectively] with the carbonate group. The remaining two ligands are in a trans arrangement relative to the quasi-planar (CBi)(2)CO(3) system. The metal atom is strongly coordinated by the N atom of one pendant arm [Bi-N = 2.739 (6) Å], almost trans to the O atom, while the N atom of the other pendant arm exhibits a weaker intra-molecular inter-action [Bi⋯N = 3.659 (7) Å] almost trans to a C atom. If both these intra-molecular N→Bi inter-actions per metal atom are considered, the overall coordination geometry at bis-muth becomes distorted square-pyramidal [(C,N)(2)BiO cores] and the compound can be described as a hypervalent 12-Bi-5 species. Additional quite short intra-molecular Bi⋯O inter-actions are also present [3.796 (8)-4.020 (9) Å]. Inter-molecular associations through weak η(6)⋯Bi inter-actions [Bi⋯centroid of benzene ring = 3.659 (1) Å] lead to a ribbon-like supra-molecular association.

Coordination Mechanism in Fast Human Movements - Experimental and Modelling Studies. Volume 1.

DTIC Science & Technology

1982-02-01

journal, possible the Journal of Motor Behavior of Experimental Brain Research. I. Proposed Experimental Studies - Year 3 At the present time we are...stimulation regimens must be devised to produce sensory imparted learning which manipulates each of these brain control mechanisms. Following the...movement center in the brain , presumably via the pyramidal tract from the cerebellum to the brainstem and spinal cord (cf. Miles and Evarts, 1979

FIDDLE: A Computer Code for Finite Difference Development of Linear Elasticity in Generalized Curvilinear Coordinates

NASA Technical Reports Server (NTRS)

Kaul, Upender K.

2005-01-01

A three-dimensional numerical solver based on finite-difference solution of three-dimensional elastodynamic equations in generalized curvilinear coordinates has been developed and used to generate data such as radial and tangential stresses over various gear component geometries under rotation. The geometries considered are an annulus, a thin annular disk, and a thin solid disk. The solution is based on first principles and does not involve lumped parameter or distributed parameter systems approach. The elastodynamic equations in the velocity-stress formulation that are considered here have been used in the solution of problems of geophysics where non-rotating Cartesian grids are considered. For arbitrary geometries, these equations along with the appropriate boundary conditions have been cast in generalized curvilinear coordinates in the present study.

Spectral, thermal, kinetic, molecular modeling and eukaryotic DNA degradation studies for a new series of albendazole (HABZ) complexes

NASA Astrophysics Data System (ADS)

El-Metwaly, Nashwa M.; Refat, Moamen S.

2011-01-01

This work represents the elaborated investigation for the ligational behavior of the albendazole ligand through its coordination with, Cu(II), Mn(II), Ni(II), Co(II) and Cr(III) ions. Elemental analysis, molar conductance, magnetic moment, spectral studies (IR, UV-Vis and ESR) and thermogravimetric analysis (TG and DTG) have been used to characterize the isolated complexes. A deliberate comparison for the IR spectra reveals that the ligand coordinated with all mentioned metal ions by the same manner as a neutral bidentate through carbonyl of ester moiety and NH groups. The proposed chelation form for such complexes is expected through out the preparation conditions in a relatively acidic medium. The powder XRD study reflects the amorphous nature for the investigated complexes except Mn(II). The conductivity measurements reflect the non-electrolytic feature for all complexes. In comparing with the constants for the magnetic measurements as well as the electronic spectral data, the octahedral structure was proposed strongly for Cr(III) and Ni(II), the tetrahedral for Co(II) and Mn(II) complexes but the square-pyramidal for the Cu(II) one. The thermogravimetric analysis confirms the presence or absence of water molecules by any type of attachments. Also, the kinetic parameters are estimated from DTG and TG curves. ESR spectrum data for Cu(II) solid complex confirms the square-pyramidal state is the most fitted one for the coordinated structure. The albendazole ligand and its complexes are biologically investigated against two bacteria as well as their effective effect on degradation of calf thymus DNA.

The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning.

PubMed

Gomes, João Gabriel Ribeiro; Gorgulho, Alessandra Augusta; de Oliveira López, Amanda; Saraiva, Crystian Wilian Chagas; Damiani, Lucas Petri; Pássaro, Anderson Martins; Salvajoli, João Victor; de Oliveira Siqueira, Ludmila; Salvajoli, Bernardo Peres; De Salles, Antônio Afonso Ferreira

2016-12-01

OBJECTIVE The role of tractography in Gamma Knife thalamotomy (GK-T) planning is still unclear. Pyramidal tractography might reduce the risk of radiation injury to the pyramidal tract and reduce motor complications. METHODS In this study, the ventralis intermedius nucleus (VIM) targets of 20 patients were bilaterally defined using Iplannet Stereotaxy Software, according to the anterior commissure-posterior commissure (AC-PC) line and considering the localization of the pyramidal tract. The 40 targets and tractography were transferred as objects to the GammaPlan Treatment Planning System (GP-TPS). New targets were defined, according to the AC-PC line in the functional targets section of the GP-TPS. The target offsets required to maintain the internal capsule (IC) constraint of < 15 Gy were evaluated. In addition, the strategies available in GP-TPS to maintain the minimum conventional VIM target dose at > 100 Gy were determined. RESULTS A difference was observed between the positions of both targets and the doses to the IC. The lateral (x) and the vertical (z) coordinates were adjusted 1.9 mm medially and 1.3 mm cranially, respectively. The targets defined considering the position of the pyramidal tract were more medial and superior, based on the constraint of 15 Gy touching the object representing the IC in the GP-TPS. The best strategy to meet the set constraints was 90° Gamma angle (GA) with automatic shaping of dose distribution; this was followed by 110° GA. The worst GA was 70°. Treatment time was substantially increased by the shaping strategy, approximately doubling delivery time. CONCLUSIONS Routine use of DTI pyramidal tractography might be important to fine-tune GK-T planning. DTI tractography, as well as anisotropy showing the VIM, promises to improve Gamma Knife functional procedures. They allow for a more objective definition of dose constraints to the IC and targeting. DTI pyramidal tractography introduced into the treatment planning may reduce the incidence of motor complications and improve efficacy. This needs to be validated in a large clinical series.

Towards deep learning with segregated dendrites

PubMed Central

Guerguiev, Jordan; Lillicrap, Timothy P

2017-01-01

Deep learning has led to significant advances in artificial intelligence, in part, by adopting strategies motivated by neurophysiology. However, it is unclear whether deep learning could occur in the real brain. Here, we show that a deep learning algorithm that utilizes multi-compartment neurons might help us to understand how the neocortex optimizes cost functions. Like neocortical pyramidal neurons, neurons in our model receive sensory information and higher-order feedback in electrotonically segregated compartments. Thanks to this segregation, neurons in different layers of the network can coordinate synaptic weight updates. As a result, the network learns to categorize images better than a single layer network. Furthermore, we show that our algorithm takes advantage of multilayer architectures to identify useful higher-order representations—the hallmark of deep learning. This work demonstrates that deep learning can be achieved using segregated dendritic compartments, which may help to explain the morphology of neocortical pyramidal neurons. PMID:29205151

Towards deep learning with segregated dendrites.

PubMed

Guerguiev, Jordan; Lillicrap, Timothy P; Richards, Blake A

2017-12-05

Deep learning has led to significant advances in artificial intelligence, in part, by adopting strategies motivated by neurophysiology. However, it is unclear whether deep learning could occur in the real brain. Here, we show that a deep learning algorithm that utilizes multi-compartment neurons might help us to understand how the neocortex optimizes cost functions. Like neocortical pyramidal neurons, neurons in our model receive sensory information and higher-order feedback in electrotonically segregated compartments. Thanks to this segregation, neurons in different layers of the network can coordinate synaptic weight updates. As a result, the network learns to categorize images better than a single layer network. Furthermore, we show that our algorithm takes advantage of multilayer architectures to identify useful higher-order representations-the hallmark of deep learning. This work demonstrates that deep learning can be achieved using segregated dendritic compartments, which may help to explain the morphology of neocortical pyramidal neurons.

Cutting solid figures by plane - analytical solution and spreadsheet implementation

NASA Astrophysics Data System (ADS)

Benacka, Jan

2012-07-01

In some secondary mathematics curricula, there is a topic called Stereometry that deals with investigating the position and finding the intersection, angle, and distance of lines and planes defined within a prism or pyramid. Coordinate system is not used. The metric tasks are solved using Pythagoras' theorem, trigonometric functions, and sine and cosine rules. The basic problem is to find the section of the figure by a plane that is defined by three points related to the figure. In this article, a formula is derived that gives the positions of the intersection points of such a plane and the figure edges, that is, the vertices of the section polygon. Spreadsheet implementations of the formula for cuboid and right rectangular pyramids are presented. The user can check his/her graphical solution, or proceed if he/she is not able to complete the section.

Photocathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Opachich, Yekaterina; MacPhee, Andrew

A photocathode designs that leverage the grazing incidence geometry yield improvements through the introduction of recessed structures, such as cones, pyramids, pillars or cavities to the photocathode substrate surface. Improvements in yield of up to 20 times have been shown to occur in grazing incidence geometry disclosed herein due to a larger path length of the X-ray photons which better matches the secondary electron escape depth within the photocathode material. A photocathode includes a substrate having a first side and a second side, the first side configured to receive x-ray energy and the second side opposing the first side. Amore » structured surface is associated with the second side of the substrate such that the structured surface includes a plurality of recesses from the second side of the substrate into the substrate.« less

Molecular and electronic structures of mononuclear iron complexes using strongly electron-donating ligands and their oxidized forms.

PubMed

Strautmann, Julia B H; George, Serena DeBeer; Bothe, Eberhard; Bill, Eckhard; Weyhermüller, Thomas; Stammler, Anja; Bögge, Hartmut; Glaser, Thorsten

2008-08-04

The ligand L (2-) (H 2L = N, N'-dimethyl- N, N'-bis(3,5-di- t-butyl-2-hydroxybenzyl)-1,2-diaminoethane) has been employed for the synthesis of two mononuclear Fe (III) complexes, namely, [LFe(eta (2)-NO 3)] and [LFeCl]. L (2-) is comprised of four strongly electron-donating groups (two tert-amines and two phenolates) that increase the electron density at the coordinated ferric ions. This property should facilitate oxidation of the complexes, that is, stabilization of the oxidized species. The molecular structures in the solid state have been established by X-ray diffraction studies. [LFeCl] is five-coordinate in a square-pyramidal coordination environment with the ligand adopting a trans-conformation, while [LFe(eta (2)-NO 3)] is six-coordinate in a distorted octahedral environment with the ligand in a beta-cis conformation. The electronic structures have been studied using magnetization, EPR, Mossbauer (with and without applied field), UV-vis-NIR, and X-ray absorption spectroscopies, which demonstrate highly anisotropic covalency from the strong sigma- and pi-donating phenolates. This analysis is supported by DFT calculations on [LFeCl]. The variations of the well-understood spectroscopic data in the solid state to the spectroscopic data in solution have been used to obtain insight in the molecular structure of the two complexes in solution. While the molecular structures of the solid states are retained in solutions of nonpolar aprotic solvents, there is, however, one common molecular structure in all protic polar solvents. The analysis of the LMCT transitions and the rhombicity E/ D clearly establish that both compounds exhibit a beta-cis conformation in these protic polar solvents. These two open coordination sites, cis to each other, allow access for two potential ligands in close proximity. Electrochemical analysis establishes two reversible oxidation waves for [LFeCl] at +0.55 V and +0.93 V vs Fc (+)/Fc and one reversible oxidation wave at +0.59 V with an irreversible oxidation at +1.07 V vs Fc (+)/Fc for [LFe(eta (2)-NO 3)]. The one- and the two-electron oxidations of [LFeCl] by chronoamperometry have been followed spectroscopically. The increase of a strong band centered at 420 nm indicates the formulation of [LFeCl] (+) as a Fe (III) monophenoxyl radical complex and of [LFeCl] (2+) as a Fe (III) bisphenoxyl radical complex. These studies imply that the ligand L (2-) is capable of providing a flexible coordination geometry with two binding sites for substrates and the allocation of two oxidation equivalents on the ligand.

Synthesis, structural characterization, reactivity, and catalytic properties of copper(I) complexes with a series of tetradentate tripodal tris(pyrazolylmethyl)amine ligands.

PubMed

Haldón, Estela; Delgado-Rebollo, Manuela; Prieto, Auxiliadora; Alvarez, Eleuterio; Maya, Celia; Nicasio, M Carmen; Pérez, Pedro J

2014-04-21

Novel tris(pyrazolylmethyl)amine ligands Tpa(Me3), Tpa*(,Br), and Tpa(Br3) have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper(I) salts as starting materials. Cationic copper(I) complexes [Tpa(x)Cu]PF6 (1-4) have been isolated from the reaction of [Cu(NCMe)4]PF6 and 1 equiv of the ligand. Complexes 2 (Tpa(x) = Tpa*) and 3 (Tpa(x) = Tpa(Me3)) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpa(x) ligand adopts a μ(2):κ(2):κ(1)-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper(I) source, neutral compounds 5-8 have been obtained. Complexes 6-8 exhibit a 1:1 metal-to-ligand ratio, whereas 5 presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa2Cu4I4] units, in which Cu4I4 presents a step-stair structure. The Tpa ligands bridge the Cu4I4 clusters, adopting also a μ(2):κ(2):κ(1)-coordination mode. As observed for the cationic derivatives, the NMR spectra of 5-8 show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper(I) derivatives 1-4 with PPh3 and CO have been explored. In all cases, 1:1 adducts [Tpa(x)CuL]PF6 [L = PPh3 (9-11), CO (12-15)] have been isolated. The crystal structure of [Tpa*Cu(PPh3)]PF6 (9) has been obtained, showing that the coordination geometry around copper(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts 13-15 exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR νCO stretching bands. Finally, the catalytic activities of complexes 1-4 have been demonstrated in carbene- and nitrene-transfer reactions.

The trigonal prism in coordination chemistry.

PubMed

Cremades, Eduard; Echeverría, Jorge; Alvarez, Santiago

2010-09-10

Herein we analyze the accessibility of the trigonal-prismatic geometry to metal complexes with different electron configurations, as well as the ability of several hexadentate ligands to favor that coordination polyhedron. Our study combines i) a structural database analysis of the occurrence of the prismatic geometry throughout the transition-metal series, ii) a qualitative molecular orbital analysis of the distortions expected for a trigonal-prismatic geometry, and iii) a computational study of complexes of several transition-metal ions with different hexadentate ligands. Also the tendency of specific electron configurations to present a cis bond-stretch Jahn-Teller distortion is analyzed.

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

NASA Astrophysics Data System (ADS)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

Construction and manipulation of functional three-dimensional droplet networks.

PubMed

Wauer, Tobias; Gerlach, Holger; Mantri, Shiksha; Hill, Jamie; Bayley, Hagan; Sapra, K Tanuj

2014-01-28

Previously, we reported the manual assembly of lipid-coated aqueous droplets in oil to form two-dimensional (2D) networks in which the droplets are connected through single lipid bilayers. Here we assemble lipid-coated droplets in robust, freestanding 3D geometries: for example, a 14-droplet pyramidal assembly. The networks are designed, and each droplet is placed in a designated position. When protein pores are inserted in the bilayers between specific constituent droplets, electrical and chemical communication pathways are generated. We further describe an improved means to construct 3D droplet networks with defined organizations by the manipulation of aqueous droplets containing encapsulated magnetic beads. The droplets are maneuvered in a magnetic field to form simple construction modules, which are then used to form larger 2D and 3D structures including a 10-droplet pyramid. A methodology to construct freestanding, functional 3D droplet networks is an important step toward the programmed and automated manufacture of synthetic minimal tissues.

Dendritic Na+ spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons

PubMed Central

Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

2014-01-01

Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na+ spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na+ spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow. DOI: http://dx.doi.org/10.7554/eLife.04551.001 PMID:25390033

Terahertz absorber based on Fano-like resonance of inverted quadrangular frustum pyramid metal grooves and sensor application

NASA Astrophysics Data System (ADS)

Yu, Yingying; Sun, Bo

2018-07-01

We investigate the multi-resonance coupling of inverted quadrangular frustum pyramid (IQFP) groove metal arrays at terahertz frequencies. The surface plasmon resonance (SPR) and groove resonance are induced, resulting in resonance coupling. The dipole of the groove resonance drives the quadrupole of the SPR and creates a sharp Fano-like resonance. The effects of geometry parameters including the width (at the bottom) and height are analyzed in detail. The results show that with the decrease in the sidewall slope of the groove, the confinement of the groove region on the electromagnetic field decreases, thereby increasing the resonance coupling. The Fano-like resonance is enhanced. The sensitivity and quality factor are discussed. The results show that the Fano-like resonance has high sensitivity and quality factor. With the increase in the sidewall slope of the groove, the sensitivity increases, and the quality factor decreases. The results show that the Fano-like resonance of IQFP groove metal arrays has a significant potential for biological monitoring and sensing.

Effects of Measurement Geometry on Spectral Reflectance and Color

DTIC Science & Technology

1998-01-01

calibration of outdoor color imagery were made using integrating sphere and 45°/0° geometry. The differing results are discussed using CIELAB linear... CIELAB color coordinate results were obtained for different measurement geometries. Such results should affect the digital photographic measurements...measurement geometry on spectral reflectance and CIELAB values using integrating sphere and 45°/0° measurement geometries. An example of the phenomenology

Cd (II) and holodirected lead (II) 3D-supramolecular coordination polymers based on nicotinic acid: Structure, fluorescence property and photocatalytic activity

NASA Astrophysics Data System (ADS)

Etaiw, Safaa El-din H.; Abd El-Aziz, Dina M.; Marie, Hassan; Ali, Elham

2018-05-01

Two new supramolecular coordination polymers namely {[Cd(NA)2(H2O)]}, SCP 1 and {[Pb(NA)2]}, SCP 2, (NA = nicotinate ligand) were synthesized by self-assembly method and structurally characterized by different analytical and spectroscopic methods. Single-crystal X-ray diffraction showed that SCP 1 extend in three dimensions containing bore structure where the 3D- network is constructed via interweaving zigzag chains. The Cd atom coordinates to (O4N2) atoms forming distorted-octahedral configuration. The structure of SCP 2 extend down the projection of the b-axis creating parallel zigzag 1D-chains connected by μ2-O2 atoms and H-bonds forming a holodirected lead (II) hexagonal bi-pyramid configuration. SCP 2 extend to 3D-network via coordinate and hydrogen bonds. The thermal stability, photoluminescence properties, photocatalytic activity for the degradation of methylene blue dye (MB) under UV-irradiation and sunlight irradiation were also studied.

Characterization of Trinuclear Oxo Bridged Cobalt Complexes in Isolation

NASA Astrophysics Data System (ADS)

Lang, Johannes; Fries, Daniela V.; Niedner-Schatteburg, Gereon

2018-05-01

This study elucidates molecular structures, fragmentation pathways and relative stabilities of isolated trinuclear oxo bridged cobalt complexes of the structural type [Co3O(OAc)6(Py)n]+ (OAc=acetate, Py=pyridine, n=0, 1, 2, 3). We present infrared multiple photon dissociation (IR-MPD) spectra in combination with quantum chemical calculations. They indicate that the coordination of axial pyridine ligands to the [Co3O(OAc)6]+ subunit disturbs the triangular geometry of the Co3O core. [Co3O(OAc)6]+ exhibits a nearly equilateral triangular Co3O core geometry. The coordination of one or two pyridine ligands disturbs this arrangement resulting in isosceles triangular Co3O core geometries (in the cases of n=1 and 2). Coordination of three pyridine ligands (n=3) results in an equilateral triangular Co3O core geometry as in the case of n=0. Collision induced dissociation (CID) studies reveal that the complexes undergo a consecutive elimination of pyridine and acetate ligands with increasing excitation energy. Relative stabilities of the complexes decrease with the number of coordinated pyridine ligands. The presented results help to gain a fundamental insight into the molecular structure of trinuclear oxo bridged cobalt complexes void of any external effects such as crystal packing or solvation.

An alkaline tin(II) halide compound Na{sub 3}Sn{sub 2}F{sub 6}Cl: Synthesis, structure, and characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Pifu; University of the Chinese Academy of Sciences, Beijing 100049; Luo, Siyang

A new alkali tin(II) halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. This compound crystallizes trigonally in space group of R-3c (167), and processes a zero-dimensional (0D) structure consisted of Na{sup +} cations, Cl{sup −} anions and the isolated [SnF{sub 3}]{sup -} trigonal pyramids in which the stereochemically active 5s{sup 2} lone pair electrons are attached to the Sn{sup 2+} cations. Interestingly, the [SnF{sub 3}]{sup −} trigonal pyramids are parallel arranged in the a-b plane, while oppositely arranged in line with rotation along the c- axis. Moreover, the energy bandgap, thermal stability and electronic structure of Na{submore » 3}Sn{sub 2}F{sub 6}Cl are characterized and the results reveal that this compound has and indirect bandgap of 3.88 eV and is stable under 270 °C. - Graphical abstract: A zero-dimensional alkaline tin halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. Interestingly, both the anions and cations coordinating polyhedra exhibit order arranged with the [SnF{sub 3}]{sup -} trigonal pyramids rotating along the c- axis.« less

Dorsal CA1 interneurons contribute to acute stress-induced spatial memory deficits.

PubMed

Yu, Jing-Ying; Fang, Ping; Wang, Chi; Wang, Xing-Xing; Li, Kun; Gong, Qian; Luo, Ben-Yan; Wang, Xiao-Dong

2018-06-01

Exposure to severely stressful experiences disrupts the activity of neuronal circuits and impairs declarative memory. GABAergic interneurons coordinate neuronal network activity, but their involvement in stress-evoked memory loss remains to be elucidated. Here, we provide evidence that interneurons in area CA1 of the dorsal hippocampus partially modulate acute stress-induced memory deficits. In adult male mice, both acute forced swim stress and restraint stress impaired hippocampus-dependent spatial memory and increased the density of c-fos-positive interneurons in the dorsal CA1. Selective activation of dorsal CA1 interneurons by chemogenetics disrupted memory performance in the spatial object recognition task. In comparison, anxiety-related behavior, spatial working memory and novel object recognition memory remained intact when dorsal CA1 interneurons were overactivated. Moreover, chemogenetic activation of dorsal CA1 interneurons suppressed the activity of adjacent pyramidal neurons, whereas a single exposure to forced swim stress but not restraint stress increased the activity of CA1 pyramidal neurons. However, chemogenetic inhibition of dorsal CA1 interneurons led to spatial memory impairments and failed to attenuate acute stress-induced memory loss. These findings suggest that acute stress may overactivate interneurons in the dorsal CA1, which reduces the activity of pyramidal neurons and in turn disrupts long-term memory. Copyright © 2018 Elsevier Ltd. All rights reserved.

Euclid and Descartes: A Partnership.

ERIC Educational Resources Information Center

Wasdovich, Dorothy Hoy

1991-01-01

Presented is a method of reorganizing a high school geometry course to integrate coordinate geometry together with Euclidean geometry at an earlier stage in the course, thus enabling students to prove subsequent theorems from either perspective. Several examples contrasting different proofs from both perspectives are provided. (MDH)

Applications of several spectral techniques to characterize coordination compounds derived from 2,6-diacetylpyridine derivative

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Sharma, Amit Kumar

2009-09-01

The coordination compounds of Cr III, Mn II and Co II metal ions derived from quinquedentate 2,6-diacetylpyridine derivative have been synthesized and characterized by using the various physicochemical studies like stoichiometric, molar conductivity and magnetic, and spectral techniques like IR, NMR, mass, UV and EPR. The general stoichiometries of the complexes are found to be [Cr(H 2L)X] and [M(HL)X], where M = Mn(II) and Co(II); H 2L = dideprotonated ligand, HL = monodeprotonated ligand and X = NO 3-, Cl - and OAc -. The studies reveal that the complexes possess monomeric compositions with six coordinated octahedral geometry (Cr III and Mn II complexes) and six coordinated tetragonal geometry (Co II complexes).

Synthesis, crystal structure and properties of a new 3D supramolecular unsymmetrical tetradentate Schiff bases copper (II) framework with stable tunnels

NASA Astrophysics Data System (ADS)

Al-Noaimi, Mousa; Awwadi, Firas F.; Al-Razagg, Raiid; Esmadi, Fatima T.

2016-12-01

Flexible unsymmetrical Schiff base ligand (L) which is derived from the half unit Y = C6H5COCH2C(Ndbnd CH2C6H4NH2)CH3 (obtained from the reaction of benzoylacetone and 2-aminobenzylamine) and 2- quinolinecarboxaldehyde have been successfully co-assembled with Cu(ClO4)2 to give out the [Cu(L)]ClO4 complex. The complex crystallizes in two different space groups; P21/n and P-1. The crystal structure of the P-1 phase indicates the presence of tunnels; the volume of these tunnels is 157 Å3 which is big enough to accommodate solvent molecules. The X-ray data indicates that these tunnels are most probably filled by highly disordered solvent molecules or solvent molecules with partial occupancy. The tunneled structure is stabilized via π-π stacking interactions to give a supramolecular MOF with 1D rhomboidal tunnels array. The copper(II) atom assumes a distorted-square pyrimidal coordination geometry where the perchlorate is located on the apex of the pyramide. In addition, this work presents and discusses the spectroscopic (IR, UV/vis), electro-chemical (cyclic voltammetry) behavior of the Cu(II) complexes. The Cu(II) oxidation state is stabilized by the novel tetradentate ligands, showing Cu(I/II) couple around 0.1 vs. Cp2Fe/Cp2Fe+.

Synthesis, characterization and biocidal activities of heterobimetallic complexes having tin(IV) as a padlock

NASA Astrophysics Data System (ADS)

Husain, Ahmad; Nami, Shahab A. A.; Siddiqi, K. S.

2010-04-01

A mononuclear precursor complex, [(CH 3) 2Sn(tpdtc)] and several of its heterobimetallic derivatives of the type, [(CH 3) 2Sn(tpdtc)]MCl 2 have been synthesized by the simple addition reaction of transition metal chlorides, MCl 2· nH 2O where tpdtc = tetraethylenepentamine bis(dithiocarbamate) anion, M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II). The synthesized complexes have been systematically characterized by the physicochemical and spectroscopic techniques. A square-pyramidal geometry has been proposed for all the transition metal atoms with chloride ions occupying the axial while the three nitrogen atoms occupying the equatorial positions. A symmetrical bidentate coordination has been observed for the dithiocarbamato moiety leading to the formation of 18 member cavity. The thermal studies reveal that the mononuclear complex decomposes in three stages while its heterobimetallic analog exhibits a simple two-stage profile. The conductivity measurement data (1 mmol solution) implies a non-electrolytic behavior for all the complexes as evident by their low conductivity values obtained at room temperature. The heterobimetallic complexes have also been tested against the bacterial ( Escherichia coli and Pseudomonas aeruginosa) and antifungal strains ( Aspergillus niger and Fusarium oxysporum). All the complexes were found to be active against the test organisms and maximum activity was found for [(CH 3) 2Sn(tpdtc)]CuCl 2 complex.

Supramolecular architecture of metal-organic frameworks involving dinuclear copper paddle-wheel complexes.

PubMed

Gomathi, Sundaramoorthy; Muthiah, Packianathan Thomas

2013-12-15

The two centrosymmetric dinuclear copper paddle-wheel complexes tetrakis(μ-4-hydroxybenzoato-κ(2)O:O')bis[aquacopper(II)] dimethylformamide disolvate dihydrate, [Cu2(C7H5O3)4(H2O)2]·2C3H7NO·2H2O, (I), and tetrakis(μ-4-methoxybenzoato-κ(2)O:O')bis[(dimethylformamide-κO)copper(II)], [Cu2(C8H7O3)4(C3H7NO)2], (II), crystallize with half of the dinuclear paddle-wheel cage unit in the asymmetric unit and, in addition, complex (I) has one dimethylformamide (DMF) and one water solvent molecule in the asymmetric unit. In both (I) and (II), two Cu(II) ions are bridged by four syn,syn-η(1):η(1):μ carboxylate groups, showing a paddle-wheel cage-type structure with a square-pyramidal coordination geometry. The equatorial positions of (I) and (II) are occupied by the carboxylate groups of 4-hydroxy- and 4-methoxybenzoate ligands, and the axial positions are occupied by aqua and DMF ligands, respectively. The three-dimensional supramolecular metal-organic framework of (I) consists of three different R2(2)(20) and an R4(4)(36) ring motif formed via O-H···O and OW-HW···O hydrogen bonds. Complex (II) simply packs as molecular species.

Scaffolded DNA origami of a DNA tetrahedron molecular container.

PubMed

Ke, Yonggang; Sharma, Jaswinder; Liu, Minghui; Jahn, Kasper; Liu, Yan; Yan, Hao

2009-06-01

We describe a strategy of scaffolded DNA origami to design and construct 3D molecular cages of tetrahedron geometry with inside volume closed by triangular faces. Each edge of the triangular face is approximately 54 nm in dimension. The estimated total external volume and the internal cavity of the triangular pyramid are about 1.8 x 10(-23) and 1.5 x 10(-23) m(3), respectively. Correct formation of the tetrahedron DNA cage was verified by gel electrophoresis, atomic force microscopy, transmission electron microscopy, and dynamic light scattering techniques.

Consensus structures of the Mo(v) sites of sulfite-oxidizing enzymes derived from variable frequency pulsed EPR spectroscopy, isotopic labelling and DFT calculations.

PubMed

Enemark, John H

2017-10-10

Sulfite-oxidizing enzymes from eukaryotes and prokaryotes have five-coordinate distorted square-pyramidal coordination about the molybdenum atom. The paramagnetic Mo(v) state is easily generated, and over the years four distinct CW EPR spectra have been identified, depending upon enzyme source and the reaction conditions, namely high and low pH (hpH and lpH), phosphate inhibited (P i ) and sulfite (or blocked). Extensive studies of these paramagnetic forms of sulfite-oxidizing enzymes using variable frequency pulsed electron spin echo (ESE) spectroscopy, isotopic labeling and density functional theory (DFT) calculations have led to the consensus structures that are described here. Errors in some of the previously proposed structures are corrected.

Disclosure of key stereoelectronic factors for efficient H2 binding and cleavage in the active site of [NiFe]-hydrogenases.

PubMed

Bruschi, Maurizio; Tiberti, Matteo; Guerra, Alessandro; De Gioia, Luca

2014-02-05

A comparative analysis of a series of DFT models of [NiFe]-hydrogenases, ranging from minimal NiFe clusters to very large systems including both the first and second coordination sphere of the bimetallic cofactor, was carried out with the aim of unraveling which stereoelectronic properties of the active site of [NiFe]-hydrogenases are crucial for efficient H2 binding and cleavage. H2 binding to the Ni-SIa redox state is energetically favored (by 4.0 kcal mol(-1)) only when H2 binds to Ni, the NiFe metal cluster is in a low spin state, and the Ni cysteine ligands have a peculiar seesaw coordination geometry, which in the enzyme is stabilized by the protein environment. The influence of the Ni coordination geometry on the H2 binding affinity was then quantitatively evaluated and rationalized analyzing frontier molecular orbitals and populations. Several plausible reaction pathways leading to H2 cleavage were also studied. It turned out that a two-step pathway, where H2 cleavage takes place on the Ni-SIa redox state of the enzyme, is characterized by very low reaction barriers and favorable reaction energies. More importantly, the seesaw coordination geometry of Ni was found to be a key feature for facile H2 cleavage. The discovery of the crucial influence of the Ni coordination geometry on H2 binding and activation in the active site of [NiFe]-hydrogenases could be exploited in the design of novel biomimetic synthetic catalysts.

The Generation of Three-Dimensional Body-Fitted Coordinate Systems for Viscous Flow Problems.

DTIC Science & Technology

1982-07-01

Geometries," NASA TM X-3206, 1975. iq p] Papers Written Under The Contract 1. "Basic Differential Models For Coordinate Generation ", Z . U. A. Warsi...8217 Ii (C) (4’) p Figure 1. Coordinate Surfaces fr. I • BASIC DIFFERENTIAL MODELS FOR COORDINATE GENERATION Z . U. A. WARSI* Department of Aerospace

Geometry with Coordinates, Student's Text, Part II, Unit 48. Revised Edition.

ERIC Educational Resources Information Center

Allen, Frank B.; And Others

This is part two of a two-part SMSG geometry text for high school students. One of the goals of the text is the development of analytic geometry hand-in-hand with synthetic geometry. The authors emphasize that both are deductive systems and that it is useful to have more than one mode of attack in solving problems. The text begins the development…

Influence of biphenyl spacer appended to the flexible phosphonate arms in modulating the dimensionality of the coordination polymers: Synthesis, structural chemistry and magnetic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripuramallu, Bharat Kumar; Das, Samar K., E-mail: skdsc@uohyd.ernet.in

2013-01-15

Two new compounds [Co (2,2 Prime -bipy) (H{sub 2}dbp)]{sub n} (1) and [Ni (2,2 Prime -bipy){sub 2}(H{sub 2}dbp)(H{sub 2}O)]{center_dot}H{sub 2}O (2) based on the flexible ligand 4,4 Prime -dimethylenebiphenyldiphosphonic acid (H{sub 4}dbp) with 2,2 Prime -bipyridine as secondary ligand have been synthesized under hydrothermal conditions. Both the compounds are well characterized by routine elemental analysis, IR, electronic spectroscopies, thermogravimetric analysis and finally by single crystal X-ray diffraction analysis. Compound 1 is a 1D extended coordination polymer and 2 is a discrete molecular compound. A comparative study between the geometries of H{sub 4}dbp ligand (in compounds 1 and 2, present study)more » and p-xylylenediphosphonic acid (H{sub 4}pxp) ligand (in previously reported compounds [Cu(2,2 Prime -bipy)(H{sub 2}pxp)]{center_dot}nH{sub 2}O (1A) and Ni(2,2 Prime -bipy){sub 2}H{sub 4}pxp]{sub n}[H{sub 2}pxp]{sub n} (2A), see text) demonstrate the effect of the twisting in the benzene rings in changing higher dimensional H{sub x}pxp (x refers to number of protonated hydroxyl groups) compounds to lower dimensional H{sub x}dbp compounds. The eight membered Co-dimer rings formed in compound 1 represents the simple and isolated Co-dimer, exhibiting weak antiferromagnetic exchange between metal centers through OPO bridges. - Graphical abstract: Two new compounds based on the dimethylenebiphenyldiphosphonic acid have been synthesized. The effect of twisting of benzene rings in the biphenyl spacer containing multidentate ligands alters dimensionality of final compounds. Highlights: Black-Right-Pointing-Pointer Cobalt containing coordination polymer and a nickel discrete compound have been synthesized. Black-Right-Pointing-Pointer Flexible ligand 4,4'-dimethylenebiphenyldiphosphonic acid has been employed. Black-Right-Pointing-Pointer Co(II) and Ni(II) ions are square pyramidal and octahedral respectively. Black-Right-Pointing-Pointer The effect of the twisting in the benzene rings in the associated ligand has been demonstrated.« less

Synthesis, structure, and DNA cleavage properties of copper(II) complexes of 1,4,7-triazacyclononane ligands featuring pairs of guanidine pendants.

PubMed

Tjioe, Linda; Joshi, Tanmaya; Brugger, Joël; Graham, Bim; Spiccia, Leone

2011-01-17

Two new ligands, L(1) and L(2), have been prepared via N-functionalization of 1,4,7-triazacyclononane (tacn) with pairs of ethyl- or propyl-guanidine pendants, respectively. The X-ray crystal structure of [CuL(1)](ClO4)2 (C1) isolated from basic solution (pH 9) indicates that a secondary amine nitrogen from each guanidine pendants coordinates to the copper(II) center in addition to the nitrogen atoms in the tacn macrocycle, resulting in a five-coordinate complex with intermediate square-pyramidal/trigonal bipyramidal geometry. The guanidines adopt an unusual coordination mode in that their amine nitrogen nearest to the tacn macrocycle binds to the copper(II) center, forming very stable five-membered chelate rings. A spectrophotometric pH titration established the pK(app) for the deprotonation and coordination of each guanidine group to be 3.98 and 5.72, and revealed that [CuL(1)](2+) is the only detectable species present in solution above pH ∼ 8. The solution speciation of the CuL(2) complex (C2) is more complex, with at least 5 deprotonation steps over the pH range 4-12.5, and mononuclear and binuclear complexes coexisting. Analysis of the spectrophotometric data provided apparent deprotonation constants, and suggests that solutions at pH ∼ 7.5 contain the maximum proportion of polynuclear complexes. Complex C1 exhibits virtually no cleavage activity toward the model phosphate diesters, bis(p-nitrophenyl)phosphate (BNPP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNPP), while C2 exhibits moderate activity. For C2, the respective kobs values measured at pH 7.0 (7.24 (± 0.08) × 10(-5) s(-1) (BNPP at 50 °C) and 3.2 (± 0.3) × 10(-5) s(-1) (HPNPP at 25 °C)) are 40- and 10-times faster than [Cu(tacn)(OH2)2](2+) complex. Both complexes cleave supercoiled pBR 322 plasmid DNA, indicating that the guanidine pendants of [CuL(1)](2+) may have been displaced from the copper coordination sphere to allow for DNA binding and subsequent cleavage. The rate of DNA cleavage by C2 is twice that measured for [Cu(tacn)(OH2)2](2+), suggesting some degree of cooperativity between the copper center and guanidinium pendants in the hydrolysis of the phosphate ester linkages of DNA. A predominantly hydrolytic cleavage mechanism was confirmed through experiments performed either in the presence of various radical scavengers or under anaerobic conditions.

Principles of disaster management lesson. 12: structuring organizations.

PubMed

Cuny, F C

2001-01-01

This lesson discusses various structures for organizations that have functional roles in disaster responses, relief, and/or management activities. It distinguishes between pyramidal and matrix structures, and notes the advantages and disadvantages of each in relation to disasters. Span of control issues are dissected including the impact of the "P" factor on the performance of disaster managers and workers including its relationship to the coordination and control function. The development of a Table of Organization and how it relates to departmentalization within an organization also is provided.

Zinc ascorbate: a combined experimental and computational study for structure elucidation

NASA Astrophysics Data System (ADS)

Ünaleroǧlu, C.; Zümreoǧlu-Karan, B.; Mert, Y.

2002-03-01

The structure of Zn(HA)2·4H2O (HA=ascorbate) has been examined by a number of techniques (13C NMR, 1H NMR, IR, EI/MS and TGA) and also modeled by the semi-empirical PM3 method. The experimental and computational results agreed on a five-fold coordination around Zn(II) where one ascorbate binds monodentately, the other bidentately and two water molecules occupy the remaining sites of a distorted square pyramid.

Trumpet slices in Kerr spacetimes.

PubMed

Dennison, Kenneth A; Baumgarte, Thomas W; Montero, Pedro J

2014-12-31

We introduce a new time-independent family of analytical coordinate systems for the Kerr spacetime representing rotating black holes. We also propose a (2+1)+1 formalism for the characterization of trumpet geometries. Applying this formalism to our new family of coordinate systems we identify, for the first time, analytical and stationary trumpet slices for general rotating black holes, even for charged black holes in the presence of a cosmological constant. We present results for metric functions in this slicing and analyze the geometry of the rotating trumpet surface.

Behavior-dependent specialization of identified hippocampal interneurons

PubMed Central

Lapray, Damien; Lasztoczi, Balint; Lagler, Michael; Viney, Tim James; Katona, Linda; Valenti, Ornella; Hartwich, Katja; Borhegyi, Zsolt; Somogyi, Peter; Klausberger, Thomas

2012-01-01

A large variety of GABAergic interneurons control information processing in hippocampal circuits governing the formation of neuronal representations. Whether distinct hippocampal interneuron types contribute differentially to information-processing during behavior is not known. We employed a novel technique for recording and labeling interneurons and pyramidal cells in drug-free, freely-moving rats. Recorded parvalbumin-expressing basket interneurons innervate somata and proximal pyramidal cell dendrites, whereas nitric-oxide-synthase- and neuropeptide-Y-expressing ivy cells provide synaptic and extrasynaptic dendritic modulation. Basket and ivy cells showed distinct spike timing dynamics, firing at different rates and times during theta and ripple oscillations. Basket but not ivy cells changed their firing rates during movement, sleep and quiet wakefulness, suggesting that basket cells coordinate cell assemblies in a behavioral state-contingent manner, whereas persistently-firing ivy cells might control network excitability and homeostasis. Different interneuron types provide GABA to specific subcellular domains at defined times and rates, thus differentially controlling network activity during behavior. PMID:22864613

Sleep and Movement Differentiates Actions of Two Types of Somatostatin-Expressing GABAergic Interneuron in Rat Hippocampus

PubMed Central

Katona, Linda; Lapray, Damien; Viney, Tim J.; Oulhaj, Abderrahim; Borhegyi, Zsolt; Micklem, Benjamin R.; Klausberger, Thomas; Somogyi, Peter

2014-01-01

Summary Neuropeptides acting on pre- and postsynaptic receptors are coreleased with GABA by interneurons including bistratified and O-LM cells, both expressing somatostatin but innervating segregated dendritic domains of pyramidal cells. Neuropeptide release requires high-frequency action potentials, but the firing patterns of most peptide/GABA-releasing interneurons during behavior are unknown. We show that behavioral and network states differentiate the activities of bistratified and O-LM cells in freely moving rats. Bistratified cells fire at higher rates during sleep than O-LM cells and, unlike O-LM cells, strongly increase spiking during sharp wave-associated ripples (SWRs). In contrast, O-LM interneurons decrease firing during sleep relative to awake states and are mostly inhibited during SWRs. During movement, both cell types fire cooperatively at the troughs of theta oscillations but with different frequencies. Somatostatin and GABA are differentially released to distinct dendritic zones of CA1 pyramidal cells during sleep and wakefulness to coordinate segregated glutamatergic inputs from entorhinal cortex and CA3. PMID:24794095

Prefrontal Parvalbumin Neurons in Control of Attention

PubMed Central

Kim, Hoseok; Ährlund-Richter, Sofie; Wang, Xinming; Deisseroth, Karl; Carlén, Marie

2016-01-01

Summary While signatures of attention have been extensively studied in sensory systems, the neural sources and computations responsible for top-down control of attention are largely unknown. Using chronic recordings in mice, we found that fast-spiking parvalbumin (FS-PV) interneurons in medial prefrontal cortex (mPFC) uniformly show increased and sustained firing during goal-driven attentional processing, correlating to the level of attention. Elevated activity of FS-PV neurons on the timescale of seconds predicted successful execution of behavior. Successful allocation of attention was characterized by strong synchronization of FS-PV neurons, increased gamma oscillations, and phase locking of pyramidal firing. Phase-locked pyramidal neurons showed gamma-phase-dependent rate modulation during successful attentional processing. Optogenetic silencing of FS-PV neurons deteriorated attentional processing, while optogenetic synchronization of FS-PV neurons at gamma frequencies had pro-cognitive effects and improved goal-directed behavior. FS-PV neurons thus act as a functional unit coordinating the activity in the local mPFC circuit during goal-driven attentional processing. PMID:26771492

Biangular Coordinates Redux: Discovering a New Kind of Geometry

ERIC Educational Resources Information Center

Winkel, Brian; Naylor, Michael

2010-01-01

Biangular coordinates specify a point on the plane by two angles giving the intersection of two rays emanating from two fixed poles. This is a dual of Cartesian coordinates wherein a point on the plane is described by two distances. Biangular coordinates, first written about in 1803 in France, were subsequently studied in Britain at the end of the…

Proof in Transformation Geometry

ERIC Educational Resources Information Center

Bell, A. W.

1971-01-01

The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

Crystal structure of bis­(μ-N-hy­droxy­picolin­amid­ato)bis­[bis­(N-hy­droxy­picolinamide)­sodium

PubMed Central

Safyanova, Inna S.; Ohui, Kateryna A.; Omelchenko, Irina V.

