Construction of Benzene Rings by Copper-Catalyzed Cycloaddition Reactions of Oximes and Maleimides: An Access to Fused Phthalimides.

PubMed

Yang, Jie; Zhao, Bo; Xi, Yue; Sun, Si; Yang, Zhen; Ye, Ying; Jiang, Kun; Wei, Ye

2018-02-16

A useful Cu-catalyzed cycloaddition protocol for the construction of benzene rings has been achieved. The reactions, utilizing readily available oximes and maleimides as starting materials, proceed under mild reaction conditions to generate a series of structurally interesting fused-phthalimides that are difficult to be prepared by conventional methods.

Organo-Lewis acid as cocatalyst for cationic homogeneous Ziegler-Natta olefin polymerizations

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2001-01-01

Organo-Lewis acids of the formula BR'R".sub.2 wherein B is boron, R' is fluorinated biphenyl, and R" is a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic fused ring group, and cationic metallocene complexes formed therewith. Such complexes are useful as polymerization catalysts.

Organo-Lewis acid as cocatalyst for cationic homogeneous Ziegler-Natta olefin polymerizations

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2002-01-01

Organo-Lewis acids of the formula BR'R".sub.2 wherein B is boron, R' is fluorinated biphenyl, and R" is a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic fused ring group, and cationic metallocene complexes formed therewith. Such complexes are useful as polymerization catalysts.

9-(3,4-Dimeth-oxy-phen-yl)-3,3,6,6-tetra-methyl-4,5,6,9-tetra-hydro-3H-xanthene-1,8(2H,7H)-dione.

PubMed

Mehdi, Sayed Hasan; Sulaiman, Othman; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-07-01

The asymmetric unit of the title xanthene compound, C(25)H(30)O(5), contains two mol-ecules in which the pyran ring and the dimeth-oxy-phenyl ring are nearly perpendicular to one another [dihedral angles = 86.81 (8) and 84.45 (9)°]. One of the meth-oxy groups in one mol-ecule is twisted away from the phenyl ring [C-O-C-C torsion angle = -103.40 (16)°]. The pyran ring adopts a boat conformation whereas the two fused cyclo-hexane rings adopt envelope conformations in both mol-ecules. In the crystal, mol-ecules are linked into a three-dimensional network by C-H⋯O hydrogen bonds.

Design of a New Fused-Ring Electron Acceptor with Excellent Compatibility to Wide-Bandgap Polymer Donors for High-Performance Organic Photovoltaics.

PubMed

Liu, Wenrui; Zhang, Jianyun; Zhou, Zichun; Zhang, Dongyang; Zhang, Yuan; Xu, Shengjie; Zhu, Xiaozhang

2018-05-16

Fused-ring electron acceptors (FREAs) have recently received intensive attention. Besides the continuing development of new FREAs, the demand for FREAs featuring good compatibility to donor materials is becoming more and more urgent, which is highly desirable for screening donor materials and achieving new breakthroughs. In this work, a new FREA is developed, ZITI, featuring an octacyclic dithienocyclopentaindenoindene central core. The core is designed by linking 2,7-dithienyl substituents and indenoindene with small methylene groups, in which the indeno[1,2-b]thiophene-2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile part provides a large and unoccupied π-surface. Most notably, ZITI possesses an excellent compatibility with commercially available polymer donors, delivering very high power conversion efficiencies of over 13%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toxicity Evaluation of Engineered Nanomaterials: Portable In Vitro Chamber to Study Realistic Occupational Exposure in Biological Systems (Phase 2 Studies)

DTIC Science & Technology

2012-01-12

the indole group contains a benzene ring fused with nitrogen containing a pyrrole ring, resulting in a delocalized π electron cloud. At the excitation...1.40 Ǻ, respectively. The C−C and C=C bond lengths of the pentagonal pyrrole ring of indole are 1.45 and 1.39 Ǻ, respectively. The C−C bond...indole- pyrrole 2.38 2.95 - Au − H 2.57 2.71 2.40 Dipole moment/D 5.97 3.78 7.44 HOMO−LUMO gap/eV 1.2 1.51 1.45 Mulliken charge/ē Au = -0.062 Trp

5-Amino-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde hemihydrate: a polarized electronic structure within hydrogen-bonded sheets of R(10)(8)(34) rings.

PubMed

Quiroga, Jairo; Trilleras, Jorge; Cobo, Justo; Glidewell, Christopher

2010-01-01

In the title compound, C(11)H(11)N(3)O.0.5H(2)O, the water molecule lies across a twofold rotation axis in the space group Pbcn. The bond distances in the organic component provide evidence for polarization of the electronic structure. The molecular components are linked into puckered sheets of R(10)(8)(34) rings by a combination of O-H...N and N-H...O hydrogen bonds; adjacent sheets are weakly linked by an aromatic pi-pi stacking interaction. Comparisons are made with some fused-ring analogues.

Triplet Tellurophene-Based Acceptors for Organic Solar Cells.

PubMed

Yang, Lei; Gu, Wenxing; Lv, Lei; Chen, Yusheng; Yang, Yufei; Ye, Pan; Wu, Jianfei; Hong, Ling; Peng, Aidong; Huang, Hui

2018-01-22

Triplet materials have been employed to achieve high-performing organic solar cells (OSCs) by extending the exciton lifetime and diffusion distances, while the triplet non-fullerene acceptor materials have never been reported for bulk heterojunction OSCs. Herein, for the first time, three triplet molecular acceptors based on tellurophene with different degrees of ring fusing were designed and synthesized for OSCs. Significantly, these molecules have long exciton lifetime and diffusion lengths, leading to efficient power conversion efficiency (7.52 %), which is the highest value for tellurophene-based OSCs. The influence of the extent of ring fusing on molecular geometry and OSCs performance was investigated to show the power conversion efficiencies (PCEs) continuously increased along with increasing the extent of ring fusing. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

1-Do-decyl-indoline-2,3-dione.

PubMed

Qachchachi, Fatima-Zahrae; Ouazzani Chahdi, Fouad; Misbahi, Houria; Bodensteiner, Michael; El Ammari, Lahcen

2014-02-01

The structure of the title compound, C20H29NO2, is isotypic to that of its homologue 1-octylindoline-2,3-dione. The indoline ring and the two carbonyl-group O atoms are approximately coplanar, the largest deviation from the mean plane being 0.0760 (10) Å. The mean plane through the fused-ring system is nearly perpendicular to the mean plane passing through the 1-dodecyl chain [dihedral angle = 77.69 (5)°]. All C atoms of the dodecyl group are in an anti-periplanar arrangement. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming a three-dimensional network.

π-Extended Star-Shaped Polycyclic Aromatic Hydrocarbons based on Fused Truxenes: Synthesis, Self-Assembly, and Facilely Tunable Emission Properties.

PubMed

Cheng, Cheng; Jiang, Yi; Liu, Cheng-Fang; Zhang, Jian-Dong; Lai, Wen-Yong; Huang, Wei

2016-12-19

A new set of star-shaped polycyclic aromatic hydrocarbons (PAHs) based on naphthalene-fused truxenes, TrNaCn (n=1-4), were synthesized and characterized. The synthesis involved a microwave-assisted six-fold Suzuki coupling reaction, followed by oxidative cyclodehydrogenation. Multiple dehydrocyclization products could be effectively isolated in a single reaction, thus suggesting that the oxidative cyclodehydrogenation reaction involved a stepwise ring-closing process. The thermal, optical, and electrochemical properties and the self-assembly behavior of the resulting oxidized samples were investigated to understand the impact of the ring-fusing process on the properties of the star-shaped PAHs. Distinct bathochromic shift of the absorption maxima (λ max ) revealed that the molecular conjugation extended with the stepwise ring-closing reactions. The optical band-gap energy of these PAHs varied significantly on increasing the number of fused rings, thereby resulting in readily tunable emissive properties of the resultant star-shaped PAHs. Interestingly, the generation of rigid "arms" by using perylene analogues caused TrNaC2 and TrNaC3 to show significantly enhanced photoluminescence quantum yields (PLQYs) in solution (η=0.65 and 0.66, respectively) in comparison with those of TrNa and TrNaC1 (η=0.08 and 0.16, respectively). Owing to strong intermolecular interactions, the TrNa precursor was able to self-assemble into rod-like microcrystals, which could be facilely identified by the naked eye, whilst TrNaC1 self-assembled into nanosheets once the naphthalene rings had fused. This study offers a unique platform to gain further insight into-and a better understanding of-the photophysical and self-assembly properties of π-extended star-shaped PAHs. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular building kit of fused-proline-derived peptide mimetics allowing specific adjustment of the dihedral Psi angle.

PubMed

Einsiedel, Juergen; Lanig, Harald; Waibel, Reiner; Gmeiner, Peter

2007-11-23

Proline-derived peptide mimetics have become an area of paramount importance in peptide and protein chemistry. Since protein crystal structures frequently display Psi angles of 140-170 degrees for prolyl moieties, our intention was to design a completely novel series of 2,3-fused-proline-derived lactams covering this particular conformational space. Extending our recently described toolset of spirocyclic reverse-turn mimetics, we synthesized pyrrolidinyl-fused seven-, eight-, and nine-membered unsaturated lactam model peptides taking advantage of Grubbs' ring-closing metathesis. Investigating the seven-membered lactam 3a by means of IR and NMR spectroscopy and semiempirical molecular dynamics simulations, we could not observe a U-turn conformation; however, increasing the ring size to give eight- and nine-membered congeners revealed moderate and high type IotaIota beta-turn inducing properties. Interestingly, the conformational properties of our model systems depend on both the ring size of the fused dehydro-Freidinger lactam and the position of the endocyclic double bond. Superior reverse-turn inducing properties could be observed for the fused azacyclononenone 3e. According to diagnostic transanular NOEs, a discrete folding principle of the lactam ring strongly deviating from the regioisomeric lactams 3c,f explains the conformational behavior. Hence, we were able to establish a molecular building kit that allows adjustments of a wide range of naturally occurring proline Psi angles and thus can be exploited to probe molecular recognition and functional properties of biological systems.

Double [4 + 2] cycloaddition reaction to approach a large acene with even-number linearly fused benzene rings: 6,9,16,19-tetraphenyl-1.20,4.5,10.11,14.15-tetrabenzooctatwistacene.

PubMed

Li, Junbo; Zhao, Yongbiao; Lu, Jing; Li, Gang; Zhang, Jingping; Zhao, Yang; Sun, Xiaowei; Zhang, Qichun

2015-01-02

It is more challenging to synthesize acenes with even-number fused benzene rings (AWEB) than acenes with odd-number fused benzene rings (AWOB) because AWEB are either synthetically asymmetric or the precursors to prepare AWEB are very difficult to obtain or to prepare from commercially available sources. In this work, we employed 2,6-naphthodiyne precursor (2) as an effective synthon to prepare a large AWEB, 6,9,16,19-tetraphenyl-1.20,4.5,10.11,14.15-tetrabenzooctatwistacene (1), through a simple, one-step, double [4 + 2] cycloaddition reaction. The physical properties of as-prepared octatwistacene (1) have been carefully studied, and the OLED performance of compound 1 was also investigated.