2017-01-01

The title compound, [Na2(C6H5N2O2)2(C6H6N2O2)4], is a centrosymmetric coordination dimer based on the sodium(I) salt of N-hy­droxy­picolinamide. The mol­ecule has an {Na2O6(μ-O)2} core with two bridging carbonyl O atoms and two hydroxamate O atoms of two mono-deprotonated residues of N-hy­droxy­picolinamide, while two neutral N-hy­droxy­picolinamide mol­ecules are coordinated in a monodentate manner to each sodium ion via the carbonyl O atoms [the Na—O distances range from 2.3044 (2) to 2.3716 (2) Å]. The penta­coordinated sodium ion exhibits a distorted trigonal–pyramidal coordination polyhedron. In the crystal, the coordination dimers are linked into chains along the c axis via N—H⋯O and N—H⋯N hydrogen bonds; the chains are linked into a two-dimensional framework parallel to (100) via weak C—H⋯O and π–π stacking inter­actions. PMID:28083127

Improvement of the recombination and infrared light losses by rear surface chemical polishing in silicon heterojunction solar cells

NASA Astrophysics Data System (ADS)

Yang, Xueliang; Zhang, Yi; Li, Feng; Sun, Yun

2017-06-01

Rear surface chemical polishing (RSCP) was investigated for the improvement of the internal reflection and surface passivation of heterojunction solar cells with intrinsic thin layers (HIT). The HIT solar cells without or with RSCP treatment were prepared by plasma-enhanced chemical vapor deposition and physical vapor deposition techniques. Scanning electron microscopy results showed that rounding of the spires and V-groove bottom of the pyramid as well as smoothing of incline surface of the pyramid were achieved. These effects would decrease the loss of infrared light transmittance and interface recombination at the rear surface of the cells. To experimentally corroborate these two points, two special geometries, ITO/c-Si/hydrogenated amorphous silicon (a-Si:H)/ITO and a-Si:H/c-Si/a-Si:H, were introduced as a test of the reflectance/transmittance spectra and the minority carrier lifetime. Weakened transmittance and enhanced lifetime were observed for the sample with RSCP, which are responsible for the improvement of J sc and V oc, respectively. Therefore, RSCP is a promising candidate for improving the performance of HIT solar cells.

Surface fitting three-dimensional bodies

NASA Technical Reports Server (NTRS)

Dejarnette, F. R.

1974-01-01

The geometry of general three-dimensional bodies is generated from coordinates of points in several cross sections. Since these points may not be smooth, they are divided into segments and general conic sections are curve fit in a least-squares sense to each segment of a cross section. The conic sections are then blended in the longitudinal direction by fitting parametric cubic-spline curves through coordinate points which define the conic sections in the cross-sectional planes. Both the cross-sectional and longitudinal curves may be modified by specifying particular segments as straight lines and slopes at selected points. Slopes may be continuous or discontinuous and finite or infinite. After a satisfactory surface fit has been obtained, cards may be punched with the data necessary to form a geometry subroutine package for use in other computer programs. At any position on the body, coordinates, slopes and second partial derivatives are calculated. The method is applied to a blunted 70 deg delta wing, and it was found to generate the geometry very well.

Crystal structure and high-temperature properties of the Ruddlesden–Popper phases Sr{sub 3−x}Y{sub x}(Fe{sub 1.25}Ni{sub 0.75})O{sub 7−δ} (0≤x≤0.75)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samain, Louise; Amshoff, Philipp; Biendicho, Jordi J.

2015-07-15

Ruddlesden–Popper n=2 member phases Sr{sub 3−x}Y{sub x}Fe{sub 1.25}Ni{sub 0.75}O{sub 7−δ}, 0≤x≤0.75, have been investigated by X-ray and neutron powder diffraction, thermogravimetry and Mössbauer spectroscopy. Both samples as-prepared at 1300 °C under N{sub 2}(g) flow and samples subsequently air-annealed at 900 °C were studied. The as-prepared x=0.75 phase is highly oxygen deficient with δ=1, the O1 atom site being vacant, and the Fe{sup 3+}/Ni{sup 2+} ions having a square pyramidal coordination. For as-prepared phases with lower x values, the Mössbauer spectral data are in good agreement with the presence of both 5- and 4-coordinated Fe{sup 3+} ions, implying in addition amore » partial occupancy of the O3 atom sites that form the basal plane of the square pyramid. The air-annealed x=0.75 sample has a δ value of 0.61(1) and the structure has Fe/Ni ions in both square pyramids and octahedra. Mössbauer spectroscopy shows the phase to contain only Fe{sup 3+}, implying that all Ni is present as Ni{sup 3+}. Air-annealed phases with lower x values are found to contain both Fe{sup 3+} and Fe{sup 4+}. For both the as-prepared and the air-annealed samples, the Y{sup 3+} cations are found to be mainly located in the perovskite block. The high-temperature thermal expansion of as-prepared and air-annealed x=0.75 phases were investigated by high-temperature X-ray diffraction and dilatometry and the linear thermal expansion coefficient determined to be 14.4 ppm K{sup −1}. Electrical conductivity measurements showed that the air-annealed samples have higher conductivity than the as-prepared ones. - Highlights: • Ruddlesden–Popper, n=2, Sr{sub 3−x}Y{sub x}Fe{sub 1.25}Ni{sub 0.75}O{sub 7−δ}, 0≤x≤0.75, have been synthesised. • The crystal structures of the phases have been determined. • Sr{sub 2.25}Y{sub 0.75}Fe{sub 1.25}Ni{sub 0.75}O{sub 6}, made in N{sub 2}(g) has Fe{sup 3+}/Ni{sup 2+} in square pyramides. • Sr{sub 2.25}Y{sub 0.75}Fe{sub 1.25}Ni{sub 0.75}O{sub 6.4}, made in air has Fe{sup 3+}/Ni{sup 3+} in square pyramides and octahedra. • Air annealed samples have higher electrical conductivity than N{sub 2}(g) annealed.« less

Conformational Preference and Donor Atom Interaction Leading to Hexacoordination vs Pentacoordination in Bicyclic Tetraoxyphosphoranes(1).

PubMed

Sherlock, David J.; Chandrasekaran, A.; Prakasha, T. K.; Day, Roberta O.; Holmes, Robert R.

1998-01-12

New bicyclic tetraoxyphosphoranes all containing a six-membered oxaphosphorinane ring, C(6)H(8)(CH(2)O)(2)P(OC(12)H(8))(OXyl) (1), (C(6)H(4)O)(2)P(OC(12)H(8))(OXyl) (2), CH(2)[(t-Bu)(2)C(6)H(2)O](2)P(OC(12)H(8))(OXyl) (3), O(2)S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (4), and S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (5), were synthesized by the oxidative addition reaction of the cyclic phosphine P(OC(12)H(8))(OXyl) (6) with an appropriate diol in the presence of N-chlorodiisopropylamine. X-ray analysis revealed trigonal bipyramidal (TBP) geometries for 1-4 where the dioxa ring varied in size from six- to eight-membered. With a sulfur donor atom as part of an eight-membered ring in place of a potential oxygen donor atom of a sulfone group as in 4, the X-ray study of 5 showed the formation of a hexacoordinated structure via a P-S interaction. Ring constraints are evaluated to give an order of conformational flexibility associated with the (TBP) tetraoxyphosphoranes 4 > 3 approximately 1 > 2 which parallels the degree of shielding from (31)P NMR chemical shifts: 4 > 3 > 1 > 2. The six- and seven-membered dioxa rings in 1 and 2, respectively, are positioned at axial-equatorial sites, whereas the eight-membered dioxa ring in 3 and 4 occupies diequatorial sites of a TBP. V-T (1)H NMR data give barriers to xylyl group rotation about the C-OXyl bond. The geometry of 5 is located along a coordinate from square pyramidal toward octahedral to the extent of 60.7%. Achieving hexacoordination in bicyclic tetraoxyphosphoranes of reduced electrophilicity relative to bicyclic pentaoxyphosphoranes appears to be dependent on the presence of a sufficiently strong donor atom.

Connective Tissue Characteristics around Healing Abutments of Different Geometries: New Methodological Technique under Circularly Polarized Light.

PubMed

Delgado-Ruiz, Rafael Arcesio; Calvo-Guirado, Jose Luis; Abboud, Marcus; Ramirez-Fernandez, Maria Piedad; Maté-Sánchez de Val, José Eduardo; Negri, Bruno; Gomez-Moreno, Gerardo; Markovic, Aleksa

2015-08-01

To describe contact, thickness, density, and orientation of connective tissue fibers around healing abutments of different geometries by means of a new method using coordinates. Following the bilateral extraction of mandibular premolars (P2, P3, and P4) from six fox hound dogs and a 2-month healing period, 36 titanium implants were inserted, onto which two groups of healing abutments of different geometry were screwed: Group A (concave abutments) and Group B (wider healing abutment). After 3 months the animals were sacrificed and samples extracted containing each implant and surrounding soft and hard tissues. Histological analysis was performed without decalcifying the samples by means of circularly polarized light under optical microscope and a system of vertical and horizontal coordinates across all the connective tissue in an area delimited by the implant/abutment, epithelium, and bone tissue. In no case had the connective tissue formed a connection to the healing abutment/implant in the internal zone; a space of 35 ± 10 μm separated the connective tissue fibers from the healing abutment surface. The total thickness of connective tissue in the horizontal direction was significantly greater in the medial zone in Group B than in Group A (p < .05). The orientation of the fibers varied according to the coordinate area so that internal coordinates showed a higher percentage of parallel fibers in Group A (p < .05) and a higher percentage of oblique fibers in Group B (p < .05); medial coordinates showed more oblique fibers (p < .05); and the area of external coordinates showed the highest percentage of perpendicular fibers (p < .05). The fiber density was higher in the basal and medial areas (p < .05). Abutment geometry influences the orientation of collagen fibers; therefore, an abutment with a profile wider than the implant platform favors oblique and perpendicular orientation of collagen fibers and greater connective tissue thickness. © 2013 Wiley Periodicals, Inc.

Metal-centred azaphosphatriptycene gear with a photo- and thermally driven mechanical switching function based on coordination isomerism.

PubMed

Ube, Hitoshi; Yasuda, Yoshihiro; Sato, Hiroyasu; Shionoya, Mitsuhiko

2017-02-08

Metal ions can serve as a centre of molecular motions due to their coordination geometry, reversible bonding nature and external stimuli responsiveness. Such essential features of metal ions have been utilized for metal-mediated molecular machines with the ability to motion switch via metallation/demetallation or coordination number variation at the metal centre; however, motion switching based on the change in coordination geometry remain largely unexplored. Herein, we report a Pt II -centred molecular gear that demonstrates control of rotor engagement and disengagement based on photo- and thermally driven cis-trans isomerization at the Pt II centre. This molecular rotary motion transmitter has been constructed from two coordinating azaphosphatriptycene rotators and one Pt II ion as a stator. Isomerization between an engaged cis-form and a disengaged trans-form is reversibly driven by ultraviolet irradiation and heating. Such a photo- and thermally triggered motional interconversion between engaged/disengaged states on a metal ion would provide a selector switch for more complex interlocking systems.

Electronic structure and reactivity of three-coordinate iron complexes.

PubMed

Holland, Patrick L

2008-08-01

[Reaction: see text]. The identity and oxidation state of the metal in a coordination compound are typically thought to be the most important determinants of its reactivity. However, the coordination number (the number of bonds to the metal) can be equally influential. This Account describes iron complexes with a coordination number of only three, which differ greatly from iron complexes with octahedral (six-coordinate) geometries with respect to their magnetism, electronic structure, preference for ligands, and reactivity. Three-coordinate complexes with a trigonal-planar geometry are accessible using bulky, anionic, bidentate ligands (beta-diketiminates) that steer a monodentate ligand into the plane of their two nitrogen donors. This strategy has led to a variety of three-coordinate iron complexes in which iron is in the +1, +2, and +3 oxidation states. Systematic studies on the electronic structures of these complexes have been useful in interpreting their properties. The iron ions are generally high spin, with singly occupied orbitals available for pi interactions with ligands. Trends in sigma-bonding show that iron(II) complexes favor electronegative ligands (O, N donors) over electropositive ligands (hydride). The combination of electrostatic sigma-bonding and the availability of pi-interactions stabilizes iron(II) fluoride and oxo complexes. The same factors destabilize iron(II) hydride complexes, which are reactive enough to add the hydrogen atom to unsaturated organic molecules and to take part in radical reactions. Iron(I) complexes use strong pi-backbonding to transfer charge from iron into coordinated alkynes and N 2, whereas iron(III) accepts charge from a pi-donating imido ligand. Though the imidoiron(III) complex is stabilized by pi-bonding in the trigonal-planar geometry, addition of pyridine as a fourth donor weakens the pi-bonding, which enables abstraction of H atoms from hydrocarbons. The unusual bonding and reactivity patterns of three-coordinate iron compounds may lead to new catalysts for oxidation and reduction reactions and may be used by nature in transient intermediates of nitrogenase enzymes.

{μ-2-[(3-Amino-2,2-dimethyl-prop-yl)imino-meth-yl]-6-meth-oxy-phenolato-1:2κ(5)O(1),O(6):N,N',O(1)}{2-[(3-amino-2,2-dimethyl-prop-yl)imino-meth-yl]-6-meth-oxy-phenolato-1κ(3)N,N',O(1)}-μ-azido-1:2κ(2)N:N-azido-2κN-methanol-2κO-dinickel(II).

PubMed

Ghaemi, Akbar; Rayati, Saeed; Fayyazi, Kazem; Ng, Seik Weng; Tiekink, Edward R T

2012-08-01

Two distinct coordination geometries are found in the binuclear title complex, [Ni(2)(C(13)H(19)N(2)O(2))(2)(N(3))(2)(CH(3)OH)], as one Schiff base ligand is penta-dentate, coordinating via the anti-cipated oxide O, imine N and amine N atoms (as for the second, tridentate, ligand) but the oxide O is bridging and coordination also occurs through the meth-oxy O atom. The Ni(II) atoms are linked by a μ(2)-oxide atom and one end of a μ(2)-azide ligand, forming an Ni(2)ON core. The coordination geometry for the Ni(II) atom coordinated by the tridentate ligand is completed by the meth-oxy O atom derived from the penta-dentate ligand, with the resulting N(3)O(3) donor set defining a fac octa-hedron. The second Ni(II) atom has its cis-octa-hedral N(4)O(2) coordination geometry completed by the imine N and amine N atoms of the penta-dentate Schiff base ligand, a terminally coordinated azide N and a methanol O atom. The arrangement is stabilized by an intra-molecular hydrogen bond between the methanol H and the oxide O atom. Linear supra-molecular chains along the a axis are formed in the crystal packing whereby two amine H atoms from different amine atoms hydrogen bond to the terminal N atom of the monodentate azide ligand.

A three-dimensional potential-flow program with a geometry package for input data generation

NASA Technical Reports Server (NTRS)

Halsey, N. D.

1978-01-01

Information needed to run a computer program for the calculation of the potential flow about arbitrary three dimensional lifting configurations is presented. The program contains a geometry package which greatly reduces the task of preparing the input data. Starting from a very sparse set of coordinate data, the program automatically augments and redistributes the coordinates, calculates curves of intersection between components, and redistributes coordinates in the regions adjacent to the intersection curves in a suitable manner for use in the potential flow calculations. A brief summary of the program capabilities and options is given, as well as detailed instructions for the data input, a suggested structure for the program overlay, and the output for two test cases.

Synthesis and decomposition of a novel carboxylate precursor to indium oxide

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Andras, Maria T.; Duraj, Stan A.; Clark, Eric B.; Hehemann, David G.; Scheiman, Daniel A.; Fanwick, Phillip E.

1994-01-01

Reaction of metallic indium with benzoyl peroxide in 4-1 methylpyridine (4-Mepy) at 25 C produces an eight-coordinate mononuclear indium(III) benzoate, In(eta(sup 2)-O2CC6H5)3(4-Mepy)2 4H2O (I), in yields of up to 60 percent. The indium(III) benzoate was fully characterized by elemental analysis, spectroscopy, and X-ray crystallography; (I) exists in the crystalline state as discrete eight-coordinate molecules; the coordination sphere around the central indium atom is best described as pseudo-square pyramidal. Thermogravimetric analysis of (I) and X-ray diffraction powder studies on the resulting pyrolysate demonstrate that this new benzoate is an inorganic precursor to indium oxide. Decomposition of (I) occurs first by loss of 4-methylpyridine ligands (100 deg-200 deg C), then loss of benzoates with formation of In2O3 at 450 C. We discuss both use of carboxylates as precursors and our approach to their preparation.

Molecular Basis of the Bohr Effect in Arthropod Hemocyanin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirota, S.; Kawahara, T; Beltramini, M

2008-01-01

Flash photolysis and K-edge x-ray absorption spectroscopy (XAS) were used to investigate the functional and structural effects of pH on the oxygen affinity of three homologous arthropod hemocyanins (Hcs). Flash photolysis measurements showed that the well-characterized pH dependence of oxygen affinity (Bohr effect) is attributable to changes in the oxygen binding rate constant, kon, rather than changes in koff. In parallel, coordination geometry of copper in Hc was evaluated as a function of pH by XAS. It was found that the geometry of copper in the oxygenated protein is unchanged at all pH values investigated, while significant changes were observedmore » for the deoxygenated protein as a function of pH. The interpretation of these changes was based on previously described correlations between spectral lineshape and coordination geometry obtained for model compounds of known structure A pH-dependent change in the geometry of cuprous copper in the active site of deoxyHc, from pseudotetrahedral toward trigonal was assigned from the observed intensity dependence of the 1s ? 4pz transition in x-ray absorption near edge structure (XANES) spectra. The structural alteration correlated well with increase in oxygen affinity at alkaline pH determined in flash photolysis experiments. These results suggest that the oxygen binding rate in deoxyHc depends on the coordination geometry of Cu(I) and suggest a structural origin for the Bohr effect in arthropod Hcs.« less

Electronic structure and spectroscopic properties of mononuclear manganese(III) Schiff base complexes: a systematic study on [Mn(acen)X] complexes by EPR, UV/vis, and MCD spectroscopy (X = Hal, NCS).

PubMed

Westphal, Anne; Klinkebiel, Arne; Berends, Hans-Martin; Broda, Henning; Kurz, Philipp; Tuczek, Felix

2013-03-04

The manganese(III) Schiff base complexes [Mn(acen)X] (H2acen: N,N'-ethylenebis(acetylacetone)imine, X: I(-), Br(-), Cl(-), NCS(-)) are considered as model systems for a combined study of the electronic structure using vibrational, UV/vis absorption, parallel-mode electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectroscopy. By variation of the co-ligand X, the influence of the axial ligand field within a given square-pyramidal coordination geometry on the UV/vis, EPR, and MCD spectra of the title compounds is investigated. Between 25000 and 35000 cm(-1), the low-temperature MCD spectra are dominated by two very intense, oppositely signed pseudo-A terms, referred to as "double pseudo-A terms", which change their signs within the [Mn(acen)X] series dependent on the axial ligand X. Based on molecular orbital (MO) and symmetry considerations, these features are assigned to π(n.b.)(s, a) → yz, z(2) ligand-to-metal charge transfer transitions. The individual MCD signs are directly determined from the calculated MOs of the [Mn(acen)X] complexes. The observed sign change is explained by an inversion of symmetry among the π(n.b.)(s, a) donor orbitals which leads to an interchange of the positive and negative pseudo-A terms constituting the "double pseudo-A term".

Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite: II. XANES analysis and simulation

USGS Publications Warehouse

Waychunas, G.A.; Fuller, C.C.; Davis, J.A.; Rehr, J.J.

2003-01-01

X-ray absorption near-edge spectroscopy (XANES) analysis of sorption complexes has the advantages of high sensitivity (10- to 20-fold greater than extended X-ray absorption fine structure [EXAFS] analysis) and relative ease and speed of data collection (because of the short k-space range). It is thus a potentially powerful tool for characterization of environmentally significant surface complexes and precipitates at very low surface coverages. However, quantitative analysis has been limited largely to "fingerprint" comparison with model spectra because of the difficulty of obtaining accurate multiple-scattering amplitudes for small clusters with high confidence. In the present work, calculations of the XANES for 50- to 200-atom clusters of structure from Zn model compounds using the full multiple-scattering code Feff 8.0 accurately replicate experimental spectra and display features characteristic of specific first-neighbor anion coordination geometry and second-neighbor cation geometry and number. Analogous calculations of the XANES for small molecular clusters indicative of precipitation and sorption geometries for aqueous Zn on ferrihydrite, and suggested by EXAFS analysis, are in good agreement with observed spectral trends with sample composition, with Zn-oxygen coordination and with changes in second-neighbor cation coordination as a function of sorption coverage. Empirical analysis of experimental XANES features further verifies the validity of the calculations. The findings agree well with a complete EXAFS analysis previously reported for the same sample set, namely, that octahedrally coordinated aqueous Zn2+ species sorb as a tetrahedral complex on ferrihydrite with varying local geometry depending on sorption density. At significantly higher densities but below those at which Zn hydroxide is expected to precipitate, a mainly octahedral coordinated Zn2+ precipitate is observed. An analysis of the multiple scattering paths contributing to the XANES demonstrates the importance of scattering paths involving the anion sublattice. We also describe the specific advantages of complementary quantitative XANES and EXAFS analysis and estimate limits on the extent of structural information obtainable from XANES analysis. ?? 2003 Elsevier Science Ltd.

GRILLIX: a 3D turbulence code based on the flux-coordinate independent approach

NASA Astrophysics Data System (ADS)

Stegmeir, Andreas; Coster, David; Ross, Alexander; Maj, Omar; Lackner, Karl; Poli, Emanuele

2018-03-01

The GRILLIX code is presented with which plasma turbulence/transport in various geometries can be simulated in 3D. The distinguishing feature of the code is that it is based on the flux-coordinate independent approach (FCI) (Hariri and Ottaviani 2013 Comput. Phys. Commun. 184 2419; Stegmeir et al 2016 Comput. Phys. Commun. 198 139). Cylindrical or Cartesian grids are used on which perpendicular operators are discretised via standard finite difference methods and parallel operators via a field line tracing and interpolation procedure (field line map). This offers a very high flexibility with respect to geometry, especially a separatrix with X-point(s) or a magnetic axis can be treated easily in contrast to approaches which are based on field aligned coordinates and suffer from coordinate singularities. Aiming finally for simulation of edge and scrape-off layer (SOL) turbulence, an isothermal electrostatic drift-reduced Braginskii model (Zeiler et al 1997 Phys. Plasmas 4 2134) has been implemented in GRILLIX. We present the numerical approach, which is based on a toroidally staggered formulation of the FCI, we show verification of the code with the method of manufactured solutions and show a benchmark based on a TORPEX blob experiment, previously performed by several edge/SOL codes (Riva et al 2016 Plasma Phys. Control. Fusion 58 044005). Examples for slab, circular, limiter and diverted geometry are presented. Finally, the results show that the FCI approach in general and GRILLIX in particular are viable approaches in order to tackle simulation of edge/SOL turbulence in diverted geometry.

General Relativity

NASA Astrophysics Data System (ADS)

Hobson, M. P.; Efstathiou, G. P.; Lasenby, A. N.

2006-02-01

1. The spacetime of special relativity; 2. Manifolds and coordinates; 3. Vector calculus on manifolds; 4. Tensor calculus on manifolds; 5. Special relativity revisited; 6. Electromagnetism; 7. The equivalence principle and spacetime curvature; 8. The gravitational field equations; 9. The Schwarzschild geometry; 10. Experimental tests of general relativity; 11. Schwarzschild black holes; 12. Further spherically-symmetric geometries; 13. The Kerr geometry; 14. The Friedmann-Robertson-Walker geometry; 15. Cosmological models; 16. Inflationary cosmology; 17. Linearised general relativity; 18. Gravitational waves; 19. A variational approach to general relativity.

Enzymatic properties and localization of motopsin (PRSS12), a protease whose absence causes mental retardation.

PubMed

Mitsui, Shinichi; Yamaguchi, Nozomi; Osako, Yoji; Yuri, Kazunari

2007-03-09

Motopsin (PRSS12) is a mosaic protease expressed in the central nervous system. Truncation of the human motopsin gene causes nonsyndromic mental retardation. Understanding the enzymatic properties and localization of motopsin protein in the central nervous system will help identify the molecular mechanism by which the loss of motopsin function causes mental retardation. Recombinant motopsin showed amidolytic activity against the synthetic substrate benzyloxycarbonyl-l-phenylalanyl-l-arginine 4-methyl-coumaryl-7-amide. Motopsin activated the single-chain tissue plasminogen activator precursor and exhibited gelatinolytic activity. This enzymatic activity was inhibited by typical serine protease inhibitors such as aprotinin, leupeptin, and (4-amidinophenyl) methanesulfonyl fluoride. Immunocytochemistry using anti-motopsin IgG revealed that both human and mouse motopsin proteins were distributed in discrete puncta along the dendrites and soma as well as axons in cultured hippocampal neurons. In the limbic system, including the cingulate and hippocampal pyramidal neurons and piriform cortex, high level of motopsin protein was expressed at postnatal day 10, but a very low level at 10-week-old mice. Motopsin and tissue plasminogen activator were co-expressed in the cingulate pyramidal neurons at postnatal day 10 and were distributed along dendrites of cultured pyramidal neurons. In cranial nuclei, a moderate level of motopsin protein was detected independently on the developmental stage. Our results suggest that motopsin has multiple functions, such as axon outgrowth, arranging perineuronal environment, and maintaining neuronal plasticity, partly in coordination with other proteases including tissue plasminogen activator.

A novel flexible field-aligned coordinate system for tokamak edge plasma simulation

NASA Astrophysics Data System (ADS)

Leddy, J.; Dudson, B.; Romanelli, M.; Shanahan, B.; Walkden, N.

2017-03-01

Tokamak plasmas are confined by a magnetic field that limits the particle and heat transport perpendicular to the field. Parallel to the field the ionised particles can move freely, so to obtain confinement the field lines are "closed" (i.e. form closed surfaces of constant poloidal flux) in the core of a tokamak. Towards, the edge, however, the field lines intersect physical surfaces, leading to interaction between neutral and ionised particles, and the potential melting of the material surface. Simulation of this interaction is important for predicting the performance and lifetime of future tokamak devices such as ITER. Field-aligned coordinates are commonly used in the simulation of tokamak plasmas due to the geometry and magnetic topology of the system. However, these coordinates are limited in the geometry they allow in the poloidal plane due to orthogonality requirements. A novel 3D coordinate system is proposed herein that relaxes this constraint so that any arbitrary, smoothly varying geometry can be matched in the poloidal plane while maintaining a field-aligned coordinate. This system is implemented in BOUT++ and tested for accuracy using the method of manufactured solutions. A MAST edge cross-section is simulated using a fluid plasma model and the results show expected behaviour for density, temperature, and velocity. Finally, simulations of an isolated divertor leg are conducted with and without neutrals to demonstrate the ion-neutral interaction near the divertor plate and the corresponding beneficial decrease in plasma temperature.

Catalytic fixation of atmospheric carbon dioxide by copper(ii) complexes of bidentate ligands.

PubMed

Muthuramalingam, Sethuraman; Khamrang, Themmila; Velusamy, Marappan; Mayilmurugan, Ramasamy

2017-11-28

New copper(ii) complexes, [Cu(L1) 2 (H 2 O)](ClO 4 ) 2 , 1 [L1 = 2-pyridin-2-yl-quinoline], [Cu(L2) 2 (H 2 O)](ClO 4 ) 2 , 2 [L2 = 2-pyridin-2-yl-quinoxaline], [Cu(L3) 2 (H 2 O)](ClO 4 ) 2 , 3 [L3 = 6,7-dimethyl-2-pyridin-2-yl-quinoxaline], [Cu(L4) 2 (H 2 O)](ClO 4 ) 2 , 4 [L4 = 4-phenyl-2-pyridin-2-yl-quinoline] and [Cu(L5) 2 (H 2 O)](ClO 4 ) 2 , 5 [L5 = 4-phenyl-2-pyridin-2-yl-quinazoline], were synthesized and characterized as catalysts for selective fixation of atmospheric CO 2 . The molecular structure of 2 was determined by single-crystal X-ray studies and shown to have an unusual trigonal bipyramid geometry (τ, 0.936) around the copper(ii) center, with the coordination of two ligand units and a water molecule. The Cu-N quin (2.040, 2.048 Å) bonds are slightly longer than the Cu-N pyr (1.987 Å) bonds but shorter than the Cu-O water bond (2.117 Å). Well-defined Cu(ii)/Cu(i) redox potentials of around 0.352 to 0.401 V were observed for 1-5 in acetonitrile. The electronic absorption spectra of 1-5 showed ligand-based transitions at around 208-286 nm with a visible shoulder at around 342-370 nm. The d-d transitions appeared at around 750-800 and 930-955 nm in acetonitrile. The rhombic EPR spectra of 1-5 exhibited three different g values g x , 2.27-2.34; g y , 2.06-2.09; and g z , 1.95-1.98 at 70 K. Atmospheric CO 2 was successfully fixed by 1-5 using Et 3 N as a sacrificial reducing agent, resulting in CO 3 2- -bound complexes of type [Cu(L)CO 3 (H 2 O)] that display an absorption band at around 614-673 nm and a ν st at 1647 cm -1 . This CO 3 2- -bound complex of 1 was crystallized from the reaction mixture and it displayed a distorted square pyramidal geometry (τ, 0.369) around the copper(ii) center via the coordination of only one ligand unit, a carbonate group, and water molecules. Furthermore, treatment of the carbonate-bound Cu(ii) complexes with one equivalent of H + under N 2 atmosphere resulted in the liberation of bicarbonate (HCO 3 - ) and regenerated the parent complexes. These regenerated catalysts were active enough to fix CO 2 in eight repeating cycles without any change in efficiency. The fixation of CO 2 possibly occurs via the formation of Cu(i)-species, which is accompanied by the formation of an MLCT band at around 450-500 nm. The rates of Cu(i)-species formation, k obs , were determined and found to be 5.41-10.31 × 10 -3 s -1 in the presence of Et 3 N in acetonitrile at 25 °C. Interestingly, the copper(i)-species of 3 has been successfully crystallized and displayed a distorted tetrahedral geometry through the coordination of two units of ligand L3.

Numerical grid generation techniques. [conference

NASA Technical Reports Server (NTRS)

1980-01-01

The state of the art in topology and flow geometry is presented. Solution techniques for partial differential equations are reviewed and included developments in coordinate transformations, conformal mapping, and invariant imbeddings. Applications of these techniques in fluid mechanics, flow geometry, boundary value problems, and fluidics are presented.

Design of specially adapted reactive coordinates to economically compute potential and kinetic energy operators including geometry relaxation

NASA Astrophysics Data System (ADS)

Thallmair, Sebastian; Roos, Matthias K.; de Vivie-Riedle, Regina

2016-06-01

Quantum dynamics simulations require prior knowledge of the potential energy surface as well as the kinetic energy operator. Typically, they are evaluated in a low-dimensional subspace of the full configuration space of the molecule as its dimensionality increases proportional to the number of atoms. This entails the challenge to find the most suitable subspace. We present an approach to design specially adapted reactive coordinates spanning this subspace. In addition to the essential geometric changes, these coordinates take into account the relaxation of the non-reactive coordinates without the necessity of performing geometry optimizations at each grid point. The method is demonstrated for an ultrafast photoinduced bond cleavage in a commonly used organic precursor for the generation of electrophiles. The potential energy surfaces for the reaction as well as the Wilson G-matrix as part of the kinetic energy operator are shown for a complex chemical reaction, both including the relaxation of the non-reactive coordinates on equal footing. A microscopic interpretation of the shape of the G-matrix elements allows to analyze the impact of the non-reactive coordinates on the kinetic energy operator. Additionally, we compare quantum dynamics simulations with and without the relaxation of the non-reactive coordinates included in the kinetic energy operator to demonstrate its influence.

Design of specially adapted reactive coordinates to economically compute potential and kinetic energy operators including geometry relaxation.

PubMed

Thallmair, Sebastian; Roos, Matthias K; de Vivie-Riedle, Regina

2016-06-21

Quantum dynamics simulations require prior knowledge of the potential energy surface as well as the kinetic energy operator. Typically, they are evaluated in a low-dimensional subspace of the full configuration space of the molecule as its dimensionality increases proportional to the number of atoms. This entails the challenge to find the most suitable subspace. We present an approach to design specially adapted reactive coordinates spanning this subspace. In addition to the essential geometric changes, these coordinates take into account the relaxation of the non-reactive coordinates without the necessity of performing geometry optimizations at each grid point. The method is demonstrated for an ultrafast photoinduced bond cleavage in a commonly used organic precursor for the generation of electrophiles. The potential energy surfaces for the reaction as well as the Wilson G-matrix as part of the kinetic energy operator are shown for a complex chemical reaction, both including the relaxation of the non-reactive coordinates on equal footing. A microscopic interpretation of the shape of the G-matrix elements allows to analyze the impact of the non-reactive coordinates on the kinetic energy operator. Additionally, we compare quantum dynamics simulations with and without the relaxation of the non-reactive coordinates included in the kinetic energy operator to demonstrate its influence.

How Does Mg2+ Modulate the RNA Folding Mechanism: A Case Study of the G:C W:W Trans Basepair.

PubMed

Halder, Antarip; Roy, Rohit; Bhattacharyya, Dhananjay; Mitra, Abhijit

2017-07-25

Reverse Watson-Crick G:C basepairs (G:C W:W Trans) occur frequently in different functional RNAs. This is one of the few basepairs whose gas-phase-optimized isolated geometry is inconsistent with the corresponding experimental geometry. Several earlier studies indicate that through post-transcriptional modification, direct protonation, or coordination with Mg 2+ , accumulation of positive charge near N7 of guanine can stabilize the experimental geometry. Interestingly, recent studies reveal significant variation in the position of putatively bound Mg 2+ . This, in conjunction with recently raised doubts regarding some of the Mg 2+ assignments near the imino nitrogen of guanine, is suggestive of the existence of multiple Mg 2+ binding modes for this basepair. Our detailed investigation of Mg 2+ -bound G:C W:W Trans pairs occurring in high-resolution RNA crystal structures shows that they are found in 14 different contexts, eight of which display Mg 2+ binding at the Hoogsteen edge of guanine. Further examination of occurrences in these eight contexts led to the characterization of three different Mg 2+ binding modes: 1) direct binding via N7 coordination, 2) direct binding via O6 coordination, and 3) binding via hydrogen-bonding interaction with the first-shell water molecules. In the crystal structures, the latter two modes are associated with a buckled and propeller-twisted geometry of the basepair. Interestingly, respective optimized geometries of these different Mg 2+ binding modes (optimized using six different DFT functionals) are consistent with their corresponding experimental geometries. Subsequent interaction energy calculations at the MP2 level, and decomposition of its components, suggest that for G:C W:W Trans , Mg 2+ binding can fine tune the basepair geometries without compromising with their stability. Our results, therefore, underline the importance of the mode of binding of Mg 2+ ions in shaping RNA structure, folding and function. Copyright © 2017. Published by Elsevier Inc.

Fast intramolecular electron transfer and dual fluorescence. Configurational change of the amino nitrogen (pyramidal{yields}planar)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haar, Th. von der; Hebecker, A.; Il'Ichev, Yu.

1996-04-01

The fast excited state intramolecular charge transfer (ICT) and dual fluorescence observed with several 4-aminobenzonitriles is discussed. It is shown that the magnitude of the energy gap between the two lowest excited states determines the occurrence or absence of ICT. The photophysical behavior of a series of four 4-aminobenzonitriles in which the amino nitrogen atom is part of a four- to seven-membered heterocyclic ring, P4C to P7C, is studied by using time-resolved fluorescence measurements. The ICT rate constant strongly decreases with decreasing ring size. With P4C in diethyl ether ICT does not occur. This is attributed to the increase ofmore » the amino nitrogen inversion barrier with decreasing ring size. The change of the amino nitrogen from pyramidal to planar is considered to be an important reaction coordinate. The photophysics of the 4-aminobenzonitriles is different from that of other ICT systems such as donor/acceptor-substituted stilbenes and 9,9'-bianthryl, which are governed by the charge distribution and macroscopic Coulombic interaction in their CT states.« less

Fast intramolecular electron transfer and dual fluorescence. Configurational change of the amino nitrogen (pyramidal-->planar)

NASA Astrophysics Data System (ADS)

von der Haar, Th.; Hebecker, A.; Il'Ichev, Yu.; Kühnle, W.; Zachariasse, K. A.

1996-04-01

The fast excited state intramolecular charge transfer (ICT) and dual fluorescence observed with several 4-aminobenzonitriles is discussed. It is shown that the magnitude of the energy gap between the two lowest excited states determines the occurrence or absence of ICT. The photophysical behavior of a series of four 4-aminobenzonitriles in which the amino nitrogen atom is part of a four- to seven-membered heterocyclic ring, P4C to P7C, is studied by using time-resolved fluorescence measurements. The ICT rate constant strongly decreases with decreasing ring size. With P4C in diethyl ether ICT does not occur. This is attributed to the increase of the amino nitrogen inversion barrier with decreasing ring size. The change of the amino nitrogen from pyramidal to planar is considered to be an important reaction coordinate. The photophysics of the 4-aminobenzonitriles is different from that of other ICT systems such as donor/acceptor-substituted stilbenes and 9,9'-bianthryl, which are governed by the charge distribution and macroscopic Coulombic interaction in their CT states.

Harmonizing water management and social needs: a necessary condition for sustainable development. The case of Israel's coastal aquifer.

PubMed

Melloul, Abraham J; Collin, Martin L

2003-04-01

This study focuses on the problem of most efficiently fulfilling the water requirements of society for sustainable water resources management. The goal is to coordinate effectively the social needs of the resident population with operational water resources management planning.The proposed approach consists of a pyramidal hierarchy of water resource management needs, similar to that suggested by psychologist Abraham Maslow for human social needs. The two pyramidal hierarchies can be simultaneously employed to delineate guidelines to synchronize planning for sustainable water resources development with the concerns and expectations of the resident population. In both hierarchies, higher level needs remain irrelevant and difficult to attain until lower level needs of the resident population have been fulfilled. Management planning measures employed with regard to Israel's coastal aquifer have been used to illustrate this approach. Observation of Israel's experience indicates markedly reduced effectiveness where such measures have failed to be properly synchronised with societal needs. Conversely, where hydrological management measures were successfully synchronized with societal concerns, increased efficiency towards attaining sustainable groundwater management was evident.

Chrna2-Martinotti Cells Synchronize Layer 5 Type A Pyramidal Cells via Rebound Excitation

PubMed Central

Leão, Richardson N.; Edwards, Steven J.

2017-01-01

Martinotti cells are the most prominent distal dendrite–targeting interneurons in the cortex, but their role in controlling pyramidal cell (PC) activity is largely unknown. Here, we show that the nicotinic acetylcholine receptor α2 subunit (Chrna2) specifically marks layer 5 (L5) Martinotti cells projecting to layer 1. Furthermore, we confirm that Chrna2-expressing Martinotti cells selectively target L5 thick-tufted type A PCs but not thin-tufted type B PCs. Using optogenetic activation and inhibition, we demonstrate how Chrna2-Martinotti cells robustly reset and synchronize type A PCs via slow rhythmic burst activity and rebound excitation. Moreover, using optical feedback inhibition, in which PC spikes controlled the firing of surrounding Chrna2-Martinotti cells, we found that neighboring PC spike trains became synchronized by Martinotti cell inhibition. Together, our results show that L5 Martinotti cells participate in defined cortical circuits and can synchronize PCs in a frequency-dependent manner. These findings suggest that Martinotti cells are pivotal for coordinated PC activity, which is involved in cortical information processing and cognitive control. PMID:28182735

The crystal structures of potassium and cesium trivanadates

USGS Publications Warehouse

Evans, H.T.; Block, S.

1966-01-01

Potassium and cesium trivanadates are monoclinic and isomorphous, space group P21/m, with the following dimensions (Z = 2): KV3O8, a = 7.640 A, b = 8.380 A, c = 4.979 A, ??= 96?? 57???; CsV3O8, a = 8.176 A, b = 8.519 A, c = 4.988 A, ?? = 95?? 32???. The crystal structure of KV3O8 has been determined from hk0, 0kl, and h0l Weissenberg data with an R factor of 0.15. The structure of CsV3O8 has been refined with 1273 hkl Weissenberg data to an R factor of 0.089. The structures consist of corrugated sheets based on a linkage of distorted VO6, octahedra. Two of the vanadium atoms lie in double, square-pyramid groups V2O8, which are linked through opposite basal corners into chains along the b axis. The chains are joined laterally along the c axis into sheets by the third vanadium atom in VO groups, also forming part of a square-pyramid coordination. Various aspects of these structures are compared with other known oxovanadate structures.

Structural characterization of tellurite glasses doped with transition metal oxides using Raman spectra and ab initio calculations.

PubMed

Mohamed, Tarek A; Shaltout, I; Al Yahyaei, K M

2006-05-01

Systems of iron tellurite glasses were prepared by melt quenching with compositions of [85%TeO2+5%Fe2O3+10%TMO], where transition metal oxides (TMO) are TiO2, V2O5, MnO, CoO, NiO and CuO. Furthermore, the main structural units of these samples have been characterized by means of Raman spectra (150-1200 cm(-1)) as well as wavenumber predictions by means of Gaussian 98 ab initio calculations for the proposed site symmetries of TeO4(4-) triagonal bipyramid (C2v) and Te2O7(6-) bridged tetrahedra (Cs and C1). Aided by normal coordinate analysis, calculated vibrational frequencies, Raman scattering activities, force constants in internal coordinates and potential energy distributions (PEDs), revised vibrational assignments for the fundamental modes have been proposed. The main structural features are correlated to the dominant units of triagonal bipyramid (tbp) or bridged tetrahedral (TeO3+1 binds to TeO3 through TeOTe bridge; corner sharing). Moreover, the Raman spectra of the investigated tellurites reflect a structural change from tbp (coordination number is four) to triagonal pyramidal (coordination number is three).

Synthesis of mononuclear copper(II) complexes of N3O2 and N4O2 donors containing Schiff base ligands: Theoretical and biological observations

NASA Astrophysics Data System (ADS)

Mancha Madha, K.; Gurumoorthy, P.; Arul Antony, S.; Ramalakshmi, N.

2017-09-01

A new series of six mononuclear copper(II) complexes were synthesized from N3O2 and N4O2 donors containing Schiff base ligands, and characterized by various spectral methods. The geometry of the complexes was determined using UV-Vis, EPR and DFT calculations. The complexes of N3O2 donors (1-3) adopted square pyramidal geometry and the remaining complexes of N4O2 donors (4-6) show distorted octahedral geometry around copper(II) nuclei. Redox properties of the complexes show a one-electron irreversible reduction process in the cathodic potential (Epc) region from -0.74 to -0.98 V. The complexes show potent antioxidant activity against DPPH radicals. Molecular docking studies of complexes showed σ-π interaction, hydrogen bonding, electrostatic and van der Waals interactions with VEGFR2 kinase receptor. In vitro cytotoxicity of the complexes was tested against human breast cancer (MDA-MB-231) cell lines and one normal human dermal fibroblasts (NHDF) cell line through MTT assay. The morphological assessment data obtained by Hoechst 33258 and AO/EB staining revealed that the complexes induce apoptosis pathway of cell death.

Excited electronic states of the methyl radical. Ab initio molecular orbital study of geometries, excitation energies and vibronic spectra

NASA Astrophysics Data System (ADS)

Mebel, Alexander M.; Lin, Sheng-Hsien

1997-03-01

The geometries, vibrational frequencies and vertical and adiabatic excitation energies of the excited valence and Rydberg 3s, 3p, 3d, and 4s electronic states of CH 3 have been studied using ab initio molecular orbital multiconfigurational SCF (CASSCF), internally contracted multireference configuration interaction (MRCI) and equation-of-motion coupled cluster (EOM-CCSD) methods. The vibronic spectra are determined through the calculation of Franck-Condon factors. Close agreement between theory and experiment has been found for the excitation energies, vibrational frequencies and vibronic spectra. The adiabatic excitation energies of the Rydberg 3s B˜ 2A' 1 and 3p 2 2A″ 2 states are calculated to be 46435 and 60065 cm -1 compared to the experimental values of 46300 and 59972 cm -1, respectively. The valence 2A″ excited state of CH 3 has been found to have a pyramidal geometry within C s symmetry and to be adiabatically by 97 kcal/mol higher in energy than the ground state. The 2A″ state is predicted to be stable by 9 and 13 kcal/mol with respect to H 2 and H elimination.

Zn(II) and Hg(II) binding to a designed peptide that accommodates different coordination geometries.

PubMed

Szunyogh, Dániel; Gyurcsik, Béla; Larsen, Flemming H; Stachura, Monika; Thulstrup, Peter W; Hemmingsen, Lars; Jancsó, Attila

2015-07-28

Designed metal ion binding peptides offer a variety of applications in both basic science as model systems of more complex metalloproteins, and in biotechnology, e.g. in bioremediation of toxic metal ions, biomining or as artificial enzymes. In this work a peptide (HS: Ac-SCHGDQGSDCSI-NH2) has been specifically designed for binding of both Zn(II) and Hg(II), i.e. metal ions with different preferences in terms of coordination number, coordination geometry, and to some extent ligand composition. It is demonstrated that HS accommodates both metal ions, and the first coordination sphere, metal ion exchange between peptides, and speciation are characterized as a function of pH using UV-absorption-, synchrotron radiation CD-, (1)H-NMR-, and PAC-spectroscopy as well as potentiometry. Hg(II) binds to the peptide with very high affinity in a {HgS2} coordination geometry, bringing together the two cysteinates close to each end of the peptide in a loop structure. Despite the high affinity, Hg(II) is kinetically labile, exchanging between peptides on the subsecond timescale, as indicated by line broadening in (1)H-NMR. The Zn(II)-HS system displays more complex speciation, involving monomeric species with coordinating cysteinates, histidine, and a solvent water molecule, as well as HS-Zn(II)-HS complexes. In summary, the HS peptide displays conformational flexibility, contains many typical metal ion binding groups, and is able to accommodate metal ions with different structural and ligand preferences with high affinity. As such, the HS peptide may be a scaffold offering binding of a variety of metal ions, and potentially serve for metal ion sequestration in biotechnological applications.

ToF-SIMS cluster ion imaging of hippocampal CA1 pyramidal rat neurons

NASA Astrophysics Data System (ADS)

Francis, J. T.; Nie, H.-Y.; Taylor, A. R.; Walzak, M. J.; Chang, W. H.; MacFabe, D. F.; Lau, W. M.

2008-12-01

Recent studies have demonstrated the power of time-of-flight secondary ion mass spectrometry (ToF-SIMS) cluster ion imaging to characterize biological structures, such as that of the rat central nervous system. A large number of the studies to date have been carried out on the "structural scale" imaging several mm 2 using mounted thin sections. In this work, we present our ToF-SIMS cluster ion imaging results on hippocampal rat brain neurons, at the cellular and sub-cellular levels. As a part of an ongoing investigation to examine gut linked metabolic factors in autism spectrum disorders using a novel rat model, we have observed a possible variation in hippocampal Cornu ammonis 1 (CA1) pyramidal neuron geometry in thin, paraformaldehyde fixed brain sections. However, the fixation process alters the tissue matrix such that much biochemical information appears to be lost. In an effort to preserve as much as possible this original information, we have established a protocol using unfixed thin brain sections, along with low dose, 500 eV Cs + pre-sputtering that allows imaging down to the sub-cellular scale with minimal sample preparation.

Syntheses and structural characterization of Co(II) and Cd(II) coordination polymers with 1,4-bis(imidazolyl)butane ligand

NASA Astrophysics Data System (ADS)

Lalegani, Arash; Khalaj, Mehdi; Sedaghat, Sajjad; Łyczko, Krzysztof; Lipkowski, Janusz

2017-11-01

Two new coordination polymers, {[Co(bib)3](PF6)2}n (1) and [Cd (bib) Cl2]n (2), were prepared at room temperature by the reaction of appropriate salts of cobalt (II) and cadmium (II) with the flexible linker ligands 1,4-bis(imidazolyl) butane (bib). The compounds were characterized by elemental analyses, IR spectroscopy and single crystal X-ray diffraction. In the polymeric structure of 1, the Co(II) ion lies on an inversion centre and adopts the CoN6 octahedral geometry, while in the structure of 2, the Cd(II) ions adopt the CdN2Cl4 pseudo-octahedral geometry. In compound 1, six bib ligands are coordinated to one central cobalt (II) to form an open 3D 2-fold interpenetrating framework of the α-polonium (pcu) type topology, while in compound 2 two bib ligands are coordinated to one central cadmium (II) to form 2D network structure.

Neuronal Diversity in GABAergic Long-Range Projections from the Hippocampus

PubMed Central

Jinno, Shozo; Klausberger, Thomas; Marton, Laszlo F.; Dalezios, Yannis; Roberts, J. David B.; Fuentealba, Pablo; Bushong, Eric A.; Henze, Darrell; Buzsáki, György; Somogyi, Peter

2008-01-01

The formation and recall of sensory, motor, and cognitive representations require coordinated fast communication among multiple cortical areas. Interareal projections are mainly mediated by glutamatergic pyramidal cell projections; only few long-range GABAergic connections have been reported. Using in vivo recording and labeling of single cells and retrograde axonal tracing, we demonstrate novel long-range GABAergic projection neurons in the rat hippocampus: (1) somatostatin- and predominantly mGluR1α-positive neurons in stratum oriens project to the subiculum, other cortical areas, and the medial septum; (2) neurons in stratum oriens, including somatostatin-negative ones; and (3) trilaminar cells project to the subiculum and/or other cortical areas but not the septum. These three populations strongly increase their firing during sharp wave-associated ripple oscillations, communicating this network state to the septotemporal system. Finally, a large population of somatostatin-negative GABAergic cells in stratum radiatum project to the molecular layers of the subiculum, presubiculum, retrosplenial cortex, and indusium griseum and fire rhythmically at high rates during theta oscillations but do not increase their firing during ripples. The GABAergic projection axons have a larger diameter and thicker myelin sheet than those of CA1 pyramidal cells. Therefore, rhythmic IPSCs are likely to precede the arrival of excitation in cortical areas (e.g., subiculum) that receive both glutamatergic and GABAergic projections from the CA1 area. Other areas, including the retrosplenial cortex, receive only rhythmic GABAergic CA1 input. We conclude that direct GABAergic projections from the hippocampus to other cortical areas and the septum contribute to coordinating oscillatory timing across structures. PMID:17699661

GEOMETRY, TENTATIVE GUIDES.

ERIC Educational Resources Information Center

KLIER, KATHERINE M.

PRESENTED IS A FUSED COURSE IN PLANE, SOLID, AND COORDINATE GEOMETRY. ELEMENTARY SET THEORY, LOGIC, AND THE PRINCIPLE OF SEPARATION PROVIDE UNIFYING THREADS THROUGHOUT THE TEXT. THE TWO CURRICULUM GUIDES HAVE BEEN PREPARED FOR USE WITH TWO DIFFERENT TEXTS. EITHER CURRICULUM GUIDE MAY BE USED DEPENDING UPON THE CHOICE OF THE TEACHER AND THE NEEDS…

Elimination of numerical Cherenkov instability in flowing-plasma particle-in-cell simulations by using Galilean coordinates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehe, Remi; Kirchen, Manuel; Godfrey, Brendan B.

Particle-in-cell (PIC) simulations of relativistic flowing plasmas are of key interest to several fields of physics (including, e.g., laser-wakefield acceleration, when viewed in a Lorentz-boosted frame) but remain sometimes infeasible due to the well-known numerical Cherenkov instability (NCI). In this article, we show that, for a plasma drifting at a uniform relativistic velocity, the NCI can be eliminated by simply integrating the PIC equations in Galilean coordinates that follow the plasma (also sometimes known as comoving coordinates) within a spectral analytical framework. The elimination of the NCI is verified empirically and confirmed by a theoretical analysis of the instability. Moreover,more » it is shown that this method is applicable both to Cartesian geometry and to cylindrical geometry with azimuthal Fourier decomposition.« less

A Lagrangian cylindrical coordinate system for characterizing dynamic surface geometry of tubular anatomic structures.

PubMed

Lundh, Torbjörn; Suh, Ga-Young; DiGiacomo, Phillip; Cheng, Christopher

2018-03-03

Vascular morphology characterization is useful for disease diagnosis, risk stratification, treatment planning, and prediction of treatment durability. To quantify the dynamic surface geometry of tubular-shaped anatomic structures, we propose a simple, rigorous Lagrangian cylindrical coordinate system to monitor well-defined surface points. Specifically, the proposed system enables quantification of surface curvature and cross-sectional eccentricity. Using idealized software phantom examples, we validate the method's ability to accurately quantify longitudinal and circumferential surface curvature, as well as eccentricity and orientation of eccentricity. We then apply the method to several medical imaging data sets of human vascular structures to exemplify the utility of this coordinate system for analyzing morphology and dynamic geometric changes in blood vessels throughout the body. Graphical abstract Pointwise longitudinal curvature of a thoracic aortic endograft surface for systole and diastole, with their absolute difference.

Elimination of numerical Cherenkov instability in flowing-plasma particle-in-cell simulations by using Galilean coordinates

DOE PAGES

Lehe, Remi; Kirchen, Manuel; Godfrey, Brendan B.; ...

2016-11-14

Particle-in-cell (PIC) simulations of relativistic flowing plasmas are of key interest to several fields of physics (including, e.g., laser-wakefield acceleration, when viewed in a Lorentz-boosted frame) but remain sometimes infeasible due to the well-known numerical Cherenkov instability (NCI). In this article, we show that, for a plasma drifting at a uniform relativistic velocity, the NCI can be eliminated by simply integrating the PIC equations in Galilean coordinates that follow the plasma (also sometimes known as comoving coordinates) within a spectral analytical framework. The elimination of the NCI is verified empirically and confirmed by a theoretical analysis of the instability. Moreover,more » it is shown that this method is applicable both to Cartesian geometry and to cylindrical geometry with azimuthal Fourier decomposition.« less

catena-Poly[[(benzil bis{[(pyridin-2-yl)methylidene]hydrazone}-κ⁴N,N',N'',N''')mercury(II)]-μ-chlorido-[dichloridomercury(II)]-μ-chlorido].

PubMed

Akkurt, Mehmet; Khandar, Ali Akbar; Tahir, Muhammad Nawaz; Hosseini-Yazdi, Seyed Abolfazl; Mahmoudi, Ghodrat

2012-07-01

In the title coordination polymer, [Hg₄Cl₄(C₂₆H₂₀N₆)](n), one Hg(II) ion is coordinated by four N atoms from the benzylbis((pyridin-2-yl)methyl-idenehydrazone) ligand and two Cl⁻ ions in a very distorted cis-HgCl₂N₄ octa-hedral geometry. The other Hg(II) ion is coordinated in a distorted tetra-hedral geometry by four Cl⁻ ions. Bridging chloride ions link the Hg(II) ions into a chain propagating in [010]: the Hg-Cl bridging bonds are significantly longer than the terminal bonds. The dihedral angle between the central benzene rings of the ligand is 83.3 (2)°. The packing is consolidated by weak C-H⋯Cl hydrogen bonds and C-H⋯π inter-actions.

A Simple Method for Drawing Chiral Mononuclear Octahedral Metal Complexes

ERIC Educational Resources Information Center

Mohamadou, Aminou; Haudrechy, Arnaud

2008-01-01

Octahedral transition-metal complexes are involved in a number of reactions and octahedral coordination geometry, frequently observed for metallic centers, includes important topographical stereochemistry. Depending on the number and nature of different ligands, octahedral coordination units with at least two different monodentate ligands give…

Latin-square three-dimensional gage master

DOEpatents

Jones, L.

1981-05-12

A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

Latin square three dimensional gage master

DOEpatents

Jones, Lynn L.

1982-01-01

A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

Syntheses, crystal structures, and properties of six new lanthanide(III) transition metal tellurium(IV) oxyhalides with three types of structures.

PubMed

Shen, Yue-Ling; Mao, Jiang-Gao

2005-07-25

Solid-state reactions of lanthanide(III) oxide (and lanthanide(III) oxyhalide), transition metal halide (and transition metal oxide), and TeO(2) at high temperature lead to six new lanthanide transition metal tellurium(IV) oxyhalides with three different types of structures, namely, DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, ErCuTe(2)O(6)Br, Sm(2)Mn(Te(5)O(13))Cl(2), Dy(2)Cu(Te(5)O(13))Br(2), and Nd(4)Cu(TeO(3))(5)Cl(3). Compounds DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, and ErCuTe(2)O(6)Br are isostructural. The lanthanide(III) ion is eight-coordinated by eight oxygen atoms, and the copper(II) ion is five-coordinated by four oxygens and a halide anion in a distorted square pyramidal geometry. The interconnection of Ln(III) and Cu(II) ions by bridging tellurite anions results in a three-dimensional (3D) network with tunnels along the a-axis; the halide anion and the lone-pair electrons of the tellurium(IV) ions are oriented toward the cavities of the tunnels. Compounds Sm(2)Mn(Te(5)O(13))Cl(2) and Dy(2)Cu(Te(5)O(13))Br(2) are isostructural. The lanthanide(III) ions are eight-coordinated by eight oxygens, and the divalent transition metal ion is octahedrally coordinated by six oxygens. Two types of polymeric tellurium(IV) oxide anions are formed: Te(3)O(8)(4)(-) and Te(4)O(10)(4)(-). The interconnection of the lanthanide(III) and divalent transition metal ions by the above two types of polymeric tellurium(IV) oxide anions leads to a 3D network with long, narrow-shaped tunnels along the b-axis. The halide anions remain isolated and are located at the above tunnels. Nd(4)Cu(TeO(3))(5)Cl(3) features a different structure. All five of the Nd(III) ions are eight-coordinated (NdO(8) for Nd(1), Nd(2), Nd(4), and Nd(5) and NdO(7)Cl for Nd(3)), and the copper(I) ion is tetrahedrally coordinated by four chloride anions. The interconnection of Nd(III) ions by bridging tellurite anions resulted in a 3D network with large tunnels along the b-axis. The CuCl(4) tetrahedra are interconnected into a 1D two-unit repeating (zweier) chain via corner-sharing. These 1D copper(I) chloride chains are inserted into the tunnels of the neodymium(III) tellurite via Nd-Cl-Cu bridges. Luminescent studies show that ErCuTe(2)O(6)Cl and Nd(4)Cu(TeO(3))(5)Cl(3) exhibit strong luminescence in the near-IR region. Magnetic measurements indicate the antiferromagnetic interactions between magnetic centers in these compounds.

Tropical geometry of statistical models.

PubMed

Pachter, Lior; Sturmfels, Bernd

2004-11-16

This article presents a unified mathematical framework for inference in graphical models, building on the observation that graphical models are algebraic varieties. From this geometric viewpoint, observations generated from a model are coordinates of a point in the variety, and the sum-product algorithm is an efficient tool for evaluating specific coordinates. Here, we address the question of how the solutions to various inference problems depend on the model parameters. The proposed answer is expressed in terms of tropical algebraic geometry. The Newton polytope of a statistical model plays a key role. Our results are applied to the hidden Markov model and the general Markov model on a binary tree.

Design of specially adapted reactive coordinates to economically compute potential and kinetic energy operators including geometry relaxation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thallmair, Sebastian; Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität München, D-80538 München; Roos, Matthias K.

Quantum dynamics simulations require prior knowledge of the potential energy surface as well as the kinetic energy operator. Typically, they are evaluated in a low-dimensional subspace of the full configuration space of the molecule as its dimensionality increases proportional to the number of atoms. This entails the challenge to find the most suitable subspace. We present an approach to design specially adapted reactive coordinates spanning this subspace. In addition to the essential geometric changes, these coordinates take into account the relaxation of the non-reactive coordinates without the necessity of performing geometry optimizations at each grid point. The method is demonstratedmore » for an ultrafast photoinduced bond cleavage in a commonly used organic precursor for the generation of electrophiles. The potential energy surfaces for the reaction as well as the Wilson G-matrix as part of the kinetic energy operator are shown for a complex chemical reaction, both including the relaxation of the non-reactive coordinates on equal footing. A microscopic interpretation of the shape of the G-matrix elements allows to analyze the impact of the non-reactive coordinates on the kinetic energy operator. Additionally, we compare quantum dynamics simulations with and without the relaxation of the non-reactive coordinates included in the kinetic energy operator to demonstrate its influence.« less

Synthesis, spectral characterization and catalytic activity of Co(II) complexes of drugs: crystal structure of Co(II)-trimethoprim complex.

PubMed

Madhupriya, Selvaraj; Elango, Kuppanagounder P

2014-01-24

New Co(II) complexes with drugs such as trimethoprim (TMP), cimetidine (CTD), niacinamide (NAM) and ofloxacin (OFL) as ligands were synthesized. The complexes were characterized by analytical analysis, various spectral techniques such as FT-IR, UV-Vis, magnetic measurements and molar conductivity. The magnetic susceptibility results coupled with the electronic spectra suggested a tetrahedral geometry for the complexes. The coordination mode of trimethoprim ligand and geometry of the complex were confirmed by single crystal X-ray studies. In this complex the metal ion possesses a tetrahedral geometry with two nitrogen atom from two TMP ligands and two chloride ions coordinated to it. The catalytic activity of the complexes in aryl-aryl coupling reaction was screened and the results indicated that among the four complexes [Co(OFL)Cl(H2O)] exhibited excellent catalytic activity. Copyright © 2013 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chumakov, Yu. M.; Tsapkov, V. I., E-mail: vtsapkov@gmail.com; Antosyak, B. Ya.

Nitrato-4-bromo-2-[(2-hydroxyethylimino)methyl]phenolatoimidazolecopper and nitrato-4-chloro-2-[(2-hydroxyethylimino)methyl]phenolatoimidazolecopper were synthesized and studied by X-ray diffraction. The crystals are isostructural. The coordination polyhedron of the copper atom can be described as a distorted square pyramid whose basal plane is formed by the phenolic and alcoholic oxygen atoms and the nitrogen atom of the monodeprotonated tridentate azomethine molecule and the imidazole nitrogen atom. The apex of the copper polyhedron is occupied by the oxygen atom of the nitrato group. The complexes are linked together by hydrogen bonds with the participation of the nitrato groups to form a three-dimensional framework.

Rationalizing the structural variability of the exocyclic amino groups in nucleobases and their metal complexes: cytosine and adenine.

PubMed

Fonseca Guerra, Célia; Sanz Miguel, Pablo J; Cebollada, Andrea; Bickelhaupt, F Matthias; Lippert, Bernhard

2014-07-28

The exocyclic amino groups of cytosine and adenine nucleobases are normally almost flat, with the N atoms essentially sp(2) hybridized and the lone pair largely delocalized into the heterocyclic rings. However, a change to marked pyramidality of the amino group (N then sp(3) hybridized, lone pair essentially localized at N) occurs during i) involvement of an amino proton in strong hydrogen bonding donor conditions or ii) with monofunctional metal coordination following removal of one of the two protons. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Torso geometry reconstruction and body surface electrode localization using three-dimensional photography.

PubMed

Perez-Alday, Erick A; Thomas, Jason A; Kabir, Muammar; Sedaghat, Golriz; Rogovoy, Nichole; van Dam, Eelco; van Dam, Peter; Woodward, William; Fuss, Cristina; Ferencik, Maros; Tereshchenko, Larisa G

We conducted a prospective clinical study (n=14; 29% female) to assess the accuracy of a three-dimensional (3D) photography-based method of torso geometry reconstruction and body surface electrodes localization. The position of 74 body surface electrocardiographic (ECG) electrodes (diameter 5mm) was defined by two methods: 3D photography, and CT (marker diameter 2mm) or MRI (marker size 10×20mm) imaging. Bland-Altman analysis showed good agreement in X (bias -2.5 [95% limits of agreement (LoA) -19.5 to 14.3] mm), Y (bias -0.1 [95% LoA -14.1 to 13.9] mm), and Z coordinates (bias -0.8 [95% LoA -15.6 to 14.2] mm), as defined by the CT/MRI imaging, and 3D photography. The average Hausdorff distance between the two torso geometry reconstructions was 11.17±3.05mm. Thus, accurate torso geometry reconstruction using 3D photography is feasible. Body surface ECG electrodes coordinates as defined by the CT/MRI imaging, and 3D photography, are in good agreement. Copyright © 2017 Elsevier Inc. All rights reserved.

The mechanism of addition to a CN triple bond. An ab initio study of the first stages of the Stephen, Gatterman and Houben-Hoesch reactions

NASA Astrophysics Data System (ADS)

Alagona, Giuliano; Tomasi, Jacopo

The mechanism of addition of HCl to the triple bond of RCN (R=H, CH,) is studied by means of ab initio SCF and CI calculations. Geometries and energies of minima (initial H-bonded complexes, products) and saddle points (transition state) are completed by a determination of the intrinsic reaction coordinate and of a relatively large portion of the energy hypersurface. The evolution of the electronic structure along the reaction coordinate is interpreted using localized orbitals. Particular attention is paid to the effect of chemical substitution, for which a new test, based on the electrostatic forces acting on nuclei along the reaction coordinate, has been employed. CI calculations performed over canonical and localized orbitals are compared to determine whether the latter formulation is more convenient for non-equilibrium geometries.

catena-Poly[[(benzil bis{[(pyridin-2-yl)methylidene]hydrazone}-κ4 N,N′,N′′,N′′′)mercury(II)]-μ-chlorido-[dichloridomercury(II)]-μ-chlorido

PubMed Central

Akkurt, Mehmet; Khandar, Ali Akbar; Tahir, Muhammad Nawaz; Hosseini-Yazdi, Seyed Abolfazl; Mahmoudi, Ghodrat

2012-01-01

In the title coordination polymer, [Hg2Cl4(C26H20N6)]n, one HgII ion is coordinated by four N atoms from the benzylbis((pyridin-2-yl)methyl­idenehydrazone) ligand and two Cl− ions in a very distorted cis-HgCl2N4 octa­hedral geometry. The other HgII ion is coordinated in a distorted tetra­hedral geometry by four Cl− ions. Bridging chloride ions link the HgII ions into a chain propagating in [010]: the Hg—Cl bridging bonds are significantly longer than the terminal bonds. The dihedral angle between the central benzene rings of the ligand is 83.3 (2)°. The packing is consolidated by weak C—H⋯Cl hydrogen bonds and C—H⋯π inter­actions. PMID:22807743

Centre of pressure correlates with pyramid performance in acrobatic gymnastics.

PubMed

Floría, Pablo; Gómez-Landero, Luis Arturo; Harrison, Andrew J

2015-01-01

Acrobatic gymnasts need excellent balance control to execute pyramids where one gymnast is supported by another. The objectives of this study were: (1) to describe balance performance by assessing the centre of pressure displacement in a group of acrobatic gymnasts executing pyramids; (2) to determine the relationship between the parameters describing the centre of pressure oscillations and pyramid score; and (3) to examine the role of each foot in providing a solid base of support to maintain the balance of the pyramid. Sixteen acrobatic gymnasts grouped in pairs performed a Half pyramid and a Straddle pyramid held for 7 s on two force platforms. Path length, variance, range trajectory, and surface area of the centre of pressure of each foot were examined to analyse the balance of the pyramid. The path length was correlated with the pyramid score (Straddle: p = 0.692 [large]; Half: p = 0.407 [moderate]). There were differences in the functions of each leg to maintain balance, with the non-preferred leg supporting a higher weight of the pyramid while the preferred leg performed control movements to maintain balance. The results suggested that quantitative analysis of balance can provide important information on pyramid performance.

Multifaceted adsorption of α-cyano-4-hydroxycinnamic acid on silver colloidal and island surfaces

NASA Astrophysics Data System (ADS)

Jung, Dawoon; Jeon, Kooknam; Yeo, Juhyun; Hussain, Shafqat; Pang, Yoonsoo

2017-12-01

The surface adsorption of organic nitrile compounds on the silver colloidal and island surfaces has been studied using surface-enhanced Raman scattering (SERS). α-Cyano-4-hydroxycinnamic acid (CHCA) with nitrile and carboxyl groups shows various surface adsorption on the silver surfaces. In acidic conditions, the surface adsorption of CHCA via the nitrile group with a more or less tilted geometry to the surface was found. When the solution pH increases, the carboxylate and nitrile groups of deprotonated CHCA participate in the surface adsorption, whereas the molecular plane of CHCA becomes more parallel to the surface. The ν(Ctbnd N) band in SERS of CHCA is the indicator of the surface adsorption geometry. The strongly red-shifted and broadened ν(Ctbnd N) band in SERS represents the surface adsorption via π-electrons of the Ctbnd N bond (side-on geometry; π-coordination). Nitriles adsorbed on the surface via the nonbonding electron pair of the nitrogen atom (end-on geometry; σ-coordination) often cause the blue-shifts and small band broadening in ν(Ctbnd N) in SERS. The surface adsorption geometry of organic nitriles based on many previous experimental results was further confirmed by the surface adsorption of CHCA on the silver island surfaces and dinitrile compounds on the silver colloidal surfaces.

Urban Public Health: Is There a Pyramid?

PubMed Central

Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

2013-01-01

Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000–2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development. PMID:23358233

Urban public health: is there a pyramid?

PubMed

Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

2013-01-28

Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000-2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development.

Differential geometry based model for eddy current inspection of U-bend sections in steam generator tubes

NASA Astrophysics Data System (ADS)

Mukherjee, Saptarshi; Rosell, Anders; Udpa, Lalita; Udpa, Satish; Tamburrino, Antonello

2017-02-01

The modeling of U-Bend segment in steam generator tubes for predicting eddy current probe signals from cracks, wear and pitting in this region poses challenges and is non-trivial. Meshing the geometry in the cartesian coordinate system might require a large number of elements to model the U-bend region. Also, since the lift-off distance between the probe and tube wall is usually very small, a very fine mesh is required near the probe region to accurately describe the eddy current field. This paper presents a U-bend model using differential geometry principles that exploit the result that Maxwell's equations are covariant with respect to changes of coordinates and independent of metrics. The equations remain unaltered in their form, regardless of the choice of the coordinates system, provided the field quantities are represented in the proper covariant and contravariant form. The complex shapes are mapped into simple straight sections, while small lift-off is mapped to larger values, thus reducing the intrinsic dimension of the mesh and stiffness matrix. In this contribution, the numerical implementation of the above approach will be discussed with regard to field and current distributions within the U-bend tube wall. For the sake of simplicity, a two dimensional test case will be considered. The approach is evaluated in terms of efficiency and accuracy by comparing the results with that obtained using a conventional FE model in cartesian coordinates.

Novel 3D Compression Methods for Geometry, Connectivity and Texture

NASA Astrophysics Data System (ADS)

Siddeq, M. M.; Rodrigues, M. A.

2016-06-01

A large number of applications in medical visualization, games, engineering design, entertainment, heritage, e-commerce and so on require the transmission of 3D models over the Internet or over local networks. 3D data compression is an important requirement for fast data storage, access and transmission within bandwidth limitations. The Wavefront OBJ (object) file format is commonly used to share models due to its clear simple design. Normally each OBJ file contains a large amount of data (e.g. vertices and triangulated faces, normals, texture coordinates and other parameters) describing the mesh surface. In this paper we introduce a new method to compress geometry, connectivity and texture coordinates by a novel Geometry Minimization Algorithm (GM-Algorithm) in connection with arithmetic coding. First, each vertex ( x, y, z) coordinates are encoded to a single value by the GM-Algorithm. Second, triangle faces are encoded by computing the differences between two adjacent vertex locations, which are compressed by arithmetic coding together with texture coordinates. We demonstrate the method on large data sets achieving compression ratios between 87 and 99 % without reduction in the number of reconstructed vertices and triangle faces. The decompression step is based on a Parallel Fast Matching Search Algorithm (Parallel-FMS) to recover the structure of the 3D mesh. A comparative analysis of compression ratios is provided with a number of commonly used 3D file formats such as VRML, OpenCTM and STL highlighting the performance and effectiveness of the proposed method.

An Encoding Method for Compressing Geographical Coordinates in 3d Space

NASA Astrophysics Data System (ADS)

Qian, C.; Jiang, R.; Li, M.

2017-09-01

This paper proposed an encoding method for compressing geographical coordinates in 3D space. By the way of reducing the length of geographical coordinates, it helps to lessen the storage size of geometry information. In addition, the encoding algorithm subdivides the whole space according to octree rules, which enables progressive transmission and loading. Three main steps are included in this method: (1) subdividing the whole 3D geographic space based on octree structure, (2) resampling all the vertices in 3D models, (3) encoding the coordinates of vertices with a combination of Cube Index Code (CIC) and Geometry Code. A series of geographical 3D models were applied to evaluate the encoding method. The results showed that this method reduced the storage size of most test data by 90 % or even more under the condition of a speed of encoding and decoding. In conclusion, this method achieved a remarkable compression rate in vertex bit size with a steerable precision loss. It shall be of positive meaning to the web 3d map storing and transmission.

A new copper(II) chelate complex with tridentate ligand: Synthesis, crystal and molecular electronic structure of aqua-(diethylenetriamine-N, N‧, N‧‧)-copper(II) sulfate monohydrate and its fire retardant properties

NASA Astrophysics Data System (ADS)

Lavrenyuk, H.; Mykhalichko, O.; Zarychta, B.; Olijnyk, V.; Mykhalichko, B.

2015-09-01

The crystals of a new aqua-(diethylenetriamine-N, N‧, N‧‧)-copper(II) sulfate monohydrate have been synthesized by direct interaction of solid copper(II) sulfate pentahydrate with diethylenetriamine (deta). The crystal structure of [Cu(deta)H2O]SO4ṡH2O (1) has been determined by X-ray diffraction methods at 100 K and characterized using X-ray powder diffraction pattern: space group P 1 bar, a = 7.2819(4), b = 8.4669(4), c = 8.7020(3) Å, α = 83.590(3), β = 89.620(4), γ = 84.946(4)°, Z = 2. The environment of the Cu(II) atom is a distorted, elongated square pyramid which consists of three nitrogen atoms of the deta molecule and oxygen atom of the water molecule in the basal plane of the square pyramid (the average lengths of the in-plane Cu-N and Cu-O bonds are 2.00 Å). The apical position of the coordination polyhedron is occupied by complementary oxygen atom of the sulfate anion (the length of the axial Cu-O bond is 2.421(1) Å). The crystal packing is governed by strong hydrogen bonds of O-H⋯O and N-H⋯O types. The ab initio quantum-chemical calculations have been performed by the restricted Hartree-Fock method with a basis set 6-31∗G using the structural data of [Cu(deta)H2O]SO4ṡH2O. It has been ascertained that the degenerate d-orbitals of the Cu2+ ion split under the co-action of both the square-pyramidal coordination and the chelation. It is significant that visually observed crystals color (blue-violet) of the [Cu(deta)H2O]SO4ṡH2O complex is in good agreement with the calculated value of wavelength of visible light (λ = 5735 Å) which is closely related to the energy of the absorbed photon (Δ = 2.161 eV). Furthermore, the stereo-chemical aspect of influence of the CuSO4 upon combustibility of modified epoxy-amine polymers has been scrutinized.

Computation Techniques for the Volume of a Tetrahedron

ERIC Educational Resources Information Center

Srinivasan, V. K.

2010-01-01

The purpose of this article is to discuss specific techniques for the computation of the volume of a tetrahedron. A few of them are taught in the undergraduate multivariable calculus courses. Few of them are found in text books on coordinate geometry and synthetic solid geometry. This article gathers many of these techniques so as to constitute a…

Automatization Project for the Carl-Zeiss-Jena Coudè Telescope of the Simón Bolívar Planetarium I. The Electro-Mechanic System

NASA Astrophysics Data System (ADS)

Núñez, A.; Maharaj, A.; Muñoz, A. G.

2009-05-01

The ``Complejo Científico, Cultural y Turístico Simón Bolívar'' (CCCTSB), located in Maracaibo, Venezuela, lodges the Simón Bolívar Planetarium and an 150 mm aperture, 2250 mm focal length Carl-Zeiss-Jena Coudè refractor telescope. In this work we discuss the schematics for the automatization project of this Telescope, the planned improvements, methodology, engines, micro-controllers, interfaces and the uptodate status of the project. This project is working on the first two levels of the automation pyramid, the sensor -- actuator level and the control or Plant floor level. The Process control level correspond to the software related section. This mean that this project work immediately with the electrical, electronic and mechanical stuffs, and with the assembler micro controller language. All the pc related stuff, like GUI (Graphic user interfaces), remote control, Grid database, and others, correspond to the next two automation pyramid levels. The idea is that little human intervention will be required to manipulate the telescope, only giving a pair of coordinates to ubicate and follow an object on the sky. A set of three servomotors, coupling it with the telescope with a gear box, are going to manipulate right ascension, declination and focus movement. For the dome rotation, a three phase induction motor will be used. For dome aperture/closure it is suggested a DC motor powered with solar panels. All those actuators are controlled by a 8 bits micro-controller, which receive the coordinate imput, the signal from the position sensors and have the PID control algorithm. This algorithm is tuned based on the mathematical model of the telescope electro-mechanical instrumentation.

Hardware architecture design of a fast global motion estimation method

NASA Astrophysics Data System (ADS)

Liang, Chaobing; Sang, Hongshi; Shen, Xubang

2015-12-01

VLSI implementation of gradient-based global motion estimation (GME) faces two main challenges: irregular data access and high off-chip memory bandwidth requirement. We previously proposed a fast GME method that reduces computational complexity by choosing certain number of small patches containing corners and using them in a gradient-based framework. A hardware architecture is designed to implement this method and further reduce off-chip memory bandwidth requirement. On-chip memories are used to store coordinates of the corners and template patches, while the Gaussian pyramids of both the template and reference frame are stored in off-chip SDRAMs. By performing geometric transform only on the coordinates of the center pixel of a 3-by-3 patch in the template image, a 5-by-5 area containing the warped 3-by-3 patch in the reference image is extracted from the SDRAMs by burst read. Patched-based and burst mode data access helps to keep the off-chip memory bandwidth requirement at the minimum. Although patch size varies at different pyramid level, all patches are processed in term of 3x3 patches, so the utilization of the patch-processing circuit reaches 100%. FPGA implementation results show that the design utilizes 24,080 bits on-chip memory and for a sequence with resolution of 352x288 and frequency of 60Hz, the off-chip bandwidth requirement is only 3.96Mbyte/s, compared with 243.84Mbyte/s of the original gradient-based GME method. This design can be used in applications like video codec, video stabilization, and super-resolution, where real-time GME is a necessity and minimum memory bandwidth requirement is appreciated.

On a Microscopic Representation of Space-Time V

NASA Astrophysics Data System (ADS)

Dahm, R.

2017-01-01

In previous parts of this publication series, starting from the Dirac algebra and SU*(4), the ’dual’ compact rank-3 group SU(4) and Lie theory, we have developed some arguments and the reasoning to use (real) projective and (line) Complex geometry directly. Here, we want to extend this approach further in terms of line and Complex geometry and give some analytical examples. As such, we start from quadratic Complexe which we’ve identified in parts III and IV already as yielding naturally the ’light cone’ x_12 + x_22 + x_32 - x_02 = 0 when being related to (homogeneous) point coordinates x_α ^2 and infinitesimal dynamics by tetrahedral Complexe (or line elements). This introduces naturally projective transformations by preserving anharmonic ratios. We summarize some old work of Plücker relating quadratic Complexe to optics and discuss briefly their relation to spherical (and Schrödinger-type) equations as well as an obvious interpretation based on homogeneous coordinates and relations to conics and second order surfaces. Discussing (linear) symplectic symmetry and line coordinates, the main purpose and thread within this paper, however, is the identification and discussion of special relativity as direct invariance properties of line/Complex coordinates as well as their relation to ’quantum field theory’ by complexification of point coordinates or Complexe. This can be established by the Lie mapping1 which relates lines/Complexe to sphere geometry so that SU(2), SU(2)×U(1), SU(2)×SU(2) and the Dirac spinor description emerge without additional assumptions. We give a short outlook in that quadratic Complexe are related to dynamics e.g. power expressions in terms of six-vector products of Complexe, and action principles may be applied. (Quadratic) products like {Fμ ν }{Fμ ν }{{ or }}{Fα {{ }μ ν }}Fμ ν ^α ,1 ≤ α ≤ 3 are natural quadratic Complex expressions which may be extended by line constraints λk · ɛ = 0 with respect to an ’action principle’ so that we identify ’quantum field theory’ with projective or line/Complex geometry having applied the Lie mapping.

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde

NASA Astrophysics Data System (ADS)

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Sumathi, S.

2012-10-01

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 μm.

In vitro antibacterial, antifungal and cytotoxic activities of some triazole Schiff bases and their oxovanadium(IV) complexes.

PubMed

Sumrra, Sajjad H; Chohan, Zahid H

2013-12-01

The condensation reaction of 3,5-diamino-1,2,4-triazole with methoxy-, chloro-, bromo-, iodo- and nitro-substituted 2-hydroxybenzaldehydes formed triazole Schiff bases (L(1))-(L(6)). The synthesized ligands have been characterized through physical, spectral and analytical data. Furthermore, the reaction of synthesized Schiff bases with the oxovanadium(IV) sulphate in (1:2) (metal:ligand) molar ratio afforded the oxovanadium(IV) complexes (1)-(6). All the complexes were non-electrolytic and showed a square-pyramidal geometry. The synthesized compounds have been screened for in-vitro antibacterial, antifungal and brine shrimp bioassay. The bioactivity data showed the complexes to be more active than the original Schiff bases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, H; Padilla, L; Hasan, Y

Purpose: To develop a standalone application, which automatically and consistently calculates the coordinates of points A and H based solely on the implanted applicator geometry for cervical cancer HDR brachytherapy. Methods: Manchester point A and ABS point H are both located 2cm lateral from the central tandem plane. While both points are located 2cm above the cervical os, surrogates for the os differ. Point A is defined relative to the anatomical cervical os. Point H is defined relative to the intersection of the tandem with the superior aspects of the ovoids. The application takes an input text file generated bymore » the treatment planning system (TPS, BrachyVision, Varian) that specifies the source geometries. It then outputs the 3D coordinates of points A and H in both the left and right directions. The algorithm was implemented and tested on 34 CT scans of 7 patients treated with HDR brachytherapy delivered using tandem and ovoids. A single experienced user retrospectively and manually placed points A and H on the CT scans, whose coordinates were used as the gold standard for the comparison to the automatically calculated points. Results: The automatically calculated coordinates of points A and H agree within 0.7mm with the gold standard. The averages and standard deviations of the 3D coordinate difference between points placed by the two methods are 0.3±0.1 and 0.4±0.1mm for points A and H, respectively. The maximum difference in 3D magnitude is 0.7mm. Conclusion: The algorithm consistently calculates dose point coordinates independently of the planner for cervical cancer brachytherapy treated with tandem and ovoids. Automated point placement based on the geometry of the implanted applicators agrees in sub-millimeter with careful manual placements by an experienced user. This algorithm expedites the planning process and eliminates dependencies on either user input or TPS visualization tools.« less

Poly[[nona­aqua­bis­(μ-5-hy­droxy­benzene-1,3-di­carboxyl­ato)(5-hy­droxy­benzene-1,3-di­carboxyl­ato)dicerium(III)] hexa­hydrate

PubMed Central

Fan, Xiao; Daiguebonne, Carole; Guillou, Olivier; Camara, Magatte

2014-01-01

In the title coordination polymer, {[Ce2(C8H4O5)3(H2O)9]·6H2O}n, the asymmetric unit is formed by two CeIII atoms, three 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligands, nine coordinating water mol­ecules and six water mol­ecules of crystallization. The two CeIII atoms are bridged by 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligands acting in a bis-bidentate coordination mode, generating infinite chains along [101]. Both independent metal atoms are nine-coordinated, one by four O atoms from the carboxyl­ate groups of two bridging 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligands and five O atoms from water mol­ecules, generating a tricapped trigonal–prismatic geometry. The coordination around the second CeIII atom is similar, except that one of the water mol­ecules is replaced by an O atom from an additional 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligand acting in a monodentate coordination mode and forming a capped square-anti­prismatic geometry. PMID:24860313

Adsorption and possible dissociation of glucose by the [BN fullerene-B6]- magnetic nanocomposite. In silico studies

NASA Astrophysics Data System (ADS)

Anota, E. Chigo; Villanueva, M. Salazar; Shakerzadeh, E.; Castro, M.

2018-02-01

The adsorption, activation and possible dissociation of the glucose molecule on the magnetic [BN fullerene-B6]- system is performed by means of density functional theory calculations. Three models of magnetic nanocomposites were inspected: i) pristine BN fullerene, BN fullerene functionalized with a magnetic B6 cluster which generates two structures: ii) pyramidal (P) and iii) triangular (T). Chemical interactions of glucose appear for all these cases; however, for the BNF:B6(T)—glucose system, the interaction generates an effect of dissociation on glucose, due to the magnetic effects, since it has high spin multiplicity. The latter nanocomposite shows electronic behavior like-conductor and like-semi-conductor for the P and T geometries, respectively. Intrinsic magnetism associated to values of 1.0 magneton bohr (µB) for the pyramidal and 5.0 µB for the triangular structure, high polarity, and low-chemical reactivity are found for these systems. These interesting properties make these functionalized fullerenes a good option for being used as nano-vehicles for drug delivery. These quantum descriptors remain invariant when the [BN]-fullerene and [BNF:B6 (P) or (T)]- nanocomposites are interacting with the glucose molecule. According to the determined adsorption energy, chemisorption regimes occur in both the phases: gas and aqueous medium.

PyramidalExplorer: A New Interactive Tool to Explore Morpho-Functional Relations of Human Pyramidal Neurons.

PubMed

Toharia, Pablo; Robles, Oscar D; Fernaud-Espinosa, Isabel; Makarova, Julia; Galindo, Sergio E; Rodriguez, Angel; Pastor, Luis; Herreras, Oscar; DeFelipe, Javier; Benavides-Piccione, Ruth

2015-01-01

This work presents PyramidalExplorer, a new tool to interactively explore and reveal the detailed organization of the microanatomy of pyramidal neurons with functionally related models. It consists of a set of functionalities that allow possible regional differences in the pyramidal cell architecture to be interactively discovered by combining quantitative morphological information about the structure of the cell with implemented functional models. The key contribution of this tool is the morpho-functional oriented design that allows the user to navigate within the 3D dataset, filter and perform Content-Based Retrieval operations. As a case study, we present a human pyramidal neuron with over 9000 dendritic spines in its apical and basal dendritic trees. Using PyramidalExplorer, we were able to find unexpected differential morphological attributes of dendritic spines in particular compartments of the neuron, revealing new aspects of the morpho-functional organization of the pyramidal neuron.

PyramidalExplorer: A New Interactive Tool to Explore Morpho-Functional Relations of Human Pyramidal Neurons

PubMed Central

Toharia, Pablo; Robles, Oscar D.; Fernaud-Espinosa, Isabel; Makarova, Julia; Galindo, Sergio E.; Rodriguez, Angel; Pastor, Luis; Herreras, Oscar; DeFelipe, Javier; Benavides-Piccione, Ruth

2016-01-01

This work presents PyramidalExplorer, a new tool to interactively explore and reveal the detailed organization of the microanatomy of pyramidal neurons with functionally related models. It consists of a set of functionalities that allow possible regional differences in the pyramidal cell architecture to be interactively discovered by combining quantitative morphological information about the structure of the cell with implemented functional models. The key contribution of this tool is the morpho-functional oriented design that allows the user to navigate within the 3D dataset, filter and perform Content-Based Retrieval operations. As a case study, we present a human pyramidal neuron with over 9000 dendritic spines in its apical and basal dendritic trees. Using PyramidalExplorer, we were able to find unexpected differential morphological attributes of dendritic spines in particular compartments of the neuron, revealing new aspects of the morpho-functional organization of the pyramidal neuron. PMID:26778972

Nonabelian Bundle Gerbes, Their Differential Geometry and Gauge Theory

NASA Astrophysics Data System (ADS)

Aschieri, Paolo; Cantini, Luigi; Jurčo, Branislav

2005-03-01

Bundle gerbes are a higher version of line bundles, we present nonabelian bundle gerbes as a higher version of principal bundles. Connection, curving, curvature and gauge transformations are studied both in a global coordinate independent formalism and in local coordinates. These are the gauge fields needed for the construction of Yang-Mills theories with 2-form gauge potential.

Virtual Reality Tumor Resection: The Force Pyramid Approach.