Synthesis and Characterization of Thianthrene-Based Polyamides

DTIC Science & Technology

1994-07-15

pyrrolidinone using triphenyl phosphite and pyridine. The fused-ring thianthrene-based polyamides were more soluble than analogous poly(thloether amide)s...pyrrolidinone using triphonyl phosphite and pyridine. The fused-ring thianthrene-based polyamides were more soluble than analogous poly(thloether amide)s...sodium hydroxide, and triphenyl phosphite (TPP) was vacuum distilled. UCI and CaCI2 were dried at 180 OC for 48 hours under vacuum. 4,4’-Oxydianiline

1-Do­decyl­indoline-2,3-dione

PubMed Central

Qachchachi, Fatima-Zahrae; Ouazzani Chahdi, Fouad; Misbahi, Houria; Bodensteiner, Michael; El Ammari, Lahcen

2014-01-01

The structure of the title compound, C20H29NO2, is isotypic to that of its homologue 1-octylindoline-2,3-dione. The indoline ring and the two carbonyl-group O atoms are approximately coplanar, the largest deviation from the mean plane being 0.0760 (10) Å. The mean plane through the fused-ring system is nearly perpendicular to the mean plane passing through the 1-dodecyl chain [dihedral angle = 77.69 (5)°]. All C atoms of the dodecyl group are in an anti­periplanar arrangement. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:24764928

Computational Prediction of One-Step Synthesis of Seven-membered Fused Rings by (5+2) Cycloaddition Utilising Cycloalkenes

NASA Astrophysics Data System (ADS)

Zhou, Chen-Chen; Ke, Xiao-Na; Xu, Xiu-Fang

2015-07-01

The (5+2) cycloaddition reaction utilising cycloalkenes is rare, although it is one of the most efficient methods of constructing seven-membered fused rings because of its high atom- and step-economy. In this study, we used quantum mechanical calculations to predict the plausibility of using the Rh-catalysed intermolecular (5+2) cycloaddition of 3-acyloxy-1,4-enynes and cycloalkenes to produce fused seven-membered carbocycles. The calculation results suggest a convenient, highly efficient and energetically practical approach. Strained cycloalkenes, such as cyclopropene, have been predicted to be active, and the desired bicyclic product should be favoured, accompanied by the formation of byproducts from rearrangement reactions. The energy barriers of the alkene insertion step were analysed by the distortion/interaction model to disclose the origins of the different reactivities of cycloalkenes with different ring sizes.

9-(3,4-Dimeth­oxy­phen­yl)-3,3,6,6-tetra­methyl-4,5,6,9-tetra­hydro-3H-xanthene-1,8(2H,7H)-dione

PubMed Central

Mehdi, Sayed Hasan; Sulaiman, Othman; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-01-01

The asymmetric unit of the title xanthene compound, C25H30O5, contains two mol­ecules in which the pyran ring and the dimeth­oxy­phenyl ring are nearly perpendicular to one another [dihedral angles = 86.81 (8) and 84.45 (9)°]. One of the meth­oxy groups in one mol­ecule is twisted away from the phenyl ring [C—O—C—C torsion angle = −103.40 (16)°]. The pyran ring adopts a boat conformation whereas the two fused cyclo­hexane rings adopt envelope conformations in both mol­ecules. In the crystal, mol­ecules are linked into a three-dimensional network by C—H⋯O hydrogen bonds. PMID:21837111

Influence of fused aromatic ring on the stability of charge transfer complex between iodine and some five membered heterocyclic molecules through ultrasonic and spectral studies

NASA Astrophysics Data System (ADS)

Ulagendran, V.; Balu, P.; Kannappan, V.; Kumar, R.; Jayakumar, S.

2017-08-01

The charge transfer (CT) interaction between two fused heterocyclic compounds with basic pyrrole group as donors, viz., indole (IND) and carbazole (CAR), and iodine (acceptor) in DMSO medium is investigated by ultrasonic and UV-visible spectral methods at 303 K. The formation of CT complex in these systems is established from the trend in acoustical and excess thermo acoustical properties with molar concentration. The frequency acoustic spectra (FAS) is also carried out on these two systems for two fixed concentrations 0.002 M and 0.02 M, and in the frequency range 1 MHz-10 MHz to justify the frequency chosen for ultrasonic study. The absorption coefficient values in solution are computed and discussed. The formation constants of these complexes are determined using Kannappan equation in ultrasonic method. The formation of 1:1 complexes between iodine and IND, CAR was established by the theory of Benesi - Hildebrand in the UV-visible spectroscopic method. The stability constants of the CT complexes determined by spectroscopic and ultrasonic methods show a similar trend. These values also indicate that the presence of fused aromatic ring influences significantly when compared with K values of similar CT complexes of parent five membered heterocyclic compound (pyrrole) reported by us earlier.

Crystal structure of 1-ferrocenyl-2-(4-methyl-benzo-yl)spiro-[11H-pyrrolidizine-3,11'-indeno[1,2-b]quinoxaline].

PubMed

Chandralekha, Kuppan; Gavaskar, Deivasigamani; Sureshbabu, Adukamparai Rajukrishnan; Lakshmi, Srinivasakannan

2014-09-01

In the title compound, [Fe(C5H5)(C34H28N3O)], the four-fused-rings system of the 11H-indeno-[1,2-b]quinoxaline unit is approximately planar [maximum deviation = 0.167 (4) Å] and forms a dihedral angle of 37.25 (6)° with the plane of the benzene ring of the methyl-benzoyl group. Both pyrrolidine rings adopt a twist conformation. An intra-molecular C-H⋯O hydrogen bond is observed. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions, forming double chains extending parallel to the c axis.

Influence of Bridgehead Substitution and Ring Annelation on the Photophysical Properties of Polycyclic DBO-Type Azoalkanes.

PubMed

Adam, Waldemar; Nikolaus, Achim; Sauer, Jürgen

1999-05-14

The photophysical data for the polycyclic, bridgehead-substituted derivatives 1-10 of the photoreluctant diazabicyclo[2.2.2]oct-2-ene (DBO) are presented. Substitution on the bridgehead positions with radical-stabilizing substituents enhances the photoreactivity (Phi(r)) and decreases the fluorescence quantum yields (Phi(f)) and lifetimes (tau) compared to the parent DBO. The annelated rings have no influence on the photoreactivity, except when steric interactions with an alpha substituent hinder the optimal radical-stabilizing conformation. The fused rings and some of the bridgehead substituents reduce the solvent-induced quenching of the singlet-excited azo chromophore by steric shielding of the azo group and, thus, increase the fluorescence quantum yields and lifetimes.

Barrier breaching device

DOEpatents

Honodel, Charles A.

1985-01-01

A barrier breaching device that is designed primarily for opening holes in interior walls of buildings uses detonating fuse for explosive force. The fuse acts as the ribs or spokes of an umbrella-like device that may be opened up to form a cone. The cone is placed against the wall so that detonating fuse that rings the base of the device and which is ignited by the spoke-like fuses serves to cut a circular hole in the wall.

Barrier breaching device

DOEpatents

Honodel, C.A.

1983-06-01

A barrier breaching device that is designed primarily for opening holes in interior walls of buildings uses detonating fuse for explosive force. The fuse acts as the ribs or spokes of an umbrella-like device that may be opened up to form a cone. The cone is placed against the wall so that detonating fuse that rings the base of the device and which is ignited by the spoke-like fuses serves to cut a circular hole in the wall.

Crystal structure of 1-(8-meth-oxy-2H-chromen-3-yl)ethanone.

PubMed

Koh, Dongsoo

2014-09-01

In the structure of the title compound, C12H12O3, the di-hydro-pyran ring is fused with the benzene ring. The di-hydro-pyran ring is in a half-chair conformation, with the ring O and methyl-ene C atoms positioned 1.367 (3) and 1.504 (4) Å, respectively, on either side of the mean plane formed by the other four atoms. The meth-oxy group is coplanar with the benzene ring to which it is connected [Cb-Cb-Om-Cm torsion angle = -0.2 (4)°; b = benzene and m = meth-oxy], and similarly the aldehyde is coplanar with respect to the double bond of the di-hydro-pyran ring [Cdh-Cdh-Ca-Oa = -178.1 (3)°; dh = di-hydro-pyran and a = aldehyde]. In the crystal, mol-ecules are linked by weak meth-yl-meth-oxy C-H⋯O hydrogen bonds into supra-molecular chains along the a-axis direction.

Combined quantum chemical density functional theory and spectroscopic Raman and UV-vis-NIR study of oligothienoacenes with five and seven rings.

PubMed

Osuna, Reyes Malavé; Zhang, Xinnan; Matzger, Adam Jay; Hernandez, Víctor; López Navarrete, Juan Teodomiro

2006-04-20

In this article, we report the characterization of novel oligothienoacenes with five and seven fused thiophene rings, materials with potential applications in organic electronics. In contrast to usual alpha-linked oligothiophenes, these fused oligothiophenes have a larger band gap than most semiconductors currently used in the fabrication of organic field-effect transistors (OFETs) and therefore they are expected to be more stable in air. The synthesis of these fused-ring oligomers was motivated by the notion that a more rigid and planar structure should reduce defects (such as torsion about single bonds between alpha-linked units or S-syn defects) and thus improve conjugation for better charge-carrier mobility. The conjugational properties of these two molecular materials have been investigated by means of FT-Raman spectroscopy, revealing that conjugation still increases in passing from the five-ring oligomer to that with seven-rings. DFT and TDDFT quantum chemical calculations have been performed, at the B3LYP/6-31G level, to assess information regarding the minimum-energy molecular structure, topologies, and absolute energies of the frontier molecular orbitals (MOs.) around the gap, vibrational normal modes related to the main Raman features, and vertical one-electron excitations giving rise to the main optical absorptions.