PubMed

Sawaya, Robin; Bugdadi, Abdulgadir; Azarnoush, Hamed; Winkler-Schwartz, Alexander; Alotaibi, Fahad E; Bajunaid, Khalid; AlZhrani, Gmaan A; Alsideiri, Ghusn; Sabbagh, Abdulrahman J; Del Maestro, Rolando F

2018-06-01

The force pyramid is a novel visual representation allowing spatial delineation of instrument force application during surgical procedures. In this study, the force pyramid concept is employed to create and quantify dominant hand, nondominant hand, and bimanual force pyramids during resection of virtual reality brain tumors. To address 4 questions: Do ergonomics and handedness influence force pyramid structure? What are the differences between dominant and nondominant force pyramids? What is the spatial distribution of forces applied in specific tumor quadrants? What differentiates "expert" and "novice" groups regarding their force pyramids? Using a simulated aspirator in the dominant hand and a simulated sucker in the nondominant hand, 6 neurosurgeons and 14 residents resected 8 different tumors using the CAE NeuroVR virtual reality neurosurgical simulation platform (CAE Healthcare, Montréal, Québec and the National Research Council Canada, Boucherville, Québec). Position and force data were used to create force pyramids and quantify tumor quadrant force distribution. Force distribution quantification demonstrates the critical role that handedness and ergonomics play on psychomotor performance during simulated brain tumor resections. Neurosurgeons concentrate their dominant hand forces in a defined crescent in the lower right tumor quadrant. Nondominant force pyramids showed a central peak force application in all groups. Bimanual force pyramids outlined the combined impact of each hand. Distinct force pyramid patterns were seen when tumor stiffness, border complexity, and color were altered. Force pyramids allow delineation of specific tumor regions requiring greater psychomotor ability to resect. This information can focus and improve resident technical skills training.

Monoatomic and dimer Mn adsorption on the Au(111) surface from first principles

NASA Astrophysics Data System (ADS)

Muñoz, Francisco; Romero, Aldo H.; Mejía-López, Jose; Morán-López, J. L.

2011-05-01

A theoretical study based on the density functional theory of the adsorption of Mn monomers and dimers on a Au-(111) surface is presented. As necessary preliminary steps, the bulk and clean surface electronic structure are calculated, which agree well with previous reports. Then, the electronic structure of the Mn adatom, chemisorbed on four different surface geometries, is analyzed. It is found that the most stable geometry is when the Mn atom is chemisorbed on threefold coordinated sites. Using this geometry for a single adatom a second Mn atom is chemisorbed and the most stable dimer geometrical structure is calculated. The lowest-energy configuration corresponds to the molecule lying parallel to the surface, adsorbed on two topological equivalent threefold coordinated sites. It is also found that the lowest-energy magnetic configuration corresponds to the antiferromagnetic arrangement with individual magnetic moments of 4.64μB. Finally, it is concluded that the dimer is not stable and should fragment at the surface.

Definition of NASTRAN sets by use of parametric geometry

NASA Technical Reports Server (NTRS)

Baughn, Terry V.; Tiv, Mehran

1989-01-01

Many finite element preprocessors describe finite element model geometry with points, lines, surfaces and volumes. One method for describing these basic geometric entities is by use of parametric cubics which are useful for representing complex shapes. The lines, surfaces and volumes may be discretized for follow on finite element analysis. The ability to limit or selectively recover results from the finite element model is extremely important to the analyst. Equally important is the ability to easily apply boundary conditions. Although graphical preprocessors have made these tasks easier, model complexity may not lend itself to easily identify a group of grid points desired for data recovery or application of constraints. A methodology is presented which makes use of the assignment of grid point locations in parametric coordinates. The parametric coordinates provide a convenient ordering of the grid point locations and a method for retrieving the grid point ID's from the parent geometry. The selected grid points may then be used for the generation of the appropriate set and constraint cards.

Aqua­[1,8-bis­(pyridin-2-yl)-3,6-dithia­octane-κ4 N,S,S′,N′]copper(II) dinitrate acetonitrile monosolvate

PubMed Central

Manzanera-Estrada, Mayra; Flores-Alamo, Marcos; Grevy M., Jean-Michel; Ruiz-Azuara, Lena; Ortiz-Frade, Luis

2012-01-01

In the title compound, [Cu(C16H20N2S2)(H2O)](NO3)2·CH3CN, the CuII atom displays a distorted square-pyramidal coordination, in which a water mol­ecule occupies the apical position and the basal plane is formed by two N atoms and two S atoms of a 1,8-bis­(pyridin-2-yl)-3,6-dithia­octane ligand. The crystal packing is stabilized by O—H⋯O and C—H⋯O hydrogen bonds. PMID:22346819

Structural diversity of silver (I) azine complexes - Effect of substituents and counter anions

NASA Astrophysics Data System (ADS)

Patra, Goutam Kumar; Mukherjee, Anindita; Mitra, Partha; Adarsh, N. N.

2011-08-01

Three new Ag(I) complexes, 1, 2, and 3 of two azine ligands diacetyl dihydrazone ( L1) and benzil dihydrazone ( L2) have been synthesized and characterized by single crystal X-ray diffraction studies (for 2 and 3), X-ray powder diffraction studies( 1 and 2), elemental analyses, IR and UV-VIS spectroscopy and TGA analysis. They represent one-dimensional polymeric assemblies and discrete dinuclear Ag(I) complex depending on functionality of the ligands and the counter anions. Tetrahedral as well as square pyramidal coordination motifs of the silver (I) ions have been observed in the supramolecular designing of such hybrid organic-inorganic materials.

Coordinate metrology using scanning probe microscopes

NASA Astrophysics Data System (ADS)

Marinello, F.; Savio, E.; Bariani, P.; Carmignato, S.

2009-08-01

New positioning, probing and measuring strategies in coordinate metrology are needed for the accomplishment of true three-dimensional characterization of microstructures, with uncertainties in the nanometre range. In the present work, the implementation of scanning probe microscopes (SPMs) as systems for coordinate metrology is discussed. A new non-raster measurement approach is proposed, where the probe is moved to sense points along free paths on the sample surface, with no loss of accuracy with respect to traditional raster scanning and scan time reduction. Furthermore, new probes featuring long tips with innovative geometries suitable for coordinate metrology through SPMs are examined and reported.

The relativistic titls of Giza pyramids' entrance-passages

NASA Astrophysics Data System (ADS)

Aboulfotouh, H.

The tilts of Giza pyramids' entrance-passages have never been considered as if they were the result of relativistic mathematical equations, and never been thought to encode the Earth's obliquity parameters. This paper presents an attempt to retrieve the method of establishing the equations that the pyramids' designer used to quantify the entrance-passages' tilts of these architectonic masterpieces. It proves that the pyramids' designer was able to include the geographic, astronomical and time parameters in one relativistic equation, encoding the date of the design of the Giza pyramids in the tilt of the entrance passage of the great pyramid.

Sublingual pyramidal lobe. Complications of subtotal thyroidectomy for Graves' disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sternberg, J.L.

1986-11-01

A potential complication of subtotal thyroidectomy where a large pyramidal lobe is present is described. The pyramidal lobe normally is immobilized inferiorly by its attachment to the thyroidal isthmus. When the isthmus is removed and the pyramidal lobe is left in situ during subtotal thyroidectomy its superior attachments will allow the pyramidal lobe to become situated sublingually. This may produce gagging and nausea. To avoid the complication, it is recommended that the pyramidal lobe be removed during subtotal thyroidectomy. If the patient also is thyrotoxic, I-131 can be used to treat this complication successfully.

Evaluation of Trap Designs and Deployment Strategies for Capturing Halyomorpha halys (Hemiptera: Pentatomidae)

PubMed Central

Morrison, William R.; Cullum, John P.; Leskey, Tracy C.

2015-01-01

Halyomorpha halys (Stål) is an invasive pest that attacks numerous crops. For growers to make informed management decisions against H. halys, an effective monitoring tool must be in place. We evaluated various trap designs baited with the two-component aggregation pheromone of H. halys and synergist and deployed in commercial apple orchards. We compared our current experimental standard trap, a black plywood pyramid trap 1.22 m in height deployed between border row apple trees with other trap designs for two growing seasons. These included a black lightweight coroplast pyramid trap of similar dimension, a smaller (29 cm) pyramid trap also ground deployed, a smaller limb-attached pyramid trap, a smaller pyramid trap hanging from a horizontal branch, and a semipyramid design known as the Rescue trap. We found that the coroplast pyramid was the most sensitive, capturing more adults than all other trap designs including our experimental standard. Smaller pyramid traps performed equally in adult captures to our experimental standard, though nymphal captures were statistically lower for the hanging traps. Experimental standard plywood and coroplast pyramid trap correlations were strong, suggesting that standard plywood pyramid traps could be replaced with lighter, cheaper coroplast pyramid traps. Strong correlations with small ground- and limb-deployed pyramid traps also suggest that these designs offer promise as well. Growers may be able to adopt alternative trap designs that are cheaper, lighter, and easier to deploy to monitor H. halys in orchards without a significant loss in sensitivity. PMID:26470309

Morphological evolution and characterization of GaN pyramid arrays fabricated by photo-assisted chemical etching

NASA Astrophysics Data System (ADS)

Zhang, Shiying; Xiu, Xiangqian; Xu, Qingjun; Li, Yuewen; Hua, Xuemei; Chen, Peng; Xie, Zili; Liu, Bin; Zhou, Yugang; Han, Ping; Zhang, Rong; Zheng, Youdou

2016-12-01

GaN pyramid arrays have been successfully synthesized by selective photo-assisted chemical etching in a K2S2O8/KOH solution. A detailed analysis of time evolution of surface morphology has been conducted, which describes an etching process of GaN pyramids. Room temperature cathodoluminescence images indicate that these pyramids are composed of crystalline GaN surrounding dislocations, which is caused by the greater recombination rate of electrons and holes at dislocation than that of crystalline GaN. The Raman results show a stress relaxation in GaN pyramids compared with unetched GaN. The optical property of both unetched GaN and GaN pyramids has been studied by photoluminescence. The formation mechanism and feature of GaN pyramids are also rationally explained.

Interactions between 2,4-bis-pteridine-1,5-benzodiazepine and group 12 dihalides: synthesis, spectral and XRD structural studies and theoretical calculations.

PubMed

Illán-Cabeza, Nuria A; Jiménez-Pulido, Sonia B; Hueso-Ureña, Francisco; Peña-Ruiz, Tomás; Quirós-Olozábal, Miguel; Moreno-Carretero, Miguel N

2016-11-28

2,4-Bis(1,3,7-trimethyl-pteridine-2,4(1H,3H)-dione-6-yl)-2,3-dihydro-2-methyl-1H-1,5-benzodiazepine (DLMBZD) has been prepared and its molecular and crystal structures have been determined from spectral and XRD data. The benzodiazepine ligand was reacted with zinc(ii), cadmium(ii) and mercury(ii) chloride, bromide and iodide to give complexes with general formula [M(DLMBZD)X 2 ]. The complexes have been synthesized and characterized by IR, NMR and elemental analysis. The structure of seven complexes has been obtained by single crystal X-ray diffraction. In all the cases, the metal is (2 + 2 + 1)-five-coordinated by two halide ligands, two nitrogen atoms from pyrazine and diazepine rings and a carbonyl oxygen from a pteridine ring. The coordinated-metal environment is a square-based pyramid, with increasing trigonality from Hg(ii) to Zn(ii) complexes. To coordinate the metals, the ligand folds itself, establishing four intramolecular σ-π interactions with the pyrimidine and pyrazine rings. A topological analysis of the electron density using the Quantum Theory of Atoms in Molecules and the complexes stability has been performed.

Convergent microRNA actions coordinate neocortical development.

PubMed

Barca-Mayo, Olga; De Pietri Tonelli, Davide

2014-08-01

Neocortical development is a complex process that, at the cellular level, involves tight control of self-renewal, cell fate commitment, survival, differentiation and delamination/migration. These processes require, at the molecular level, the precise regulation of intrinsic signaling pathways and extrinsic factors with coordinated action in a spatially and temporally specific manner. Transcriptional regulation plays an important role during corticogenesis; however, microRNAs (miRNAs) are emerging as important post-transcriptional regulators of various aspects of central nervous system development. miRNAs are a class of small, single-stranded noncoding RNA molecules that control the expression of the majority of protein coding genes (i.e., targets). How do different miRNAs achieve precise control of gene networks during neocortical development? Here, we critically review all the miRNA-target interactions validated in vivo, with relevance to the generation and migration of pyramidal-projection glutamatergic neurons, and for the initial formation of cortical layers in the embryonic development of rodent neocortex. In particular, we focus on convergent miRNA actions, which are still a poorly understood layer of complexity in miRNA signaling, but potentially one of the keys to disclosing how miRNAs achieve the precise coordination of complex biological processes such as neocortical development.

Expression of Kv3.1b potassium channel is widespread in macaque motor cortex pyramidal cells: A histological comparison between rat and macaque

PubMed Central

Soares, David; Goldrick, Isabelle; Lemon, Roger N.; Kraskov, Alexander; Greensmith, Linda

2017-01-01

Abstract There are substantial differences across species in the organization and function of the motor pathways. These differences extend to basic electrophysiological properties. Thus, in rat motor cortex, pyramidal cells have long duration action potentials, while in the macaque, some pyramidal neurons exhibit short duration “thin” spikes. These differences may be related to the expression of the fast potassium channel Kv3.1b, which in rat interneurons is associated with generation of thin spikes. Rat pyramidal cells typically lack these channels, while there are reports that they are present in macaque pyramids. Here we made a systematic, quantitative comparison of the Kv3.1b expression in sections from macaque and rat motor cortex, using two different antibodies (NeuroMab, Millipore). As our standard reference, we examined, in the same sections, Kv3.1b staining in parvalbumin‐positive interneurons, which show strong Kv3.1b immunoreactivity. In macaque motor cortex, a large sample of pyramidal neurons were nearly all found to express Kv3.1b in their soma membranes. These labeled neurons were identified as pyramidal based either by expression of SMI32 (a pyramidal marker), or by their shape and size, and lack of expression of parvalbumin (a marker for some classes of interneuron). Large (Betz cells), medium, and small pyramidal neurons all expressed Kv3.1b. In rat motor cortex, SMI32‐postive pyramidal neurons expressing Kv3.1b were very rare and weakly stained. Thus, there is a marked species difference in the immunoreactivity of Kv3.1b in pyramidal neurons, and this may be one of the factors explaining the pronounced electrophysiological differences between rat and macaque pyramidal neurons. PMID:28213922

Evaluation of the Cost-Effectiveness of Pyramidal, Modified Pyramidal and Monoscreen Traps for the Control of the Tsetse Fly, Glossina fuscipes fuscipes, in Uganda

PubMed Central

Abila, P.P.; Okello-Onen, J.; Okoth, J.O.; Matete, G.O.; Wamwiri, F.; Politzar, H.

2007-01-01

Several trap designs have been used for sampling and control of the tsetse fly, Glossina fuscipes fuscipes, Newstead (Diptera: Glossinidae) based on preferences of individual researchers and program managers with little understanding of the comparative efficiency and cost-effectiveness of trap designs. This study was carried out to evaluate the cost-effectiveness of four commonly used trap designs: monoscreen, modified pyramidal and pyramidal, relative to the standard biconical trap. The study was performed under high tsetse challenge on Buvuma Island, Lake Victoria, Uganda, using a 4 × 4 Latin square design replicated 3 times, so as to separate the trap positions and day effects from the treatment effect. A total of 12 trap positions were tested over 4 days. The monoscreen trap caught significantly higher numbers of G. f. fuscipes (P<0.05) followed by biconical, modified pyramidal and pyramidal traps. Analysis of variance showed that treatment factor was a highly significant source of variation in the data. The index of increase in trap catches relative biconical were O.60 (pyramidal), 0.68 (modified pyramidal) and 1.25 (monoscreen). The monoscreen trap was cheaper (US$ 2.61) and required less material to construct than pyramidal trap (US$ 3.48), biconical and the modified pyramidal traps (US$ 4.06 each). Based on the number of flies caught per meter of material, the monoscreen trap proved to be the most cost-effective (232 flies/m) followed by the biconical trap (185 flies/m). The modified pyramidal and the pyramidal traps caught 112 and 125 flies/m, respectively. PMID:20345292

Synthesis, structural and biochemical activity studies of a new hexadentate Schiff base ligand and its Cu(II), Ni(II), and Co(II) complexes

NASA Astrophysics Data System (ADS)

Ekmekcioglu, Pinar; Karabocek, Nevin; Karabocek, Serdar; Emirik, Mustafa

2015-11-01

A new Schiff base ligand (H2L) and its metal complexes have been prepared and characterized by elemental analysis, magnetic moment and spectral studies. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics activity under the standard control of different concentrations revealed that the metal complexes (6-8) showed enhanced antimicrobial activities in general as compared to free ligand. As an exception, the free ligand showed better activity against Trichoderma. The antifungal activity experiments were performed in triplicate. The order of biochemical activity for metal complexes were observed as in the following. CuL > CoL > NiL, which is exactly same as the order of stability constants of these complexes. Additionally, we performed DFT and TD-DFT calculation for free ligand and Cu(II) complex to support the experimental data. The geometries of the Cu(II) complex have been optimized using the B3LYP level of theory. The theoretical calculations confirm that the copper (II) center exhibits a distorted square pyramidal geometry which is favored by experimental results.

Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes

PubMed Central

Sakthivel, A.; Rajasekaran, K.

2007-01-01

New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml. PMID:24015086

Sodium chloride crystallization from thin liquid sheets, thick layers, and sessile drops in microgravity

NASA Astrophysics Data System (ADS)

Fontana, Pietro; Pettit, Donald; Cristoforetti, Samantha

2015-10-01

Crystallization from aqueous sodium chloride solutions as thin liquid sheets, 0.2-0.7 mm thick, with two free surfaces supported by a wire frame, thick liquid layers, 4-6 mm thick, with two free surfaces supported by metal frame, and hemispherical sessile drops, 20-32 mm diameter, supported by a flat polycarbonate surface or an initially flat gelatin film, were carried out under microgravity on the International Space Station (ISS). Different crystal morphologies resulted based on the fluid geometry: tabular hoppers, hopper cubes, circular [111]-oriented crystals, and dendrites. The addition of polyethylene glycol (PEG-3350) inhibited the hopper growth resulting in flat-faced surfaces. In sessile drops, 1-4 mm tabular hopper crystals formed on the free surface and moved to the fixed contact line at the support (polycarbonate or gelatin) self-assembling into a shell. Ring formation created by sessile drop evaporation to dryness was observed but with crystals 100 times larger than particles in terrestrially formed coffee rings. No hopper pyramids formed. By choosing solution geometries offered by microgravity, we found it was possible to selectively grow crystals of preferred morphologies.

Synthesis, structure, and luminescence property of a series of Ag–Ln coordination polymers with the N-heterocyclic carboxylato ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Jing, E-mail: jinjing_crystal@126.com; Chen, Chong; Gao, Yan

Six Ln–Ag coordination polymers {[LnAg_2(IN)_4(H_2O)_5]·NO_3·2H_2O}{sub n} (Ln=Ho (1) and Tb (2), HIN=isonicotinic acid), {[PrAg_2(IN)_4(H_2O)_2]·NO_3·H_2O}{sub n} (3), [LnAg(pdc){sub 2}]{sub n} (Ln=Eu(4) and Pr (5), H{sub 2}pdc=3,4-pyridine-dicarboxylic acid) and [NdAg(bidc){sub 2}(H{sub 2}O){sub 4}]{sub n} (6) (H{sub 2}bidc=benzimidazole-5,6-dicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV–vis-NIR absorption spectra, fluorescence spectra and thermogravimetric analysis. Structural analyses reveal that the six polymers exhibit 0D (polymer (1)), 1D (polymer (2)), 2D (polymers (3) and (5)) and 3D (polymers (4) and (6)) infinite structures, respectively. Polymers (1)–(6) exhibit the Ln(III) characteristic emission in the near-infrared (NIR) region or inmore » the visible region. Especially, the NIR emission bands of polymers 1, 5 and 6 evidently present shift or splitting due to formation of the Ln–Ag coordination polymers. This can be attributed to the tune of inner levels in Ln–Ag system caused by the interact and influence between the 4d orbital of the Ag(I) ion and the 4f orbital of the Ln(III) ion, which can be confirmed by the UV–vis-NIR absorption spectra of the polymers. In addition, the distortion of coordination geometry as well as difference of the coordination number around the Ag(I) ion affect the structure framework. - Graphical abstract: Six Ag–Ln coordination polymers have been hydrothermally synthesized and characterized. The photoluminescence properties were studied. The distortion of coordination geometry of Ag(I) ion affect structure framework. Introduction of Ag(I) cause wonderful changes to the NIR emission of Ln(III) ions. - Highlights: • Six Ln–Ag polymers have been synthesized and characterized. • The distortion of coordination geometry of Ag(I) ion affect structure framework. • Introduction of Ag(I) cause wonderful changes to the NIR emission of Ln(III) ions.« less

Computation of transonic potential flow about 3 dimensional inlets, ducts, and bodies

NASA Technical Reports Server (NTRS)

Reyhner, T. A.

1982-01-01

An analysis was developed and a computer code, P465 Version A, written for the prediction of transonic potential flow about three dimensional objects including inlet, duct, and body geometries. Finite differences and line relaxation are used to solve the complete potential flow equation. The coordinate system used for the calculations is independent of body geometry. Cylindrical coordinates are used for the computer code. The analysis is programmed in extended FORTRAN 4 for the CYBER 203 vector computer. The programming of the analysis is oriented toward taking advantage of the vector processing capabilities of this computer. Comparisons of computed results with experimental measurements are presented to verify the analysis. Descriptions of program input and output formats are also presented.

Towards the Rational Design of MRI Contrast Agents: Electron Spin Relaxation Is Largely Unaffected by the Coordination Geometry of Gadolinium(III)–DOTA-Type Complexes

PubMed Central

Bean, Jonathan F.; Clarkson, Robert B.; Helm, Lothar; Moriggi, Loïck; Sherry, A. Dean

2009-01-01

Electron-spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electron-spin relaxation is that it is closely related to the ligand-field parameters of the Gd3+ ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTA-type ligands could be synthesised that, when coordinated to Gd3+, would adopt well defined coordination geometries and are not subject to the problems of intramolecular motion of other complexes. The EPR properties of these two chelates were studied and the results examined with theory to probe their electron-spin relaxation properties. PMID:18283704

Computation of Relative Magnetic Helicity in Spherical Coordinates

NASA Astrophysics Data System (ADS)

Moraitis, Kostas; Pariat, Étienne; Savcheva, Antonia; Valori, Gherardo

2018-06-01

Magnetic helicity is a quantity of great importance in solar studies because it is conserved in ideal magnetohydrodynamics. While many methods for computing magnetic helicity in Cartesian finite volumes exist, in spherical coordinates, the natural coordinate system for solar applications, helicity is only treated approximately. We present here a method for properly computing the relative magnetic helicity in spherical geometry. The volumes considered are finite, of shell or wedge shape, and the three-dimensional magnetic field is considered to be fully known throughout the studied domain. Testing of the method with well-known, semi-analytic, force-free magnetic-field models reveals that it has excellent accuracy. Further application to a set of nonlinear force-free reconstructions of the magnetic field of solar active regions and comparison with an approximate method used in the past indicates that the proposed method can be significantly more accurate, thus making our method a promising tool in helicity studies that employ spherical geometry. Additionally, we determine and discuss the applicability range of the approximate method.

Theoretical study of pyramid sizes and scattering effects in silicon photovoltaic module stacks.

PubMed

Höhn, Oliver; Tucher, Nico; Bläsi, Benedikt

2018-03-19

Front side pyramids are the industrial standard for wafer based monocrystalline silicon solar cells. These pyramids fulfill two tasks: They act as anti-reflective structure on the one hand and as a light-trapping structure on the other hand. In recent development smaller pyramids with sizes below 1 µm attract more and more interest. In this paper an optical analysis of periodically arranged front side pyramids is performed. The impact on the reflectance as well as on the useful absorption within the solar cell is investigated depending on the pyramids size, the amount of additional scattering in the system and the quality of the rear side reflector. In contrast to other investigations not only the solar cell, but the full photovoltaic (PV) module stack is considered. This can strongly influence results, as we show in this paper. The results indicate that in a PV module stack with realistic assumptions for the amount of scattering as well as for the rear side reflectance only small differences for pyramids with sizes above 600 nm occur. Preliminary conclusions for random pyramids deduced from these results for periodically arranged pyramids indicate that these differences could become even smaller.

Stabilizing embedology: Geometry-preserving delay-coordinate maps

NASA Astrophysics Data System (ADS)

Eftekhari, Armin; Yap, Han Lun; Wakin, Michael B.; Rozell, Christopher J.

2018-02-01

Delay-coordinate mapping is an effective and widely used technique for reconstructing and analyzing the dynamics of a nonlinear system based on time-series outputs. The efficacy of delay-coordinate mapping has long been supported by Takens' embedding theorem, which guarantees that delay-coordinate maps use the time-series output to provide a reconstruction of the hidden state space that is a one-to-one embedding of the system's attractor. While this topological guarantee ensures that distinct points in the reconstruction correspond to distinct points in the original state space, it does not characterize the quality of this embedding or illuminate how the specific parameters affect the reconstruction. In this paper, we extend Takens' result by establishing conditions under which delay-coordinate mapping is guaranteed to provide a stable embedding of a system's attractor. Beyond only preserving the attractor topology, a stable embedding preserves the attractor geometry by ensuring that distances between points in the state space are approximately preserved. In particular, we find that delay-coordinate mapping stably embeds an attractor of a dynamical system if the stable rank of the system is large enough to be proportional to the dimension of the attractor. The stable rank reflects the relation between the sampling interval and the number of delays in delay-coordinate mapping. Our theoretical findings give guidance to choosing system parameters, echoing the tradeoff between irrelevancy and redundancy that has been heuristically investigated in the literature. Our initial result is stated for attractors that are smooth submanifolds of Euclidean space, with extensions provided for the case of strange attractors.

Stabilizing embedology: Geometry-preserving delay-coordinate maps.

PubMed

Eftekhari, Armin; Yap, Han Lun; Wakin, Michael B; Rozell, Christopher J

2018-02-01

Delay-coordinate mapping is an effective and widely used technique for reconstructing and analyzing the dynamics of a nonlinear system based on time-series outputs. The efficacy of delay-coordinate mapping has long been supported by Takens' embedding theorem, which guarantees that delay-coordinate maps use the time-series output to provide a reconstruction of the hidden state space that is a one-to-one embedding of the system's attractor. While this topological guarantee ensures that distinct points in the reconstruction correspond to distinct points in the original state space, it does not characterize the quality of this embedding or illuminate how the specific parameters affect the reconstruction. In this paper, we extend Takens' result by establishing conditions under which delay-coordinate mapping is guaranteed to provide a stable embedding of a system's attractor. Beyond only preserving the attractor topology, a stable embedding preserves the attractor geometry by ensuring that distances between points in the state space are approximately preserved. In particular, we find that delay-coordinate mapping stably embeds an attractor of a dynamical system if the stable rank of the system is large enough to be proportional to the dimension of the attractor. The stable rank reflects the relation between the sampling interval and the number of delays in delay-coordinate mapping. Our theoretical findings give guidance to choosing system parameters, echoing the tradeoff between irrelevancy and redundancy that has been heuristically investigated in the literature. Our initial result is stated for attractors that are smooth submanifolds of Euclidean space, with extensions provided for the case of strange attractors.

Mitochondrial Damage: A Diagnostic and Metabolic Approach in Traumatic Brain Injury and Post-Traumatic Disorder

DTIC Science & Technology

2013-01-29

Scanning Confocal Microscope (Zeiss- Pascal) using 20x obj. and edited using Zeiss Image Examiner Ver 5.0. The iso-cortical pyramidal layers 1 and 2 are...NeuN immunoreactivity is seen in the neuronal cytoplasm and especially apical dendrites of pyramidal neurons (white arrows), which facilitates the...identification of the pyramidal cell morphology in the outer pyramidal cell layer of neo-cortex (see picture A, depicted as py). Cortical Pyramidal

Estimation of ICBM (Intercontinental Ballistic Missile) Performance Parameters

DTIC Science & Technology

1985-12-01

Formulation . . . . . 42 Staging Event Detection . . . . . . 43 Staging Estimator for Two State System . 46 * Staging Time and Vehicle Parameter...6 4. Land Based Sensor Coordinate System . . . . 10 5. Radar Site Geometry . . . . . . . . . 1 6. Observation Geometry . . . . . . . . . 12 7...Ve dm mi + dmi+d Figure 3. Rocket Thrust of fuel, the equation of motion of the rocket can be devel--S oped. This is a closed system of particles

The Formation and Characterization of GaN Hexagonal Pyramids

NASA Astrophysics Data System (ADS)

Zhang, Shi-Ying; Xiu, Xiang-Qian; Lin, Zeng-Qin; Hua, Xue-Mei; Xie, Zi-Li; Zhang, Rong; Zheng, You-Dou

2013-05-01

GaN with hexagonal pyramids is fabricated using the photo-assisted electroless chemical etching method. Defective areas of the GaN substrate are selectively etched in a mixed solution of KOH and K2S2O8 under ultraviolet illumination, producing submicron-sized pyramids. Hexagonal pyramids on the etched GaN with well-defined {101¯1¯} facets and very sharp tips are formed. High-resolution x-ray diffraction shows that etched GaN with pyramids has a higher crystal quality, and micro-Raman spectra reveal a tensile stress relaxation in GaN with pyramids compared with normal GaN. The cathodoluminescence intensity of GaN after etching is significantly increased by three times, which is attributed to the reduction in the internal reflection, high-quality GaN with pyramids and the Bragg effect.

Dichlorido-1κCl,3κCl-bis­{μ-2,2′-[pro­pane-1,3-diylbis(imino­methyl­ene)]di­phenol­ato}-1:2κ6 O,N,N′,O′:O,O′;2:3κ6 O,O′:O,N,N′,O′-tricopper(II)

PubMed Central

Ateş, Bürke Meltem; Ercan, Filiz; Svoboda, Ingrid; Fuess, Hartmut; Atakol, Orhan

2008-01-01

The title linear trinuclear copper(II) complex, [Cu3(C17H20N2O2)2Cl2], was obtained from N,N′-bis­(2-hydroxy­benz­yl)-1,3-propane­diamine and CuCl2. The overall charge of the three Cu2+ ions is balanced by four deprotonated phenol groups and two Cl− ligands. The complex is centrosymmetric with the central Cu2+ occupying a special position (). This Cu2+ ion is coordinated by the four phenolate O atoms in a square-planar fashion. The second Cu2+ occupies a general position in a square-pyramidal fashion. Two phenolate O atoms and two amine N form the basal plane, with Cl− ligands occupying the fifth coordination site. PMID:21201868

Photoinduced Cobalt(III)-Trifluoromethyl Bond Activation Enables Arene C-H Trifluoromethylation.

PubMed

Harris, Caleb F; Kuehner, Christopher S; Bacsa, John; Soper, Jake D

2018-01-26

Visible-light capture activates a thermodynamically inert Co III -CF 3 bond for direct C-H trifluoromethylation of arenes and heteroarenes. New trifluoromethylcobalt(III) complexes supported by a redox-active [OCO] pincer ligand were prepared. Coordinating solvents, such as MeCN, afford green, quasi-octahedral [( S OCO)Co III (CF 3 )(MeCN) 2 ] (2), but in non-coordinating solvents the complex is red, square pyramidal [( S OCO)Co III (CF 3 )(MeCN)] (3). Both are thermally stable, and 2 is stable in light. But exposure of 3 to low-energy light results in facile homolysis of the Co III -CF 3 bond, releasing . CF 3 radical, which is efficiently trapped by TEMPO . or (hetero)arenes. The homolytic aromatic substitution reactions do not require a sacrificial or substrate-derived oxidant because the Co II by-product of Co III -CF 3 homolysis produces H 2 . The photophysical properties of 2 and 3 provide a rationale for the disparate light stability. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Teacher Acquisition of Functional Analysis Methods Using Pyramidal Training

ERIC Educational Resources Information Center

Pence, Sacha T.; St. Peter, Claire C.; Giles, Aimee F.

2014-01-01

Pyramidal training involves an experienced professional training a subset of individuals who, in turn, train additional individuals. Pyramidal training is effective for training a variety of behavior-analytic skills with direct-care staff, parents, and teachers. As teachers' roles in behavioral assessment increase, pyramidal training may be…

Ti K-edge EXAFS and XANES study on tektites from different strewnfields

NASA Astrophysics Data System (ADS)

Wang, L.; Furuta, T.; Okube, M.; Yoshiasa, A.

2011-12-01

The concentration and local structure of each element may have various kinds of information about the asteroid impact and mass extinction. Farges and Brown have discussed about the Ti local structure by XANES, and concluded that Ti in tektite occupies 4-coordinated site. EXAFS can be analyzed to give precise information about the distance from Ti to near neighbors. The XAFS measurement of Ti local structure was preformed at the beamline 9C of the Photon Factory in KEK, Tsukuba, Japan. The specimens of tektites are from different strewnfields, they are: indochinite, bediasite, hainanite, philippinite, australite and moldavite. Sample for comparison are Libya desert glass and suevite. The k3χ(k) function was transformed into the radial structure function (RSF) for Ti K-edge of six tektites. The RSF for the Ti atom in indochinite and bediasite are similar; hainanite, australite and philippinite are similar; and moldavite is discriminated from others. It indicates that they have the same local atomic environmental around the Ti atoms and extended structure respectively. Coordination numbers and radial structure function are determined by EXAFS analyses (Table 1). We classified the tektites in three types: in indochinite and bediasite, Ti occupies 4-coordinated tetrahedral site and Ti-O distances are 1.84-1.81 Å; in hainanite, australite and philippinite, Ti occupies 5-coordinated trigonal bi-pyramidal or tetragonal pyramidal site and Ti-O distances are 1.92-1.87 Å; in moldavite, Ti occupies the 6-coordinated octahedral site and Ti-O distance is 2.00-1.96 Å. Formation of tektites is related to the impact process. It is generally recognized that tektites were formed under higher temperature and high pressure. But through this study, local structures of Ti are differing in three strewnfields and even different locations of the same strewnfield. What caused the various local structures will be another topic of tektite studies. Local structure of Ti may be changed in the impact event and the following stage. Tektites splashed to the space and travel in several kinds of processes and routes, which lead to different temperature and pressure history. Local structure of Ti should be related with the temperature, pressure, quenching rate, sizes of impact meteorite and size of falling melts. [1] Koeberl. Ann.Rev.Earth Planet.Sci. 14, 323-350 (1986) [2] François Farges & Gordon E. Brown Jr Geochim. Cosmo. Acta.61, 1863-1870 (1997). [3]Paris, E., Dingwell, D., Seifert, F., Mottana, A. & Romano, C. (1994). Phys. Chem. Miner. 21, 520-525.
Table 1 Structure parameters determined by EXAFS

Shock imprint and rolling direction influence upon the breaking tenacity for 2P armor steel

NASA Astrophysics Data System (ADS)

Zichil, V.; Coseru, A.; Schnakovszky, C.; Herghelegiu, E.; Radu, C.

2016-08-01

The state of art in present literature shows that the breaking tenacity of a material is influenced by the integrity of the structure. Since armors used in aviation and to protect military vehicles are frequently impact loaded, through the contact between armor sheet and projectiles, or other foreign bodies, the authors have proposed to study the dependence between the breaking tenacity of 2P armor steel depending on the direction of the rolling of the armor plate, of the geometry (spherical imprint, pyramidal and linear imprint) and the depth of the deformation that results after impact. Tests were conducted upon CT (ASTM E- 399) specimen type, using the critical factor of stress intensity during the state of planar strain.

Documentation of program COORDC to generate and coordinate system for 3D corners with or without fillet using body fitted curvilinear coordinates, part 2

NASA Technical Reports Server (NTRS)

Kumar, D.

1980-01-01

The computer program COORDC generates a body fitted curvilinear coordinate system for corner geometry with or without corner fillets. It is assumed that at any given xi, x remains constant; consequently the only variation is in y and z. It is also assumed that for all xi's in the physical plane the coordinate system in y-z plane is similar. This enables solution of coordinate system for one particular xi = 1 (x for xi = 1 is arbitrarily chosen to be 0.0) and the solution for all other xi plane can be easily specified once the coordinates in the physical plane on the line 1 or = to xi or = to IMAX, eta = 1, zeta = 1 are specified.

Optimizing pyramided transgenic Bt crops for sustainable pest management.

PubMed

Carrière, Yves; Crickmore, Neil; Tabashnik, Bruce E

2015-02-01

Transgenic crop pyramids producing two or more Bacillus thuringiensis (Bt) toxins that kill the same insect pest have been widely used to delay evolution of pest resistance. To assess the potential of pyramids to achieve this goal, we analyze data from 38 studies that report effects of ten Bt toxins used in transgenic crops against 15 insect pests. We find that compared with optimal low levels of insect survival, survival on currently used pyramids is often higher for both susceptible insects and insects resistant to one of the toxins in the pyramid. Furthermore, we find that cross-resistance and antagonism between toxins used in pyramids are common, and that these problems are associated with the similarity of the amino acid sequences of domains II and III of the toxins, respectively. This analysis should assist in future pyramid design and the development of sustainable resistance management strategies.

The Learning Pyramid: Does It Point Teachers in the Right Direction?

ERIC Educational Resources Information Center

Lalley, James P.; Miller, Robert H.

2007-01-01

This paper raises serious questions about the reliability of the learning pyramid as a guide to retention among students. The pyramid suggests that certain teaching methods are connected with a corresponding hierarchy of student retention. No specific credible research was uncovered to support the pyramid, which is loosely associated with the…

High level continuity for coordinate generation with precise controls

NASA Technical Reports Server (NTRS)

Eiseman, P. R.

1982-01-01

Coordinate generation techniques with precise local controls have been derived and analyzed for continuity requirements up to both the first and second derivatives, and have been projected to higher level continuity requirements from the established pattern. The desired local control precision was obtained when a family of coordinate surfaces could be uniformly distributed without a consequent creation of flat spots on the coordinate curves transverse to the family. Relative to the uniform distribution, the family could be redistributed from an a priori distribution function or from a solution adaptive approach, both without distortion from the underlying transformation which may be independently chosen to fit a nontrivial geometry and topology.

Effect of housing rats within a pyramid on stress parameters.

PubMed

Bhat, Surekha; Rao, Guruprasad; Murthy, K Dilip; Bhat, P Gopalakrishna

2003-11-01

The Giza pyramids of Egypt have been the subject of much research. Pyramid models with the same base to height ratio as of the Great Pyramid of Giza, when aligned on a true north-south axis, are believed to generate, transform and transmit energy. Research done with such pyramid models has shown that they induced greater relaxation in human subjects, promoted better wound healing in rats and afforded protection against stress-induced neurodegnerative changes in mice. The present study was done to assess the effects of housing Wistar rats within the pyramid on the status of oxidative damage and antioxidant defense in their erythrocytes and cortisol levels in their plasma. Rats were housed in cages under standard laboratory conditions. Cages were left in the open (normal control), under a wooden pyramid model (experimental rats) or in a cubical box of comparable dimensions (6 hr/day for 14 days). Erythrocyte malondialdehyde and plasma cortisol levels were significantly decreased in rats kept within the pyramid as compared to the normal control and those within the square box. Erythrocyte reduced glutathione levels, erythrocyte glutathione peroxidase and superoxide dismutase activities were significantly increased in the rats kept in the pyramid as compared to the other two groups. There was no significant difference in any of the parameters between the normal control and rats kept in the square box. The results showed that exposure of adult female Wistar rats to pyramid environment reduces stress oxidative stress and increases antioxidant defense in them.

A Thumb Carpometacarpal Joint Coordinate System Based on Articular Surface Geometry

PubMed Central

Halilaj, Eni; Rainbow, Michael J.; Got, Christopher; Moore, Douglas C.; Crisco, Joseph J.

2013-01-01

The thumb carpometacarpal (CMC) joint is a saddle-shaped articulation whose in vivo kinematics can be explored more accurately with computed tomography (CT) imaging methods than with previously used skin-based marker systems. These CT-based methods permit a detailed analysis of the morphology of the joint, and thus the prominent saddle-shaped geometry can be used to define a coordinate system that is inherently aligned with the primary directions of motion at the joint. The purpose of this study was to develop a CMC joint coordinate systems that is based on the computed principal directions of curvature on the trapezium and the first metacarpal. We evaluated the new coordinate system using bone surface models segmented from the CT scans of twenty-four healthy subjects. An analysis of sensitivity to the manual selection of articular surfaces resulted in mean orientation differences of 0.7±0.7° and mean location differences of 0.2±0.1mm. Inter-subject variability, which mostly emanates from anatomical differences, was evaluated with whole bone registration and resulted in mean orientation differences of 3.1±2.7° and mean location differences of 0.9±0.5mm. The proposed joint coordinate system addresses concerns of repeatability associated with bony landmark identification and provides a robust platform for describing the complex kinematics of the CMC joint. PMID:23357698

Expression of Kv3.1b potassium channel is widespread in macaque motor cortex pyramidal cells: A histological comparison between rat and macaque.

PubMed

Soares, David; Goldrick, Isabelle; Lemon, Roger N; Kraskov, Alexander; Greensmith, Linda; Kalmar, Bernadett

2017-06-15

There are substantial differences across species in the organization and function of the motor pathways. These differences extend to basic electrophysiological properties. Thus, in rat motor cortex, pyramidal cells have long duration action potentials, while in the macaque, some pyramidal neurons exhibit short duration "thin" spikes. These differences may be related to the expression of the fast potassium channel Kv3.1b, which in rat interneurons is associated with generation of thin spikes. Rat pyramidal cells typically lack these channels, while there are reports that they are present in macaque pyramids. Here we made a systematic, quantitative comparison of the Kv3.1b expression in sections from macaque and rat motor cortex, using two different antibodies (NeuroMab, Millipore). As our standard reference, we examined, in the same sections, Kv3.1b staining in parvalbumin-positive interneurons, which show strong Kv3.1b immunoreactivity. In macaque motor cortex, a large sample of pyramidal neurons were nearly all found to express Kv3.1b in their soma membranes. These labeled neurons were identified as pyramidal based either by expression of SMI32 (a pyramidal marker), or by their shape and size, and lack of expression of parvalbumin (a marker for some classes of interneuron). Large (Betz cells), medium, and small pyramidal neurons all expressed Kv3.1b. In rat motor cortex, SMI32-postive pyramidal neurons expressing Kv3.1b were very rare and weakly stained. Thus, there is a marked species difference in the immunoreactivity of Kv3.1b in pyramidal neurons, and this may be one of the factors explaining the pronounced electrophysiological differences between rat and macaque pyramidal neurons. © 2017 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Static Posturography and Falls According to Pyramidal, Sensory and Cerebellar Functional Systems in People with Multiple Sclerosis

PubMed Central

Kalron, Alon; Givon, Uri; Frid, Lior; Dolev, Mark; Achiron, Anat

2016-01-01

Balance impairment is common in people with multiple sclerosis (PwMS) and frequently impacts quality of life by decreasing mobility and increasing the risk of falling. However, there are only scarce data examining the contribution of specific neurological functional systems on balance measures in MS. Therefore, the primary aim of our study was to examine the differences in posturography parameters and fall incidence according to the pyramidal, cerebellar and sensory systems functional systems in PwMS. The study included 342 PwMS, 211 women and mean disease duration of 8.2 (S.D = 8.3) years. The study sample was divided into six groups according to the pyramidal, cerebellar and sensory functional system scores, derived from the Expanded Disability Status Scale (EDSS) data. Static postural control parameters were obtained from the Zebris FDM-T Treadmill (zebris® Medical GmbH, Germany). Participants were defined as "fallers" and "non-fallers" based on their fall history. Our findings revealed a trend that PwMS affected solely in the pyramidal system, have reduced stability compared to patients with cerebellar and sensory dysfunctions. Moreover, the addition of sensory impairments to pyramidal dysfunction does not exacerbate postural control. The patients in the pure sensory group demonstrated increased stability compared to each of the three combined groups; pyramidal-cerebellar, pyramidal-sensory and pyramidal-cerebellar-sensory groups. As for fall status, the percentage of fallers in the pure pyramidal, cerebellar and sensory groups were 44.3%, 33.3% and 19.5%, respectively. As for the combined functional system groups, the percentage of fallers in the pyramidal-cerebellar, pyramidal-sensory and pyramidal-cerebellar-sensory groups were 59.7%, 40.7% and 65%, respectively. This study confirms that disorders in neurological functional systems generate different effects on postural control and incidence of falls in the MS population. From a clinical standpoint, the present information can benefit all those engaged in physical rehabilitation of PwMS. PMID:27741268

Digital microfabrication of user-defined 3D microstructures in cell-laden hydrogels.

PubMed

Soman, Pranav; Chung, Peter H; Zhang, A Ping; Chen, Shaochen

2013-11-01

Complex 3D interfacial arrangements of cells are found in several in vivo biosystems such as blood vasculature, renal glomeruli, and intestinal villi. Current tissue engineering techniques fail to develop suitable 3D microenvironments to evaluate the concurrent effects of complex topography and cell encapsulation. There is a need to develop new fabrication approaches that control cell density and distribution within complex 3D features. In this work, we present a dynamic projection printing process that allows rapid construction of complex 3D structures using custom-defined computer-aided-design (CAD) files. Gelatin-methacrylate (GelMA) constructs featuring user-defined spiral, pyramid, flower, and dome micro-geometries were fabricated with and without encapsulated cells. Encapsulated cells demonstrate good cell viability across all geometries both on the scaffold surface and internal to the structures. Cells respond to geometric cues individually as well as collectively throughout the larger-scale patterns. Time-lapse observations also reveal the dynamic nature of mechanical interactions between cells and micro-geometry. When compared to conventional cell-seeding, cell encapsulation within complex 3D patterned scaffolds provides long-term control over proliferation, cell morphology, and geometric guidance. Overall, this biofabrication technique offers a flexible platform to evaluate cell interactions with complex 3D micro-features, with the ability to scale-up towards high-throughput screening platforms. © 2013 Wiley Periodicals, Inc.

Tailoring force sensitivity and selectivity by microstructure engineering of multidirectional electronic skins

NASA Astrophysics Data System (ADS)

Park, Jonghwa; Kim, Jinyoung; Hong, Jaehyung; Lee, Hochan; Lee, Youngoh; Cho, Seungse; Kim, Sung-Woo; Kim, Jae Joon; Kim, Sung Youb; Ko, Hyunhyub

2018-04-01

Electronic skins (e-skins) with high sensitivity to multidirectional mechanical stimuli are crucial for healthcare monitoring devices, robotics, and wearable sensors. In this study, we present piezoresistive e-skins with tunable force sensitivity and selectivity to multidirectional forces through the engineered microstructure geometries (i.e., dome, pyramid, and pillar). Depending on the microstructure geometry, distinct variations in contact area and localized stress distribution are observed under different mechanical forces (i.e., normal, shear, stretching, and bending), which critically affect the force sensitivity, selectivity, response/relaxation time, and mechanical stability of e-skins. Microdome structures present the best force sensitivities for normal, tensile, and bending stresses. In particular, microdome structures exhibit extremely high pressure sensitivities over broad pressure ranges (47,062 kPa-1 in the range of <1 kPa, 90,657 kPa-1 in the range of 1-10 kPa, and 30,214 kPa-1 in the range of 10-26 kPa). On the other hand, for shear stress, micropillar structures exhibit the highest sensitivity. As proof-of-concept applications in healthcare monitoring devices, we show that our e-skins can precisely monitor acoustic waves, breathing, and human artery/carotid pulse pressures. Unveiling the relationship between the microstructure geometry of e-skins and their sensing capability would provide a platform for future development of high-performance microstructured e-skins.

Heterobimetallic Complexes Comprised of Nb and Fe: Isolation of a Coordinatively Unsaturated NbIII/Fe0 Bimetallic Complex Featuring a Nb≡Fe Triple Bond.

PubMed

Culcu, Gursu; Iovan, Diana A; Krogman, Jeremy P; Wilding, Matthew J T; Bezpalko, Mark W; Foxman, Bruce M; Thomas, Christine M

2017-07-19

Heterometallic multiple bonds between niobium and other transition metals have not been reported to date, likely owing to the highly reactive nature of low-valent niobium centers. Herein, a C 3 -symmetric tris(phosphinoamide) ligand framework is used to construct a Nb/Fe heterobimetallic complex Cl-Nb( i PrNPPh 2 ) 3 Fe-Br (2), which features a Fe→Nb dative bond with a metal-metal distance of 2.4269(4) Å. Reduction of 2 in the presence of PMe 3 affords Nb( i PrNPPh 2 ) 3 Fe-PMe 3 (6), a compound with an unusual trigonal pyramidal geometry at a Nb III center, a Nb≡Fe triple bond, and the shortest bond distance (2.1446(8) Å) ever reported between Nb and any other transition metal. Complex 6 is thermally unstable and degrades via P-N bond cleavage to form a Nb V ═NR imide complex, i PrN═Nb( i PrNPPh 2 ) 3 Fe-PMe 3 (9). The heterobimetallic complexes i PrN═Nb( i PrNPPh 2 ) 3 Fe-Br (8) and 9 are independently synthesized, revealing that the strongly π-bonding imido functionality prevents significant metal-metal interactions. The 57 Fe Mössbauer spectra of 2, 6, 8, and 9 show a clear trend in isomer shift (δ), with a decrease in δ as metal-metal interactions become stronger and the Fe center is reduced. The electronic structure and metal-metal bonding of 2, 6, 8, and 9 are explored through computational studies, and cyclic voltammetry is used to better understand the effect of metal-metal interaction in early/late heterobimetallic complexes on the redox properties of the two metals involved.

Computational fluid dynamics for propulsion technology: Geometric grid visualization in CFD-based propulsion technology research

NASA Technical Reports Server (NTRS)

Ziebarth, John P.; Meyer, Doug

1992-01-01

The coordination is examined of necessary resources, facilities, and special personnel to provide technical integration activities in the area of computational fluid dynamics applied to propulsion technology. Involved is the coordination of CFD activities between government, industry, and universities. Current geometry modeling, grid generation, and graphical methods are established to use in the analysis of CFD design methodologies.

Idea Bank: Assessing Your Curriculum with the Creative Rights Pyramid

ERIC Educational Resources Information Center

Thibeault, Matthew D.

2011-01-01

This article presents a creative rights pyramid that was developed as part of the author's efforts to: (1) teach about copyright and intellectual property; and (2) increase students' awareness of their own intellectual property in and outside the music classroom. The pyramid is based on the U.S. Department of Agriculture's food pyramid to suggest…

Using the Food Guide Pyramid: A Resource for Nutrition Educators.

ERIC Educational Resources Information Center

Shaw, Anne; Fulton, Lois; Davis, Carole; Hogbin, Myrtle

This booklet provides information to assist nutrition educators in helping their audiences use the Food Guide Pyramid to plan and prepare foods for a healthy diet. It reviews the objectives set in developing the Food Guide Pyramid and illustrates their impact on the application of the Food Guide Pyramid to planning menus. In particular, the…

A gaze-contingent display to study contrast sensitivity under natural viewing conditions

NASA Astrophysics Data System (ADS)

Dorr, Michael; Bex, Peter J.

2011-03-01

Contrast sensitivity has been extensively studied over the last decades and there are well-established models of early vision that were derived by presenting the visual system with synthetic stimuli such as sine-wave gratings near threshold contrasts. Natural scenes, however, contain a much wider distribution of orientations, spatial frequencies, and both luminance and contrast values. Furthermore, humans typically move their eyes two to three times per second under natural viewing conditions, but most laboratory experiments require subjects to maintain central fixation. We here describe a gaze-contingent display capable of performing real-time contrast modulations of video in retinal coordinates, thus allowing us to study contrast sensitivity when dynamically viewing dynamic scenes. Our system is based on a Laplacian pyramid for each frame that efficiently represents individual frequency bands. Each output pixel is then computed as a locally weighted sum of pyramid levels to introduce local contrast changes as a function of gaze. Our GPU implementation achieves real-time performance with more than 100 fps on high-resolution video (1920 by 1080 pixels) and a synthesis latency of only 1.5ms. Psychophysical data show that contrast sensitivity is greatly decreased in natural videos and under dynamic viewing conditions. Synthetic stimuli therefore only poorly characterize natural vision.

Effect of Heteroatoms on Field-Induced Slow Magnetic Relaxation of Mononuclear FeIII ( S = 5/2) Ions within Polyoxometalates.

PubMed

Minato, Takuo; Aravena, Daniel; Ruiz, Eliseo; Yamaguchi, Kazuya; Mizuno, Noritaka; Suzuki, Kosuke

2018-06-01

In this paper, the synthesis and magnetic properties of mononuclear Fe III -containing polyoxometalates (POMs) with different types of heteroatoms, TBA 7 H 10 [(A-α-XW 9 O 34 ) 2 Fe] (II X , X = Ge, Si; TBA = tetra- n-butylammonium), are reported. In these POMs, mononuclear highly distorted six-coordinate octahedral [FeO 6 ] 9- units are sandwiched by two trivacant lacunary units [A-α-XW 9 O 34 ] 10- (X = Ge, Si). These POMs exhibit field-induced slow magnetic relaxation based on the single high-spin Fe III magnetic center ( S = 5/2). Combining experiment and ab initio calculations, we investigated the effect of heteroatoms of the lacunary units on the field-induced slow magnetic relaxation of these POMs. By changing the heteroatoms from Si (II Si ) to Ge (II Ge ), the coordination geometry around the Fe III ion is mildly changed. Concretely, the axial Fe-O bond length in II Ge is shortened compared with that in II Si , and consequently the distortion of the [FeO 6 ] 9- unit in II Ge from the ideal octahedral coordination geometry becomes larger than that in II Si . The effective demagnetization barrier of II Ge (11.4 K) is slightly larger than that of II Si (9.2 K). Multireference ab initio calculations predict zero-field splitting parameters in good agreement with experiment. Although the differences in the coordination geometries and magnetic properties of II Ge and II Si are quite small, ab initio calculations indicate subtle changes in the magnetic anisotropy which are in line with the observed magnetic relaxation properties.

Influence of probe geometry on pitot-probe displacement in supersonic turbulent flow

NASA Technical Reports Server (NTRS)

Allen, J. M.

1975-01-01

An experiment was conducted to determine the varying effects of six different probe-tip and support-shaft configurations on pitot tube displacement. The study was stimulated by discrepancies between supersonic wind-tunnel tests conducted by Wilson and Young (1949) and Allen (1972). Wilson (1973) had concluded that these discrepancies were caused by differences in probe geometry. It is shown that in fact, no major differences in profiles of streamwise velocity over streamwise velocity at boundary-layer edge vs normal coordinate over boundary-layer total thickness result from geometry. The true cause of the discrepancies, however, remains to be discovered.

Poly[[sesqui[mu2-1,4-bis(imidazol-1-ylmethyl)benzene-kappa(2)N:N'](carbonato-kappa(2)O,O')copper(II)] 1,4-bis(imidazol-1-ylmethyl)benzene hemisolvate pentahydrate].

PubMed

Dai, Yu-Mei; Tang, En; Huang, Jin-Feng; Yang, Qiu-Yan

2008-10-01

The asymmetric unit of the title compound, {[Cu(CO(3))(C(14)H(14)N(4))(1.5)] x 0.5 C(14)H(14)N(4) x 5 H(2)O}(n), contains one Cu(II) cation in a slightly distorted square-pyramidal coordination environment, one CO(3)(2-) anion, one full and two half 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands, one half-molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)(1.5)](n) molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 A. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu(II) atom is completed by two O atoms of the CO(3)(2-) anion. The framework is further strengthened by extensive O-H...O and O-H...N hydrogen bonds involving the water molecules, the O atoms of the CO(3)(2-) anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures.

Relevance of the pyramidal syndrome in amyotrophic lateral sclerosis.

PubMed

Álvarez, N; Díez, L; Avellaneda, C; Serra, M; Rubio, M Á

Pyramidal signs (hyperreflexia, spasticity, Babinski sign) are essential for the diagnosis of amyotrophic lateral sclerosis (ALS). However, these signs are not always present at onset and may vary over time, besides which their role in disease evolution is controversial. Our goal was to describe which pyramidal signs were present and how they evolved in a cohort of patients with ALS, as well as their role in prognosis. Retrospective analysis of prospectively collected patients diagnosed with ALS in our centre from 1990 to 2015. Of a total of 130 patients with ALS, 34 (26.1%) patients showed no pyramidal signs at the first visit while 15 (11.5%) had a complete pyramidal syndrome. Of those patients without initial pyramidal signs, mean time of appearance of the first signs was 4.5 months. Babinski sign was positive in 64 (49.2%) patients, hyperreflexia in 90 (69.2%) and 22 (16.9%) patients had spasticity. Pyramidal signs tended to remain unchanged over time, although they seem to appear at later stages or even disappear with time in some patients. We found no association between survival and the presence of changes to pyramidal signs, although decreased spasticity was associated with greater clinical deterioration (ALSFR scale) (P<.001). A quarter of patients with ALS initially showed no pyramidal signs and in some cases they even disappear over time. These data support the need for tools that assess the pyramidal tract. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Measurement of drill grinding parameters using laser sensor

NASA Astrophysics Data System (ADS)

Yanping, Peng; Kumehara, Hiroyuki; Wei, Zhang; Nomura, Takashi

2005-12-01

To measure the grinding parameters and geometry parameters accurately for a drill point is essential to its design and reconditioning. In recent years, a number of non-contact coordinate measuring apparatuses, using CCD camera or laser sensors, are developed. But, a lot work is to be done for further improvement. This paper reports another kind of laser coordinate meter. As an example of its application, the method for geometry inspection of the drill flank surface is detailed. Measured data from laser scanning on the flank surface around some points with several 2-dimensional curves are analyzed with mathematical procedure. If one of these curves turns to be a straight line, it must be the generatrix of the grinding cone. Thus, the grinding parameters are determined by a set of three generatrices. Then, the measurement method and data processing procedure are proposed. Its validity is assessed by measuring a sample with given parameters. The point geometry measured agrees well with the known values. In comparison with other methods in the published literature, it is simpler in computation and more accurate in results.

Palladium-catalyzed cocyclotrimerization of arynes with a pyramidalized alkene.

PubMed

Alonso, José M; Quiroga, Sabela; Codony, Sandra; Turcu, Andreea L; Barniol-Xicota, Marta; Pérez, Dolores; Guitián, Enrique; Vázquez, Santiago; Peña, Diego

2018-05-23

The metal-catalyzed [2+2+2] cocycloaddition of arynes with pyramidalized alkenes is presented. The generation of a highly reactive pyramidalized alkene in the presence of a large excess of in situ-produced arynes led to the corresponding cocyclotrimerization (1 : 2)-adducts in good yields, establishing the first example of a palladium-based reaction of a pyramidalized alkene.

[Pyramidal syndrome in lateral amyotrophic sclerosis: clinico-morphological analysis].

PubMed

Musaeva, L S; Zavalishin, I A; Gulevskaia, T S

2003-01-01

Retrospective clinical analysis with a special focus on pyramidal syndrome expression in the disease course as well as morphological study of brain and spinal structures in all levels of cortical-spinal projection (from brain motor cortex to spinal lumbar segments) have been conducted for 11 section cases of lateral amyotrophic sclerosis (LAS), sporadic type. Two groups of patients were studied: with pronounced pyramidal syndrome (spasticity, hyperreflexia, etc)--7 cases and with some signs of pyramidal deficiency (anisoreflexia, stability of peritoneal reflexes)--4 cases. Pyramidal syndrome in LAS is considered as an emergence of current neurodegenerative process, embracing a significant part of upper motor neurons of both precentral convolution and its axons along the whole length of cerebrospinal axis in the form of cytoplasmic inclusions and axonal spheroids. A presence of pathomorphological changes in other upper segmental structures of motor control reveals their role in pyramidal deficiency. Comparative analysis showed that expression of pyramidal syndrome signs and its correlation to atrophic paresis appearances is specifically determined by the severity of upper and lower motor neurons lesions. With regard to morphological changes in CNS structures, the peculiarities of some pyramidal syndrome appearances in LAS are analyzed.

Virtual pyramid wavefront sensor for phase unwrapping.

PubMed

Akondi, Vyas; Vohnsen, Brian; Marcos, Susana

2016-10-10

Noise affects wavefront reconstruction from wrapped phase data. A novel method of phase unwrapping is proposed with the help of a virtual pyramid wavefront sensor. The method was tested on noisy wrapped phase images obtained experimentally with a digital phase-shifting point diffraction interferometer. The virtuality of the pyramid wavefront sensor allows easy tuning of the pyramid apex angle and modulation amplitude. It is shown that an optimal modulation amplitude obtained by monitoring the Strehl ratio helps in achieving better accuracy. Through simulation studies and iterative estimation, it is shown that the virtual pyramid wavefront sensor is robust to random noise.

Pyramid beam splitter

DOEpatents

McKeown, Mark H.; Beason, Steven C.; Fairer, George

1992-01-01

The apparatus of the present invention provides means for obtaining accurate, dependable, measurement of bearings and directions for geologic mapping in subterranean shafts, such as, for example, nuclear waste storage investigations. In operation, a laser beam is projected along a reference bearing. A pyramid is mounted such that the laser beam is parallel to the pyramid axis and can impinge on the apex of the pyramid thus splitting the beam several ways into several beams at right angles to each other and at right angles to the reference beam. The pyramid is also translatable and rotatable in a plane perpendicular to the reference beam.

Efficacy and connectivity of intracolumnar pairs of layer 2/3 pyramidal cells in the barrel cortex of juvenile rats

PubMed Central

Feldmeyer, Dirk; Lübke, Joachim; Sakmann, Bert

2006-01-01

Synaptically coupled layer 2/3 (L2/3) pyramidal neurones located above the same layer 4 barrel (‘barrel-related’) were investigated using dual whole-cell voltage recordings in acute slices of rat somatosensory cortex. Recordings were followed by reconstructions of biocytin-filled neurones. The onset latency of unitary EPSPs was 1.1 ± 0.4 ms, the 20–80% rise time was 0.7 ± 0.2 ms, the average amplitude was 1.0 ± 0.7 mV and the decay time constant was 15.7 ± 4.5 ms. The coefficient of variation (c.v.) of unitary EPSP amplitudes decreased with increasing EPSP peak and was 0.33 ± 0.18. Bursts of APs in the presynaptic pyramidal cell resulted in EPSPs that, over a wide range of frequencies (5–100 Hz), displayed amplitude depression. Anatomically the barrel-related pyramidal cells in the lower half of layer 2/3 have a long apical dendrite with a small terminal tuft, while pyramidal cells in the upper half of layer 2/3 have shorter and often more ‘irregularly’ shaped apical dendrites that branch profusely in layer 1. The number of putative excitatory synaptic contacts established by the axonal collaterals of a L2/3 pyramidal cell with a postsynaptic pyramidal cell in the same column varied between 2 and 4, with an average of 2.8 ± 0.7 (n = 8 pairs). Synaptic contacts were established predominantly on the basal dendrites at a mean geometric distance of 91 ± 47 μm from the pyramidal cell soma. L2/3-to-L2/3 connections formed a blob-like innervation domain containing 2.8 mm of the presynaptic axon collaterals with a bouton density of 0.3 boutons per μm axon. Within the supragranular layers of its home column a single L2/3 pyramidal cell established about 900 boutons suggesting that 270 pyramidal cells in layer 2/3 are innervated by an individual pyramidal cell. In turn, a single pyramidal cell received synaptic inputs from 270 other L2/3 pyramidal cells. The innervation domain of L2/3-to-L2/3 connections superimposes almost exactly with that of L4-to-L2/3 connections. This suggests that synchronous feed-forward excitation of L2/3 pyramidal cells arriving from layer 4 could be potentially amplified in layer 2/3 by feedback excitation within a column and then relayed to the neighbouring columns. PMID:16793907

Accuracy aspects of stereo side-looking radar. [analysis of its visual perception and binocular vision

NASA Technical Reports Server (NTRS)

Leberl, F. W.

1979-01-01

The geometry of the radar stereo model and factors affecting visual radar stereo perception are reviewed. Limits to the vertical exaggeration factor of stereo radar are defined. Radar stereo model accuracies are analyzed with respect to coordinate errors caused by errors of radar sensor position and of range, and with respect to errors of coordinate differences, i.e., cross-track distances and height differences.

Structure of thallium(III) chloride, bromide, and cyanide complexes in aqueous solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blixt, J.; Glaser, J.; Sandstroem, M.

1995-05-10

The structures of the hydrated thallium(III) halide and pseudohalide complexes, [TlX{sub n}(OH{sub 2}){sub m}]{sup (3-d)+}, X = Cl, Br, CN, in aqueous solution have been studied by a combination of X-ray absorption fine structure spectroscopy (XAFS), large-angle X-ray scattering (LAXS), and vibrational spectroscopic (Raman and IR) techniques including far-infrared studies of aqueous solutions and some solid phases with known structures. The vibrational Tl-X frequencies of all complexes are reported, force constants are calculated using normal coordinate analysis, and assignments are given. The structural results are consistent with octahedral six-coordination for the cationic complexes Tl(OH{sub 2}){sub 6}{sup 3$PLU}, TlX(OH{sub 2}){sub 5}{supmore » 2+}, and trans-TlX{sub 2}(OH{sub 2}){sub 4}{sup +}. The coordination geometry changes to trigonal bipyramidal for the neutral TlBr{sub 3}(OH{sub 2}){sub 2} complex and possibly also for TlCl{sub 3}(OH{sub 2}){sub 2}. The TlX{sub 4}{sup -} complexes are all tetrahedral. Higher chloride complexes, TlCl{sub 5}(OH{sub 2}){sup 2-} and TlCl{sub 6}{sup 3-}, are formed and have again octahedral coordination geometry. 65 refs., 7 figs., 5 tabs.« less

Controlled coordination in vanadium(V) dimethylhydrazido compounds.

PubMed

Sakuramoto, Takashi; Moriuchi, Toshiyuki; Hirao, Toshikazu

2016-11-01

The vanadium(V) dimethylhydrazido compounds were structurally characterized to elucidate the effect of the alkoxide ligands in the coordination environment of vanadium(V) hydrazido center. The single-crystal X-ray structure determination of the vanadium(V) dimethylhydrazido compound with isopropoxide ligands revealed a dimeric structure with the V(1)-N(1) distance of 1.680(5)Å, in which each vanadium atom is coordinated in a distorted trigonal-bipyramidal geometry (τ 5 =0.81) with the hydrazido and bridging isopropoxide ligands in the apical positions. On the contrary, nearly tetrahedral arrangement around the vanadium metal center (τ 4 =0.06) with the V(1)-N(1) distance of 1.660(2)Å was observed in the vanadium(V) dimethylhydrazido compound with tert-butoxide ligands. The introduction of the 2,2',2″-nitrilotriethoxide ligand led to a pseudo-trigonal-bipyramidal geometry (τ 5 =0.92) at the vanadium center with the V(1)-N(1) distance of 1.691(5)Å, wherein vanadium atom is pulled out of the plane formed by the nitrilotriethoxide oxygen atoms in the direction of the hydrazido nitrogen. The coordination from the apical ligand in the vanadium(V) dimethylhydrazido compound was found to result in the longer V(1)-N(1) distance. Copyright © 2016 Elsevier Inc. All rights reserved.

ESR, spectroscopic, and quantum-chemical studies on the electronic structures of complexes formed by Cu(I) with radicals (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritsan, N.P.; Usov, O.M.; Shokhirev, N.V.

1986-07-01

The optical and ESR spectra have been examined for complexes of Cu(I) with various radicals, which contain various numbers of Cl/sup -/ ions in the central-atom coordination sphere. The spin-Hamiltonian parameters have been determined for all these radical complexes, and the observed ESR spectra have been compared with those calculated with allowance for second-order effects. The observed values for the isotropic and anisotropic components of the HFI constant from the central ion have been used to estimate the contributions from the 4s and 3d/sup 2//sub z/ orbitals of the copper ion to the unpaired-electron MO. Quantum-chemical calculations have been performedmore » by the INDO method on the electronic structures and geometries of complexes formed by CH/sub 2/OH with Cu(I) for various Cl/sup -/ contents in the coordination sphere. The radical is coordinated by the ..pi.. orbital on the carbon atom, and the stabilities of the radical complexes decrease as the number of Cl/sup -/ ions in the coordination sphere increases. A geometry close to planar for the CuCl/sub 4//sup 3 -/ fragment in a complex containing four Cl/sup -/ ions.« less

Crystal structures of palladium(II) ternary complexes of 5-x-2-aminobenzoic acid with 1,10-phenanthroline and their interaction with calf thymus DNA (where X=Cl, Br and I).

PubMed

Wang, Yue; Okabe, Nobuo; Odoko, Mamiko

2005-10-01

The crystal structures of a series of three palladium(II) ternary complexes of 5-halogeno-2-aminobenzoic acid (5-X-AB, where X=Cl, Br and I) with 1,10-phenanthroline [Pd(5-Cl-AB)(phen)] (1), [Pd(5-Br-AB)(phen)] (2) and [Pd(5-I-AB)(phen)] (3) have been determined, and their coordination geometries and the crystal architecture characterized. All of the complexes are an isostructure in which each Pd(II) atom has basically similar square planar coordination geometry. The substitute halogen group at 5-position of AB plays an important role in producing the coordination bonds of the carboxylate and amino groups in which the carboxylate O atom and the amino N atom act as the negative monodentate ligand atoms. The coordination bond distances of O-Pd increase in the order 1<2<3, while those of N-Pd decrease in the same order. The binding of the complexes to the calf thymus DNA has also been studied by the fluorescence method. Each of the complexes shows high binding propensity to DNA which can be reflected as the relative order 1<2<3.

Finite difference solutions of heat conduction problems in multi-layered bodies with complex geometries

NASA Technical Reports Server (NTRS)

Masiulaniec, K. C.; Keith, T. G., Jr.; Dewitt, K. J.

1984-01-01

A numerical procedure is presented for analyzing a wide variety of heat conduction problems in multilayered bodies having complex geometry. The method is based on a finite difference solution of the heat conduction equation using a body fitted coordinate system transformation. Solution techniques are described for steady and transient problems with and without internal energy generation. Results are found to compare favorably with several well known solutions.

Imaging a Pyramid Interior by ERT-3D Methods, Preliminar Results at El Castillo Pyramid, Chichen Itza, Mexico

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Tejero, A.; Cifuentes, G.; HernaNdez-Quintero, J. E.; Garcia-Serrano, A.

2016-12-01

The well known Pyramid El Castillo, located in the archaeological site of Chichen Itza, in the Yucatan Peninsula is the emblematic structure of this archaeological site and elected as one of the man-made world seven wonders. The archaeological team that restored this structure during the 1920's discovered a smaller pyramid inside this prehispanic body, which corresponded to an older Mayan period. The possibility of finding other constructive periods inside this edifice should be important to reconstruct the Mayan history. Previous geophysical studies carried out by us in 2014, employed novel Electrical Resistivity Tomography (ERT) arrays that surrounded the pyramids surface with flat electrodes to obtain a 3D image of the subsoil. At that time, a low resistivity body was found beneath the pyramid, which was associated to a sinkhole filled with sweet water. Employing the same technique, a series of flat electrodes were deployed on each body conforming the pyramid, a total of 10 bodies were covered, employing a different number of electrodes trying to keep the distance between each electrode constant ( 3 m). Each body was treated as a single observation cube, where the apparent resistivity data measured was later inverted. A precise topographic control for each electrode was realized and introduced in the inversion process. 45,000 observation points within the pyramid were obtained. Initially, each working cube corresponding to a given pyramid's body was inverted. A composition of each inversion was assembled to form the resistivity distribution within the pyramid using a smooth interpolation method. A high resistivity anomaly was found towards the northern portion of the model that could be associated to the main stairway of the inner pyramid. The cavity detected during the 2014 survey was observed as a low resistivity anomaly found at the pyramid's base. At the moment, we are assembling the full observed resistivity data as a single file to compute an integrated geophysical model that could be inverted. We expect to compute such final model soon.

Spectral geometry of {kappa}-Minkowski space

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Andrea, Francesco

After recalling Snyder's idea [Phys. Rev. 71, 38 (1947)] of using vector fields over a smooth manifold as 'coordinates on a noncommutative space', we discuss a two-dimensional toy-model whose 'dual' noncommutative coordinates form a Lie algebra: this is the well-known {kappa}-Minkowski space [Phys. Lett. B 334, 348 (1994)]. We show how to improve Snyder's idea using the tools of quantum groups and noncommutative geometry. We find a natural representation of the coordinate algebra of {kappa}-Minkowski as linear operators on an Hilbert space (a major problem in the construction of a physical theory), study its 'spectral properties', and discuss how tomore » obtain a Dirac operator for this space. We describe two Dirac operators. The first is associated with a spectral triple. We prove that the cyclic integral of Dimitrijevic et al. [Eur. Phys. J. C 31, 129 (2003)] can be obtained as Dixmier trace associated to this triple. The second Dirac operator is equivariant for the action of the quantum Euclidean group, but it has unbounded commutators with the algebra.« less

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-05-30

ISS017-E-008285 (30 May 2008) --- Pyramids of Dashur, Egypt are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. While the pyramids of Giza are perhaps the most famous, there are several other ancient Egyptian royal necropolis ("city of the dead") sites situated along the Nile River and its delta. One of these sites is located near the village of Dashur (upper right). The gray-brown built area of Dashur is surrounded by green agricultural land of the Nile Delta, which forms a distinct boundary with the tan desert to the west. It is in the desert that the monuments of the ancient rulers of Egypt are found. Several monuments are visible in this image, including the large Red and Bent Pyramids built by Snofru, first king of the 4th Dynasty that lasted from 2575-2465 BC. Other visible monuments include the pyramid complexes of Amenemhat III and Sesostris III, both kings of the 12th Dynasty (1991-1783 BC). Both of these complexes are poorly preserved, due both to unstable ground conditions, and dismantling of the limestone blocks forming the outer pyramid casings during later historical periods. The Bent Pyramid (lower right) is so called as the slope of the outer face was lessened halfway through construction, leading to a distinctive "bent" profile -- explanations for why this was done include decreasing the mass of the pyramid to prevent collapse, or to reduce the work necessary to complete it. The Red Pyramid to the north (center) was built after the Bent Pyramid, and is named for the coloration of the building stone at the structure's core. An irregular dark feature to the southeast of the Bent Pyramid is not a shadow cast by a monument; it is an irrigation feature extending into the desert.

High In-content InGaN nano-pyramids: Tuning crystal homogeneity by optimized nucleation of GaN seeds

NASA Astrophysics Data System (ADS)

Bi, Zhaoxia; Gustafsson, Anders; Lenrick, Filip; Lindgren, David; Hultin, Olof; Wallenberg, L. Reine; Ohlsson, B. Jonas; Monemar, Bo; Samuelson, Lars

2018-01-01

Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent {" separators="| 10 1 ¯ 1 } facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, {" separators="| 10 1 ¯ 1 } and (0001). Typically, the InGaN growth on {" separators="| 10 1 ¯ 1 } planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by {" separators="| 10 1 ¯ 1 }-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.

A Rebuttal of NTL Institute's Learning Pyramid

ERIC Educational Resources Information Center

Letrud, Kare

2012-01-01

This article discusses the learning pyramid corroborated by National Training Laboratories Institute. It present and compliment historical and methodological critique against the learning pyramid, and call upon NTL Institute ought to retract their model.

The 2005 Food Guide Pyramid: an opportunity lost?

PubMed

Chiuve, Stephanie E; Willett, Walter C

2007-11-01

Dietary quality has a vital role in the prevention of chronic disease. In 2005, the US Department of Agriculture released a new food guide, MyPyramid, because the previous pyramid was in substantial discordance with current scientific evidence. The US Department of Agriculture pyramids are the most visible source of US nutrition policy and dietary guidance and it is, therefore, imperative they provide scientifically derived recommendations for a healthy diet. Unfortunately, MyPyramid strays from much of the evidence generated through years of research and, in our opinion, fails to provide the public with clear information about healthy food choices. In this Review, we discuss the policy and process behind the development of MyPyramid, assess the current evidence linking diet to chronic diseases, including cardiovascular disease, cancer and diabetes, and suggest potential alternatives for dietary recommendations.

Effect of varying durations of pyramid exposure - an indication towards a possibility of overexposure.

PubMed

Bhat, Surekha; Rao, Guruprasad; Murthy, K Dilip; Bhat, P Gopalakrishna

2009-10-01

Miniature replicas modeled after the Great Pyramid of Giza are believed to concentrate geoelectromagnetic energy within their cavities and hence act as antistressors in humans and animals. Although there are not many reports of adverse effects of 'overexposure' in the pyramid, subjects have claimed to feel uneasy after certain duration of staying in the pyramid. The present study was aimed to analyze the effects of prolonged pyramid exposure on plasma cortisol level, markers of oxidative damage and antioxidant defense in erythrocytes of adult female Wistar rats. Rats were divided into three groups, normal controls (NC, n=6) that were maintained under standard laboratory conditions in their home cages, pyramid exposed group-2 (PE-2, n=6) & pyramid exposed group-4 (PE-4, n=6) where the rats were housed under the pyramid for 6 hours/day for 2 weeks and 4 weeks respectively. Plasma cortisol and erythrocyte TBARS levels were significantly lower in both PE-2 and PE-4 rats and erythrocyte GSH levels and GSH-Px activity were significantly higher in them as compared to the NC rats. There was no significant difference in the results for these parameters between the PE-2 and PE-4 rats except for erythrocyte GSH-Px activity which was significantly more in the PE-2 rats than in the PE-4 rats. Although these results don't confirm any adverse effects of prolonged exposure in pyramids, they indicate a possibility of such adverse effects.

Challenges to rebuilding the US food pyramid.

PubMed

Kinney, John M

2005-01-01

Twelve years have passed since the US Department of Agriculture introduced the Food Guide Pyramid as a single visual expression of the major food groups and their relative amounts in a healthy diet. Unfortunately, no regular review has been conducted to incorporate new knowledge. Some feel that the pyramid format is too limited for modern use, while others wish it to continue with new information. It seems timely to review what features of the pyramid design have been useful over past years and how it can be improved with new concepts while maintaining ease of understanding by the average consumer. Examples are presented of adapting the pyramid to diets promoted by a special group or to support particular dietary beliefs, in contrast to the goal of seeking a single standardized format. Inherent limitations of the pyramid format are discussed. One proposal is discussed which seeks to redesign the pyramid into a modern educational tool presenting current concepts supported by recent studies and outcomes data. Popular beliefs about what is a healthy diet have perhaps never been as varied as now. This is partly due to sharply differing opinions about which highly publicized weight-loss diet is most effective. The educational benefits of the pyramid format need objective study in view of the inherent limitations of that configuration. Only when the specific visual advantages for the consumer are shown can a decision be made as to the benefit of major new efforts to construct a single modern pyramid.

Optical Design for Extremely Large Telescope Adaptive Optics Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauman, Brian J.

2003-01-01

Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,{bar y} method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method ismore » shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro-electromechanical system (MEMS) to track the LGS light subaperture by subaperture as the light is returned from the upward-propagating laser pulse. A second method can be used if the laser is not pulsed. A lenslet array is described which creates ''pixels'' which are aligned with the axes of the elongated spot of each subaperture, without requiring special charge-coupled devices (CCD's).« less

Synthesis and spectroscopic studies of binuclear metal complexes of a tetradentate N2O2 Schiff base ligand derived from 4,6-diacetylresorcinol and benzylamine.

PubMed

Shebl, Magdy

2008-09-01

A tetradentate N2O2 donor Schiff base ligand, H2L, was synthesized by the condensation of 4,6-diacetylresorcinol with benzylamine. The structure of the ligand was elucidated by elemental analyses, IR, 1H NMR, electronic and mass spectra. Reaction of the Schiff base ligand with nickel(II), cobalt(II), iron(III), cerium(III), vanadyl(IV) and uranyl(VI) ions in 1:2 molar ratio afforded binuclear metal complexes. Also, reaction of the ligand with several copper(II) salts, including Cl-, NO3-, AcO-, ClO4- and SO42- afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO(4)(-) anion as compared to the strongly coordinating power of SO42- and Cl- anions. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, 1H NMR, electronic, mass and ESR spectra as well as magnetic susceptibility measurements. The metal complexes exhibited different geometrical arrangements such as square planar, octahedral, square pyramidal and pentagonal bipyramidal arrangements. The variety in the geometrical arrangements depends on the nature of both the anion and the metal ion.

Numerically constructed internal-coordinate Hamiltonian with Eckart embedding and its application for the inversion tunneling of ammonia.

PubMed

Fábri, Csaba; Mátyus, Edit; Császár, Attila G

2014-02-05

It is shown that the use of an Eckart-frame embedding with a kinetic energy operator expressed in curvilinear internal coordinates becomes feasible and straightforward to implement for arbitrary molecular compositions and internal coordinates if the operator is defined numerically over a (discrete variable representation) grid. The algorithm proposed utilizes the transformation method of Dymarsky and Kudin to maintain the rotational Eckart condition. In order to demonstrate the applicability and flexibility of our approach the non-rigid ammonia molecule is considered and the corresponding rotational-vibrational energy levels and wave functions are computed using kinetic energy operators with three different embeddings. Two of them fulfill the Eckart conditions corresponding to a trigonal pyramidal (C3v) and a trigonal planar (D3h) reference structure and the third one is a non-Eckart frame. The computed energy levels are, of course, identical, and the structure of the three different wave-function representations are analyzed in terms of the rigid rotor functions for a symmetric top. The possible advantages of one frame representation over another are discussed concerning the interpretation of the rovibrational states in terms of the traditional rigid rotor labels. Copyright © 2013 Elsevier B.V. All rights reserved.

Crystal structure and Hirshfeld surface analysis of aqua-bis-(nicotinamide-κN)bis-(4-sulfamoylbenzoato-κO1)copper(II).

PubMed

Hökelek, Tuncer; Yavuz, Vijdan; Dal, Hakan; Necefoğlu, Hacali

2018-01-01

In the crystal of the title complex, [Cu(C 7 H 6 NO 4 S) 2 (C 6 H 6 N 2 O) 2 (H 2 O)], the Cu II cation and the O atom of the coordinated water mol-ecule reside on a twofold rotation axis. The Cu II ion is coordinated by two carboxyl-ate O atoms of the two symmetry-related 4-sulfamoylbenzoate (SB) anions and by two N atoms of the two symmetry-related nicotinamide (NA) mol-ecules at distances of 1.978 (2) and 2.025 (3) Å, respectively, forming a slightly distorted square-planar arrangement. The distorted square-pyramidal coordination environment is completed by the water O atom in the axial position at a distance of 2.147 (4) Å. In the crystal, the mol-ecules are linked via O-H⋯O and N-H⋯O hydrogen bonds with R 2 2 (8) and R 2 2 (18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (42.2%), H⋯H (25.7%) and H⋯C/C⋯H (20.0%) inter-actions.

Light-induced charge separation across bio-inorganic interface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dimitrijevic, N. M.; Rajh, T.; De La Garza, L.

Rational design of hybrid biomolecule - nanoparticulate semiconductor conjugates enables coupling of functionality of biomolecules with the capability of semiconductors for solar energy capture, that can have potential application in energy conversion, sensing and catalysis. The particular challenge is to obtain efficient charge separation analogous to the natural photosynthesis process. The synthesis of axially anisotropic TiO{sub 2} nano-objects such as tubes, rods and bricks, as well as spherical and faceted nanoparticles has been developed in our laboratory. Depending on their size and shape, these nanostructures exhibit different domains of crystallinity, surface areas and aspect ratios. Moreover, in order to accommodatemore » for high curvature in nanoscale regime, the surfaces of TiO{sub 2} nano-objects reconstructs resulting in changes in the coordination of surface Ti atoms from octahedral (D{sub 2d}) to square pyramidal structures (C{sub 4v}). The formation of these coordinatively unsaturated Ti atoms, thus depends strongly on the size and shape of nanocrystallites and affects trapping and reactivity of photogenerated charges. We have exploited these coordinatively unsaturated Ti atoms to coupe electron-donating (such as dopamine) and electron-accepting (pyrroloquinoline quinone) conductive linkers that allow wiring of biomolecules and proteins resulting in enhanced charge separation which increases the yield of ensuing chemical transformations.« less

Coordination geometry of lead carboxylates - spectroscopic and crystallographic evidence.

PubMed

Catalano, Jaclyn; Murphy, Anna; Yao, Yao; Yap, Glenn P A; Zumbulyadis, Nicholas; Centeno, Silvia A; Dybowski, Cecil

2015-02-07

Despite their versatility, only a few single-crystal X-ray structures of lead carboxylates exist, due to difficulties with solubility. In particular, the structures of long-chain metal carboxylates have not been reported. The lone electron pair in Pb(ii) can be stereochemically active or inactive, leading to two types of coordination geometries commonly referred to as hemidirected and holodirected structures, respectively. We report (13)C and (207)Pb solid-state NMR and infrared spectra for a series of lead carboxylates, ranging from lead hexanoate (C6) to lead hexadecanoate (C18). The lead carboxylates based on consistent NMR parameters can be divided in two groups, shorter-chain (C6, C7, and C8) and longer-chain (C9, C10, C11, C12, C14, C16, and C18) carboxylates. This dichotomy suggests two modes of packing in these solids, one for the short-chain lead carboxylates and one for long-chain lead carboxylates. The consistency of the (13)C and (207)Pb NMR parameters, as well as the IR data, in each group suggests that each motif represents a structure characteristic of each subgroup. We also report the single-crystal X-ray diffraction structure of lead nonanoate (C9), the first single-crystal structure to have been reported for the longer-chain subgroup. Taken together the evidence suggests that the coordination geometry of C6-C8 lead carboxylates is hemidirected, and that of C9-C14, C16 and C18 lead carboxylates is holodirected.

Near-unity thermally activated delayed fluorescence efficiency in three- and four-coordinate Au(i) complexes with diphosphine ligands.

PubMed

Osawa, Masahisa; Aino, Masa-Aki; Nagakura, Takaki; Hoshino, Mikio; Tanaka, Yuya; Akita, Munetaka

2018-05-14

The synthesis and photoluminescence properties of three-coordinate Au(i) complexes with rigid diphosphine ligands LMe {1,2-bis[bis(2-methylphenyl)phosphino]benzene}, LEt {1,2-bis[bis(2-ethylphenyl)phosphino]benzene}, and LiPr {1,2-bis[bis(2-isopropylphenyl)phosphino]benzene} are investigated. The LMe and LEt ligands afford two types of complexes: dinuclear complexes [μ-LMe(AuCl)2] (1d) and [μ-LEt(AuCl)2] (2d) with an Au(i)-Au(i) bond and mononuclear three-coordinate Au(i) complexes LMeAuCl (1) and LEtAuCl (2). On the other hand, the bulkiest ligand, LiPr, affords three-coordinate Au(i) complexes, LiPrAuCl (3) and LiPrAuI (4), but no dinuclear complexes. X-ray analysis suggests that both 3 and 4 possess a highly distorted trigonal planar geometry. Moreover, luminescence data reveal that at room temperature, 3 and 4 exhibit yellow-green thermally activated delayed fluorescence in the crystalline state with maximum emission wavelengths at 558 and 549 nm, respectively. The emission yields are close to unity. Quantum chemical calculations suggest that the emission of 4 originates from the (σ + X) → π* excited state that possesses strong intraligand charge-transfer character. The luminescent properties of four-coordinate Au(i) complex (5) possessing a tetrahedral geometry are discussed on the basis of the emission spectra and decay times measured in a temperature range of 309-77 K.

Crystal structure of (pyridine-κN)bis(quinolin-2-olato-κ2 N,O)copper(II) monohydrate

PubMed Central

Hawks, Benjamin; Yan, Jingjing; Basa, Prem; Burdette, Shawn

2015-01-01

The title complex, [Cu(C9H6NO)2(C5H4N)]·H2O, adopts a slightly distorted square-pyramidal geometry in which the axial pyridine ligand exhibits a long Cu—N bond of 2.305 (3) Å. The pyridine ligand forms dihedral angles of 79.5 (5) and 88.0 (1)° with the planes of the two quinolin-2-olate ligands, while the dihedral angle between the quinoline groups of 9.0 (3)° indicates near planarity. The water mol­ecule connects adjacent copper complexes through O—H⋯O hydrogen bonds to phenolate O atoms, forming a network inter­connecting all the complexes in the crystal lattice. PMID:25878845

First-Principles Study of Structural, Electronic and Magnetic Properties of Metal-Centered Tetrahexahedral V15+ Cluster

PubMed Central

Ren, Hongjiang; Huang, Xinwei; Li, Shuna

2017-01-01

The V-centered bicapped hexagonal antiprism structure (A), as the most stable geometry of the cationic V15+ cluster, is determined by using infrared multiple photo dissociation (IR-MPD) in combination with density functional theory computations. It is found that the A structure can be stabilized by 18 delocalized 3c-2e σ-bonds on outer V3 triangles of the bicapped hexagonal antiprism surface and 12 delocalized 4c-2e σ-bonds on inner trigonal pyramidal V4 moiety, and the features are related to the strong p-d hybridization of the cluster. The total magnetic moments on the cluster are predicted to be 2.0 µB, which come mainly from the central vanadium atom. PMID:28665337

The effect of suppressors and muzzle brakes on shock wave strength

NASA Astrophysics Data System (ADS)

Phan, K. C.; Stollery, J. L.