Carboxylic acid isosteres improve the activity of ring-fused 2-pyridones that inhibit pilus biogenesis in E. coli

PubMed Central

Åberg, Veronica; Das, Pralay; Chorell, Erik; Hedenström, Mattias; Pinkner, Jerome S.; Hultgren, Scott J.; Almqvist, Fredrik

2009-01-01

Ring-fused 2-pyridones, termed pilicides, are small synthetic compounds that inhibit pilus assembly in uropathogenic E. coli. Their biological activity is clearly dependent upon a carboxylic acid functionality. Here we present the synthesis and biological evaluation of carboxylic acid isosteres, including e.g. tetrazoles, acyl sulfonamides and hydroxamic acids, of two lead 2-pyridones. Two independent biological evaluations show that acyl sulfonamides and tetrazoles significantly improve pilicide activity against uropathogenic E. coli. PMID:18499455

Organo-Lewis acids of enhanced utility, uses thereof, and products based thereon

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2001-01-01

The organo-Lewis acids are novel triarylboranes which are highly fluorinated. Triarylboranes of one such type contain at least one ring substituent other than fluorine. These organoboranes have a Lewis acid strength essentially equal to or greater than that of the corresponding organoborane in which the substituent is replaced by fluorine, or have greater solubility in organic solvents. Another type of new organoboranes have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these triorganoboranes, because of their ligand abstracting properties, produce corresponding anions which are capable of only weakly, if at all, coordinating to the metal center, and thus do not interfere in various polymerization processes such as are described.

Organo-Lewis acids of enhanced utility, uses thereof, and products based thereon

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2002-01-01

The organo-Lewis acids are novel triarylboranes which are are highly fluorinated. Triarylboranes of one such type contain at least one ring substituent other than fluorine. These organoboranes have a Lewis acid strength essentially equal to or greater than that of the corresponding organoborane in which the substituent is replaced by fluorine, or have greater solubility in organic solvents. Another type of new organoboranes have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these triorganoboranes, because of their ligand abstracting properties, produce corresponding anions which are capable of only weakly, if at all, coordinating to the metal center, and thus do not interfere in various polymerization processes such as are described.

Structural, energetic, spectroscopic and QTAIM analyses of cation-π interactions involving mono- and bi-cyclic ring fused benzene systems.

PubMed

Hassan, Ayorinde; Dinadayalane, Tandabany C; Grabowski, Sławomir J; Leszczynski, Jerzy

2013-12-28

The effect of increasing the number of monocyclic six-membered rings or bicyclic rings of bicyclo[2.1.1]hexenyl fused to benzene on cation-π interactions involving alkali metal ions (Li(+), Na(+), and K(+)) has been investigated. The binding energy data at the B3LYP/6-311+G(2d,2p) level clearly indicate that the binding affinity of the metal ion with benzene is enhanced by increasing the number of rings fused irrespective of a monocyclic or a bicyclic ring. Calculated binding energies are in good agreement with the available experimental results. The binding strength of cations with ligands decreases in the order Li(+) > Na(+) > K(+). Our study establishes that trisannelation of bicyclo[2.1.1]hexene to benzene facilitates a very strong interaction between benzene and cations. Infrared (IR) frequencies and nuclear magnetic resonance (NMR) chemical shifts are shown to be valuable in characterizing cation-π interactions. The C-C bonds of the central six-membered rings are weakened due to metal ion binding. Based on the Quantum Theory of Atoms in Molecules (QTAIM), we have observed the presence of stabilizing H∙∙∙H interactions in two of the considered systems as opposed to the frequent description of these interactions as non-bonded repulsive interactions. Alkali metal ion binding with those two ligands slightly reduces the strength of such H∙∙∙H interactions.

3β,5α,6β-Trihy­droxy­androstan-17-one

PubMed Central

Andrade, L.C.R.; de Almeida, M.J.B.M.; Paixão, J.A.; Carvalho, J.F.S.; Sá e Melo, M.L.

2011-01-01

The title compound, C19H30O4, is an androstan-17-one derivative synthesized from the dehydro­epiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)3 (OTf is trifluoro­methane­sulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the mol­ecules are connected by O—H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree–Fock calculation of the free mol­ecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values. PMID:21754383

1-(Prop-2-yn-yl)indoline-2,3-dione.

PubMed

Qachchachi, Fatima-Zahrae; Ouazzani Chahdi, Fouad; Misbahi, Houria; Bodensteiner, Michael; El Ammari, Lahcen

2014-03-01

The structure of the title compound, C11H7NO2, is isotypic to that of its homologue, 1-octylindoline-2,3-dione [Qachchachi et al. (2013 ▶). Acta Cryst. E69, o1801]. The indoline ring and the two carbonyl O atoms are approximately coplanar, the largest deviation from the mean plane being 0.021 (1) Å for one of the O atoms. The mean plane through the fused ring system is nearly perpendicular to the propynyl group, as indicated by the N-C-C-C torsion angle of 77.9 (1)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and π-π inter-actions between benzene rings [inter-centroid distance = 3.5630 (10) Å], forming a three-dimensional structure.

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

Lee, Jongbok; Li, Huanbin; Kalin, Alexander J.

Well-defined, fused-ring aromatic oligomers represent promising candidates for the fundamental understanding and application of advanced carbon-rich materials, though bottom-up synthesis and structure–property correlation of these compounds remain challenging. In this work, an efficient synthetic route was employed to construct extended benzo[k]tetraphene-derived oligomers with up to 13 fused rings. The molecular and electronic structures of these compounds were clearly elucidated. Precise correlation of molecular sizes and crystallization dynamics was established, thus demonstrating the pivotal balance between intermolecular interaction and molecular mobility for optimized processing of highly ordered solids of these extended conjugated molecules.

Synthesis and structure-activity relationships of constrained heterocyclic analogues of combretastatin A4.

PubMed

Arthuis, Martin; Pontikis, Renée; Chabot, Guy G; Seguin, Johanne; Quentin, Lionel; Bourg, Stéphane; Morin-Allory, Luc; Florent, Jean-Claude

2011-09-05

A series of combretastatin A4 (CA4) analogues with a lactam or lactone ring fused to the trimethoxyphenyl or the B-phenyl moiety were synthesized in an efficient and stereoselective manner by using a domino Heck-Suzuki-Miyaura coupling reaction. The vascular-disrupting potential of these conformationally restricted CA4 analogues was assessed by various in vitro assays: inhibition of tubulin polymerization, modification of endothelial cell morphology, and disruption of endothelial cell cords. Compounds were also evaluated for their growth inhibitory effects against murine and human tumor cells. B-ring-constrained derivatives that contain an oxindole ring (in contrast to compounds with a benzofuranone ring) as well as analogues bearing a six-membered lactone core fused to the trimethoxyphenyl ring are endowed with significant biological activity. The most potent compound of this series (oxindole 9 b) is of particular interest, as it combines chemical stability and a biological activity profile characteristic of a vascular-disrupting agent. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fused-ring structure of decahydroisoquinolin as a novel scaffold for SARS 3CL protease inhibitors.

PubMed

Shimamoto, Yasuhiro; Hattori, Yasunao; Kobayashi, Kazuya; Teruya, Kenta; Sanjoh, Akira; Nakagawa, Atsushi; Yamashita, Eiki; Akaji, Kenichi

2015-02-15

The design and evaluation of a novel decahydroisoquinolin scaffold as an inhibitor for severe acute respiratory syndrome (SARS) chymotrypsin-like protease (3CL(pro)) are described. Focusing on hydrophobic interactions at the S2 site, the decahydroisoquinolin scaffold was designed by connecting the P2 site cyclohexyl group of the substrate-based inhibitor to the main-chain at the α-nitrogen atom of the P2 position via a methylene linker. Starting from a cyclohexene enantiomer obtained by salt resolution, trans-decahydroisoquinolin derivatives were synthesized. All decahydroisoquinolin inhibitors synthesized showed moderate but clear inhibitory activities for SARS 3CL(pro), which confirmed the fused ring structure of the decahydroisoquinolin functions as a novel scaffold for SARS 3CL(pro) inhibitor. X-ray crystallographic analyses of the SARS 3CL(pro) in a complex with the decahydroisoquinolin inhibitor revealed the expected interactions at the S1 and S2 sites, as well as additional interactions at the N-substituent of the inhibitor. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel stereocontrolled approach to syn- and anti-oxepene-cyclogeranyl trans-fused polycyclic systems: asymmetric total synthesis of (-)-Aplysistatin, (+)-Palisadin A, (+)-Palisadin B, (+)-12-hydroxy-palisadin B, and the AB ring system of adociasulfate-2 and toxicol A.

PubMed

Couladouros, Elias A; Vidali, Veroniki P

2004-08-06

A new stereocontrolled method for the formation of trans-anti cyclogeranyl-oxepene systems is described. The demanding stereochemistry is secured by stereoselective coupling of a cyclogeranyl tertiary alcohol with a 1,2-unsymmetrically substituted epoxide, while the formation of the highly strained oxepene is achieved employing ring-closing metathesis. Since the stereochemistry of the trans-fused 6,7-ring system is determined by the epoxide, the method also allows the construction of trans-syn 6,7-ring systems. This approach leads to the synthesis of the AB fragment of Adociasulfate-2 and Toxicol A, for the first time. The flexibility and efficiency of the presented strategy is demonstrated by the total asymmetric synthesis of (-)-Aplysistatin, (+)-Palisadin A, (+)-12-hydroxy-Palisadin B, and (+)-Palisadin B, employing two similar key intermediates.

1-(Prop-2-yn­yl)indoline-2,3-dione

PubMed Central

Qachchachi, Fatima-Zahrae; Ouazzani Chahdi, Fouad; Misbahi, Houria; Bodensteiner, Michael; El Ammari, Lahcen

2014-01-01

The structure of the title compound, C11H7NO2, is isotypic to that of its homologue, 1-octylindoline-2,3-dione [Qachchachi et al. (2013 ▶). Acta Cryst. E69, o1801]. The indoline ring and the two carbonyl O atoms are approximately coplanar, the largest deviation from the mean plane being 0.021 (1) Å for one of the O atoms. The mean plane through the fused ring system is nearly perpendicular to the propynyl group, as indicated by the N—C—C—C torsion angle of 77.9 (1)°. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds and π–π inter­actions between benzene rings [inter­centroid distance = 3.5630 (10) Å], forming a three-dimensional structure. PMID:24765046

Sequential allylic substitution/Pauson-Khand reaction: a strategy to bicyclic fused cyclopentenones from MBH-acetates of acetylenic aldehydes.

PubMed

Raji Reddy, Chada; Kumaraswamy, Paridala; Singarapu, Kiran K

2014-09-05

An efficient approach for the construction of novel bicyclic fused cyclopentenones starting from Morita-Baylis-Hillman (MBH) acetates of acetylenic aldehydes with flexible scaffold diversity has been achieved using a two-step reaction sequence involving allylic substitution and the Pauson-Khand reaction. This strategy provided a facile access to various bicyclic cyclopentenones fused with either a carbocyclic or a heterocyclic ring system in good yield.

Assembly of tissue engineered blood vessels with spatially-controlled heterogeneities.