Experimental simulations of a gun blast were performed in the course of an optimization study of shock-wave suppressor and muzzle-brake geometry. A single-spark schlieren system was used to photograph the shock waves emerging from a 32-mm shock tube. The suppressor systems tested with respect to the overpressure level included a perforated tube enclosed in an expansion chamber, a cup-and-box suppressor, and noise-absorbent materials inside a suppressor; high suppression efficiency was observed for the first two. Recoil simulation tests, performed with plain and pyramidal baffles, disk, and cylinder, show that the blast level is generally higher for a more efective muzzle brake. An optimum distance from the muzzle to the brake is suggested to be in the region of one caliber.

Recent faulting in western Nevada revealed by multi-scale seismic reflection

USGS Publications Warehouse

Frary, Roxanna N.; Louie, John N.; Stephenson, William J.; Odum, Jackson K.; Kell, Annie; Eisses, Amy; Kent, Graham M.; Driscoll, Neal W.; Karlin, Robert; Baskin, Robert L.; Pullammanappallil, Satish; Liberty, Lee M.

2011-01-01

The main goal of this study is to compare different reflection methods used to image subsurface structure within different physical environments in western Nevada. With all the methods employed, the primary goal is fault imaging for structural information toward geothermal exploration and seismic hazard estimation. We use seismic CHIRP (a swept-frequency marine acquisition system), weight drop (an accelerated hammer source), and two different vibroseis systems to characterize fault structure. We focused our efforts in the Reno metropolitan area and the area within and surrounding Pyramid Lake in northern Nevada. These different methods have provided valuable constraints on the fault geometry and activity, as well as associated fluid movement. These are critical in evaluating the potential for large earthquakes in these areas, and geothermal exploration possibilities near these structures.

Towards nonaxisymmetry; initial results using the Flux Coordinate Independent method in BOUT++

NASA Astrophysics Data System (ADS)

Shanahan, B. W.; Hill, P.; Dudson, B. D.

2016-11-01

Fluid simulation of stellarator edge transport is difficult due to the complexities of mesh generation; the stochastic edge and strong nonaxisymmetry inhibit the use of field aligned coordinate systems. The recent implementation of the Flux Coordinate Independent method for calculating parallel derivatives in BOUT++ has allowed for more complex geometries. Here we present initial results of nonaxisymmetric diffusion modelling as a step towards stellarator turbulence modelling. We then present initial (non-turbulent) transport modelling using the FCI method and compare the results with analytical calculations. The prospects for future stellarator transport and turbulence modelling are discussed.

Low coordinated mononuclear erbium(iii) single-molecule magnets with C3v symmetry: a method for altering single-molecule magnet properties by incorporating hard and soft donors.

PubMed

Zhang, Haitao; Nakanishi, Ryo; Katoh, Keiichi; Breedlove, Brian K; Kitagawa, Yasutaka; Yamashita, Masahiro

2018-01-02

Structures and magnetic characteristics of two three-coordinate erbium(iii) compounds with C 3v geometry, tris(2,6-di-tert-butyl-p-cresolate)erbium, Er(dbpc) 3 (1) and tris(bis(trimethylsilyl)methyl)erbium, Er(btmsm) 3 (2), were determined. Both underwent temperature-dependent slow magnetic relaxation processes in the absence of an external magnetic field. As a result of the differences in the coordination environment, they exhibit different energy barriers and quantum tunneling of magnetization (QTM) constants.

Disposable gold coated pyramidal SERS sensor on the plastic platform.

PubMed

Oo, S Z; Siitonen, S; Kontturi, V; Eustace, D A; Charlton, M D B

2016-01-11

In this paper we investigate suitability of arrays of gold coated pyramids for surface-enhanced Raman scattering (SERS) sensing applications. Pyramidarrays composed of 1000 nm pit size with 1250 nm pitch lengthwerereplicated on a plastic substrate by roll-to-roll (R2R) ultraviolet (UV) embossing. The level of SERS enhancement, and qualitative performance provided by the new substrate is investigated by comparing Raman spectrum of benzenethiol (BTh) test molecules to the benchmark Klarite SERS substrate which comprises inverted pyramid arrays(1500 nm pit size with 2000 nm pitch length) fabricated on a silicon substrate. The new substrate is found to provide upto 11 times increase in signal in comparison to the inverted pyramid (IV-pyramid) arrays fabricated on an identical plastic substrate. Numerical simulation and experimental evidence suggest that strongly confined electromagnetic fields close to the base of the pyramids, are mainly responsible for the Raman enhancement factor, instead of the fields localized around the tip. Unusually strong plasmon fields are projected upto 200nm from the sidewalls at the base of the pyramid increasing the cross sectional sensing volume.

Pyramidal Cells in Prefrontal Cortex of Primates: Marked Differences in Neuronal Structure Among Species

PubMed Central

Elston, Guy N.; Benavides-Piccione, Ruth; Elston, Alejandra; Manger, Paul R.; DeFelipe, Javier

2010-01-01

The most ubiquitous neuron in the cerebral cortex, the pyramidal cell, is characterized by markedly different dendritic structure among different cortical areas. The complex pyramidal cell phenotype in granular prefrontal cortex (gPFC) of higher primates endows specific biophysical properties and patterns of connectivity, which differ from those in other cortical regions. However, within the gPFC, data have been sampled from only a select few cortical areas. The gPFC of species such as human and macaque monkey includes more than 10 cortical areas. It remains unknown as to what degree pyramidal cell structure may vary among these cortical areas. Here we undertook a survey of pyramidal cells in the dorsolateral, medial, and orbital gPFC of cercopithecid primates. We found marked heterogeneity in pyramidal cell structure within and between these regions. Moreover, trends for gradients in neuronal complexity varied among species. As the structure of neurons determines their computational abilities, memory storage capacity and connectivity, we propose that these specializations in the pyramidal cell phenotype are an important determinant of species-specific executive cortical functions in primates. PMID:21347276

Unconventional Solar Sailing

NASA Astrophysics Data System (ADS)

Ceriotti, Matteo

The idea of exploiting solar radiation pressure for space travel, or solar sailing, is more than a 100 years old, and yet most of the research thus far has considered only a limited number of sail configurations. However solar sails do not have to be inertially-pointing squares, spin-stabilised discs or heliogyros: there is a range of different configurations and concepts that present some advantageous features. This chapter will show and discuss three non-conventional solar sail configurations and their applications. In the first, the sail is complemented by an electric thruster, resulting in a hybrid-propulsion spacecraft which is capable to hover above the Earth's Poles in a stationary position (pole-sitter). The second concept makes use of a variable-geometry pyramidal sail, naturally pointing towards the sun, to increase or decrease the orbit altitude without the need of propellant or attitude manoeuvres. Finally, the third concept shows that the orbit altitude can also be changed, without active manoeuvres or geometry change, if the sail naturally oscillates synchronously with the orbital motion. The main motivation behind these novel configurations is to overcome some of the engineering limitations of solar sailing; the resulting concepts pose some intriguing orbital and attitude dynamics problems, which will be discussed.

Influence of Geometry on the Drug Release Profiles of Stereolithographic (SLA) 3D-Printed Tablets.

PubMed

Martinez, Pamela Robles; Goyanes, Alvaro; Basit, Abdul W; Gaisford, Simon

2018-06-08

Additive manufacturing (3D printing) permits the fabrication of tablets in shapes unattainable by powder compaction, and so the effects of geometry on drug release behavior is easily assessed. Here, tablets (printlets) comprising of paracetamol dispersed in polyethylene glycol were printed using stereolithographic 3D printing. A number of geometric shapes were produced (cube, disc, pyramid, sphere and torus) with either constant surface area (SA) or constant surface area/volume ratio (SA/V). Dissolution testing showed that printlets with constant SA/V ratio released drug at the same rate, while those with constant SA released drug at different rates. A series of tori with increasing SA/V ratio (from 0.5 to 2.4) were printed, and it was found that dissolution rate increased as the SA/V ratio increased. The data show that printlets can be fabricated in multiple shapes and that dissolution performance can be maintained if the SA/V ratio is constant or that dissolution performance of printlets can be fine-tuned by varying SA/V ratio. The results suggest that 3D printing is therefore a suitable manufacturing method for personalized dosage forms.

Crystal structure, spectral property, antimicrobial activity and DFT calculation of N-(coumarin-3-yl)-N‧-(2-amino-5-phenyl-1,3,4-thiadiazol-2-yl) urea

NASA Astrophysics Data System (ADS)

Zhang, Hong-Song; Zhang, Kong-Yan; Chen, Li-Chuan; Li, Yao-Xin; Chai, Lan-Qin

2017-10-01

N-(coumarin-3-yl)-N‧-(2-amino-5-phenyl-1,3,4-thiadiazol-2-yl) urea was synthesized and characterized by elemental analysis, IR, 1H NMR, 13C NMR, UV-Vis and emission spectroscopy, as well as by single-crystal X-ray diffraction. X-ray crystallographic analyses have indicated that the crystal structure consists of two dimethyl sulfoxide (DMSO) solvent molecules and the structural geometry of DMSO is a trigonal pyramid in shape. In the crystal structure, a self-assembling two-dimensional (2-D) layer supramolecular architecture is formed through intermolecular hydrogen bonds, Cdbnd O···π (thiadiazole ring) and π···π stacking interactions. The geometry of the compound has been optimized by the DFT method and the results are compared with the X-ray diffraction data. The electronic transitions and spectral features of the compound were carried out by using DFT/B3LYP method. In addition, the antimicrobial activity was also studied, and the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and HOMO-LUMO gap were also calculated.

Recommended GIS Analysis Methods for Global Gridded Population Data

NASA Astrophysics Data System (ADS)

Frye, C. E.; Sorichetta, A.; Rose, A.

2017-12-01

When using geographic information systems (GIS) to analyze gridded, i.e., raster, population data, analysts need a detailed understanding of several factors that affect raster data processing, and thus, the accuracy of the results. Global raster data is most often provided in an unprojected state, usually in the WGS 1984 geographic coordinate system. Most GIS functions and tools evaluate data based on overlay relationships (area) or proximity (distance). Area and distance for global raster data can be either calculated directly using the various earth ellipsoids or after transforming the data to equal-area/equidistant projected coordinate systems to analyze all locations equally. However, unlike when projecting vector data, not all projected coordinate systems can support such analyses equally, and the process of transforming raster data from one coordinate space to another often results unmanaged loss of data through a process called resampling. Resampling determines which values to use in the result dataset given an imperfect locational match in the input dataset(s). Cell size or resolution, registration, resampling method, statistical type, and whether the raster represents continuous or discreet information potentially influence the quality of the result. Gridded population data represent estimates of population in each raster cell, and this presentation will provide guidelines for accurately transforming population rasters for analysis in GIS. Resampling impacts the display of high resolution global gridded population data, and we will discuss how to properly handle pyramid creation using the Aggregate tool with the sum option to create overviews for mosaic datasets.

A Managerial Approach to NASA’s Cultural Changes: Open System Model

DTIC Science & Technology

2007-12-01

in both societies was different, even though both resemble a similar pyramid shape. For the Egyptians , pyramids were tombs , and for the Mayans...to understand, Schein (2004) points out they may be difficult to decipher. An example is Egyptian and Mayan pyramids. The meaning of the structures...pyramids were both tombs and temples. Therefore, care must be taken deriving meaning from artifacts, especially in different societies (Schein, 2004

Light extraction efficiency of GaN-based LED with pyramid texture by using ray path analysis.

PubMed

Pan, Jui-Wen; Wang, Chia-Shen

2012-09-10

We study three different gallium-nitride (GaN) based light emitting diode (LED) cases based on the different locations of the pyramid textures. In case 1, the pyramid texture is located on the sapphire top surface, in case 2, the pyramid texture is locate on the P-GaN top surface, while in case 3, the pyramid texture is located on both the sapphire and P-GaN top surfaces. We study the relationship between the light extraction efficiency (LEE) and angle of slant of the pyramid texture. The optimization of total LEE was highest for case 3 among the three cases. Moreover, the seven escape paths along which most of the escaped photon flux propagated were selected in a simulation of the LEDs. The seven escape paths were used to estimate the slant angle for the optimization of LEE and to precisely analyze the photon escape path.

How to determine spiral bevel gear tooth geometry for finite element analysis

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Litvin, Faydor L.

1991-01-01

An analytical method was developed to determine gear tooth surface coordinates of face milled spiral bevel gears. The method combines the basic gear design parameters with the kinematical aspects for spiral bevel gear manufacturing. A computer program was developed to calculate the surface coordinates. From this data a 3-D model for finite element analysis can be determined. Development of the modeling method and an example case are presented.

A collection of edge-based elements

NASA Technical Reports Server (NTRS)

Kempel, Leo C.; Volakis, John L.

1992-01-01

Edge-based elements have proved useful in solving electromagnetic problems since they are nondivergent. Previous authors have presented several two and three dimensional elements. Herein, we present four types of elements which are suitable for modeling several types of three dimensional geometries. Distorted brick and triangular prism elements are given in cartesian coordinates as well as the specialized cylindrical shell and pie-shaped prism elements which are suitable for problems best described in polar cylindrical coordinates.

Buried chloride stereochemistry in the Protein Data Bank

PubMed Central

2014-01-01

Background Despite the chloride anion is involved in fundamental biological processes, its interactions with proteins are little known. In particular, we lack a systematic survey of its coordination spheres. Results The analysis of a non-redundant set (pairwise sequence identity?

Buried chloride stereochemistry in the Protein Data Bank.

PubMed

Carugo, Oliviero

2014-09-23

Despite the chloride anion is involved in fundamental biological processes, its interactions with proteins are little known. In particular, we lack a systematic survey of its coordination spheres. The analysis of a non-redundant set (pairwise sequence identity < 30%) of 1739 high resolution (<2 Å) crystal structures that contain at least one chloride anion shows that the first coordination spheres of the chlorides are essentially constituted by hydrogen bond donors. Amongst the side-chains positively charged, arginine interacts with chlorides much more frequently than lysine. Although the most common coordination number is 4, the coordination stereochemistry is closer to the expected geometry when the coordination number is 5, suggesting that this is the coordination number towards which the chlorides tend when they interact with proteins. The results of these analyses are useful in interpreting, describing, and validating new protein crystal structures that contain chloride anions.

Computation techniques for the volume of a tetrahedron

NASA Astrophysics Data System (ADS)

Srinivasan, V. K.

2010-10-01

The purpose of this article is to discuss specific techniques for the computation of the volume of a tetrahedron. A few of them are taught in the undergraduate multivariable calculus courses. Few of them are found in text books on coordinate geometry and synthetic solid geometry. This article gathers many of these techniques so as to constitute a minor survey of a teaching-oriented article, useful to both students and teachers according to their needs in the classrooms.

Lorentz symmetric n-particle systems without ``multiple times''

NASA Astrophysics Data System (ADS)

Smith, Felix

2013-05-01

The need for multiple times in relativistic n-particle dynamics is a consequence of Minkowski's postulated symmetry between space and time coordinates in a space-time s = [x1 , . . ,x4 ] = [ x , y , z , ict ] , Eq. (1). Poincaré doubted the need for this space-time symmetry, believing Lorentz covariance could also prevail in some geometries with a three-dimensional position space and a quite different time coordinate. The Hubble expansion observed later justifies a specific geometry of this kind, a negatively curved position 3-space expanding with time at the Hubble rate lH (t) =lH , 0 + cΔt (F. T. Smith, Ann. Fond. L. de Broglie, 30, 179 (2005) and 35, 395 (2010)). Its position 4-vector is not s but q = [x1 , . . ,x4 ] = [ x , y , z , ilH (t) ] , and shows no 4-space symmetry. What is observed is always a difference 4-vector Δq = [ Δx , Δy , Δz , icΔt ] , and this displays the structure of Eq. (1) perfectly. Thus we find the standard 4-vector of special relativity in a geometry that does not require a Minkowski space-time at all, but a quite different geometry with a expanding 3-space symmetry and an independent time. The same Lorentz symmetry with but a single time extends to 2 and n-body systems.

Exploration of the Ca2+ interaction modes of the nifedipine calcium channel antagonist.

PubMed

Liu, Huichun; Zhang, Liang; Li, Ping; Cukier, Robert I; Bu, Yuxiang

2007-02-02

A comprehensive study is carried out using quantum chemical computation and molecular dynamics (MD) simulations to gain insight into the interaction between Ca(2+) ions and the most important class of calcium channel antagonists--nifedipine. First, the chelating structures and energetic characters of nifedipine-Ca(2+) in the gas phase are explored, and 25 isomers are found. The most favorable chelating mode is a tridentate one, that is, Ca(2+) binds to two carbonyl O atoms and one nitryl O atom, where Ca(2+) is above the plane of the three O atoms to form a pyramidal structure. Accurate geometric structures, relative stabilities, vertical and adiabatic binding energies, and charge distributions are discussed. The differences in the geometries and energies among these isomers are analyzed from the contributions of chelating sites, electrostatics and polarizations, steric repulsions, and charge distributions. The interconversions among isomers with similar geometries and energies are also investigated because of the importance of the geometric transformation in the biological system. Furthermore, certain numbers of water molecules are added to the nifedipine-Ca(2+) system to probe the effect of water. A detailed study is performed on the hydrated geometries on the basis of the most stable isomer 1. Stepwise hydration can weaken the nifedipine-Ca(2+) interaction, and the chelating sites of nifedipine are gradually replaced by the added water molecules. Hexacoordination is found to be the most favorable geometry no matter how many water molecules were added, which can be verified by the MD simulations. The transfer of water molecules from the inner shell to the outer shell is also supported by MD simulations of the hexahydrated complexes.

Theoretical study of electronic structures and spectroscopic properties of Ga3Sn, GaSn3, and their ions.

PubMed

Zhu, Xiaolei

2007-01-01

Ground and excited states of mixed gallium stannide tetramers (Ga3Sn, Ga3Sn+, Ga3Sn-, GaSn3, GaSn3+, and GaSn3-) are investigated employing the complete active space self-consistent-field (CASSCF), density function theory (DFT), and the coupled-cluster single and double substitution (including triple excitations) (CCSD(T)) methods. The ground states of Ga3Sn, Ga3Sn+, and Ga3Sn- are found to be the 2A1, 3B1, and 1A1 states in C2v symmetry with a planar quadrilateral geometry, respectively. The ground states of GaSn3 and GaSn3- is predicted to be the 2A1 and 1A1 states in C2v point group with a planar quadrilateral structure, respectively, while the ground state of GaSn3+ is the 1A1 state with ideal triangular pyramid C3v geometry. Equilibrium geometries, vibrational frequencies, binding energies, electron affinities, ionization energies, and other properties of Ga3Sn and GaSn3 are computed and discussed. The anion photoelectron spectra of Ga3Sn- and GaSn3- are also predicted. It is interesting to find that the amount of charge transfer between Ga and Sn2 atoms in the 1A1 state of GaSn3+ greatly increases upon electron ionization from the 2A1 state of GaSn3, which may be caused by large geometry change. On the other hand, the results of the low-lying states of Ga3Sn and GaSn3 are compared with those of Ga3Si and GaSi3.

Theoretical study of electronic structures and spectroscopic properties of Ga 3Sn, GaSn 3, and their ions

NASA Astrophysics Data System (ADS)

Zhu, Xiaolei

2007-01-01

Ground and excited states of mixed gallium stannide tetramers (Ga 3Sn, Ga 3Sn +, Ga 3Sn -, GaSn 3, GaSn 3+, and GaSn 3-) are investigated employing the complete active space self-consistent-field (CASSCF), density function theory (DFT), and the coupled-cluster single and double substitution (including triple excitations) (CCSD(T)) methods. The ground states of Ga 3Sn, Ga 3Sn +, and Ga 3Sn - are found to be the 2A 1, 3B 1, and 1A 1 states in C2v symmetry with a planar quadrilateral geometry, respectively. The ground states of GaSn 3 and GaSn 3- is predicted to be the 2A 1 and 1A 1 states in C2v point group with a planar quadrilateral structure, respectively, while the ground state of GaSn 3+ is the 1A 1 state with ideal triangular pyramid C3v geometry. Equilibrium geometries, vibrational frequencies, binding energies, electron affinities, ionization energies, and other properties of Ga 3Sn and GaSn 3 are computed and discussed. The anion photoelectron spectra of Ga 3Sn - and GaSn 3- are also predicted. It is interesting to find that the amount of charge transfer between Ga and Sn 2 atoms in the 1A 1 state of GaSn 3+ greatly increases upon electron ionization from the 2A 1 state of GaSn 3, which may be caused by large geometry change. On the other hand, the results of the low-lying states of Ga 3Sn and GaSn 3 are compared with those of Ga 3Si and GaSi 3.

Geometrical approach to neural net control of movements and posture

NASA Technical Reports Server (NTRS)

Pellionisz, A. J.; Ramos, C. F.

1993-01-01

In one approach to modeling brain function, sensorimotor integration is described as geometrical mapping among coordinates of non-orthogonal frames that are intrinsic to the system; in such a case sensors represent (covariant) afferents and motor effectors represent (contravariant) motor efferents. The neuronal networks that perform such a function are viewed as general tensor transformations among different expressions and metric tensors determining the geometry of neural functional spaces. Although the non-orthogonality of a coordinate system does not impose a specific geometry on the space, this "Tensor Network Theory of brain function" allows for the possibility that the geometry is non-Euclidean. It is suggested that investigation of the non-Euclidean nature of the geometry is the key to understanding brain function and to interpreting neuronal network function. This paper outlines three contemporary applications of such a theoretical modeling approach. The first is the analysis and interpretation of multi-electrode recordings. The internal geometries of neural networks controlling external behavior of the skeletomuscle system is experimentally determinable using such multi-unit recordings. The second application of this geometrical approach to brain theory is modeling the control of posture and movement. A preliminary simulation study has been conducted with the aim of understanding the control of balance in a standing human. The model appears to unify postural control strategies that have previously been considered to be independent of each other. Third, this paper emphasizes the importance of the geometrical approach for the design and fabrication of neurocomputers that could be used in functional neuromuscular stimulation (FNS) for replacing lost motor control.

An interactive user-friendly approach to surface-fitting three-dimensional geometries

NASA Technical Reports Server (NTRS)

Cheatwood, F. Mcneil; Dejarnette, Fred R.

1988-01-01

A surface-fitting technique has been developed which addresses two problems with existing geometry packages: computer storage requirements and the time required of the user for the initial setup of the geometry model. Coordinates of cross sections are fit using segments of general conic sections. The next step is to blend the cross-sectional curve-fits in the longitudinal direction using general conics to fit specific meridional half-planes. Provisions are made to allow the fitting of fuselages and wings so that entire wing-body combinations may be modeled. This report includes the development of the technique along with a User's Guide for the various menus within the program. Results for the modeling of the Space Shuttle and a proposed Aeroassist Flight Experiment geometry are presented.

Inhibition and oxygen activation in copper amine oxidases.

PubMed

Shepard, Eric M; Dooley, David M

2015-05-19

Copper-containing amine oxidases (CuAOs) use both copper and 2,4,5-trihydroxyphenylalanine quinone (TPQ) to catalyze the oxidative deamination of primary amines. The CuAO active site is highly conserved and comprised of TPQ and a mononuclear type II copper center that exhibits five-coordinate, distorted square pyramidal coordination geometry with histidine ligands and equatorially and axially bound water in the oxidized, resting state. The active site is buried within the protein, and CuAOs from various sources display remarkable diversity with respect to the composition of the active site channel and cofactor accessibility. Structural and mechanistic factors that influence substrate preference and inhibitor sensitivity and selectivity have been defined. This Account summarizes the strategies used to design selective CuAO inhibitors based on active site channel characteristics, leading to either enhanced steric fits or the trapping of reactive electrophilic products. These findings provide a framework to support the future development of candidate molecules aimed at minimizing the negative side effects associated with drugs containing amine functionalities. This is vital given the existence of human diamine oxidase and vascular adhesion protein-1, which have distinct amine substrate preferences and are associated with different metabolic processes. Inhibition of these enzymes by antifungal or antiprotozoal agents, as well as classic monoamine oxidase (MAO) inhibitors, may contribute to the adverse side effects associated with drug treatment. These observations provide a rationale for the limited clinical value associated with certain amine-containing pharmaceuticals and emphasize the need for more selective AO inhibitors. This Account also discusses the novel roles of copper and TPQ in the chemistry of O2 activation and substrate oxidation. Reduced CuAOs exist in a redox equilibrium between the Cu(II)-TPQAMQ (aminoquinol) and Cu(I)-TPQSQ (semiquinone). Elucidating the roles of Cu(I), TPQSQ, and TPQAMQ in O2 activation, for example, distinguishing inner-sphere versus outer-sphere electron transfer mechanisms, has been actively investigated since the discovery of TPQSQ in 1991 and has only recently been clarified. Kinetics and spectroscopic studies encompassing metal substitution, stopped-flow and temperature-jump relaxation methods, and oxygen kinetic isotope experiments have provided strong support for an inner-sphere electron transfer step from Cu(I) to O2. Data for two enzymes support a mechanism wherein O2 prebinds to a three-coordinate Cu(I) site, yielding a [Cu(II)(η(1)-O2(-1))](+) intermediate, with H2O2 generated from ensuing rate-determining proton coupled electron transfer from TPQSQ. While kinetics data from the cobalt-substituted yeast enzyme indicated that O2 is reduced through an outer-sphere process involving TPQAMQ, new findings with a bacterial CuAO demonstrate that both the Cu(II) and Co(II) forms of the enzyme operate via parallel mechanisms involving metal-superoxide intermediates. Structural observations of a coordinated TPQSQ-Cu(I) complex in two CuAOs supports previous indications that Cu(II)/(I) ligand substitution chemistry may be mechanistically relevant. Substantial evidence indicates that rapid and reversible inner-sphere reduction of O2 at a three-coordinate Cu(I) site occurs, but the existence of a coordinated semiquinone in some AOs suggests that, in these enzymes, an outer-sphere reaction between O2 and TPQSQ may also be possible, since this is expected to be energetically favorable compared with outer-sphere electron transfer from TPQAMQ to O2.

Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons.

PubMed

Morishima, Kunihiro; Kuno, Mitsuaki; Nishio, Akira; Kitagawa, Nobuko; Manabe, Yuta; Moto, Masaki; Takasaki, Fumihiko; Fujii, Hirofumi; Satoh, Kotaro; Kodama, Hideyo; Hayashi, Kohei; Odaka, Shigeru; Procureur, Sébastien; Attié, David; Bouteille, Simon; Calvet, Denis; Filosa, Christopher; Magnier, Patrick; Mandjavidze, Irakli; Riallot, Marc; Marini, Benoit; Gable, Pierre; Date, Yoshikatsu; Sugiura, Makiko; Elshayeb, Yasser; Elnady, Tamer; Ezzy, Mustapha; Guerriero, Emmanuel; Steiger, Vincent; Serikoff, Nicolas; Mouret, Jean-Baptiste; Charlès, Bernard; Helal, Hany; Tayoubi, Mehdi

2017-12-21

The Great Pyramid, or Khufu's Pyramid, was built on the Giza plateau in Egypt during the fourth dynasty by the pharaoh Khufu (Cheops), who reigned from 2509 bc to 2483 bc. Despite being one of the oldest and largest monuments on Earth, there is no consensus about how it was built. To understand its internal structure better, we imaged the pyramid using muons, which are by-products of cosmic rays that are only partially absorbed by stone. The resulting cosmic-ray muon radiography allows us to visualize the known and any unknown voids in the pyramid in a non-invasive way. Here we report the discovery of a large void (with a cross-section similar to that of the Grand Gallery and a minimum length of 30 metres) situated above the Grand Gallery. This constitutes the first major inner structure found in the Great Pyramid since the nineteenth century. The void, named ScanPyramids' Big Void, was first observed with nuclear emulsion films installed in the Queen's chamber, then confirmed with scintillator hodoscopes set up in the same chamber and finally re-confirmed with gas detectors outside the pyramid. This large void has therefore been detected with high confidence by three different muon detection technologies and three independent analyses. These results constitute a breakthrough for the understanding of the internal structure of Khufu's Pyramid. Although there is currently no information about the intended purpose of this void, these findings show how modern particle physics can shed new light on the world's archaeological heritage.

Rational Design, Synthesis and Evaluation of First Generation Inhibitors of the Giardia lamblia Fructose-1,6-biphosphate Aldolase

PubMed Central

Li, Zhimin; Liu, Zhengang; Cho, Dae Won; Zou, Jiwen; Gong, Maozhen; Breece, Robert M.; Galkin, Andrey; Li, Ling; Zhao, Hong; Maestas, Gabriel D.; Tierney, David L.; Herzberg, Osnat; Dunaway-Mariano, Debra; Mariano, Patrick S.

2011-01-01

Inhibitors of the Giardia lamblia fructose 1,6-bisphosphate aldolase (GlFBPA), which transforms fructose 1,6-bisphosphate (FBP) to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, were designed based on 3-hydroxy-2-pyridone and 1,2-dihydroxypyridine scaffolds that position two negatively charged tetrahedral groups for interaction with substrate phosphate binding residues, a hydrogen bond donor to the catalytic Asp83, and a Zn2+ binding group. The inhibition activities for the GlFBPA catalyzed reaction of FBP of the prepared alkyl phosphonate/phosphate substituted 3-hydroxy-2-pyridinones and a dihydroxypyridine were determined. The 3-hydroxy-2-pyridone inhibitor 8 was found to bind to GlFBPA with an affinity (Ki = 14 μM) that is comparable to that of FBP (Km = 2 μM) or its inert analog TBP (Ki = 1 μM). The X-ray structure of the GlFBPA-inhibitor 8 complex (2.3 Å) shows that 8 binds to the active site in the manner predicted by in silico docking with the exception of coordination with Zn2+. The observed distances and orientation of the pyridone ring O=C-C-OH relative to Zn2+ are not consistent with a strong interaction. To determine if Zn2+coordination occurs in the GlFBPA-inhibitor 8 complex in solution, EXAFS spectra were measured. A four coordinate geometry comprised of the three enzyme histidine ligands and an oxygen atom from the pyridone ring O=C-C-OH was indicated. Analysis of the Zn2+ coordination geometries in recently reported structures of class II FBPAs suggests that strong Zn2+ coordination is reserved for the enediolate-like transition state, accounting for minimal contribution of Zn2+ coordination to binding of 8 to GlFBPA. PMID:21333622

Identifying the Unique Properties of α-Bi 2Mo 3O 12 for the Activation of Propene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Licht, Rachel B.; Getsoian, Andrew; Bell, Alexis T.

In order to understand the remarkable activity of α-Bi 2Mo 3O 12 for selective oxidation and ammoxidation of propene, the propene activation ability of four molybdenum-based mixed metal oxides - Bi 2Mo 3O 12, PbMoO 4, Bi 2Pb 5Mo 8O 32, and MoO 3 - was investigated using density functional theory. Propene activation is considered to occur via abstraction of a hydrogen atom from the methyl group of physisorbed propene by lattice oxygen. For each material, the apparent activation energy was estimated by summing the heat of adsorption of propene, the C-H bond dissociation energy, and the hydrogen attachment energymore » (HAE) for hydrogen addition to lattice oxygen; this sum provides a lower bound for the apparent activation energy. It was found that two structural features of oxide surfaces are essential to achieve low activation barriers: under-coordinated surface cation sites enable strong propene adsorption, and suitable 5- or 6-coordinate geometries at molybdenum result in favorable HAEs. The impact of molybdenum coordination on HAE was elucidated by carrying out a molecular orbital analysis using a cluster model of the molybdate unit. This effort revealed that, in 5- and 6-coordinate molybdates, oxygen donor atoms trans to molybdenyl oxo atoms destabilize the molybdate prior to H addition but stabilize the molybdate after H addition, thereby providing an HAE ~15 kcal/mol more favorable than that on 4-coordinate molybdate oxo atoms. Bi 3+ cations in Bi 2Mo 3O 12 thus promote catalytic activity by providing both strong adsorption sites for propene and forcing molybdate into 5-coordinate geometries that lead to particularly favorable values of the HAE. (Graph Presented).« less

Identifying the Unique Properties of α-Bi 2Mo 3O 12 for the Activation of Propene

DOE PAGES

Licht, Rachel B.; Getsoian, Andrew; Bell, Alexis T.

2016-12-30

In order to understand the remarkable activity of α-Bi 2Mo 3O 12 for selective oxidation and ammoxidation of propene, the propene activation ability of four molybdenum-based mixed metal oxides - Bi 2Mo 3O 12, PbMoO 4, Bi 2Pb 5Mo 8O 32, and MoO 3 - was investigated using density functional theory. Propene activation is considered to occur via abstraction of a hydrogen atom from the methyl group of physisorbed propene by lattice oxygen. For each material, the apparent activation energy was estimated by summing the heat of adsorption of propene, the C-H bond dissociation energy, and the hydrogen attachment energymore » (HAE) for hydrogen addition to lattice oxygen; this sum provides a lower bound for the apparent activation energy. It was found that two structural features of oxide surfaces are essential to achieve low activation barriers: under-coordinated surface cation sites enable strong propene adsorption, and suitable 5- or 6-coordinate geometries at molybdenum result in favorable HAEs. The impact of molybdenum coordination on HAE was elucidated by carrying out a molecular orbital analysis using a cluster model of the molybdate unit. This effort revealed that, in 5- and 6-coordinate molybdates, oxygen donor atoms trans to molybdenyl oxo atoms destabilize the molybdate prior to H addition but stabilize the molybdate after H addition, thereby providing an HAE ~15 kcal/mol more favorable than that on 4-coordinate molybdate oxo atoms. Bi 3+ cations in Bi 2Mo 3O 12 thus promote catalytic activity by providing both strong adsorption sites for propene and forcing molybdate into 5-coordinate geometries that lead to particularly favorable values of the HAE. (Graph Presented).« less

Rebuilding the Food Pyramid.

ERIC Educational Resources Information Center

Willet, Walter C.; Stampfer, Meir J.

2003-01-01

Discusses the old food guide pyramid released in 1992 by the U.S. Department of Agriculture. Contradicts the message that fat is bad, which was presented to the public by nutritionists, and the effects of plant oils on cholesterol. Introduces a new food pyramid. (YDS)

Triaqua-1κO,2κ2 O-bis­(2,2′-bipyridine)-1κ2 N,N′;2κ2 N,N′-chlorido-1κCl-μ-terephthalato-1:2κ2 O 1:O 4-dicopper(II) nitrate monohydrate

PubMed Central

Liu, Yang; Feng, Yong-Lan; Kuang, Dai-Zhi

2012-01-01

In the binuclear title compound, [Cu2(C8H4O4)Cl(C10H8N2)2(H2O)3]NO3·H2O, the two crystallographically independent CuII ions have similar coordination environments. One of the CuII ions has a square-pyramidal arrangement, which is defined by a water mol­ecule occupying the apical position, with the equatorial ligators consisting of two N atoms from a 2,2′-bipyridine mol­ecule, one carboxyl­ate O atom from a terephthalate ligand and one O atom from a water mol­ecule. The other CuII ion has a similar coordination environment, except that the apical position is occupied by a chloride ligand instead of a water mol­ecule. An O—H⋯O and O—H⋯Cl hydrogen-bonded three-dimensional network is formed between the components. PMID:22719307

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolyniuk, Juli-Anna; Zaikina, Julia V.; Kaseman, Derrick C.

A new clathrate type has been discovered in the Ba/Cu/Zn/P system. The crystal structure of the Ba 8M 24P 28+δ (M=Cu/Zn) clathrate is composed of the pentagonal dodecahedra common to clathrates along with a unique 22-vertex polyhedron with two hexagonal faces capped by additional partially occupied phosphorus sites. This is the first example of a clathrate compound where the framework atoms are not in tetrahedral or trigonal-pyramidal coordination. In Ba 8M 24P 28+δ a majority of the framework atoms are five- and six-coordinated, a feature more common to electron-rich intermetallics. The crystal structure of this new clathrate was determined bymore » a combination of X-ray and neutron diffraction and was confirmed with solid-state 31P NMR spectroscopy. Based on chemical bonding analysis, the driving force for the formation of this new clathrate is the excess of electrons generated by a high concentration of Zn atoms in the framework. The rattling of guest atoms in the large cages results in a very low thermal conductivity, a unique feature of the clathrate family of compounds.« less

Behavior-Dependent Activity and Synaptic Organization of Septo-hippocampal GABAergic Neurons Selectively Targeting the Hippocampal CA3 Area.

PubMed

Joshi, Abhilasha; Salib, Minas; Viney, Tim James; Dupret, David; Somogyi, Peter

2017-12-20

Rhythmic medial septal (MS) GABAergic input coordinates cortical theta oscillations. However, the rules of innervation of cortical cells and regions by diverse septal neurons are unknown. We report a specialized population of septal GABAergic neurons, the Teevra cells, selectively innervating the hippocampal CA3 area bypassing CA1, CA2, and the dentate gyrus. Parvalbumin-immunopositive Teevra cells show the highest rhythmicity among MS neurons and fire with short burst duration (median, 38 ms) preferentially at the trough of both CA1 theta and slow irregular oscillations, coincident with highest hippocampal excitability. Teevra cells synaptically target GABAergic axo-axonic and some CCK interneurons in restricted septo-temporal CA3 segments. The rhythmicity of their firing decreases from septal to temporal termination of individual axons. We hypothesize that Teevra neurons coordinate oscillatory activity across the septo-temporal axis, phasing the firing of specific CA3 interneurons, thereby contributing to the selection of pyramidal cell assemblies at the theta trough via disinhibition. VIDEO ABSTRACT. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Improving socio-emotional health for pupils in early secondary education with Pyramid: A school-based, early intervention model.

PubMed

Jayman, Michelle; Ohl, Maddie; Hughes, Bronach; Fox, Pauline

2018-05-01

Policymakers are focusing increased attention on the role of schools to promote and support children's mental health, and evidence-based models of good practice are in demand. Pyramid Club is a school-based, socio-emotional intervention, demonstrably effective with primary-aged pupils. This study extends previous Pyramid Club evaluations by examining effectiveness with pupils in early secondary education; service users' perceptions and experiences were investigated to increase understanding of Pyramid's impact, thus supporting enhanced practice. Participants (n = 126) comprised selected pupils, aged 11-14 (52 males; 74 females), who completed the 10 week programme (Pyramid group) and a non-intervention comparison group. Club leaders (n = 23) were trained, Pyramid volunteers. A mixed-methods design was implemented. The Strengths and Difficulties Questionnaire (SDQ), informant-rated version (Goodman, 1997, J Child Psychol Psychiat, 38, 581) and self-report version (Goodman, Meltzer, & Bailey, 1998, Europ Child Adolesc Psychiatry, 7, 125), was used to measure socio-emotional well-being: pre-club (baseline assessment), post-test (within 2 weeks of programme completion), and at 12-month follow-up (informant-rated version only). Focus groups were conducted separately with Pyramid pupils and Club leaders. Findings from informants and self-reports identified significant improvements for the Pyramid group in total difficulties and on pertinent SDQ subscales (e.g., emotional symptoms and peer relationship problems) at post-test. Improvements were sustained at 12-month follow-up. Comparison pupils demonstrated minimal change over time. Thematic analysis of qualitative data supported the quantitative findings and provided valuable insights into the Pyramid Club experience. Findings contribute to evidence-based, preventative models for the early adolescent population and support the social validity of Pyramid Club. © 2018 The Authors. British Journal of Education Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

Callosal responses in a retrosplenial column.

PubMed

Sempere-Ferràndez, Alejandro; Andrés-Bayón, Belén; Geijo-Barrientos, Emilio

2018-04-01

The axons forming the corpus callosum sustain the interhemispheric communication across homotopic cortical areas. We have studied how neurons throughout the columnar extension of the retrosplenial cortex integrate the contralateral input from callosal projecting neurons in cortical slices. Our results show that pyramidal neurons in layers 2/3 and the large, thick-tufted pyramidal neurons in layer 5B showed larger excitatory callosal responses than layer 5A and layer 5B thin-tufted pyramidal neurons, while layer 6 remained silent to this input. Feed-forward inhibitory currents generated by fast spiking, parvalbumin expressing  interneurons recruited by callosal axons mimicked the response size distribution of excitatory responses across pyramidal subtypes, being larger in those of superficial layers and in the layer 5B thick-tufted pyramidal cells. Overall, the combination of the excitatory and inhibitory currents evoked by callosal input had a strong and opposed effect in different layers of the cortex; while layer 2/3 pyramidal neurons were powerfully inhibited, the thick-tufted but not thin-tufted pyramidal neurons in layer 5 were strongly recruited. We believe that these results will help to understand the functional role of callosal connections in physiology and disease.

The New Modern Mediterranean Diet Italian Pyramid.

PubMed

Vitiello, V; Germani, A; Capuzzo Dolcetta, E; Donini, L M; Del Balzo, V

2016-01-01

Epidemiological studies have established the health benefits associated with the adherence to the MD (Mediterranean Diet), mainly in relation to reducing the risk of developing the non communicable diseases. The MD is a sustainable diet model that respects the environment, promotes the bio-diversity, the local cultural heritages, the social interaction and economic aspects. The pyramid is a graphical representation designed to represent the frequencies of consumption and portion sizes of each food according to the Mediterranean model and tradition. The pyramid was developed taking into account the LARN (Reference Intake of nutrients and energy for Italian Population) and the Italian Guidelines for a healthy diet. The frequency of consumption and the portion size recommended are located at the different level of the pyramid. At the base of the pyramid there are the foods that should be consumed every meal and some concepts typical of the Mediterranean culture. In the middle there are foods that should be consumed daily and at the top of the pyramid the foods consumed on a weekly basis. The new modern MD Italian Pyramid is an important tool to promote the MD and improve the adherence to the MD dietary pattern.

Pyramided rice lines harbouring Allium sativum (asal) and Galanthus nivalis (gna) lectin genes impart enhanced resistance against major sap-sucking pests.

PubMed

Bharathi, Y; Vijaya Kumar, S; Pasalu, I C; Balachandran, S M; Reddy, V D; Rao, K V

2011-03-20

We have developed transgene pyramided rice lines, endowed with enhanced resistance to major sap-sucking insects, through sexual crosses made between two stable transgenic rice lines containing Allium sativum (asal) and Galanthus nivalis (gna) lectin genes. Presence and expression of asal and gna genes in pyramided lines were confirmed by PCR and western blot analyses. Segregation analysis of F₂ progenies disclosed digenic (9:3:3:1) inheritance of the transgenes. Homozygous F₃ plants carrying asal and gna genes were identified employing genetic and molecular methods besides insect bioassays. Pyramided lines, infested with brown planthopper (BPH), green leafhopper (GLH) and whitebacked planthopper (WBPH), proved more effective in reducing insect survival, fecundity, feeding ability besides delayed development of insects as compared to the parental transgenics. Under infested conditions, pyramided lines were found superior to the parental transgenics in their seed yield potential. This study represents first report on pyramiding of two lectin genes into rice exhibiting enhanced resistance against major sucking pests. The pyramided lines appear promising and might serve as a novel genetic resource in rice breeding aimed at durable and broad based resistance against hoppers. Copyright © 2011 Elsevier B.V. All rights reserved.

Presque Isle Peninsula, Frie, Pennsylvania. Volume II. Appendices. Revised.

DTIC Science & Technology

1980-11-01

Population Pyramid 9 c. Employment 9 d. Labor Force 9 .e. Public Facilities and Services 14 1. Transportation 14 2. Health Facilities. 14 3. Communications 14...Distribution of Shoreline Use and Overship, 3 Erie County, PA B2 Population Pyramid of Erie County 13 53 Travel Demand Curve Peak Day Good Weather 38...are also experiencing a decline in total population. 4(5) Population Pyramid B2.13 Figure B2, the population pyramid of Erie County, PA, for the years

Earth orientation from lunar laser range-differencing. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Leick, A.

1978-01-01

For the optimal use of high precision lunar laser ranging (LLR), an investigation regarding a clear definition of the underlying coordinate systems, identification of estimable quantities, favorable station geometry and optimal observation schedule is given.

The molecular structure and vibrational spectra of corrolazine metal complexes (CzM) by density functional theory

NASA Astrophysics Data System (ADS)

Wang, Hongming; Yang, Chuanlu; Zhang, Zhihong; Wang, Meishan; Han, Keli

2006-06-01

The ground-state geometries, electronic structures and vibrational frequencies of metal corrolazine complexes, CzM (M = Mn, Co, Ni and Fe) have been studied using B3LYP/6-311g(d) method. The molecular geometries are sensitive to the species of the metal, and the bond length of the M sbnd N is increase with the metal atom radii. The ground-state electronic structures indicate that there are strong interactions between d of the metal fragments and the corrolazine fragments. The calculations also indicate that the CzNi is the stabilest among the four metal corrolazine complexes. Vibrational frequencies of these metal corrolazine complexes were also calculated and were assigned to the local coordinates of the corrolazine ring, which reveals the some common feature of the molecular vibrations of the metal corrolazine complexes as four-coordination metallocorrolazines.

Tris(4,4′-bi-1,3-thia­zole-κ2 N,N′)iron(II) tetra­bromidoferrate(III) bromide

PubMed Central

Abedi, Anita; Amani, Vahid; Safari, Nasser

2011-01-01

In the [Fe(4,4′-bit)3]2+ (4,4′-bit is 4,4′-bi-1,3-thia­zole) cation of the title compound, [Fe(C6H4N2S2)3][FeBr4]Br, the FeII atom (3 symmetry) is six-coordinated in a distorted octa­hedral geometry by six N atoms from three 4,4′-bit ligands. In the [FeBr4]− anion, the FeIII atom (3 symmetry) is four-coordinated in a distorted tetra­hedral geometry. In the crystal, inter­molecular C—H⋯Br hydrogen bonds and Br⋯π inter­actions [Br⋯centroid distances = 3.562 (3) and 3.765 (2) Å] link the cations and anions, stabilizing the structure. PMID:21522247

Coordination Polymer: Synthesis, Spectral Characterization and Thermal Behaviour of Starch-Urea Based Biodegradable Polymer and Its Polymer Metal Complexes

PubMed Central

Malik, Ashraf; Parveen, Shadma; Ahamad, Tansir; Alshehri, Saad M.; Singh, Prabal Kumar; Nishat, Nahid

2010-01-01

A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), 1H-NMR spectroscopy, 13C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry, while Cu(II) and Zn(II) complexes show square planar and tetrahedral geometry, respectively. The thermogravimetric analysis revealed that all the polymeric metal complexes are more thermally stable than the parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM standards of biodegradable polymers by CO2 evolution method. PMID:20414461

Jahn-Teller distortion in the phosphorescent excited state of three-coordinate Au(I) phosphine complexes.

PubMed

Barakat, Khaldoon A; Cundari, Thomas R; Omary, Mohammad A

2003-11-26

DFT calculations were used to optimize the phosphorescent excited state of three-coordinate [Au(PR3)3]+ complexes. The results indicate that the complexes rearrange from their singlet ground-state trigonal planar geometry to a T-shape in the lowest triplet luminescent excited state. The optimized structure of the exciton contradicts the structure predicted based on the AuP bonding properties of the ground-state HOMO and LUMO. The rearrangement to T-shape is a Jahn-Teller distortion because an electron is taken from the degenerate e' (5dxy, 5dx2-y2) orbital upon photoexcitation of the ground-state D3h complex. The calculated UV absorption and visible emission energies are consistent with the experimental data and explain the large Stokes' shifts while such correlations are not possible in optimized models that constrained the exciton to the ground-state trigonal geometry.

Mass effects and internal space geometry in triatomic reaction dynamics

NASA Astrophysics Data System (ADS)

Yanao, Tomohiro; Koon, Wang S.; Marsden, Jerrold E.

2006-05-01

The effect of the distribution of mass in triatomic reaction dynamics is analyzed using the geometry of the associated internal space. Atomic masses are appropriately incorporated into internal coordinates as well as the associated non-Euclidean internal space metric tensor after a separation of the rotational degrees of freedom. Because of the non-Euclidean nature of the metric in the internal space, terms such as connection coefficients arise in the internal equations of motion, which act as velocity-dependent forces in a coordinate chart. By statistically averaging these terms, an effective force field is deduced, which accounts for the statistical tendency of geodesics in the internal space. This force field is shown to play a crucial role in determining mass-related branching ratios of isomerization and dissociation dynamics of a triatomic molecule. The methodology presented can be useful for qualitatively predicting branching ratios in general triatomic reactions, and may be applied to the study of isotope effects.

Tensors and Differential Geometry Applied to Analytic and Numerical Coordinate Generation

DTIC Science & Technology

1981-01-01

or surfaces. Since the writing of the first memoir on the subject of tensor analysis by Ricci and Levi - Civita [11 in 1901 some very significant...available in the standard texts, such as, Levi - Civita [2], Weatherburn [3), McConnell [41, Eisenhart [51, [6], Tolman [7], Graustein [8], Synge and...Equations (216) have been used in Ref. [29] to compute the coordinates for arbitrary shaped two -dimensional bodies . §7. Miscellaneous Derivations. In this

The First Seven-Coordinated Triiodo Complex of Rhenium(III)

NASA Astrophysics Data System (ADS)

Schoultz, X.; Gerber, T. I. A.; Betz, R.; Hosten, E. C.

2017-12-01

The reaction of cis-[ReO2I(P Ph 3)2] with tert-butyl isocyanide in benzene led to the isolation of the complex [ReI3(CN- t-Bu)3(P Ph 3)] ( 1). The complex is unusual since it contains bulky ligands with large cone angles, i.e. three iodides, three isocyanides with tert-butyl groups and a triphenylphosphine as ligands in a seven-coordinate geometry around the rhenium(III) metal ion.

A New Computational Methodology for Structural Dynamics Problems

DTIC Science & Technology

2008-04-01

by approximating the geometry of the midsurface of the shell (as in continuum-based finite element models), are prevented from the beginning...iiθ , such that the surface 03=θ defines the midsurface ( )R tM M of the region ( )R tB B . The coordinate 3θ is the measure of the distance...assumption for the shell model: “the displacement field is considered as a linear expansion of the thickness coordinate around the midsurface . The

Conformal Geometry, Hotine’s Conjecture, and Differential Geodesy.

DTIC Science & Technology

1987-07-27

ellipsoid (Stokes Theorem). Rayleigh and Poincare extensively studied tides. Starting around 1900 the close connection between geodesy and mathematics...locally conformal maps on neighborhoods of M ,.’ P -a ,r r’ " % "% J and M’ For example, consider the 2-sphere S and the plane E It 2 2 is well...coordinates where the coordinate surfaces are respectively planes ; planes and cylinders; and planes , spheres, - and cones. we give one less trivial example

Novel Cobalt(II) complexes containing N,N-di(2-picolyl)amine based ligands; Synthesis, characterization and application towards methyl methacrylate polymerisation

NASA Astrophysics Data System (ADS)

Ahn, Seoung Hyun; Choi, Sang-Il; Jung, Maeng Joon; Nayab, Saira; Lee, Hyosun

2016-06-01

The reaction of [CoCl2·6H2O] with N‧-substituted N,N-di(2-picolyl)amine ligands such as 1-cyclohexyl-N,N-bis(pyridin-2-ylmethyl)methanamine (LA), 2-methoxy-N,N-bis(pyridin-2-ylmethyl)ethan-1-amine (LB), and 3-methoxy-N,N-bis(pyridin-2-ylmethyl)propan-1-amine (LC), yielded [LnCoCl2] (Ln = LA, LB and LC), respectively. The Co(II) centre in [LnCoCl2] (Ln = LA, and LC) adopted distorted bipyramidal geometries through coordination of nitrogen atoms of di(2-picolyl)amine moiety to the Co(II) centre along with two chloro ligands. The 6-coordinated [LBCoCl2] showed a distorted octahedral geometry, achieved through coordination of the two pyridyl units, two chloro units, and bidentate coordination of nitrogen and oxygen in the N‧-methoxyethylamine to the Co(II) centre. [LCCoCl2] (6.70 × 104 gPMMA/molCo h) exhibited higher catalytic activity for the polymerisation of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) compared to rest of Co(II) complexes. The catalytic activity was considered as a function of steric properties of ligand architecture and increased steric bulk around the metal centre resulted in the decrease catalytic activity. All Co(II) initiators yielded syndiotactic poly(methylmethacrylate) (PMMA).

Fabricating Bis(phthalocyaninato) Terbium SIM into Tetrakis(phthalocyaninato) Terbium SMM with Enhanced Performance through Sodium Coordination.

PubMed

Chen, Yuxiang; Liu, Chao; Ma, Fang; Qi, Dongdong; Liu, Qingyun; Sun, Hao-Ling; Jiang, Jianzhuang

2018-04-23

The non-peripherally substituted 1,4,8,11,15,18,22,25-octa(butoxy)-phthalocyanine-involved unsymmetrical heteroleptic bis(phthalocyaninato) terbium double-decker, Tb(Pc){H[Pc(α-OC 4 H 9 ) 8 ]} (Pc=unsubstituted phthalocyanine) (1), was revealed to exhibit typical single ion magnet (SIM) behavior with effective energy barrier, 180 K (125 cm -1 ), and blocking temperature, 2 K, due to the severe deviation of the terbium coordination polyhedron from square-antiprismatic geometry. Fabrication of this double-decker compound into the novel tetrakis(phthalocyaninato) terbium pseudo-quadruple-decker Na 2 {Tb(Pc)[Pc(α-OC 4 H 9 ) 8 ]} 2 (2) single molecule magnet (SMM) not only optimizes the coordination polyhedron of terbium ion towards the square-antiprismatic geometry and intensifies the coordination field strength, but more importantly significantly enhances the molecular magnetic anisotropy in the unsymmetrical bis(phthalocyaninato) double-decker unit, along with the change of the counter cation from H + of 1 to Na + of 2, leading to an significantly enhanced magnetic behavior with spin-reversal energy barrier, 528 K (367 cm -1 ), and blocking temperature, 25 K. The present result is surely helpful towards developing novel tetrapyrrole lanthanide SMMs through rational design and self-assembly from bis(tetrapyrrole) lanthanide single ion magnet (SIM) building block. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A multi-focus image fusion method via region mosaicking on Laplacian pyramids

PubMed Central

Kou, Liang; Zhang, Liguo; Sun, Jianguo; Han, Qilong; Jin, Zilong

2018-01-01

In this paper, a method named Region Mosaicking on Laplacian Pyramids (RMLP) is proposed to fuse multi-focus images that is captured by microscope. First, the Sum-Modified-Laplacian is applied to measure the focus of multi-focus images. Then the density-based region growing algorithm is utilized to segment the focused region mask of each image. Finally, the mask is decomposed into a mask pyramid to supervise region mosaicking on a Laplacian pyramid. The region level pyramid keeps more original information than the pixel level. The experiment results show that RMLP has best performance in quantitative comparison with other methods. In addition, RMLP is insensitive to noise and can reduces the color distortion of the fused images on two datasets. PMID:29771912

Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.

PubMed

Shaltout, I; Mohamed, Tarek A

2007-06-01

Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).

Behavior‐dependent activity patterns of GABAergic long‐range projecting neurons in the rat hippocampus

PubMed Central

Micklem, Ben; Borhegyi, Zsolt; Swiejkowski, Daniel A.; Valenti, Ornella; Viney, Tim J.; Kotzadimitriou, Dimitrios; Klausberger, Thomas

2017-01-01

ABSTRACT Long‐range glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and O‐LM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotin‐labeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp wave‐ripples, most projection cells, including a novel SOM+ GABAergic back‐projecting cell, increased their activity similar to bistratified cells, but unlike O‐LM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and O‐LM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behavior‐ and network state‐dependent binding of neuronal assemblies amongst functionally‐related brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:27997999

Phase transitions in orthopyroxene (En 90) to 49GPa from single-crystal X-ray diffraction

DOE PAGES

Finkelstein, Gregory J.; Dera, Przemyslaw K.; Duffy, Thomas S.

2014-10-29

Synchrotron-based high-pressure single-crystal X-ray diffraction experiments were conducted on ~Mg 0.9Fe 0.1SiO 3 (En 90) orthopyroxene crystals at room temperature to a maximum pressure of 48.5 GPa. The sample was compressed in a diamond anvil cell with a neon pressure medium and a gold pressure calibrant. In addition to the previously described orthopyroxene to β-opx transition (designated HPCEN2 in previous studies), we observe two further phase transitions at 29.9 GPa and 40.3 GPa. However, we do not observe the γ-opx phase recently described in an Fe-rich orthopyroxene composition. The structures of both of the new phases were solved in spacemore » group Pca21. While their Mg-O layers remain pyroxene-like, their Si-O layers transform in a stepwise fashion to akimotoite-like sheets, with sites in 4-, 5-, or 6-fold coordination, depending on the specific structure and layer. Due to the increased Si-O coordination number, we designate the new structures α- and β-post-orthopyroxene (α-popx and β-popx). α-popx has one Si-O layer that is entirely tetrahedral, and one layer that contains both tetrahedra and 5-coordinated Si in distorted square pyramids. β-popx retains the mixed 4- and 5-coordinated Si layer found in α-popx, while the other Si layer adopts fully octahedral coordination. The α- and β-popx structures show a progressive transformation towards the arrangement of Si layers found in akimotoite, a potentially important phase in the earth’s transition zone. Metastable transformations in pyroxenes are of interest for understanding possible metastability in geological environments such as subducting slabs and meteorite impacts« less

Synthesis, crystal structure, and magnetic properties of two-dimensional divalent metal glutarate/dipyridylamine coordination polymers, with a single crystal-to-single crystal transformation in the copper derivative

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montney, Matthew R.; Supkowski, Ronald M.; Staples, Richard J.

Hydrothermal reaction of divalent metal chlorides with glutaric acid and 4,4'-dipyridylamine (dpa) has afforded an isostructural family of coordination polymers with formulation [M(glu)(dpa)]{sub n} (M=Co (1), Ni (2), Cu (3); glu=glutarate). Square pyramidal coordination is seen in 1-3, with semi-ligation of a sixth donor to produce a '5+1' extended coordination sphere. Neighboring metal atoms are linked into 1D [M(glu)]{sub n} neutral chains through chelating/monodentate bridging glutarate moieties with a syn-anti binding mode, and semi-chelation of the pendant carboxylate oxygen. These chains further connect into 2D layers through dipodal dpa ligands. Neighboring layers stack into the pseudo 3D crystal structure ofmore » 1-3 through supramolecular hydrogen bonding between dpa amine units and the semi-chelated glutarate oxygen atoms. The variable temperature magnetic behavior of 1-3 was explored and modeled as infinite 1D Heisenberg chains. Notably, complex 3 undergoes a thermally induced single crystal-to-single crystal transformation between centric and acentric space groups, with a conformationally disordered unilayer structure at 293 K and an ordered bilayer structure at 173 K. All materials were further characterized via infrared spectroscopy and elemental and thermogravimetric analyses. - Graphical abstract: The coordination polymers [M(glu)(dpa)]{sub n} (M=Co (1), Ni (2), Cu (3); glu=glutarate, dpa=4,4'-dipyridylamine) exhibit 2D layer structures based on 1D [M(glu)]{sub n} chains linked through dpa tethers. Antiferromagnetic coupling is observed for 2 and 3, while ferromagnetism is predominant in 1. Compound 3 undergoes a thermally induced single crystal-to-single crystal transformation from an acentric to a centrosymmetric space group.« less

Phase transitions in orthopyroxene (En 90) to 49GPa from single-crystal X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finkelstein, Gregory J.; Dera, Przemyslaw K.; Duffy, Thomas S.

Synchrotron-based high-pressure single-crystal X-ray diffraction experiments were conducted on ~Mg 0.9Fe 0.1SiO 3 (En 90) orthopyroxene crystals at room temperature to a maximum pressure of 48.5 GPa. The sample was compressed in a diamond anvil cell with a neon pressure medium and a gold pressure calibrant. In addition to the previously described orthopyroxene to β-opx transition (designated HPCEN2 in previous studies), we observe two further phase transitions at 29.9 GPa and 40.3 GPa. However, we do not observe the γ-opx phase recently described in an Fe-rich orthopyroxene composition. The structures of both of the new phases were solved in spacemore » group Pca21. While their Mg-O layers remain pyroxene-like, their Si-O layers transform in a stepwise fashion to akimotoite-like sheets, with sites in 4-, 5-, or 6-fold coordination, depending on the specific structure and layer. Due to the increased Si-O coordination number, we designate the new structures α- and β-post-orthopyroxene (α-popx and β-popx). α-popx has one Si-O layer that is entirely tetrahedral, and one layer that contains both tetrahedra and 5-coordinated Si in distorted square pyramids. β-popx retains the mixed 4- and 5-coordinated Si layer found in α-popx, while the other Si layer adopts fully octahedral coordination. The α- and β-popx structures show a progressive transformation towards the arrangement of Si layers found in akimotoite, a potentially important phase in the earth’s transition zone. Metastable transformations in pyroxenes are of interest for understanding possible metastability in geological environments such as subducting slabs and meteorite impacts« less

Influence of Deposition Pressure on the Properties of Round Pyramid Textured a-Si:H Solar Cells for Maglev.

PubMed

Lee, Jaehyeong; Choi, Wonseok; Lee, Kyuil; Lee, Daedong; Kang, Hyunil

2016-05-01

HIT (Heterojunction with Intrinsic Thin-layer) photovoltaic cells is one of the highest efficiencies in the commercial solar cells. The pyramid texturization for reducing surface reflectance of HIT solar cells silicon wafers is widely used. For the low leakage current and high shunt of solar cells, the intrinsic amorphous silicon (a-Si:H) on substrate must be uniformly thick of pyramid structure. However, it is difficult to control the thickness in the traditional pyramid texturing process. Thus, we textured the intrinsic a-Si:H thin films with the round pyramidal structure by using HNO3, HF, and CH3COOH solution. The characteristics of round pyramid a-Si:H solar cells deposited at pressure of 500, 1000, 1500, and 2000 mTorr by PECVD (Plasma Enhanced Chemical Vapor Deposition) was investigated. The lifetime, open circuit voltage, fill factor and efficiency of a-Si:H solar cells were investigated with respect to various deposition pressure.

Determining which mechanisms lead to activation in the motor cortex: a modeling study of transcranial magnetic stimulation using realistic stimulus waveforms and sulcal geometry1

PubMed Central

Salvador, R.; Silva, S.; Basser, P. J.; Miranda, P. C.

2010-01-01

Objective To determine which mechanisms lead to activation of neurons in the motor cortex during transcranial magnetic stimulation (TMS) with different current directions and pulse waveforms. Methods The total electric field induced in a simplified model of a cortical sulcus by a figure-eight coil was calculated using the finite element method (FEM). This electric field was then used as the input to determine the response of compartmental models of several types of neurons. Results The modeled neurons were stimulated at different sites: fiber bends for pyramidal tract neurons, axonal terminations for cortical interneurons and axon collaterals, and a combination of both for pyramidal association fibers. All neurons were more easily stimulated by a PA directed electric field, except association fibers. Additionally, the second phase of a biphasic pulse was found to be more efficient than the first phase of either monophasic or biphasic pulses. Conclusion The stimulation threshold for different types of neurons depends on the pulse waveform and current direction. The reported results might account for the range of responses obtained in TMS of the motor cortex when using different stimulation parameters. Significance Modeling studies combining electric field calculations and neuronal models may lead to a deeper understanding of the effect of the TMS-induced electric field on cortical tissue, and may be used to evaluate improvements in TMS coil and waveform design. PMID:21035390

Earth Observation

NASA Image and Video Library

2012-07-25

ISS032-E-009123 (26 July 2012) --- Pyramids at Giza, Egypt are featured in this image photographed by an Expedition 32 crew member on the International Space Station. The Great Pyramids at Giza (center) are the last of the Seven Wonders of the Ancient World, and are perhaps the most famous of the ancient monuments in the Nile River Delta region of Egypt. They are also a favorite subject of photography from orbit ? particularly when high resolution imagery can be obtained. The southeast-facing sides of the pyramids of the pharaohs Khufu, Khafre, and Menkaure are all brightly illuminated by the sun, while the northwest facing sides are in shadow. This shadowing also highlights smaller unfinished pyramids to the south of Menkaure?s pyramid, as well as fields of rectangular flat roofed mastabas (tombs) to the east and west of Khufu?s pyramid. While not as grand as the pyramids, mastabas were the burial places of prominent persons during the periods of the ancient pharaohs. To the southeast of Khufu?s pyramid, the head and rear haunches of the Sphinx are also visible (albeit not clearly). It is a short distance between the glories of ancient Egypt and the modern Cairo metropolitan area to the north and east. The green vegetation of a hotel golf course (center left), and the numerous building and streets of El Giza, provide stark contrast to the bare rock and soil of the adjacent desert. Roadways visible in the desert (right) connect the urban regions to the east with further development to the north.

Experimental implementation of a Pyramid WFS: Towards the first SCAO systems for E-ELT

NASA Astrophysics Data System (ADS)

Bond, C.; El Hadi, K.; Sauvage, J. F.; Correia, C.; Fauvarque, O.; Rabaud, D.; Neichel, B.; Fusco, T.

2015-12-01

Investigations into the Pyramid wavefront sensor (P-WFS) have experimentally demonstrated the ability to achieve a better performance than with a standard Shack-Hartmann sensor (SH-WFS). Implementation on the Large Binocular Telescope (LBT) provided the first operational demonstration on a facility-class instrument of a P-WFS on sky. The desire to implement a Pyramid on an Extremely Large Telescope (ELT) requires further characterisation in order to optimise the performance and match our knowledge and understanding of other wave-front sensors (WFSs). Within the framework of the European Extremely Large Telescope (E-ELT), the Laboratoire d'Astrophysique de Marseille (LAM) is involved in the preparation of the Single Conjugate Adaptive Optics (SCAO) system of HARMONI, E-ELT's 1st light integral field spectrograph (IFU). The current baseline WFS for this adaptive optics system is a Pyramid WFS using a high speed and sensitive OCAM2 camera. At LAM we are currently carrying out laboratory demonstrations of a Pyramid-WFS, with the aim to fully characterise the behaviour of the Pyramid in terms of sensitivity and linear range. This will lead to a full operational procedure for the use of the Pyramid on-sky, assisting with current designs and future implementations. The final goal is to provide an on sky comparison between the Pyramid and Shack-Hartmann at Observatoire de la Côte d'Azur (OCA). Here we present our experimental setup and preliminary results.

Instrument and method for X-ray diffraction, fluorescence, and crystal texture analysis without sample preparation

NASA Technical Reports Server (NTRS)

Gendreau, Keith (Inventor); Martins, Jose Vanderlei (Inventor); Arzoumanian, Zaven (Inventor)

2010-01-01

An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

Rhenium(V) Oxo Complexes of Novel N(2)S(2) Dithiourea (DTU) Chelate Ligands: Synthesis and Structural Characterization.

PubMed

Lipowska, Malgorzata; Hayes, Brittany L.; Hansen, Lory; Taylor, Andrew; Marzilli, Luigi G.

1996-07-03

The compounds RNHC(=S)NH(CH(2))(n)()NHC(=S)NHR were prepared in a search for new, relatively small N(2)S(2) ligands. These dithiourea (DTU) ligands are the first chelates containing two potentially bidentate thiourea moieties. A one-step reaction of 1,3-diaminopropane (1) with aryl or alkyl isothiocyanates or of 1,2-diaminoethane (2) with phenyl isothiocyanate afforded the target ligands in excellent yields (95-98%). The Re(V)=O complexes of RNHC(=S)NH(CH(2))(3)NHC(=S)NHR ligands were obtained through ligand exchange reactions with Re(V) precursors. The chemistry required neither protection of the sulfur atoms for ligand synthesis nor deprotection prior to metal complexation. The structure of (1-phenyl-3-(3-phenylthioureido)propyl]thioureato)oxorhenium(V) (7a), determined by X-ray diffraction methods, revealed the expected pseudo-square-pyramidal geometry with an N(2)S(2) basal and an apical oxo donor set. Both coordinated N's (N(c)) were deprotonated. One uncoordinated N (N(u)) was deprotonated, producing a neutral complex containing an unexpected new type of dianionic, four-membered N,S chelate. In the crystal, the N(u) atoms, N(3)H and N(4), of one complex each formed an H-bond with N(4) and N(3)H, respectively, of a symmetry-related complex. The N(c)-C-S bond angles (106.1(6) and 101.5(6) degrees ) were severely distorted from the 120 degrees expected for an sp(2)-hybridized C. However, these small bite angles and the large N-Re-N bond angle (86.1(3) degrees ) allowed for the formation of two four-membered chelate rings with normal Re-N and Re-S bond distances. Attempts to prepare complexes with the PhNHC(=S)NH(CH(2))(2)NHC(=S)NHPh ligand were unsuccessful. These results suggest that a central five-membered chelate ring is too small to accommodate bidentate coordination of both thiourea moieties. NMR studies in methanol established that the neutral complex with one uncoordinated N deprotonated was the favored form in neutral and basic solutions. However, under acidic conditions, a cationic form with both uncoordinated N's protonated was favored.

Synthesis, characterization and biological application of four novel metal-Schiff base complexes derived from allylamine and their interactions with human serum albumin: Experimental, molecular docking and ONIOM computational study.

PubMed

Kazemi, Zahra; Rudbari, Hadi Amiri; Sahihi, Mehdi; Mirkhani, Valiollah; Moghadam, Majid; Tangestaninejad, Shahram; Mohammadpoor-Baltork, Iraj; Gharaghani, Sajjad

2016-09-01

Novel metal-based drug candidate including VOL2, NiL2, CuL2 and PdL2 have been synthesized from 2-hydroxy-1-allyliminomethyl-naphthalen ligand and have been characterized by means of elemental analysis (CHN), FT-IR and UV-vis spectroscopies. In addition, (1)H and (13)C NMR techniques were employed for characterization of the PdL2 complex. Single-crystal X-ray diffraction technique was utilized to characterise the structure of the complexes. The Cu(II), Ni(II) and Pd(II) complexes show a square planar trans-coordination geometry, while in the VOL2, the vanadium center has a distorted tetragonal pyramidal N2O3 coordination sphere. The HSA-binding was also determined, using fluorescence quenching, UV-vis spectroscopy, and circular dichroism (CD) titration method. The obtained results revealed that the HSA affinity for binding the synthesized compounds follows as PdL2>CuL2>VOL2>NiL2, indicating the effect of metal ion on binding constant. The distance between these compounds and HSA was obtained based on the Förster's theory of non-radiative energy transfer. Furthermore, computational methods including molecular docking and our Own N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) were carried out to investigate the HSA-binding of the compounds. Molecular docking calculation indicated the existence of hydrogen bond between amino acid residues of HSA and all synthesized compounds. The formation of the hydrogen bond in the HSA-compound systems leads to their stabilization. The ONIOM method was utilized in order to investigate HSA binding of compounds more precisely in which molecular mechanics method (UFF) and semi empirical method (PM6) were selected for the low layer and the high layer, respectively. The results show that the structural parameters of the compounds changed along with binding to HSA, indicating the strong interaction between the compounds and HSA. The value of binding constant depends on the extent of the resultant changes. This should be mentioned that both theoretical methods calculated the Kb values in the same sequence and are in a good agreement with the experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Poly[tetra­aqua-μ3-benzene-1,2-di­carboxyl­ato-μ3-bromido-penta-μ2-bromido-octa-μ3-isonicotinato-hepta­copper(I)trilanthanum(III)

PubMed Central

Wang, Guo-Ming; Li, Zeng-Xin; Xue, Shu-Yun; Liu, Hui-Luan

2009-01-01

A new lanthanum(III)–copper(I) heterometallic coordination polymer, [Cu7La3Br6(C6H4NO2)8(C8H4O4)(H2O)4]n, has been prepared by a hydro­thermal method. Of the three La atoms in the asymmetric unit, two are eight-coordinate with bicapped trigonal–prismatic configurations; the third is nine-coordinated and has a tricapped trigonal–prismatic coordination geometry. Of the seven Cu atoms, two are two-coordinate with CuBrN and CuN2 ligand sets, three have trigonal configurations, viz. CuBrN2, CuBr2N and CuBr3, while the remaining two adopt distorted tetra­hedral CuBr3N geometries. In the crystal structure, adjacent La centers are linked by isonicotinate (IN−) and benzene-1,2-dicarboxyl­ate ligands to form a two-dimensional La–carboxyl­ate layer in the ab plane. These layers are further inter­connected with each other by bridging [Cu(IN)2] motifs, leading to an unusual three-dimensional heterometallic Cu–halide–lanthanide–organic framework, with the inorganic [Cu6Br6]n chains located in the resulting channels. Two Cu atoms are disordered over two positions, both with site occupancy factors of 0.80 and 0.20. O—H⋯O hydrogen bonding between water molecules and carboxylate O atoms helps to consolidate the crystal packing. PMID:21583784

Stereochemical and electronic control of M-SO/sub 2/ bonding geometry in d/sup 6/ molybdenum and tungsten SO/sub 2/ complexes: novel n/sup 1/reverse arrown/sup 2/ SO/sub 2/ linkage isomerization in Mo(CO)/sub 2/(PPh/sub 3/)/sub 2/(CNR)(SO/sub 2/) and structures of Mo(CO)/sub 3/(P-i-Pr/sub 3/)/sub 2/(SO/sub 2/) and (Mo(CO)/sub 2/(py)(PPh/sub 3/)(. mu. -SO/sub 2/))/sub 2/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubas, G.J.; Jarvinen, G.D.; Ryan, R.R.

1983-04-06

New complexes, mer,trans,M(CO)/sub 3/(PR/sub 3/)/sub 2/(SO/sub 2/) (M = Mo,W; R = Ph,Cy,i-Pr) (I), cis,trans-Mo(CO)/sub 2/-(PPh/sub 3/)/sub 2/(SO/sub 2/)(L) (L = NCMe,py,CNCy,CN-t-Bu and CN(p-tolyl))(II), and (Mo(CO)/sub 2/(py)(PPh/sub 3/)(..mu..-SO/sub 2/))/sub 2/, have been prepared and characterized by infrared spectroscopy, /sup 17/O and /sup 31/P NMR spectroscopy, and X-ray crystallography. Syntheses for fac-Mo(CO)/sub 3/(n/sup 2/-SO/sub 2/)(LL) (LL = dppe,bpy,phen,2 py) have also been developed. Depending upon L, II has been found to coordinate SO/sub 2/ either in the S-bonded (n/sup 1/ planar) or O,S-bonded (n/sup 2/) geometries. Remarkably, for L = CNCy or CN-t-Bu, II has been found to contain, in themore » solid state, an apparent equimixture of both coordination types. Isomerization of fac-M(CO)/sub 3/(dppe)(n/sup 2/-SO/sub 2/) (M=Mo,w; dppe = 1,2-bis(diphenylphosphino)ethane) to an n/sup 1/-planar SO/sub 2/ form, mer-M(CO)/sub 3/(dppe)(SO/sub 2/), has also been found to occur. Thus, control of the SO/sub 2/ coordination geometry has been achieved by varying either the electronic properties of the ancillary ligands or their disposition with respect to the SO/sub 2/. The X-ray crystal structure of mer,trans-Mo(CO)/sub 3/(P-i-Pr/sub 3/)/sub 2/(SO/sub 2/) revealed n/sup 1/-planar SO/sub 2/ binding, the first example of this geometry for group 6 metals. The M-S distance, 2.239 (3) angstrom, is the longest such distance for this geometry recorded to date. Crystal data: Pbca, Z=8, a=24.712(8) angstrom, b=16.033(6) angstrom, c=14.058(5) angstrom, R=0.079 for 2934 reflections with Igreater than or equal to2sigma(I). The structure of (Mo(CO)/sub 2/(py)(PPh/sub 3/)(..mu..-SO/sub 2/))/sub 2/ showed a novel SO/sub 2/ bridging geometry in which all three atoms of SO/sub 2/ are metal coordinated. Crystal data: P1, Z=1, a=14.883(4) angstrom, b=9.264(2) angstrom, c=10.808(2) angstrom, R=0.039 for 3282 reflections with Igreater than or equal to2sigma(I).« less

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Application of the Fourier pseudospectral time-domain method in orthogonal curvilinear coordinates for near-rigid moderately curved surfaces.

PubMed

Hornikx, Maarten; Dragna, Didier

2015-07-01

The Fourier pseudospectral time-domain method is an efficient wave-based method to model sound propagation in inhomogeneous media. One of the limitations of the method for atmospheric sound propagation purposes is its restriction to a Cartesian grid, confining it to staircase-like geometries. A transform from the physical coordinate system to the curvilinear coordinate system has been applied to solve more arbitrary geometries. For applicability of this method near the boundaries, the acoustic velocity variables are solved for their curvilinear components. The performance of the curvilinear Fourier pseudospectral method is investigated in free field and for outdoor sound propagation over an impedance strip for various types of shapes. Accuracy is shown to be related to the maximum grid stretching ratio and deformation of the boundary shape and computational efficiency is reduced relative to the smallest grid cell in the physical domain. The applicability of the curvilinear Fourier pseudospectral time-domain method is demonstrated by investigating the effect of sound propagation over a hill in a nocturnal boundary layer. With the proposed method, accurate and efficient results for sound propagation over smoothly varying ground surfaces with high impedances can be obtained.

Pyramid Lake Renewable Energy Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Jackson

2008-03-14

The Pyramid Lake Paiute Tribe is a federally recognized Tribe residing on the Pyramid Lake Reservation in western Nevada. The funding for this project was used to identify blind geothermal systems disconnected from geothermal sacred sites and develop a Tribal energy corporation for evaluating potential economic development for profit.

Single CA3 pyramidal cells trigger sharp waves in vitro by exciting interneurones.

PubMed

Bazelot, Michaël; Teleńczuk, Maria T; Miles, Richard

2016-05-15

The CA3 hippocampal region generates sharp waves (SPW), a population activity associated with neuronal representations. The synaptic mechanisms responsible for the generation of these events still require clarification. Using slices maintained in an interface chamber, we found that the firing of single CA3 pyramidal cells triggers SPW like events at short latencies, similar to those for the induction of firing in interneurons. Multi-electrode records from the CA3 stratum pyramidale showed that pyramidal cells triggered events consisting of putative interneuron spikes followed by field IPSPs. SPW fields consisted of a repetition of these events at intervals of 4-8 ms. Although many properties of induced and spontaneous SPWs were similar, the triggered events tended to be initiated close to the stimulated cell. These data show that the initiation of SPWs in vitro is mediated via pyramidal cell synapses that excite interneurons. They do not indicate why interneuron firing is repeated during a SPW. Sharp waves (SPWs) are a hippocampal population activity that has been linked to neuronal representations. We show that SPWs in the CA3 region of rat hippocampal slices can be triggered by the firing of single pyramidal cells. Single action potentials in almost one-third of pyramidal cells initiated SPWs at latencies of 2-5 ms with probabilities of 0.07-0.76. Initiating pyramidal cells evoked field IPSPs (fIPSPs) at similar latencies when SPWs were not initiated. Similar spatial profiles for fIPSPs and middle components of SPWs suggested that SPW fields reflect repeated fIPSPs. Multiple extracellular records showed that the initiated SPWs tended to start near the stimulated pyramidal cell, whereas spontaneous SPWs could emerge at multiple sites. Single pyramidal cells could initiate two to six field IPSPs with distinct amplitude distributions, typically preceeded by a short-duration extracellular action potential. Comparison of these initiated fields with spontaneously occurring inhibitory field motifs allowed us to identify firing in different interneurones during the spread of SPWs. Propagation away from an initiating pyramidal cell was typically associated with the recruitment of interneurones and field IPSPs that were not activated by the stimulated pyramidal cell. SPW fields initiated by single cells were less variable than spontaneous events, suggesting that more stereotyped neuronal ensembles were activated, although neither the spatial profiles of fields, nor the identities of interneurone firing were identical for initiated events. The effects of single pyramidal cell on network events are thus mediated by different sequences of interneurone firing. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Probable Earthquake Archaeological Effects in the ancient pyramids of Quetzalcóatl and Sun in Teotihuacán (Central Mexico)

NASA Astrophysics Data System (ADS)

Perez-Lopez, Raul; Rodríguez-Pascua, Miguel Angel; Garduño-Monroy, Victor Hugo; Oliveros, Arturo; Giner-Robles, Jorge L.; Silva, Pablo G.

2010-05-01

Teotihuacán was one of the blooming and greater cities of the Prehispanic cultural period within the central valley of México and one of the best archaeological findings of the Earth. During the period of splendour (Middle-Late Classic Period, 350-650 AD), almost 125.000 inhabitants lived in a vast city with more than 2000 stucco and block buildings, including the great religious and ceremonial pyramids: the Great Sun Pyramid, built between 1- 150 AD, the Moon Pyramid, built during a large time span (1-650 AD) and the outstanding Quetzalcóatl Pyramid (Feathered Snake Temple), built in two phases: the first original edifice built before 350 AD and the second one mainly are repairs of the west side and dated post-350 AD. The Quetzalcóatl Pyramid (Q- pyramid) shows a quadrangular base of ca. 3500 m2 with an extraordinary decoration of feathered snakes (attributed to the God Quetzalcóatl) and lizards. The second phase of construction consisted in a townhouse façade covering the west side of the pyramid (post 350AD), up to now with no evidence to justify such annexed wrapper of this west side. This ceremonial building was built within the Citadel, a complex area of Teotihuacán with residential and common zones as well (i.e. market). A detailed view of the steps of the west side stairs, displays different patterns of deformation affecting the blocks of the stair. The original and ancient stair exhibits rotated, overturned and displaced blocks, being stronger this deformation at the base of the pyramid. Moreover, the upper corners of the blocks appear broken in a similar form than the seismic-related feature defined as dipping broken corners or chipped corners. However, the horizontal disposition of the blocks suggests lateral vibration between them from horizontal shaking propagation. Besides, this feature appears lesser evident affecting the lower blocks of the annexed west façade, the only originally preserved ones. We have carried out a systematic measurement of this feature across the original west stairs of the Q- pyramid and the first stair level of the Sun pyramid. Furthermore, these horizontal dipping broken corners were also described affecting the new stairs of the annexed façade of the Q- pyramid. This suggests that seismic shaking could produce that deformation with a relative date of 350 AD post-quem. More data are necessary to properly test the earthquake occurrence and to bracket a probable intensity value.

Computational Cardiac Anatomy Using MRI

PubMed Central

Beg, Mirza Faisal; Helm, Patrick A.; McVeigh, Elliot; Miller, Michael I.; Winslow, Raimond L.

2005-01-01

Ventricular geometry and fiber orientation may undergo global or local remodeling in cardiac disease. However, there are as yet no mathematical and computational methods for quantifying variation of geometry and fiber orientation or the nature of their remodeling in disease. Toward this goal, a landmark and image intensity-based large deformation diffeomorphic metric mapping (LDDMM) method to transform heart geometry into common coordinates for quantification of shape and form was developed. Two automated landmark placement methods for modeling tissue deformations expected in different cardiac pathologies are presented. The transformations, computed using the combined use of landmarks and image intensities, yields high-registration accuracy of heart anatomies even in the presence of significant variation of cardiac shape and form. Once heart anatomies have been registered, properties of tissue geometry and cardiac fiber orientation in corresponding regions of different hearts may be quantified. PMID:15508155

Analysis of optimisation method for a two-stroke piston ring using the Finite Element Method and the Simulated Annealing Method

NASA Astrophysics Data System (ADS)

Kaliszewski, M.; Mazuro, P.

2016-09-01

Simulated Annealing Method of optimisation for the sealing piston ring geometry is tested. The aim of optimisation is to develop ring geometry which would exert demanded pressure on a cylinder just while being bended to fit the cylinder. Method of FEM analysis of an arbitrary piston ring geometry is applied in an ANSYS software. The demanded pressure function (basing on formulae presented by A. Iskra) as well as objective function are introduced. Geometry definition constructed by polynomials in radial coordinate system is delivered and discussed. Possible application of Simulated Annealing Method in a piston ring optimisation task is proposed and visualised. Difficulties leading to possible lack of convergence of optimisation are presented. An example of an unsuccessful optimisation performed in APDL is discussed. Possible line of further optimisation improvement is proposed.

Planetary Image Geometry Library

NASA Technical Reports Server (NTRS)

Deen, Robert C.; Pariser, Oleg

2010-01-01

The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A Java wrapper around the library allows parts of it to be used from Java code (via a native JNI interface). Future conversions of all or part of the library to Java are contemplated.

The Piirto Pyramid of Talent Development: A Conceptual Framework for Talking about Talent.

ERIC Educational Resources Information Center

Piirto, Jane

2000-01-01

This article presents the "Piirto Pyramid" framework for identification of talent potential. It explains how the pyramid identifies influences that are significant in the development of talents, including genetics, personality attributes, cognitive ability, talent, vocational, and environmental. Examples using Roy Rogers and Michelangelo are…

Personalizing the Food Pyramid. Teaching Techniques.

ERIC Educational Resources Information Center

Allen, Donna

1996-01-01

Presents a strategy for health and home economics teachers to use in evaluating secondary students' eating and nutritional patterns. Students keep two-day food journals then complete a colorful personal food pyramid with the results. This creates a personal pyramid of food choices that lets students explore their eating habits. (SM)

Sulfolobus turreted icosahedral virus c92 protein responsible for the formation of pyramid-like cellular lysis structures.

PubMed

Snyder, Jamie C; Brumfield, Susan K; Peng, Nan; She, Qunxin; Young, Mark J

2011-07-01

Host cells infected by Sulfolobus turreted icosahedral virus (STIV) have been shown to produce unusual pyramid-like structures on the cell surface. These structures represent a virus-induced lysis mechanism that is present in Archaea and appears to be distinct from the holin/endolysin system described for DNA bacteriophages. This study investigated the STIV gene products required for pyramid formation in its host Sulfolobus solfataricus. Overexpression of STIV open reading frame (ORF) c92 in S. solfataricus alone is sufficient to produce the pyramid-like lysis structures in cells. Gene disruption of c92 within STIV demonstrates that c92 is an essential protein for virus replication. Immunolocalization of c92 shows that the protein is localized to the cellular membranes forming the pyramid-like structures.

Layer 5 Pyramidal Neurons' Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis

PubMed Central

Urrego, Diana; Troncoso, Julieta; Múnera, Alejandro

2015-01-01

This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1). It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans. PMID:26064916

Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder

PubMed Central

Arion, Dominique; Corradi, John P.; Tang, Shaowu; Datta, Dibyadeep; Boothe, Franklyn; He, Aiqing; Cacace, Angela M.; Zaczek, Robert; Albright, Charles F.; Tseng, George; Lewis, David A.

2014-01-01

Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3, and to a lesser extent in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression specifically in DLPFC layer 3 or 5 pyramidal cells would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by qPCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly down-regulated in the patient group (p values for MT-related and UPS-related pathways were <10−7 and <10−5 respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell-specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects, were not present or present to a lesser degree in the schizoaffective disorder subjects (diagnosis of schizoaffective disorder was the most significant covariate, p<10−6), and were not attributable to factors frequently comorbid with schizophrenia. In summary, our findings reveal expression deficits in MT- and UPS-related genes specific to layer 3 and/or layer 5 pyramidal cells in the DLPFC of schizophrenia subjects. These cell type-specific transcriptome signatures are not characteristic of schizoaffective disorder, providing a potential molecular-cellular basis of differences in clinical phenotypes. PMID:25560755

Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder.

PubMed

Arion, D; Corradi, J P; Tang, S; Datta, D; Boothe, F; He, A; Cacace, A M; Zaczek, R; Albright, C F; Tseng, G; Lewis, D A

2015-11-01

Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3 and, to a lesser extent, in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell-type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression, specifically in DLPFC layer 3 or 5 pyramidal cells, would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at the time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by quantitative PCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly downregulated in the patient group (P-values for MT-related and UPS-related pathways were <10(-7) and <10(-5), respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects were not present or present to a lesser degree in the schizoaffective disorder subjects (diagnosis of schizoaffective disorder was the most significant covariate, P<10(-6)) and were not attributable to factors frequently comorbid with schizophrenia. In summary, our findings reveal expression deficits in MT- and UPS-related genes specific to layer 3 and/or layer 5 pyramidal cells in the DLPFC of schizophrenia subjects. These cell type-specific transcriptome signatures are not characteristic of schizoaffective disorder, providing a potential molecular-cellular basis of differences in clinical phenotypes.

Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

DOE PAGES

Kaercher, Pamela M.; Zepeda-Alarcon, Eloisa; Prakapenka, Vitali B.; ...

2014-11-07

Although the crystal structure of the high pressure SiO 2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientationmore » and find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.« less

Controlled Growth of Ordered III-Nitride Core-Shell Nanostructure Arrays for Visible Optoelectronic Devices

DOE PAGES

Rishinaramangalam, Ashwin K.; Mishkat Ul Masabih, Saadat; Fairchild, Michael N.; ...