PubMed

Strobel, Hannah A; Hookway, Tracy; Piola, Marco; Fiore, Gianfranco Beniamino; Soncini, Monica; Alsberg, Eben; Rolle, Marsha

2018-05-04

Tissue-engineered human blood vessels may enable in vitro disease modeling and drug screening to accelerate advances in vascular medicine. Existing methods for tissue engineered blood vessel (TEBV) fabrication create homogenous tubes not conducive to modeling the focal pathologies characteristic of vascular disease. We developed a system for generating self-assembled human smooth muscle cell ring-units, which were fused together into TEBVs. The goal of this study was to assess the feasibility of modular assembly and fusion of ring building units to fabricate spatially-controlled, heterogeneous tissue tubes. We first aimed to enhance fusion and reduce total culture time, and determined that reducing ring pre-culture duration improved tube fusion. Next, we incorporated electrospun polymer ring units onto tube ends as reinforced extensions, which allowed us to cannulate tubes after only 7 days of fusion, and culture tubes with luminal flow in a custom bioreactor. To create focal heterogeneities, we incorporated gelatin microspheres into select ring units during self-assembly, and fused these rings between ring units without microspheres. Cells within rings maintained their spatial position within tissue tubes after fusion. This work describes a platform approach for creating modular TEBVs with spatially-defined structural heterogeneities, which may ultimately be applied to mimic focal diseases such as intimal hyperplasia or aneurysm.

Design, Sustainable Synthesis, and Programmed Reactions of Templated N-Heteroaryl-Fused Vinyl Sultams.

PubMed

Laha, Joydev K; Sharma, Shubhra; Kirar, Seema; Banerjee, Uttam C

2017-09-15

A de novo design and synthesis of N-heteroaryl-fused vinyl sultams as templates for programming chemical reactions on vinyl sultam periphery or (hetero)aryl ring is described. The key features include rational designing and sustainable synthesis of the template, customized reactions of vinyl sultams at C═C bond or involving N-S bond cleavage, and reactions on the periphery of the heteroaryl ring for late-stage diversification. The simple, easy access to the template coupled with opportunities for the synthesis of diversely functionalized heterocyles from a single template constitutes a rare study in contemporary organic synthesis.

Synthesis and structure-activity relationship studies of furan-ring fused chalcones as antiproliferative agents.

PubMed

Saito, Yusuke; Kishimoto, Maho; Yoshizawa, Yuko; Kawaii, Satoru

2015-02-01

As part of our continuing investigation of flavonoid derivatives as potential anticancer substances, the synthesis of 25 cinnamoyl derivatives of benzofuran as furan-fused chalcones was carried-out and these compounds were further evaluated for their antiproliferative activity towards HL60 promyelocytic leukemia cells. In comparison with 2',4'-dihydroxychalcone, attachment of a furan moiety on the A-ring enhanced activity by more than twofold. Benzofurans may be useful in the design of biologically active flavonoids. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Interferometric measurement of the temperature dependence of an index of refraction: application to fused silica.

PubMed

Dupouy, Paul-Edouard; Büchner, Matthias; Paquier, Philippe; Trénec, Gérard; Vigué, Jacques

2010-02-01

The light reflected by an uncoated Fabry-Perot etalon presents dark rings which give a very sensitive measurement of the variations of the return optical path in the etalon. By measuring the diameters of these rings as a function of the etalon temperature T, we get a sensitive measurement of the derivative dn/dT of the index of refraction n. We have made this experiment with a fused silica etalon and we have achieved a 2% relative uncertainty on dn/dT, comparable to the uncertainty of the best experiments.

ent-Kaurane-Based Regio- and Stereoselective Inverse Electron Demand Hetero-Diels-Alder Reactions: Synthesis of Dihydropyran-Fused Diterpenoids†

PubMed Central

Ding, Chunyong; Wang, Lili; Chen, Haijun; Wild, Christopher; Ye, Na; Ding, Ye; Wang, Tianzhi; White, Mark A.; Shen, Qiang; Zhou, Jia

2014-01-01

A mild and concise approach for the construction of 3,4-dihydro-2H-pyran ring integrated into the A-ring of the natural product oridonin using an optimized inverse electron demand hetero-Diels-Alder (IED HDA) reaction is reported herein. A self-dimerization of the exocyclic enone installed in the A-ring through a homo-HDA reaction was identified to exclusively give a dimeric ent-kaurane diterpenoid with the spirochroman core. Moreover, the efficient cross-HDA cycloadditions of this enone with various vinyl ethers or vinyl sulfides, instead of its own homo-HDA dimerization, were achieved in regio- and stereoselective manners, thus providing the access to novel dihydropyran-fused diterpenoids as potential anticancer agents to overcome chemoresistance. PMID:25225052

Chemoselective N-heterocyclic carbene-catalyzed cross-benzoin reactions: importance of the fused ring in triazolium salts.

PubMed

Langdon, Steven M; Wilde, Myron M D; Thai, Karen; Gravel, Michel

2014-05-28

Morpholinone- and piperidinone-derived triazolium salts are shown to catalyze highly chemoselective cross-benzoin reactions between aliphatic and aromatic aldehydes. The reaction scope includes ortho-, meta-, and para-substituted benzaldehyde derivatives with a range of electron-donating and -withdrawing groups as well as branched and unbranched aliphatic aldehydes. Catalytic loadings as low as 5 mol % give excellent yields in these reactions (up to 99%).

Radical-mediated reduction of the dithiocarbamate group under tin-free conditions.

PubMed

McMaster, Claire; Bream, Robert N; Grainger, Richard S

2012-06-28

Reductive desulfurisation of dithiocarbamates is conveniently achieved using H(3)PO(2)-Et(3)N-ACCN in refluxing dioxane. Fused and spirocyclic β-lactams, prepared through 4-exo trig carbamoyl radical cyclisation-dithiocarbamate group transfer reactions, are reduced without fragmentation of the strained 4-membered ring. Diethyl tetraacetyl-d-glucopyranosyl dithiocarbamate is selectively reduced with or without acyloxy group migration depending on reaction conditions and choice of reductant. Deuterium incorporation from D(3)PO(2)-Et(3)N is observed for a system involving a nucleophilic radical intermediate, but not in the case of the electrophilic radical obtained through acyloxy group migration on a glucose derivative.

Reagent-based DOS: developing a diastereoselective methodology to access spirocyclic- and fused heterocyclic ring systems.

PubMed

Damerla, V Surendra Babu; Tulluri, Chiranjeevi; Gundla, Rambabu; Naviri, Lava; Adepally, Uma; Iyer, Pravin S; Murthy, Y L N; Prabhakar, Nampally; Sen, Subhabrata

2012-10-01

Herein, we report a diversity-oriented-synthesis (DOS) approach for the synthesis of biologically relevant molecular scaffolds. Our methodology enables the facile synthesis of fused N-heterocycles, spirooxoindolones, tetrahydroquinolines, and fused N-heterocycles. The two-step sequence starts with a chiral-bicyclic-lactam-directed enolate-addition/substitution step. This step is followed by a ring-closure onto the built-in scaffold electrophile, thereby leading to stereoselective carbocycle- and spirocycle-formation. We used in silico tools to calibrate our compounds with respect to chemical diversity and selected drug-like properties. We evaluated the biological significance of our scaffolds by screening them in two cancer cell-lines. In summary, our DOS methodology affords new, diverse scaffolds, thereby resulting in compounds that may have significance in medicinal chemistry. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembling, cystine-derived, fused nanotubes based on spirane architecture: design, synthesis, and crystal structure of cystinospiranes.

PubMed

Ranganathan, D; Samant, M P; Karle, I L

2001-06-20

A novel family of cystine-based spirobicyclic peptides (cystinospiranes) has been synthesized by a single-step procedure involving condensation of pentaerythritol-derived tetrachloride with either the simple L-cystine dimethyl ester or its C,C'-extended bispeptides leading to a variety of 19-membered spirobicyclic peptides or its N,N'-extended bispeptides affording the ring-expanded 25-membered cystinospiranes. The design is flexible with respect to the ring size that can be adjusted depending upon the length of the N,N'-extended cystine bispeptide, and the choice of an amino acid, as illustrated here with the preparation of a large number of cystinospiranes containing a wide variety of amino acids. X-ray crystal structure of the parent spirane (5a) revealed nanotube formation by vertical stacking of relatively flat spirobicyclic molecules through contiguous NH- - -O==C hydrogen bonding. The fused pair of parallel nanotubes is open-ended, hollow, and extends to infinity. Crystallographic parameters are the following: C(33)H(52)N(4)O(16)S(4), space group C2, a = 42.181(3) A, b = 5.1165(7) A, c = 11.8687(9) A, beta = 106.23(1) degrees.

Delayed cure bismaleimide resins

DOEpatents

Adams, Johnnie E.; Jamieson, Donald R.

1984-08-07

Polybismaleimides prepared by delayed curing of bis-imides having the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, Cl or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the --(CH.sub.2).sub.n -- group, optionally, is substituted by 1-3 methyl groups or by fluorine.

A new approach to construct a fused 2-ylidene chromene ring: highly regioselective synthesis of novel chromeno quinoxalines.

PubMed

Kumar, K Shiva; Rambabu, D; Prasad, Bagineni; Mujahid, Mohammad; Krishna, G Rama; Rao, M V Basaveswara; Reddy, C Malla; Vanaja, G R; Kalle, Arunasree M; Pal, Manojit

2012-06-28

Regioselective construction of a fused 2-ylidene chromene ring was achieved for the first time by using AlCl(3)-induced C-C bond formation followed by Pd/C-Cu mediate coupling-cyclization strategy. A number of chromeno[4,3-b]quinoxaline derivatives were prepared by using this strategy. Single crystal X-ray diffraction study of a representative compound e.g. 6-(2,2-dimethylpropylidene)-4-methyl-6H-chromeno[4,3-b]quinoxalin-3-ol confirmed the presence of an exocyclic C-C double bond with Z-geometry. The crystal structure analysis and hydrogen bonding patterns of the same compound along with its structure elaboration via propargylation followed by Sonogashira coupling of the resulting terminal alkyne is presented. A probable mechanism for the formation of 2-ylidene chromene ring is discussed. Some of the compounds synthesized showed anticancer properties when tested in vitro.

Stereostructure of a norbornane diexo-condensed 1,3-oxazine[2,3-a]isoindolone An X-ray study

NASA Astrophysics Data System (ADS)

Argay, Gy.; Kálmán, A.; Stájer, G.; Bernáth, G.

1994-12-01

The structure of 3,6-methano-12b-p-tolyl-2a,3,4,5,6,6a,7,12b-octahydro-2H-3,1-benzoxazino[2,3-a]isoindol-8-one (C23H23NO2, Mr = 345.42), prepared from 2-p-toluoylbenzoic acid and diexo-3-hydroxymethylbicyclo[2.2.1]heptyl-2-amine, has been established by X-ray crystallography from diffractometer data: it crystallizes in the triclinic space group Poverline1 with a = 8.186(2) Å, b = 8.683(2) Å, c = 13.324(5) Å, α = 83.46(4)°, β = 75.48(6)°, γ = 77.60(4)°, V = 893.6(4) Å3, Z = 2, Dc = 1.284 g cm-3 and μ(Cu Kα) = 0.641 mm-1. The structure was solved by direct methods and refined to R = 0.061 for 3685 observed reflections. The molecule exhibits diexo-annelation between the 1,3-oxazine ring and the norbornane moiety. The p-tolyl group and norbonane annelation hydrogens are trans and the 1,3-oxazine ring is fused to an almost planar γ-lactam ring. Consequently, the six-membered hetero ring assumes an irregular conformation among the canonical forms 1S6, 1T3 and B3,6.