2014-10-21

In our paper, we demonstrate the growth of ordered arrays of nonpolar {101 ¯ 0} core–shell nanowalls and semipolar {101 ¯ 1} core–shell pyramidal nanostripes on c-plane (0001) sapphire substrates using selective-area epitaxy and metal organic chemical vapor deposition. The nanostructure arrays are controllably patterned into LED mesa regions, demonstrating a technique to impart secondary lithography features into the arrays. Moreover, we study the dependence of the nanostructure cores on the epitaxial growth conditions and show that the geometry and morphology are strongly influenced by growth temperature, V/III ratio, and pulse interruption time. We also demonstrate the growth of InGaNmore » quantum well shells on the nanostructures and characterize the structures by using micro-photoluminescence and cross-section scanning tunneling electron microscopy.« less

DRAPING SIMULATION OF WOVEN FABRICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodgers, William; Jin, Xiaoshi; Zhu, Jiang

2016-09-07

Woven fabric composites are extensively used in molding complex geometrical shapes due to their high conformability compared to other fabrics. Preforming is an important step in the overall process, where the two-dimensional fabric is draped to become the three-dimensional shape of the part prior to resin injection. During preforming, the orientation of the yarns may change significantly compared to the initial orientations. Accurate prediction of the yarn orientations after molding is important for evaluating the structural performance of the final part. This paper presents a systematic investigation of the angle changes during the preform operation for carbon fiber twill andmore » satin weave fabrics. Preforming experiments were conducted using a truncated pyramid mold geometry designed and fabricated at the General Motors Research Laboratories. Predicted results for the yarn orientations were compared with experimental results and good agreement was observed« less

Measuring bacterial cells size with AFM

PubMed Central

Osiro, Denise; Filho, Rubens Bernardes; Assis, Odilio Benedito Garrido; Jorge, Lúcio André de Castro; Colnago, Luiz Alberto

2012-01-01

Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described. PMID:24031837

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, and density functional theory calculations.

PubMed

Hänninen, Mikko M; Välivaara, Juha; Mota, Antonio J; Colacio, Enrique; Lloret, Francesc; Sillanpää, Reijo

2013-02-18

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.

Recent faulting in western Nevada revealed by multi-scale seismic reflection

USGS Publications Warehouse

Frary, R.N.; Louie, J.N.; Stephenson, W.J.; Odum, J.K.; Kell, A.; Eisses, A.; Kent, G.M.; Driscoll, N.W.; Karlin, R.; Baskin, R.L.; Pullammanappallil, S.; Liberty, L.M.

2011-01-01

The main goal of this study is to compare different reflection methods used to image subsurface structure within different physical environments in western Nevada. With all the methods employed, the primary goal is fault imaging for structural information toward geothermal exploration and seismic hazard estimation. We use seismic CHIRP a swept-frequency marine acquisition system, weight drop an accelerated hammer source, and two different vibroseis systems to characterize fault structure. We focused our efforts in the Reno metropolitan area and the area within and surrounding Pyramid Lake in northern Nevada. These different methods have provided valuable constraints on the fault geometry and activity, as well as associated fluid movement. These are critical in evaluating the potential for large earthquakes in these areas, and geothermal exploration possibilities near these structures. ?? 2011 Society of Exploration Geophysicists.

True and masked three-coordinate T-shaped platinum(II) intermediates.

PubMed

Ortuño, Manuel A; Conejero, Salvador; Lledós, Agustí

2013-01-01

Although four-coordinate square-planar geometries, with a formally 16-electron counting, are absolutely dominant in isolated Pt(II) complexes, three-coordinate, 14-electron Pt(II) complexes are believed to be key intermediates in a number of platinum-mediated organometallic transformations. Although very few authenticated three-coordinate Pt(II) complexes have been characterized, a much larger number of complexes can be described as operationally three-coordinate in a kinetic sense. In these compounds, which we have called masked T-shaped complexes, the fourth position is occupied by a very weak ligand (agostic bond, solvent molecule or counteranion), which can be easily displaced. This review summarizes the structural features of the true and masked T-shaped Pt(II) complexes reported so far and describes synthetic strategies employed for their formation. Moreover, recent experimental and theoretical reports are analyzed, which suggest the involvement of such intermediates in reaction mechanisms, particularly C-H bond-activation processes.

Coordination geometries of solvated lanthanide(II) ions: Molecular structures of the cationic species [(DIME)[sub 3]Ln][sup 2+] (DIME = diethylene glycol dimethyl ether; Ln[sup 2+] = Sm, Yb), [(DIME)[sub 2]Yb(CH[sub 3]CN)[sub 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, J.P. III; Deng, H.; Boyd, E.P.

1994-04-13

The first lanthanide(II) cationic species with coordination numbers 7,8, and 9 have been structurally characterized. Mercury amalgams of the elemental lanthanides (Ln(Hg) where Ln = Sm, Eu, Yb) cleanly reduce Mn[sub 2](CO)[sub 10] and Co[sub 2](CO)[sub 8] in polydentate ethers to [Mn(CO)[sub 5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Shashi B.; Shopov, Dimitar Y.; Sharninghausen, Liam S.

We describe facial and meridional isomers of [RhIII(pyalk)3], as well as meridional [RhIV(pyalk)3]+ {pyalk =2-(2-pyridyl)-2-propanoate}, the first coordination complex in an N,O-donor environment to show a clean, reversible RhIII/IV redox couple and to have a stable Rh(IV) form, which we characterize by EPR and UV–visible spectroscopy as well as X-ray crystallography. The unprecedented stability of the Rh(IV) species is ascribed to the exceptional donor strength of the ligands, their oxidation resistance, and the meridional coordination geometry.

Incorporating Floating Surface Objects into a Fully Dispersive Surface Wave Model

DTIC Science & Technology

2016-04-19

surface objects Sigma -coordinate Navier-Stokes Finite volume Immersed boundary a b s t r a c t The shock-capturing, non-hydrostatic, three...ontaining object or fluid, respectively. A 3D object with geometry escribed in Cartesian coordinates ( x, y, z ) was first projected onto he NHWAVE...17) . Specifically, the mask values re assigned by ASK = 0 if object projection includes u , v point (i, j) and k = k b ∼ k t ASK = 1 otherwise

Nitrilotris(methylenephosphonato)potassium K[μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3}H{sub 4}]: Synthesis, structure, and the nature of the K–O chemical bond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Somov, N. V., E-mail: somov@phys.unn.ru; Chausov, F. F., E-mail: xps@ftiudm.ru; Zakirova, R. M., E-mail: ftt@udsu.ru

2016-07-15

The crystal structure of nitrilotris(methylenephosphonato)potassium K[μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3}H{sub 4}]—a three-dimensional coordination polymer—was determined. The potassium atom is coordinated by seven oxygen atoms belonging to the six nearest ligand molecules, resulting in distorted monocapped octahedral coordination geometry. The complex contains the four-membered chelate ring K–O–P–O. The K–O chemical bond is predominantly ionic. Meanwhile, the bonds of the potassium atom with some oxygen atoms have a noticeable covalent component. In addition to coordination bonds, the molecules in the crystal packing are linked by hydrogen bonds.

Poly[diaqua­tris­(μ4-1,3-phenyl­enediacetato)­dineodymium(III)

PubMed Central

Gao, Zhu-Qing; Lv, Dong-Yu; Li, Hong-Ji; Gu, Jin-Zhong

2011-01-01

In the title coordination polymer, [Nd2(C10H8O4)3(H2O)2]n, each of the two NdIII ions is nine-coordinated by eight O atoms from six different 2,2′-(m-phenyl­ene)diacetate (pda) bivalent anions and by one O atom from a water mol­ecule, forming a distorted tricapped trigonal–prismatic coordination geometry. Eight NdIII ions and 12 pda ligands form a large [Nd8(pda)12] ring, and four NdIII ions and six pda ligands form a small [Nd4(pda)6] ring. These rings are further connected by the coordination inter­actions of pda ligands and NdIII, generating a three-dimensional supra­molecular framework. PMID:21522305

Aging-Related Hyperexcitability in CA3 Pyramidal Neurons Is Mediated by Enhanced A-Type K+ Channel Function and Expression.

PubMed

Simkin, Dina; Hattori, Shoai; Ybarra, Natividad; Musial, Timothy F; Buss, Eric W; Richter, Hannah; Oh, M Matthew; Nicholson, Daniel A; Disterhoft, John F

2015-09-23

Aging-related impairments in hippocampus-dependent cognition have been attributed to maladaptive changes in the functional properties of pyramidal neurons within the hippocampal subregions. Much evidence has come from work on CA1 pyramidal neurons, with CA3 pyramidal neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing in the hippocampal circuit. Here, we use whole-cell current-clamp to demonstrate that aged rat (29-32 months) CA3 pyramidal neurons fire significantly more action potentials (APs) during theta-burst frequency stimulation and that this is associated with faster AP repolarization (i.e., narrower AP half-widths and enlarged fast afterhyperpolarization). Using a combination of patch-clamp physiology, pharmacology, Western blot analyses, immunohistochemistry, and array tomography, we demonstrate that these faster AP kinetics are mediated by enhanced function and expression of Kv4.2/Kv4.3 A-type K(+) channels, particularly within the perisomatic compartment, of CA3 pyramidal neurons. Thus, our study indicates that inhibition of these A-type K(+) channels can restore the intrinsic excitability properties of aged CA3 pyramidal neurons to a young-like state. Significance statement: Age-related learning deficits have been attributed, in part, to altered hippocampal pyramidal neuronal function with normal aging. Much evidence has come from work on CA1 neurons, with CA3 neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing. Hence, we conducted a series of experiments to identify the cellular mechanisms that underlie the hyperexcitability reported in the CA3 region. Contrary to CA1 neurons, we demonstrate that postburst afterhyperpolarization is not altered with aging and that aged CA3 pyramidal neurons are able to fire significantly more action potentials and that this is associated with faster action potential repolarization through enhanced expression of Kv4.2/Kv4.3 A-type K(+) channels, particularly within the cell bodies of CA3 pyramidal neurons. Copyright © 2015 the authors 0270-6474/15/3513206-13$15.00/0.

Evaluation of nature and extent of injuries during Dahihandi festival.

PubMed

Nemade, P; Wade, R; Patwardhan, A R; Kale, S

2012-01-01

Injuries related to the Hindu festival of Dahihandi where a human pyramid is formed and a pot of money kept at a height is broken, celebrated in the state of Maharashtra, have seen a significant rise in the past few years. The human pyramid formed is multi-layered and carries with it a high risk of injury including mortality. To evaluate the nature, extent and influencing factors of injuries related to Dahihandi festival. We present a retrospective analysis of patients who presented in a tertiary care center with injuries during the Dahihandi festival in the year 2010. 124 patients' records were evaluated for timing of injury, height of the Dahihandi pyramid, position of the patient in the multi-layered pyramid, mode of pyramid collapse and mechanism of an injury. A binary regression logistic analysis for risk factors was done at 5% significance level. Univariate and multi-variate binary logistic regression of the risk factors for occurrence of a major or minor injury was done using Minitab™ version 16.0 at 5% significance. Out of 139 patients presented to the center, 15 were not involved directly in the formation of pyramid, rest 124 were included in the analysis. A majority of the patients were above 15 years of age [110 (83.6%)]. 46 (37.1%) patients suffered major injuries. There were 39 fractures, 3 cases of chest wall trauma with 10 cases of head injuries and 1 death. More than half of the patients [78 (56.1%)] were injured after 1800 hours. 73 (58.9%) injured participants were part of the pyramid constructed to reach the Dahihandi placed at 30 feet or more above the ground. 72 (51.8%) participants were part of the middle layers of the pyramid. Fall of a participant from upstream layers on the body was the main mechanism of injury, and majority [101 (81.5%)] of the patients suffered injury during descent phase of the pyramid. There is a considerable risk of serious, life-threatening injuries inherent to human pyramid formation and descent in the Dahihandi festival. Safety guidelines are urgently needed to minimize risk and prevent loss of human life.

Aging-Related Hyperexcitability in CA3 Pyramidal Neurons Is Mediated by Enhanced A-Type K+ Channel Function and Expression

PubMed Central

Simkin, Dina; Hattori, Shoai; Ybarra, Natividad; Musial, Timothy F.; Buss, Eric W.; Richter, Hannah; Oh, M. Matthew

2015-01-01

Aging-related impairments in hippocampus-dependent cognition have been attributed to maladaptive changes in the functional properties of pyramidal neurons within the hippocampal subregions. Much evidence has come from work on CA1 pyramidal neurons, with CA3 pyramidal neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing in the hippocampal circuit. Here, we use whole-cell current-clamp to demonstrate that aged rat (29–32 months) CA3 pyramidal neurons fire significantly more action potentials (APs) during theta-burst frequency stimulation and that this is associated with faster AP repolarization (i.e., narrower AP half-widths and enlarged fast afterhyperpolarization). Using a combination of patch-clamp physiology, pharmacology, Western blot analyses, immunohistochemistry, and array tomography, we demonstrate that these faster AP kinetics are mediated by enhanced function and expression of Kv4.2/Kv4.3 A-type K+ channels, particularly within the perisomatic compartment, of CA3 pyramidal neurons. Thus, our study indicates that inhibition of these A-type K+ channels can restore the intrinsic excitability properties of aged CA3 pyramidal neurons to a young-like state. SIGNIFICANCE STATEMENT Age-related learning deficits have been attributed, in part, to altered hippocampal pyramidal neuronal function with normal aging. Much evidence has come from work on CA1 neurons, with CA3 neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing. Hence, we conducted a series of experiments to identify the cellular mechanisms that underlie the hyperexcitability reported in the CA3 region. Contrary to CA1 neurons, we demonstrate that postburst afterhyperpolarization is not altered with aging and that aged CA3 pyramidal neurons are able to fire significantly more action potentials and that this is associated with faster action potential repolarization through enhanced expression of Kv4.2/Kv4.3 A-type K+ channels, particularly within the cell bodies of CA3 pyramidal neurons. PMID:26400949

Ventromedial prefrontal cortex pyramidal cells have a temporal dynamic role in recall and extinction of cocaine-associated memory.

PubMed

Van den Oever, Michel C; Rotaru, Diana C; Heinsbroek, Jasper A; Gouwenberg, Yvonne; Deisseroth, Karl; Stuber, Garret D; Mansvelder, Huibert D; Smit, August B

2013-11-13

In addicts, associative memories related to the rewarding effects of drugs of abuse can evoke powerful craving and drug seeking urges, but effective treatment to suppress these memories is not available. Detailed insight into the neural circuitry that mediates expression of drug-associated memory is therefore of crucial importance. Substantial evidence from rodent models of addictive behavior points to the involvement of the ventromedial prefrontal cortex (vmPFC) in conditioned drug seeking, but specific knowledge of the temporal role of vmPFC pyramidal cells is lacking. To this end, we used an optogenetics approach to probe the involvement of vmPFC pyramidal cells in expression of a recent and remote conditioned cocaine memory. In mice, we expressed Channelrhodopsin-2 (ChR2) or Halorhodopsin (eNpHR3.0) in pyramidal cells of the vmPFC and studied the effect of activation or inhibition of these cells during expression of a cocaine-contextual memory on days 1-2 (recent) and ∼3 weeks (remote) after conditioning. Whereas optical activation of pyramidal cells facilitated extinction of remote memory, without affecting recent memory, inhibition of pyramidal cells acutely impaired recall of recent cocaine memory, without affecting recall of remote memory. In addition, we found that silencing pyramidal cells blocked extinction learning at the remote memory time-point. We provide causal evidence of a critical time-dependent switch in the contribution of vmPFC pyramidal cells to recall and extinction of cocaine-associated memory, indicating that the circuitry that controls expression of cocaine memories reorganizes over time.

Discovery of a big void in Khufu’s Pyramid by observation of cosmic-ray muons

NASA Astrophysics Data System (ADS)

Morishima, Kunihiro; Kuno, Mitsuaki; Nishio, Akira; Kitagawa, Nobuko; Manabe, Yuta; Moto, Masaki; Takasaki, Fumihiko; Fujii, Hirofumi; Satoh, Kotaro; Kodama, Hideyo; Hayashi, Kohei; Odaka, Shigeru; Procureur, Sébastien; Attié, David; Bouteille, Simon; Calvet, Denis; Filosa, Christopher; Magnier, Patrick; Mandjavidze, Irakli; Riallot, Marc; Marini, Benoit; Gable, Pierre; Date, Yoshikatsu; Sugiura, Makiko; Elshayeb, Yasser; Elnady, Tamer; Ezzy, Mustapha; Guerriero, Emmanuel; Steiger, Vincent; Serikoff, Nicolas; Mouret, Jean-Baptiste; Charlès, Bernard; Helal, Hany; Tayoubi, Mehdi

2017-12-01

The Great Pyramid, or Khufu’s Pyramid, was built on the Giza plateau in Egypt during the fourth dynasty by the pharaoh Khufu (Cheops), who reigned from 2509 BC to 2483 BC. Despite being one of the oldest and largest monuments on Earth, there is no consensus about how it was built. To understand its internal structure better, we imaged the pyramid using muons, which are by-products of cosmic rays that are only partially absorbed by stone. The resulting cosmic-ray muon radiography allows us to visualize the known and any unknown voids in the pyramid in a non-invasive way. Here we report the discovery of a large void (with a cross-section similar to that of the Grand Gallery and a minimum length of 30 metres) situated above the Grand Gallery. This constitutes the first major inner structure found in the Great Pyramid since the nineteenth century. The void, named ScanPyramids’ Big Void, was first observed with nuclear emulsion films installed in the Queen’s chamber, then confirmed with scintillator hodoscopes set up in the same chamber and finally re-confirmed with gas detectors outside the pyramid. This large void has therefore been detected with high confidence by three different muon detection technologies and three independent analyses. These results constitute a breakthrough for the understanding of the internal structure of Khufu’s Pyramid. Although there is currently no information about the intended purpose of this void, these findings show how modern particle physics can shed new light on the world’s archaeological heritage.

Crystal structure and Hirshfeld surface analysis of aqua­bis­(nicotinamide-κN)bis­(4-sulfamoylbenzoato-κO 1)copper(II)

PubMed Central

Hökelek, Tuncer; Yavuz, Vijdan; Dal, Hakan; Necefoğlu, Hacali

2018-01-01

In the crystal of the title complex, [Cu(C7H6NO4S)2(C6H6N2O)2(H2O)], the CuII cation and the O atom of the coordinated water mol­ecule reside on a twofold rotation axis. The CuII ion is coordinated by two carboxyl­ate O atoms of the two symmetry-related 4-sulfamoylbenzoate (SB) anions and by two N atoms of the two symmetry-related nicotinamide (NA) mol­ecules at distances of 1.978 (2) and 2.025 (3) Å, respectively, forming a slightly distorted square-planar arrangement. The distorted square-pyramidal coordination environment is completed by the water O atom in the axial position at a distance of 2.147 (4) Å. In the crystal, the mol­ecules are linked via O—H⋯O and N—H⋯O hydrogen bonds with R 2 2(8) and R 2 2(18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (42.2%), H⋯H (25.7%) and H⋯C/C⋯H (20.0%) inter­actions. PMID:29416889

Structures of nitrato-(2-hydroxybenzaldehydo) (2,2 Prime -bipyridyl)copper and nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chumakov, Yu. M.; Paladi, L. G.; Antosyak, B. Ya.

2011-03-15

Nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper (I) and nitrato-(2-hydroxybenzaldehydo)(2,2 Prime -bipyridyl)copper (II) were synthesized and characterized by X-ray diffraction. The coordination polyhedron of the central copper atom in complex I can be described as a distorted tetragonal pyramid whose base is formed by the phenol and carbonyl oxygen atoms of the monodeprotonated 2-hydroxy-5nitrobenzaldehyde molecule and the nitrogen atoms of the 2,2 Prime -bipyridyl ligand and whose apex is occupied by the oxygen atom of the nitrato group. In the crystal structure, complexes I are linked by the acido ligands and the NO{sub 2} groups of the aldehyde molecule into infinite chains. In complexmore » II, the central copper atom is coordinated by 2-hydroxybenzaldehyde, 2,2 Prime -bipyridyl, and the nitrato group, resulting in the formation of centrosymmetric dimers. The coordination polyhedron of the central copper atom can be described as a bipyramid (4 + 1 + 1) with the same base as in complex I. The axial vertices of the bipyramid are occupied by the oxygen atom of the nitrato group and the bridging phenol oxygen atom of the adjacent complex related to the initial complex by a center of symmetry. In the crystal structure, complexes II are hydrogen bonded into infinite chains.« less

Co(II) Coordination in Prokaryotic Zinc Finger Domains as Revealed by UV-Vis Spectroscopy

PubMed Central

Sivo, Valeria; D'Abrosca, Gianluca; Russo, Luigi; Iacovino, Rosa; Pedone, Paolo Vincenzo; Fattorusso, Roberto

2017-01-01

Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis2 coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis2 coordination an intense d-d transition band, blue-shifted with respect to the Cys2His2 sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere. PMID:29386985

Co(II) Coordination in Prokaryotic Zinc Finger Domains as Revealed by UV-Vis Spectroscopy.

PubMed

Sivo, Valeria; D'Abrosca, Gianluca; Russo, Luigi; Iacovino, Rosa; Pedone, Paolo Vincenzo; Fattorusso, Roberto; Isernia, Carla; Malgieri, Gaetano

2017-01-01

Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis 2 coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis 2 coordination an intense d - d transition band, blue-shifted with respect to the Cys 2 His 2 sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere.

Commentary on "Management Education and the Base of the Pyramid"

ERIC Educational Resources Information Center

Rosile, Grace Ann

2008-01-01

This commentary asks some critical questions concerning the article "Management Education and the Base of the Pyramid" included in this special issue. Are "bottom of the pyramid" (BOP) multidisciplinary action project (MAP) students prepared to critically assess the impact of their interventions beyond a narrow definition of profit in complex and…

Pyramid solar micro-grid

NASA Astrophysics Data System (ADS)

Huang, Bin-Juine; Hsu, Po-Chien; Wang, Yi-Hung; Tang, Tzu-Chiao; Wang, Jia-Wei; Dong, Xin-Hong; Hsu, Hsin-Yi; Li, Kang; Lee, Kung-Yen

2018-03-01

A novel pyramid solar micro-grid is proposed in the present study. All the members within the micro-grid can mutually share excess solar PV power each other through a binary-connection hierarchy. The test results of a 2+2 pyramid solar micro-grid consisting of 4 individual solar PV systems for self-consumption are reported.

Estimation of Food Guide Pyramid Serving Sizes by College Students.

ERIC Educational Resources Information Center

Knaust, Gretchen; Foster, Irene M.

2000-01-01

College students (n=158) used the Food Guide Pyramid to select serving sizes on a questionnaire (73% had been instructed in its use). Overall mean scores (31% correct) indicated they generally did not know recommended serving sizes. Those who had read about or received instruction in the pyramid had higher mean scores. (SK)

The Literacy Pyramid Organization of Reading/Writing Activities in a Whole Language Classroom (Early Childhood).

ERIC Educational Resources Information Center

Bruneau, Beverly J.

1997-01-01

Describes the Literacy Pyramid (based on the United States Department of Agriculture food pyramid), a classification of eight instructional events, which is intended as a framework for teachers to think about the purpose of various instructional formats and about organizing time for language arts instruction. (SR)

A Comparison of Pyramidal Staff Training and Direct Staff Training in Community-Based Day Programs

ERIC Educational Resources Information Center

Haberlin, Alayna T.; Beauchamp, Ken; Agnew, Judy; O'Brien, Floyd

2012-01-01

This study evaluated two methods of training staff who were working with individuals with developmental disabilities: pyramidal training and consultant-led training. In the pyramidal training, supervisors were trained in the principles of applied behavior analysis (ABA) and in delivering feedback. The supervisors then trained their direct-care…

Structural and dynamic properties of propane coordinated to TpRh(CNR) from a confrontation between theory and experiment

PubMed Central

Clot, Eric; Eisenstein, Odile; Jones, William D.

2007-01-01

Density functional calculations with the B3PW91 functional have been carried out on the TpRh(CNMe) species [Tp = HB(pyrazolyl)3] as a model for Tp′Rh(CNCH2CMe3) [Tp′ = HB(3,5-dimethylpyrazolyl)3] in interaction with propane. Two σ complexes have been found as minima coordinated through either a methyl or a methylene CH bond, the former being more stable. The approach of the alkane to TpRh(CNMe) has been studied. Although no transition state could be located, study of this path reveals the key importance of the partial decoordination of one pyrazole ring. The full coordination of the alkane can only be achieved when the metal is essentially in a square pyramid coordination with one of the three pyrazole groups only weakly interacting with Rh. The main reaction of the methyl σ complex is oxidative addition, leading to the n-propyl hydride complex. In contrast, two reactions are found for the methylene σ complex: (i) oxidative addition to give the isopropyl complex and (ii) exchange between the secondary and primary CH bonds to convert the methylene complex of propane into a methyl complex of propane. This latter reaction has a much lower barrier than the oxidative addition at the methylene CH bond. The results account well for most of the experimental results obtained from kinetic studies. Steric factors are found to control the energy barriers between these various processes, disfavoring any process that brings the central carbon into close proximity to Rh. PMID:17412834

Partnering against cancer today: a blueprint for coordinating efforts through communication science.

PubMed

Hesse, Bradford W; Cole, Galen E; Powe, Barbara D

2013-12-01

One of the hallmarks of the communication revolution over the past decade has been its support for participation, whether that be in the active engagement of patients searching the Web for answers to vital health questions, or in the collective energies of self-organizing communities through social media. At the same time, some of the major obstacles to achieving a full and equitable reach of evidence-based cancer control knowledge have been traced back to discontinuities in communication either within clinical care or the broader public awareness system. Communication scientists from the National Cancer Institute, the Centers for Disease Control and Prevention, and the American Cancer Society joined forces in 2010 to investigate ways in which communication science can be used to improve coordination and enhance participation in cancer control for the nation. From 2010 to 2013, the three organizations worked together in 1) convening two meetings designed to assess the status of funded research in communication science, 2) completing a systematic review of literature published over the previous 10 years, and 3) authoring a blueprint for coordinated efforts using the implications of communication science. The blueprint consists of three major goals: first, to identify high-yield targets of opportunity using the health impact pyramid articulated by Centers for Disease Control and Prevention Director, Thomas Frieden; second, to leverage opportunities within the new communication environment, including the opportunities catalyzed by national efforts to create an infrastructure for evidence implementation through health information technology; and third, to assist in coordinating efforts across collaborative entities through participative media.

Partnering Against Cancer Today: A Blueprint for Coordinating Efforts Through Communication Science

PubMed Central

2013-01-01

One of the hallmarks of the communication revolution over the past decade has been its support for participation, whether that be in the active engagement of patients searching the Web for answers to vital health questions, or in the collective energies of self-organizing communities through social media. At the same time, some of the major obstacles to achieving a full and equitable reach of evidence-based cancer control knowledge have been traced back to discontinuities in communication either within clinical care or the broader public awareness system. Communication scientists from the National Cancer Institute, the Centers for Disease Control and Prevention, and the American Cancer Society joined forces in 2010 to investigate ways in which communication science can be used to improve coordination and enhance participation in cancer control for the nation. From 2010 to 2013, the three organizations worked together in 1) convening two meetings designed to assess the status of funded research in communication science, 2) completing a systematic review of literature published over the previous 10 years, and 3) authoring a blueprint for coordinated efforts using the implications of communication science. The blueprint consists of three major goals: first, to identify high-yield targets of opportunity using the health impact pyramid articulated by Centers for Disease Control and Prevention Director, Thomas Frieden; second, to leverage opportunities within the new communication environment, including the opportunities catalyzed by national efforts to create an infrastructure for evidence implementation through health information technology; and third, to assist in coordinating efforts across collaborative entities through participative media. PMID:24395998

Generation and Reactions of an Octacyclic Hindered Pyramidalized Alkene.

PubMed

Camps, Pelayo; Lozano, David; Barbaraci, Carla; Font-Bardia, Merce; Luque, F Javier; Estarellas, Carolina

2018-05-18

Octacyclo[10.6.1.0 1,10 .0 3,7 .0 4,9 .0 8,19 .0 11,16 .0 13,17 ]nonadeca-5,8,14-triene (27), a hindered pyramidalized alkene, has been generated from a diiodide precursor. Contrary to the usual behavior of known pyramidalized alkenes, no Diels-Alder adducts were obtained from the present alkene when it was generated by different standard procedures in the presence of different dienes. However, products derived from the reduction, t-BuLi addition, condensation with the solvent, or dimerization were isolated from these reactions, depending on the conditions used to generate it. No [2 + 2] cross product among this pyramidalized alkene and tricyclo[3.3.1.0 3,7 ]non-3(7)-ene was formed when a mixture of the corresponding precursor diiodides was reacted with sodium amalgam. The analysis of selected geometrical and orbital parameters determined from quantum mechanical calculations indicates that the degree of pyramidalization of this alkene and its higher steric hindrance compared with other polycyclic pyramidalized alkenes may explain its peculiar reactivity.

Pyramiding of transgenic Pm3 alleles in wheat results in improved powdery mildew resistance in the field.

PubMed

Koller, Teresa; Brunner, Susanne; Herren, Gerhard; Hurni, Severine; Keller, Beat

2018-04-01

The combined effects of enhanced total transgene expression level and allele-specificity combination in transgenic allele-pyramided Pm3 wheat lines result in improved powdery mildew field resistance without negative pleiotropic effects. Allelic Pm3 resistance genes of wheat confer race-specific resistance to powdery mildew (Blumeria graminis f. sp. tritici, Bgt) and encode nucleotide-binding domain, leucine-rich repeat (NLR) receptors. Transgenic wheat lines overexpressing alleles Pm3a, b, c, d, f, and g have previously been generated by transformation of cultivar Bobwhite and tested in field trials, revealing varying degrees of powdery mildew resistance conferred by the transgenes. Here, we tested four transgenic lines each carrying two pyramided Pm3 alleles, which were generated by crossbreeding of lines transformed with single Pm3 alleles. All four allele-pyramided lines showed strongly improved powdery mildew resistance in the field compared to their parental lines. The improved resistance results from the two effects of enhanced total transgene expression levels and allele-specificity combinations. In contrast to leaf segment tests on greenhouse-grown seedlings, no allelic suppression was observed in the field. Plant development and yield scores of the pyramided lines were similar to the mean scores of the corresponding parental lines, and thus, the allele pyramiding did not cause any negative effects. On the contrary, in pyramided line, Pm3b × Pm3f normal plant development was restored compared to the delayed development and reduced seed set of parental line Pm3f. Allele-specific RT qPCR revealed additive transgene expression levels of the two Pm3 alleles in the pyramided lines. A positive correlation between total transgene expression level and powdery mildew field resistance was observed. In summary, allele pyramiding of Pm3 transgenes proved to be successful in enhancing powdery mildew field resistance.

GABAA receptor-mediated currents in interneurons and pyramidal cells of rat visual cortex

PubMed Central

Xiang, Zixiu; Huguenard, John R; Prince, David A

1998-01-01

We compared γ-aminobutyric acid (GABA)-mediated responses of identified pyramidal cells and fast spiking interneurons in layer V of visual cortical slices from young rats (P11-14). The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) was similar in pyramidal cells and interneurons (1.7 vs. 1.9 Hz). For events with 10-90 % rise times less than 0.9 ms, no significant differences were found in mean amplitude (61 vs. 65 pA), mean rise time (0.58 vs. 0.61 ms), or the first time constant of decay (τ1, 6.4 vs. 6.5 ms) between pyramidal cells and interneurons. The second decay time constant (τ2) was significantly longer in interneurons than in pyramidal cells (49 vs. 22 ms). The difference in sIPSC decay kinetics between two cell types also existed in adult rats (P36-42), suggesting the kinetic difference is not due to differential development of GABAA receptors in these cell types. The decay kinetics of monosynaptic evoked IPSCs were also longer in interneurons. As in the case of sIPSCs, the difference was accounted for by the second decay time constant. τ1 and τ2 were, respectively, 13 and 64 ms for interneurons and 12 and 47 ms for pyramidal cells. Cell-attached patch recordings revealed that the mean open time for single Cl− channels in response to 2 μM GABA was significantly longer in interneurons than pyramidal cells (5.0 vs. 2.8 ms). The chord conductance of these channels in interneurons (12 pS) was significantly smaller than in pyramidal cells (15 pS). Single channel currents reversed polarity when the pipette potential was approximately -10 mV for both cell types. These results show that there is a functional diversity of GABAA receptors in electrophysiologically and morphologically identified cortical pyramidal cells and interneurons. This diversity might derive from the different molecular composition of the receptors in these two cell types. PMID:9503333

Comparison between non-modulation four-sided and two-sided pyramid wavefront sensor.

PubMed

Wang, Jianxin; Bai, Fuzhong; Ning, Yu; Huang, Linhai; Wang, Shengqian

2010-12-20

Based on the diffraction theory the paper analyzes non-modulation Pyramid wavefront sensor (PWFS, namely, four-sided pyramid) and two-sided pyramid wavefront sensor (TSPWFS), and expresses the detected signals as a function of the measured wavefront. The expressions of the detected signals show that non-modulation PWFS and TSPWFS hold the same properties of both slope and direct phase sensors. We compare both sensors working in slope and phase sensing by theory and numerical simulations. The results demonstrate that the performance of TSPWFS excels that of PWFS. Additionally, the influence of interference between adjacent pupils is discussed.

Searching for possible hidden chambers in the Pyramid of the Sun

NASA Astrophysics Data System (ADS)

Alfaro, R.; Belmont, E.; Grabski, V.; Manzanilla, L.; Martinez-Davalos, A.; Menchaca-Rocha, A.; Moreno, M.; Sandoval, A.

The Pyramid of the Sun, at Teotihuacan, Mexico, is being searched for possible hidden chambers, using a muon tracking technique inspired in the experiment carried out by Luis Alvarez over 30 years ago at the Chephren Pyramid, in Giza. A fortunate similarity between this monument and the Pyramid of the Sun is a tunnel, running 8 m below the base and ending close to the symmetry axis, which permits the use muon attenuation measurements. A brief account of the project, including planning, detector design, construction and simulations, as well as the current status of the project is presented

Ischemic stroke of the pyramidal decussation causing quadriplegia and anarthria.

PubMed

Wilkins, Emilia G; Kamel, Hooman; Johnson, Eric C B; Shalev, Sarah M; Josephson, S Andrew

2012-10-01

A 52-year-old man with a history of hypertension and previously irradiated head and neck cancer presented with quadriplegia and anarthria sparing the face and sensory functions. Brain magnetic resonance imaging (MRI) demonstrated acute infarction of the pyramidal decussation. We describe the clinical and radiological characteristics of infarction at the pyramidal decussation and review the arterial supply to this region in the lower brainstem. Although rare, infarction of the pyramidal decussation should be considered in the differential diagnosis when patients present with atraumatic pure motor quadriplegia. Copyright © 2012 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Introduction of a pyramid guiding process for general musculoskeletal physical rehabilitation.

PubMed

Stark, Timothy W

2006-06-08

Successful instruction of a complicated subject as Physical Rehabilitation demands organization. To understand principles and processes of such a field demands a hierarchy of steps to achieve the intended outcome. This paper is intended to be an introduction to a proposed pyramid scheme of general physical rehabilitation principles. The purpose of the pyramid scheme is to allow for a greater understanding for the student and patient. As the respected Food Guide Pyramid accomplishes, the student will further appreciate and apply supported physical rehabilitation principles and the patient will understand that there is a progressive method to their functional healing process.

Accuracy increase of the coordinate measurement based on the model production of geometrical parts specifications

NASA Astrophysics Data System (ADS)

Zlatkina, O. Yu

2018-04-01

There is a relationship between the service properties of component parts and their geometry; therefore, to predict and control the operational characteristics of parts and machines, it is necessary to measure their geometrical specifications. In modern production, a coordinate measuring machine is the advanced measuring instrument of the products geometrical specifications. The analysis of publications has shown that during the coordinate measurements the problems of choosing locating chart of parts and coordination have not been sufficiently studied. A special role in the coordination of the part is played by the coordinate axes informational content. Informational content is the sum of the degrees of freedom limited by the elementary item of a part. The coordinate planes of a rectangular coordinate system have different informational content (three, two, and one). The coordinate axes have informational content of four, two and zero. The higher the informational content of the coordinate plane or axis, the higher its priority for reading angular and linear coordinates is. The geometrical model production of the coordinate measurements object taking into account the information content of coordinate planes and coordinate axes allows us to clearly reveal the interrelationship of the coordinates of the deviations in location, sizes and deviations of their surfaces shape. The geometrical model helps to select the optimal locating chart of parts for bringing the machine coordinate system to the part coordinate system. The article presents an algorithm the model production of geometrical specifications using the example of the piston rod of a compressor.

Involvement of intracellular Zn2+ signaling in LTP at perforant pathway-CA1 pyramidal cell synapse.

PubMed

Tamano, Haruna; Nishio, Ryusuke; Takeda, Atsushi

2017-07-01

Physiological significance of synaptic Zn 2+ signaling was examined at perforant pathway-CA1 pyramidal cell synapses. In vivo long-term potentiation (LTP) at perforant pathway-CA1 pyramidal cell synapses was induced using a recording electrode attached to a microdialysis probe and the recording region was locally perfused with artificial cerebrospinal fluid (ACSF) via the microdialysis probe. Perforant pathway LTP was not attenuated under perfusion with CaEDTA (10 mM), an extracellular Zn 2+ chelator, but attenuated under perfusion with ZnAF-2DA (50 μM), an intracellular Zn 2+ chelator, suggesting that intracellular Zn 2+ signaling is required for perforant pathway LTP. Even in rat brain slices bathed in CaEDTA in ACSF, intracellular Zn 2+ level, which was measured with intracellular ZnAF-2, was increased in the stratum lacunosum-moleculare where perforant pathway-CA1 pyramidal cell synapses were contained after tetanic stimulation. These results suggest that intracellular Zn 2+ signaling, which originates in internal stores/proteins, is involved in LTP at perforant pathway-CA1 pyramidal cell synapses. Because the influx of extracellular Zn 2+ , which originates in presynaptic Zn 2+ release, is involved in LTP at Schaffer collateral-CA1 pyramidal cell synapses, synapse-dependent Zn 2+ dynamics may be involved in plasticity of postsynaptic CA1 pyramidal cells. © 2017 Wiley Periodicals, Inc.

The obesity crisis: don't blame it on the pyramid.

PubMed

Goldberg, Jeanne P; Belury, Martha A; Elam, Peggy; Finn, Susan Calvert; Hayes, Dayle; Lyle, Roseann; St Jeor, Sachiko; Warren, Michelle; Hellwig, Jennifer P

2004-07-01

Since its release in 1992, the Food Guide Pyramid has become one of the most recognized nutrition education tools in US history. As such, it has been subject to criticism, particularly in several recent media reports that implicate it as the culprit in America's current obesity epidemic. What these reports often overlook, however, is that the diets of many Americans do not adhere to the dietary guidelines illustrated by the Pyramid, refuting the notion that the Pyramid is the cause of the nation's obesity problem. Data indicate that the more likely causes of escalating obesity rates are increased per capita caloric consumption and larger portion sizes, along with a lack of adequate physical activity. Although the Pyramid graphic was designed more than a decade ago, it still communicates three key concepts that continue to be the cornerstone of federal dietary guidance: variety, proportionality, and moderation. As such, it remains a viable and relevant nutrition education tool, especially when used by dietetics professionals as a component of individualized, comprehensive nutrition education and behavior modification interventions. As the United States Department of Agriculture begins to investigate whether the food intake patterns illustrated by the Pyramid are in need of updating, research is urgently needed to determine how nutrition education tools, including the Pyramid, can be most effectively implemented to help consumers adopt healthful eating behaviors and to improve the public health of America.

Characterization and Effects of Fiber Pull-Outs in Hole Quality of Carbon Fiber Reinforced Plastics Composite.

PubMed

Alizadeh Ashrafi, Sina; Miller, Peter W; Wandro, Kevin M; Kim, Dave

2016-10-13

Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal.

An investigation of dynamic-analysis methods for variable-geometry structures

NASA Technical Reports Server (NTRS)

Austin, F.

1980-01-01

Selected space structure configurations were reviewed in order to define dynamic analysis problems associated with variable geometry. The dynamics of a beam being constructed from a flexible base and the relocation of the completed beam by rotating the remote manipulator system about the shoulder joint were selected. Equations of motion were formulated in physical coordinates for both of these problems, and FORTRAN programs were developed to generate solutions by numerically integrating the equations. These solutions served as a standard of comparison to gauge the accuracy of approximate solution techniques that were developed and studied. Good control was achieved in both problems. Unstable control system coupling with the system flexibility did not occur. An approximate method was developed for each problem to enable the analyst to investigate variable geometry effects during a short time span using standard fixed geometry programs such as NASTRAN. The average angle and average length techniques are discussed.

Integrating Early Childhood Mental Health Consultation with the Pyramid Model. Issue Brief

ERIC Educational Resources Information Center

Perry, Deborah F.; Kaufmann, Roxane K.

2009-01-01

A growing number of states and communities are implementing the Pyramid Model in early care and education settings, and in many of these places there are also early childhood mental health consultation (ECMHC) programs operating. This policy brief provides an overview of ECMHC, how it can support the implementation of the Pyramid Model and the…

The "Teaching Pyramid": A Model for the Implementation of Classroom Practices within a Program-Wide Approach to Behavior Support

ERIC Educational Resources Information Center

Hemmeter, Mary Louise; Fox, Lise

2009-01-01

The "Teaching Pyramid" (Fox, Dunlap, Hemmeter, Joseph, & Strain, 2003) is a framework for organizing evidence-based practices for promoting social-emotional development and preventing and addressing challenging behavior in preschool programs. In this article, we briefly describe the "Teaching Pyramid" as a framework for implementing effective…

An Empirical Comparison of Two-Stage and Pyramidal Adaptive Ability Testing.

ERIC Educational Resources Information Center

Larkin, Kevin C.; Weiss, David J.

A 15-stage pyramidal test and a 40-item two-stage test were constructed and administered by computer to 111 college undergraduates. The two-stage test was found to utilize a smaller proportion of its potential score range than the pyramidal test. Score distributions for both tests were positively skewed but not significantly different from the…

Putting the Pyramid into Practice. Science Topics.

ERIC Educational Resources Information Center

Texas Child Care, 1994

1994-01-01

Explains the new U.S. Department of Agriculture (USDA) Food Guide Pyramid, which can help children and adults visualize the basics of sound nutrition. The pyramid chart places five food groups from top to bottom in inverse proportion to the number of servings that should be consumed. Special symbols are used to indicate fat content and added…

Tribonacci-Like Sequences and Generalized Pascal's Pyramids

ERIC Educational Resources Information Center

Anatriello, Giuseppina; Vincenzi, Giovanni

2014-01-01

A well-known result of Feinberg and Shannon states that the tribonacci sequence can be detected by the so-called "Pascal's pyramid." Here we will show that any tribonacci-like sequence can be obtained by the diagonals of the "Feinberg's triangle" associated to a suitable "generalized Pascal's pyramid."…

Management Education and the Base of the Pyramid

ERIC Educational Resources Information Center

Gordon, Michael D.

2008-01-01

Doing business at the base of the pyramid is a topic of increasing interest to business practitioners and academics. Base of the pyramid business offers the promise of great economic gains for companies and the possibility of a powerful new approach to alleviate poverty. At the same time, it may threaten local culture and independence while…

Data Decision-Making and Program-Wide Implementation of the Pyramid Model. Roadmap to Effective Intervention Practices #7

ERIC Educational Resources Information Center

Fox, Lise; Veguilla, Myrna; Perez Binder, Denise

2014-01-01

The Technical Assistance Center on Social Emotional Intervention for Young Children (TACSEI) Roadmap on "Data Decision-Making and Program-Wide Implementation of the Pyramid Model" provides programs with guidance on how to collect and use data to ensure the implementation of the Pyramid Model with fidelity and decision-making that…

Effect of lures and colors on capture of lady beetles (coleoptera: coccinellidae) in tedders pyramidal traps

USDA-ARS?s Scientific Manuscript database

Purposeful attraction and/or aggregation of adult Coccinellidae at target sites would be useful for sampling purposes and/or pest suppression. We field-tested 1) lures in yellow and black pyramidal traps and 2) pyramidal traps that had been painted one or two colors (without lures) to determine if ...