Fundamental study of FC-72 pool boiling surface temperature fluctuations and bubble behavior

NASA Astrophysics Data System (ADS)

Griffin, Alison R.

A heater designed to monitor surface temperature fluctuations during pool boiling experiments while the bubbles were simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were micro-fabricated using the liftoff process to deposit the nickel and copper metal films. The TFTC elements were 50 mum wide and overlapped to form a 25 mum by 25 mum junction. TFTC voltages were recorded by a DAQ at a sampling rate of 50 kHz. A high-speed CCD camera recorded bubble images from below the heater at 2000 frames/second. A trigger sent to the camera by the DAQ synchronized the bubble images and the surface temperature data. As the bubbles and their contact rings grew over the TFTC junction, correlations between bubble behavior and surface temperature changes were demonstrated. On the heaters with fused silica insulation layers, 1--2°C temperature drops on the order of 1 ms occurred as the contact ring moved over the TFTC junction during bubble growth and as the contact ring moved back over the TFTC junction during bubble departure. These temperature drops during bubble growth and departure were due to microlayer evaporation and liquid rewetting the heated surface, respectively. Microlayer evaporation was not distinguished as the primary method of heat removal from the surface. Heaters with sapphire insulation layers did not display the measurable temperature drops observed with the fused silica heaters. The large thermal diffusivity of the sapphire compared to the fused silica was determined as the reason for the absence of these temperature drops. These findings were confirmed by a comparison of temperature drops in a 2-D simulation of a bubble growing over the TFTC junction on both the sapphire and fused silica heater surfaces. When the fused silica heater produced a temperature drop of 1.4°C, the sapphire heater produced a drop of only 0.04°C under the same conditions. These results verified that the lack of temperature drops present in the sapphire data was due to the thermal properties of the sapphire layer. By observing the bubble departure frequency and site density on the heater, as well as the bubble departure diameter, the contribution of nucleate boiling to the overall heat removal from the surface could be calculated. These results showed that bubble vapor generation contributed to approximately 10% at 1 W/cm2, 23% at 1.75 W/cm2, and 35% at 2.9 W/cm 2 of the heat removed from a fused silica heater. Bubble growth and contact ring growth were observed and measured from images obtained with the high-speed camera. Bubble data recorded on a fused silica heater at 3 W/cm2, 4 W/cm2, and 5 W/cm 2 showed that bubble departure diameter and lifetime were negligibly affected by the increase in heat flux. Bubble and contact ring growth rates demonstrated significant differences when compared on the fused silica and sapphire heaters at 3 W/cm2. The bubble departure diameters were smaller, the bubble lifetimes were longer, and the bubble departure frequency was larger on the sapphire heater, while microlayer evaporation was faster on the fused silica heater. Additional considerations revealed that these differences may be due to surface conditions as well as differing thermal properties. Nucleate boiling curves were recorded on the fused silica and sapphire heaters by adjusting the heat flux input and monitoring the local surface temperature with the TFTCs. The resulting curves showed a temperature drop at the onset of nucleate boiling due to the increase in heat transfer coefficient associated with bubble nucleation. One of the TFTC locations on the sapphire heater frequently experienced a second temperature drop at a higher heat flux. When the heat flux was started from 1 W/cm2 instead of zero or returned to zero only momentarily, the temperature overshoot did not occur. In these cases sufficient vapor remained in the cavities to initiate boiling at a lower superheat.

Design and Synthesis of Highly Potent HIV-1 Protease Inhibitors Containing Tricyclic Fused Ring Systems as Novel P2 Ligands: Structure-Activity Studies, Biological and X-ray Structural Analysis.

PubMed

Ghosh, Arun K; R Nyalapatla, Prasanth; Kovela, Satish; Rao, Kalapala Venkateswara; Brindisi, Margherita; Osswald, Heather L; Amano, Masayuki; Aoki, Manabu; Agniswamy, Johnson; Wang, Yuan-Fang; Weber, Irene T; Mitsuya, Hiroaki

2018-05-24

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2' ligands are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand-backbone interactions in the protease active site. Inhibitors 5c and 5d containing this unprecedented fused 6-5-5 ring system as the P2 ligand, an aminobenzothiazole as the P2' ligand, and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson-Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors.

The first stable lower fullerene: C{sub 36}

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

Piskoti, C.; Zettl, A.

1998-08-01

A new pure carbon material, presumably composed of thirty six carbon atom molecules, has been synthesized and isolated in milligram quantities. It appears as though these molecules have a closed cage structure making them the smallest member of a new class of molecules known as fullerenes, most notably of which is the soccer ball shaped C{sub 60}. However, unlike other known fullerenes, any closed, fullerene-like C{sub 36} cage will necessarily contain fused pentagon rings. Therefore, this molecule apparently violates the isolated pentagon rule, a criterion which requires isolated pentagons for stability in fullerene molecules. Striking parallels between this problem andmore » the synthesis of other fused five member fused ring systems will be discussed. Also, it will be shown that certain biological structures known as clathrin behave in a manner which gives excellent predictions about fullerenes and nanotubes. These predictions help to explain the presence of abundant quantities of C{sub 36} in arced graphite soot. {copyright} {ital 1998 American Institute of Physics.}« less

(Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2001-01-01

The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

The structure evolution of biochar from biomass pyrolysis and its correlation with gas pollutant adsorption performance.

PubMed

Chen, Yingquan; Zhang, Xiong; Chen, Wei; Yang, Haiping; Chen, Hanping

2017-12-01

Biochar is carbon-rich, porous and with a great potential in gas pollutant controlling. The physical-chemical structure of biochar is important for the application. This paper firstly reviewed the evolution behavior of physical-chemical structure for biochar during pyrolysis. At lower temperature (<500°C), biomass firstly transformed to "3D network of benzene rings" with abundant functional groups. With temperature increasing (500-700°C), it converted to "2D structure of fused rings" with abundant porosity. As temperature increasing further (>700°C), it may transit into a "graphite microcrystalline structure", the porosity and functional groups were diminished correspondingly. The modification of biochar and its application as sorbent for gas pollutant were also reviewed. Activation and doping can significantly increase the porosity and special functional groups in biochar, which is favorable for gas pollutant adsorption. With a higher porosity, the adsorption capacity of gas pollutant is bigger, however, the functional groups determined the sorption stability of gas pollutant. Copyright © 2017 Elsevier Ltd. All rights reserved.

(Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2002-01-01

The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

Rhodium(I)-catalyzed cyclization of allenynes with a carbonyl group through unusual insertion of a C-O bond into a rhodacycle intermediate.

PubMed

Oonishi, Yoshihiro; Yokoe, Takayuki; Hosotani, Akihito; Sato, Yoshihiro

2014-01-20

Rhodium(I)-catalyzed cyclization of allenynes with a tethered carbonyl group was investigated. An unusual insertion of a CO bond into the C(sp(2) )-rhodium bond of a rhodacycle intermediate occurs via a highly strained transition state. Direct reductive elimination from the obtained rhodacyle intermediate proceeds to give a tricyclic product containing an 8-oxabicyclo[3.2.1]octane skeleton, while β-hydride elimination from the same intermediate gives products that contain fused five- and seven-membered rings in high yields. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gold (III) Chloride-Catalyzed 6-endo-trig Oxa-Michael Addition Reactions for Diastereoselective Synthesis of Fused Tetrahydropyranones

PubMed Central

Ciesielski, Jennifer; Lebœuf, David; Stern, Harry A.

2013-01-01

Alkynones were treated with boron trifluoride diethyl etherate to generate β-iodoallenolates, which underwent intramolecular aldol reactions to produce cycloalkenyl alcohols. Diastereoselective oxa-Michael ring closure could then be induced by treatment with a catalytic amount of gold(III) chloride, affording highly functionalized tetrahydropyran-containing ring systems. PMID:24032002

Anti-cancer agents based on N-acyl-2, 3-dihydro-1H-pyrrolo[2,3-b] quinoline derivatives and a method of making

DOEpatents

Gakh, Andrei; Krasavin, Mikhail; Karapetian, Ruben; Rufanov, Konstantin A; Konstantinov, Igor; Godovykh, Elena; Soldatkina, Olga; Sosnov, Andrey V

2013-04-16

The present disclosure relates to novel compounds that can be used as anti-cancer agents in the prostate cancer therapy. In particular, the invention relates to N-acyl derivatives of 2,3-dihydro-1H-pyrrolo[2,3-b]quinolines having the structural Formula (I), ##STR00001## stereoisomers, tautomers, racemics, prodrugs, metabolites thereof, or pharmaceutically acceptable salt and/or solvate thereof. The meaning of R1 is independently selected from H; C1-C6 Alkyl, cyclo-Alkyl or iso-Alkyl substituents; R2 is selected from C1-C6 Alkyl, cyclo-Alkyl or iso-Alkyl; substituted or non-substituted, fused or non-fused to substituted or non-substituted aromatic ring, aryl or heteroaryl groups. The invention also relates to methods for preparing said compounds, and to pharmaceutical compositions comprising said compounds.

Tannins and terpenoids as major precursors of Suwannee River fulvic acid

USGS Publications Warehouse

Leenheer, Jerry A.; Rostad, Colleen E.

2004-01-01

Suwannee River fulvic acid (SRFA) was fractionated into 7 fractions by normal-phase chromatography on silica gel followed by reverse-phase fractionation on XAD-8 resin that produced 18 subfractions. Selected major subfractions were characterized by 13C-nuclear magnetic resonance (NMR), infrared spectrometry, and elemental analyses. 13C-NMR spectra of the subfractions were more indicative of precursor structures than unfractionated SRFA, and gave spectral profiles that indicated SRFA mass was about equally split between tannin precursors and terpenoid precursors. Lignin precursors were minor components. Synthesis of 13C-NMR data with elemental data for subfractions derived from both tannin and terpenoid precursors revealed high ring contents and low numbers of carbon per rings which is indicative of fused ring structures that are extensively substituted with carboxyl and methyl groups. These results ruled out extended chain structures for SRFA. This information is useful for determining sources and properties of fulvic acid in drinking water supplies as tannins are more reactive with chlorine to produce undesirable disinfection by-products than are terpenoids.

Ethyl 2-(4-meth-oxy-phen-yl)-6-oxa-3-aza-bicyclo[3.1.0]hexane-3-carboxyl-ate: crystal structure and Hirshfeld analysis.

PubMed

Zukerman-Schpector, Julio; Sugiyama, Fabricia H; Garcia, Ariel L L; Correia, Carlos Roque D; Jotani, Mukesh M; Tiekink, Edward R T

2017-07-01

The title compound, C 14 H 17 NO 4 , features an epoxide-O atom fused to a pyrrolidyl ring, the latter having an envelope conformation with the N atom being the flap. The 4-meth-oxy-phenyl group is orthogonal to [dihedral angle = 85.02 (6)°] and lies to the opposite side of the five-membered ring to the epoxide O atom, while the N-bound ethyl ester group (r.m.s. deviation of the five fitted atoms = 0.0187 Å) is twisted with respect to the ring [dihedral angle = 17.23 (9)°]. The most prominent inter-actions in the crystal are of the type methine-C-H⋯O(carbon-yl) and these lead to the formation of linear supra-molecular chains along the c axis; weak benzene-C-H⋯O(epoxide) and methine-C-H⋯O(meth-oxy) inter-actions connect these into a three-dimensional architecture. The analysis of the Hirshfeld surface confirms the presence of C-H⋯O inter-actions in the crystal, but also the dominance of H⋯H dispersion contacts.

SPECIAL ISSUE DEVOTED TO THE 80TH BIRTHDAY OF S.A. AKHMANOV: Discrete conical emission rings observed upon filamentation of a femtosecond laser pulse in quartz

NASA Astrophysics Data System (ADS)

Dormidonov, A. E.; Kandidov, V. P.; Kompanets, V. O.; Chekalin, Sergei V.

2009-07-01

Supercontinuum emission observed upon filamentation of transform-limited collimated femtosecond laser pulses in a transparent condensed medium (fused KU-1 quartz) is studied experimentally and numerically. The splitting of diverging conical supercontinuum emission into discrete rings was observed with increasing the pulse energy.

1,2,3-Triphenyl-1,2-dihydro­quinoxaline

PubMed Central

Edelmann, Frank T.; Blaurock, Steffen; Lorenz, Volker; Fischer, Axel

2008-01-01

The title compound, C26H20N2, first reported in 1891, was obtained as a by-product in the preparation of benzildianil from benzil and excess aniline. The dihedral angles between the fused benzene ring and the pendant phenyl rings are 17.93 (11), 53.18 (10) and 89.08 (12)°. PMID:21201177

Synthesis of Benzo[a]carbazoles and an Indolo[2,3-a]carbazole from 3-Aryltetramic Acids.

PubMed

Truax, Nathanyal J; Banales Mejia, Fernando; Kwansare, Deborah O; Lafferty, Megan M; Kean, Maeve H; Pelkey, Erin T

2016-08-05

A simple and flexible approach to 3-pyrrolin-2-one fused carbazoles is disclosed. The key step involves the BF3-mediated electrophilic substitution of indoles with N-alkyl-substituted 3-aryltetramic acids, which provides access to indole-substituted 3-pyrrolin-2-ones. Scholl-type oxidative cyclizations of these materials led to the formation of the corresponding 3-pyrrolin-2-one-fused benzo[a]carbazoles and indolo[2,3-a]carbazoles. This work represents the first synthesis of the benzo[a]pyrrolo[3,4-c]carbazol-3(8H)-one ring system, while the indolo[2,3-a]pyrrolo[3,4-c]carbazol-5-one ring system is found in a number of biologically active compounds including the protein kinase C (PKC) inhibitor, staurosporine.

Tricyclic [1,2,4]triazine 1,4-dioxides as hypoxia selective cytotoxins.

PubMed

Hay, Michael P; Hicks, Kevin O; Pchalek, Karin; Lee, Ho H; Blaser, Adrian; Pruijn, Frederik B; Anderson, Robert F; Shinde, Sujata S; Wilson, William R; Denny, William A

2008-11-13

A series of novel tricyclic triazine-di- N-oxides (TTOs) related to tirapazamine have been designed and prepared. A wide range of structural arrangements with cycloalkyl, oxygen-, and nitrogen-containing saturated rings fused to the triazine core, coupled with various side chains linked to either hemisphere, resulted in TTO analogues that displayed hypoxia-selective cytotoxicity in vitro. Optimal rates of hypoxic metabolism and tissue diffusion coefficients were achieved with fused cycloalkyl rings in combination with both the 3-aminoalkyl or 3-alkyl substituents linked to weakly basic soluble amines. The selection was further refined using pharmacokinetic/pharmacodynamic model predictions of the in vivo hypoxic potency (AUC req) and selectivity (HCD) with 12 TTO analogues predicted to be active in vivo, subject to the achievement of adequate plasma pharmacokinetics.

Tricyclic [1,2,4]Triazine 1,4-Dioxides As Hypoxia Selective Cytotoxins

PubMed Central

Hay, Michael P.; Hicks, Kevin O.; Pchalek, Karin; Lee, Ho H.; Blaser, Adrian; Pruijn, Frederik B.; Anderson, Robert F.; Shinde, Sujata S.; Wilson, William R.; Denny, William A.

2009-01-01

A series of novel tricyclic triazine-di-N-oxides (TTOs) related to tirapazamine have been designed and prepared. A wide range of structural arrangements with cycloalkyl, oxygen- and nitrogen-containing saturated rings fused to the triazine core, coupled with various side chains linked to either hemisphere, resulted in TTO analogues that displayed hypoxia-selective cytotoxicity in vitro. Optimal rates of hypoxic metabolism and tissue diffusion coefficients were achieved with fused cycloalkyl rings in combination with both the 3-aminoalkyl or 3-alkyl substituents linked to weakly basic soluble amines. The selection was further refined using pharmacokinetic/pharmacodynamic model predictions of the in vivo hypoxic potency (AUCreq) and selectivity (HCD) with 12 TTO analogues predicted to be active in vivo, subject to the achievement of adequate plasma pharmacokinetics. PMID:18847185

Theoretical investigation on the chemoselective N-heterocyclic carbene-catalyzed cross-benzoin reactions.

PubMed

Liu, Tao; Han, Shu-Min; Han, Ling-Li; Wang, Lu; Cui, Xiang-Yang; Du, Chong-Yang; Bi, Siwei

2015-03-28

A density functional theory study was performed to understand the detailed mechanisms of the cross-benzoin reactions catalyzed by N-heterocyclic carbene (NHC) species. Our theoretical study predicted that the first H-transfer operates with water in solution as a mediator, and the second H-transfer undergoes a concerted mechanism rather than a stepwise one. In addition, the chemoselectivity of the reactions studied in this work has been explored. P1 was obtained as a major product mainly due to the more stable intermediate formed by reaction of NHC with reactant R1. Different steric effects resulting from the fused six-membered ring in transition state TS7 and the fused five-membered ring in transition state TS13 are the origin leading to the chemoselectivity.

Synthesis of Structurally Diverse 2,3-Fused Indoles via Microwave-Assisted AgSbF6-Catalysed Intramolecular Difunctionalization of o-Alkynylanilines

PubMed Central

Huang, Yuanqiong; Yang, Yan; Song, Hongjian; Liu, Yuxiu; Wang, Qingmin

2015-01-01

2,3-Fused indoles are found in numerous natural products and drug molecules. Although several elegant methods for the synthesis of this structural motif have been reported, long reaction times and harsh conditions are sometimes required, and the yields tend to be low. Herein, we report a microwave method for straightforward access to various types of 2,3-fused indoles via AgSbF6-catalysed intramolecular difunctionalization of o-alkynylanilines. AgSbF6 played a role in both the hydroamination step and the imine-formation step. This method, which exhibited excellent chemoselectivity (no ring-fused 1,2-dihydroquinolines were formed), was used for formal syntheses of the natural products conolidine and ervaticine and the antihistamine drug latrepirdine. PMID:26310858

5Beta,6beta-epoxy-17-oxoandrostan-3beta-yl acetate and 5beta,6beta-epoxy-20-oxopregnan-3beta-yl acetate.

PubMed

Pinto, Rui M A; Salvador, Jorge A R; Paixão, José A

2008-05-01

In the title compounds, C(21)H(30)O(4), (I), and C(23)H(34)O(4), (II), respectively, which are valuable intermediates in the synthesis of important steroid derivatives, rings A and B are cis-(5beta,10beta)-fused. The two molecules have similar conformations of rings A, B and C. The presence of the 5beta,6beta-epoxide group induces a significant twist of the steroid nucleus and a strong flattening of the B ring. The different C17 substituents result in different conformations for ring D. Cohesion of the molecular packing is achieved in both compounds only by weak intermolecular interactions. The geometries of the molecules in the crystalline environment are compared with those of the free molecules as given by ab initio Roothan Hartree-Fock calculations. We show in this work that quantum mechanical ab initio methods reproduce well the details of the conformation of these molecules, including a large twist of the steroid nucleus. The calculated twist values are comparable, but are larger than the observed values, indicating a possible small effect of the crystal packing on the twist angles.

2,4,8,10,13-Penta­methyl-6-phenyl-13,14-dihydro-12H-6λ5-dibenzo[d,i][1,3,7,2]dioxaza­phosphecin-6-thione

PubMed Central

Krishnaiah, M.; Babu, V.H.H. Surendra; Sankar, A. Uma Ravi; Raju, C. Naga; Kant, Rajni

2010-01-01

In the title compound, C25H28NO2PS, the cyclo­decene ring exhibits a crown conformation. The two dimethyl­benzene rings which are fused symmetrically on either side of the ten-membered ring, make dihedral angles of 20.2 (1) and 18.0 (1)°. The phenyl ring substituted at P is perpendicular to the heterocyclic ring, making a dihedral angle of 88.4 (1)°. The crystal structure is stabilized by very weak intra­molecular C—H⋯O hydrogen bonding. PMID:21580010

(Polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

DOEpatents

Marks, Tobin J.; Chen, You-Xian

2001-01-01

The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interefere in the ethylene polymerization process, while affecting the the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

Can Baird's and Clar's Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4nπ- and (4n + 2)π-Rings?

PubMed

Ayub, Rabia; Bakouri, Ouissam El; Jorner, Kjell; Solà, Miquel; Ottosson, Henrik

2017-06-16

Compounds that can be labeled as "aromatic chameleons" are π-conjugated compounds that are able to adjust their π-electron distributions so as to comply with the different rules of aromaticity in different electronic states. We used quantum chemical calculations to explore how the fusion of benzene rings onto aromatic chameleonic units represented by biphenylene, dibenzocyclooctatetraene, and dibenzo[a,e]pentalene modifies the first triplet excited states (T 1 ) of the compounds. Decreases in T 1 energies are observed when going from isomers with linear connectivity of the fused benzene rings to those with cis- or trans-bent connectivities. The T 1 energies decreased down to those of the parent (isolated) 4nπ-electron units. Simultaneously, we observe an increased influence of triplet state aromaticity of the central 4n ring as given by Baird's rule and evidenced by geometric, magnetic, and electron density based aromaticity indices (HOMA, NICS-XY, ACID, and FLU). Because of an influence of triplet state aromaticity in the central 4nπ-electron units, the most stabilized compounds retain the triplet excitation in Baird π-quartets or octets, enabling the outer benzene rings to adapt closed-shell singlet Clar π-sextet character. Interestingly, the T 1 energies go down as the total number of aromatic cycles within a molecule in the T 1 state increases.

High-density human mesenchymal stem cell rings with spatiotemporally-controlled morphogen presentation as building blocks for engineering bone diaphyseal tissue

PubMed Central

Herberg, Samuel; Varghai, Daniel; Cheng, Yuxuan; Dikina, Anna D.; Dang, Phuong N.; Rolle, Marsha W.; Alsberg, Eben

2018-01-01

Emerging biomimetic tissue engineering strategies aim to partially recapitulate fundamental events that transpire during embryonic skeletal development; namely, cellular self-organization and targeted morphogenetic pathway activation. Here, we describe self-assembled, scaffold-free human mesenchymal stem cell (hMSC) rings featuring microparticle-mediated presentation of transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2). We tested the hypothesis that spatiotemporally-controlled dual presentation of TGF-β1 and BMP-2 is superior in modulating in vitro endochondral ossification of high-density cellular constructs compared to single morphogen delivery. hMSC rings were engineered by seeding cells with microparticles presenting (1) TGF-β1, (2) BMP-2, or (3) TGF-β1 + BMP-2 in custom agarose wells to facilitate self-assembly within 2 d, followed by horizontal culture on glass tubes for 5 weeks. At day 2, hMSC rings across groups revealed homogenous cellular organization mimetic of early mesenchymal condensation with no evidence of new matrix or mineral deposition. Significant early chondrogenic and osteogenic priming occurred with TGF-β1 + BMP-2 presentation compared to single morphogen-loaded groups. By week 5, TGF-β1-loaded hMSC rings had undergone chondrogenesis, while presentation of BMP-2 alone or in conjunction with TGF-β1 stimulated chondrogenesis, chondrocyte hypertrophy, and osteogenesis indicative of endochondral ossification. Importantly, tissue mineralization was most compelling with TGF-β1 + BMP-2 loading. Lastly, hMSC ring 'building blocks' were shown to efficiently fuse into tubes within 6 d post self-assembly. The resulting tubular tissue units exhibited structural integrity, highlighting the translational potential of this advanced biomimetic technology for potential early implantation in long bone defects. PMID:29577017

9-(3,4-Dimeth-oxy-phen-yl)-3,4,5,6,7,9-hexa-hydroxanthene-1,8(2H)-dione.

PubMed

Mehdi, Sayed Hasan; Hashim, Rokiah; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-06-01

In the title compound, C(21)H(22)O(5), the mean planes of the pyran and dimeth-oxy-phenyl rings are nearly perpendicular to one another, with the dihedral angle between them being 88.21 (8)°. The pyran ring adopts a boat conformation whereas the two fused cyclo-hexane rings adopt envelope conformations. In the crystal, mol-ecules are linked into a three-dimensional network by inter-molecular C-H⋯O hydrogen bonds.

1-[(6-Chloro-3-pyrid­yl)meth­yl]-5-eth­oxy-8-nitro-1,2,3,5,6,7-hexa­hydro­imidazo[1,2-a]pyridine

PubMed Central

Tian, Zhongzhen; Li, Dongmei; Li, Zhong

2009-01-01

In the title compound, C15H19ClN4O3, an active agrochemical possessing insecticidal activity, the dihedral angle between the mean planes passing through the pyridine ring and the five-membered ring is 87.3 (2)°. The fused pyridine ring adopts a twisted sofa conformation. The mol­ecular structure features close intra­molecular C—H⋯N and C—H⋯O hydrogen bonding. PMID:21577964

Fused-Ring Acceptors with Asymmetric Side Chains for High-Performance Thick-Film Organic Solar Cells.

PubMed

Feng, Shiyu; Zhang, Cai'e; Liu, Yahui; Bi, Zhaozhao; Zhang, Zhe; Xu, Xinjun; Ma, Wei; Bo, Zhishan

2017-11-01

A kind of new fused-ring electron acceptor, IDT-OB, bearing asymmetric side chains, is synthesized for high-efficiency thick-film organic solar cells. The introduction of asymmetric side chains can increase the solubility of acceptor molecules, enable the acceptor molecules to pack closely in a dislocated way, and form favorable phase separation when blended with PBDB-T. As expected, PBDB-T:IDT-OB-based devices exhibit high and balanced hole and electron mobility and give a high power conversion efficiency (PCE) of 10.12%. More importantly, the IDT-OB-based devices are not very sensitive to the film thickness, a PCE of 9.17% can still be obtained even the thickness of active layer is up to 210 nm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diosgenin hemihydrate

PubMed Central

Hernández Linares, María-Guadalupe; Bernès, Sylvain; Flores-Alamo, Marcos; Guerrero-Luna, Gabriel; Martínez-Gallegos, Anselmo A.

2012-01-01

Diosgenin [or (22R,25R)-spirost-5-en-3β-ol] is the starting material of the Marker degradation, a cheap semi-synthesis of progesterone, which has been designated as an Inter­national Historic Chemical Landmark. Thus far, a single X-ray structure for diosgenin is known, namely its dimethyl sulfoxide solvate [Zhang et al. (2005 ▶). Acta Cryst. E61, o2324–o2325]. We have now determined the structure of the hemihydrate, C27H42O3·0.5H2O. The asymmetric unit contains two diosgenin mol­ecules, with quite similar conformations, and one water mol­ecule. Hy­droxy groups in steroids and water mol­ecules form O—H⋯O hydrogen-bonded R 5 4(10) ring motifs. Fused edge-sharing R(10) rings form a backbone oriented along [100], which aggregates the diosgenin mol­ecules in the crystal structure. PMID:22904823

N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-meth­oxy­benzene­sulfonamide hemi­hydrate

PubMed Central

Chicha, Hakima; Kouakou, Assoman; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N—N—C—C torsion angle of 79.2 (3)°. In the crystal, the water mol­ecule, lying on a twofold axis, forms O—H⋯N and accepts N—H⋯O hydrogen bonds. Additional C—H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction. PMID:24109418

N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide hemi-hydrate.

PubMed

Chicha, Hakima; Kouakou, Assoman; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N-N-C-C torsion angle of 79.2 (3)°. In the crystal, the water mol-ecule, lying on a twofold axis, forms O-H⋯N and accepts N-H⋯O hydrogen bonds. Additional C-H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction.

7-Meth­oxy-2-phenyl­chroman-4-one

PubMed Central

Piaskowska, Agata; Hodorowicz, Maciej; Nitek, Wojciech

2013-01-01

In the title compound, C16H14O3, the ring O atom and the two adjacent non-fused C atoms, as well as the attached phenyl ring, exhibit static disorder [occupancy ratio 0.559 (12):0.441 (12)]. The crystal packing features π–π [centroid–centroid distance = 3.912 (1) Å] and C—H⋯π inter­actions. PMID:23424545

2-Propyl-4H-thia­zolo[3,2-a][1,3,5]triazine-4-thione

PubMed Central

Yunus, Uzma; Tahir, Muhammad Kalim; Bhatti, Moazzam Hussain; Wong, Wai-Yeung

2008-01-01

In the title compound, C8H9N3S2, the n-propyl chain is disordered over two orientations (site-occupancy ratio = 0.522:0.478) and is roughly perpendicular to the fused thia­zolotriazine system. The angle between the fused ring and the propyl chain is 83.6 (1)° [ 82.2 (1)° for the disordered chain]. The structure is stabilized by C—H⋯N hydrogen bonds. PMID:21202112

Ir-Catalyzed, Silyl-Directed, peri-Borylation of C-H Bonds in Fused Polycyclic Arenes and Heteroarenes.

PubMed

Su, Bo; Hartwig, John F

2018-05-20

peri-Disubstituted naphthalenes exhibit interesting physical properties and unique chemical reactivity, due to the parallel arrangement of the bonds to the two peri-disposed substituents. Regioselective installation of a functional group at the position peri to 1-substituted naphthalenes is challenging due to the steric interaction between the existing substituent and the position at which the second one would be installed. We report an iridium-catalyzed borylation of the C-H bond peri to a silyl group in naphthalenes and analogous polyaromatic hydrocarbons. The reaction occurs under mild conditions with wide functional group tolerance. The silyl group and the boryl group in the resulting products are precursors to a range of functional groups bound to the naphthalene ring through C-C, C-O, C-N, C-Br and C-Cl bonds. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Solution-Processable Molecule using Thieno[3,2-b]thiophene as Building Block for Efficient Organic Solar Cells.

PubMed

Wei, Huan; Chen, Weichao; Han, Liangliang; Wang, Ting; Bao, Xichang; Li, Xiaoyun; Liu, Jie; Zhou, Yuanhang; Yang, Renqiang

2015-08-01

A solution-processed acceptor-π-donor-π-acceptor (A-π-D-π-A) type small molecule, namely DCATT, has been designed and synthesized for the application as donor material in organic solar cells. The fused aromatic unit thieno[3,2-b]thiophene (TT) flanked with thiophene is applied as π bridge, while 4,8-bisthienyl substituted benzodithiophene (BDT) and 2-ethylhexyl cyanoacetate are chosen as the central building block and end group, respectively. Introduction of fused ring to the small molecule enhances the conjugation length of the main chain, and gives a strong tendency to form π-π stacking with a large overlapping area which favors to high charge carrier transport. Small-molecule organic solar cells based on blends of DCATT and fullerene acceptor exhibit power conversion efficiencies as high as 5.20 % under the illumination of AM 1.5G, 100 mW cm(-2) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unexpected regioselective carbon-hydrogen bond activation/cyclization of indolyl aldehydes or ketones with alkynes to benzo-fused oxindoles.

PubMed

Liu, Xingyan; Li, Gaocan; Song, Feijie; You, Jingsong

2014-09-25

Rhodium-catalyzed carbon-hydrogen bond activation has attracted great interest in the construction of carbon-carbon and carbon-heteroatom bonds. In recent years, transition metal-mediated oxygen transposition through a 'dehydration-rehydration' process has been considered as a promising strategy towards oxygen-functionalized compounds. Here we describe an unexpected rhodium-catalyzed regioselective carbon-hydrogen bond activation/cyclization of easily available indolyl aldehydes or ketones with alkynes to afford benzo-fused oxindoles, involving the sequential carbonyl-assisted carbon-hydrogen activation of the indole ring at the 4-position, [4+2] cyclization, aromatization via dehydration, nucleophilic addition of water to iminium and oxidation. Isotopic labelling experiments disclose the occurrence of apparent oxygen transposition via dehydration-rehydration from the indolyl-3-carbonyl group to the 2-position of pyrrole to forge a new carbonyl bond. The tandem reaction has been used as the key step for the concise synthesis of priolines, a type of alkaloid isolated from the roots of Salvia prionitis.

Regioselective intramolecular Pauson-Khand reactions of C60: an electrochemical study and theoretical underpinning.

PubMed

Martín, Nazario; Altable, Margarita; Filippone, Salvatore; Martín-Domenech, Angel; Poater, Albert; Solà, Miquel

2005-04-22

Suitably functionalized fulleropyrrolidines endowed with one or two propargyl groups at the C-2 position of the pyrrolidine ring (1,6-enynes) react efficiently and regioselectively with [Co2(CO)8] to afford the respective Pauson-Khand products with an unprecedented three (5 a-d, 7, and 24) or five (25) pentagonal rings, respectively, fused onto the fullerene sphere. Fulleropyrrolidines with 1,7-, 1,9-, 1,10-, or 1,11-enyne moieties do not undergo the PK reaction and, instead, the intermediate dicobalt complexes formed with the alkynyl group are isolated in quantitative yields. These differences in reactivity have been studied by DFT calculations with a generalized gradient approximation (GGA) functional and several important energy and structural differences were found for the intermediates formed by the interaction between the coordinatively unsaturated Co atom and the pi system of C60 in 1,6- and 1,7-enynes. The different lengths of the alkyne chains are responsible for the observed reactivities. Cyclic voltammetry reveals that the presence of the cyclopentenone's carbonyl group connected directly to the C60 core results in PK compounds with remarkable electron-accepting ability.

Bismaleimide compounds

DOEpatents

Adams, J.E.; Jamieson, D.R.

1986-01-14

Bismaleimides of the formula shown in the diagram wherein R[sub 1] and R[sub 2] each independently is H, C[sub 1-4]-alkyl, C[sub 1-4]-alkoxy, Cl or Br, or R[sub 1] and R[sub 2] together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R[sub 1] and R[sub 2] are not t-butyl or t-butoxy; X is O, S or Se; n is 1--3; and the alkylene bridging group, optionally, is substituted by 1--3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

Bismaleimide compounds

DOEpatents

Adams, Johnnie E.; Jamieson, Donald R.

1986-01-14

Bismaleimides of the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, C1 or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the alkylene bridging group, optionally, is substituted by 1-3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

3-Ethyl-5-(4-meth­oxy­phen­oxy)-2-(pyridin-4-yl)-3H-imidazo[4,5-b]pyridine

PubMed Central

Ranjith, S.; SubbiahPandi, A.; Suresh, A. D.; Pitchumani, K.

2011-01-01

In the title compound, C20H18N4O2, the imidazopyridine fused ring system is almost perpendicular to the benzene ring [dihedral angle = 87.6 (5)°]. The pyridine ring makes a dihedral angle of 35.5 (5)° with the mean plane of the imidazopyridine fragment. The crystal structure is stabilized by an aromatic π–π stacking inter­action between the phenyl rings of neighbouring mol­ecules [centroid–centroid distance = 3.772 (2) Å, inter­planar distance = 3.546 (2) Å and slippage = 1.286 (2) Å]. PMID:21837144

Crystal structure of 3-amino-1-(4-meth-oxy-phen-yl)-1H-benzo[f]chromene-2-carbo-nitrile.

PubMed

Mohamed, Shaaban K; Horton, Peter N; Akkurt, Mehmet; Younes, Sabry H H; Albayati, Mustafa R

2015-07-01

In the title compound, C21H16N2O2, the meth-oxy-benzene ring is almost perpendicular to the mean plane of the naphthalene ring system, making a dihedral angle of 83.62 (5)°. The 4H-pyran ring fused with the naphthalene ring system is almost planar [maximum deviation = 0.033 (1) Å]. In the crystal, mol-ecules are linked into inversion dimers by pairs of N-H⋯N hydrogen bonds. N-H⋯O hydrogen bonds connect the dimers, forming a helical supra-molecular chain along the a-axis direction. The crystal packing also features C-H⋯π inter-actions.

Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxabicyclo[3.1.0]hexane Scaffold | Center for Cancer Research

Cancer.gov

Beginning with a known 3-oxabicyclo[3.1.0]-hexane scaffold, the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel

Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors.

PubMed

Chen, Hu; Hurhangee, Michael; Nikolka, Mark; Zhang, Weimin; Kirkus, Mindaugas; Neophytou, Marios; Cryer, Samuel J; Harkin, David; Hayoz, Pascal; Abdi-Jalebi, Mojtaba; McNeill, Christopher R; Sirringhaus, Henning; McCulloch, Iain

2017-09-01

The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm 2 V -1 s -1 in bottom-gate top-contact organic field-effect transistors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

9-(3,4-Dimeth­oxy­phen­yl)-3,4,5,6,7,9-hexa­hydroxanthene-1,8(2H)-dione

PubMed Central

Mehdi, Sayed Hasan; Hashim, Rokiah; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-01-01

In the title compound, C21H22O5, the mean planes of the pyran and dimeth­oxy­phenyl rings are nearly perpendicular to one another, with the dihedral angle between them being 88.21 (8)°. The pyran ring adopts a boat conformation whereas the two fused cyclo­hexane rings adopt envelope conformations. In the crystal, mol­ecules are linked into a three-dimensional network by inter­molecular C—H⋯O hydrogen bonds. PMID:21754824

Spontaneous symmetry breaking by double lithium adsorption in polyacenes

NASA Astrophysics Data System (ADS)

Ortiz, Yenni. P.; Seligman, Thomas H.

2010-12-01

We show that adsorption of one lithium atom to polyacenes, i.e. chains of linearly fused benzene rings, will cause such chains to be slightly deformed. If we adsorb a second identical atom on the opposite side of the same ring, this deformation is dramatically enhanced despite the fact that a symmetric configuration seems possible. We argue, that this may be due to an instability of the Jahn-Teller type possibly indeed to a Peierls instability.

Spontaneous symmetry breaking by double lithium adsorption in polyacenes

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

Ortiz, Yenni. P.; Seligman, Thomas H.; Centro Internacional de Ciencias, Cuernavaca, Morelos

2010-12-23

We show that adsorption of one lithium atom to polyacenes, i.e. chains of linearly fused benzene rings, will cause such chains to be slightly deformed. If we adsorb a second identical atom on the opposite side of the same ring, this deformation is dramatically enhanced despite the fact that a symmetric configuration seems possible. We argue, that this may be due to an instability of the Jahn-Teller type possibly indeed to a Peierls instability.

Determination of Acid Dissociation Constants (pKa) of Bicyclic Thiohydantoin-Pyrrolidine Compounds in 20% Ethanol-Water Hydroorganic Solvent

PubMed Central

Nural, Yahya; Döndaş, H. Ali; Sarı, Hayati; Atabey, Hasan; Belveren, Samet; Gemili, Müge

2014-01-01

The acid dissociation constants of potential bioactive fused ring thiohydantoin-pyrrolidine compounds were determined by potentiometric titration in 20% (v/v) ethanol-water mixed at 25 ± 0.1°C, at an ionic background of 0.1 mol/L of NaCl using the HYPERQUAD computer program. Proton affinities of potential donor atoms of the ligands were calculated by AM1 and PM3 semiempiric methods. We found, potentiometrically, three different acid dissociation constants for 1a–f. We suggest that these acid dissociation constants are related to the carboxyl, enol, and amino groups. PMID:24799905

Sophopterocarpan A, a novel pterocarpine derivative with a benzotetrahydrofuran-fused bicyclo [3.3.1] nonane from Sophora flavescens.

PubMed

Zhu, Hui; Yang, Ya-Nan; Xu, Kuo; Xie, Jing; Feng, Zi-Ming; Jiang, Jian-Shuang; Zhang, Pei-Cheng

2017-07-05

Sophopterocarpan A (1), with a novel benzotetrahydrofuran-fused bicyclo [3.3.1] nonane ring, was isolated from the roots of Sophora flavescens Ait. Its unusual structure, including its stereochemistry, was determined on the basis of a comprehensive spectroscopic data analysis. A plausible biogenetic pathway for 1 is presented. Sophopterocarpan A was identified as a potential autophagy activator. Additionally, it was found that 1 exhibited cytotoxic activity in MCF-7 cells with an IC 50 of 29.36 μM.

[Evaluation of bond strength between low fusing porcelain with goldplated cobalt-chromium alloys].

PubMed

Guo, Jing; Zhu, Jia; Zhu, Hong-shui

2014-02-01

To evaluate the bond strength of Vita OMEGA 900 low fusing porcelain fused with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. Low fusing porcelain was fused with the cobalt-chromium alloy strips(group A) and the goldplated cobalt-chromium alloy strips(group B) respectively according to ISO9693 (A:8,B:10). 8 specimens of each group were submitted to three point bending test. Two more test pieces fused with gold plated cobalt-chromium alloys were made (group B'). One test piece of both group B and group B' were observed under scanning electron microscope (SEM) randomly. The data was analyzed with SPSS 16.0 software package. The bond strength (MPa) of group A and group B was 29.92±4.28 and 28.20±5.21, respectively (P>0.05), both higher than 25 MPa required by ISO9693. SEM showed that Vita OMEGA 900 low fusing porcelain and the goldplated Wirobond cobalt-chrome metalt ceramic alloy combined together closely without cracks. Much gold was fused to the cobalt-chrome alloy surface of breaking porcelain specimen after testing. Vita OMEGA 900 low fusing porcelain can match with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. Supported by Foundation of Education Department of Jiangxi Province (GJJ10367).

AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar

PubMed Central

Patrut, Adrian; Patrut, Roxana T.; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Lowy, Daniel A.; von Reden, Karl F.

2016-01-01

The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old. PMID:26760300

AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar.

PubMed

Patrut, Adrian; Patrut, Roxana T; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Lowy, Daniel A; von Reden, Karl F

2016-01-01

The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old.

Ring-rearrangement metathesis of nitroso Diels-Alder cycloadducts.

PubMed

Vincent, Guillaume; Kouklovsky, Cyrille

2011-03-01

Strained nitroso Diels-Alder bicyclo[2.2.1] or [2.2.2] adducts functionalized with alkene side chains of diverse length undergo a ring-rearrangement metathesis process with external alkenes and Grubbs II or Hoveyda-Grubbs II ruthenium catalysts, under microwave irradiation or classical heating, to deliver cis-fused bicycles of various ring sizes, which contain a N-O bond. These scaffolds are of synthetic relevance for the generation of molecular diversity and to the total synthesis of alkaloids. The observation of unexpected reactions, such as epimerization or one-carbon homologation of the alkene side chain, is also reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

N-(1H-Indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-10-26

In the title compound, C14H13N3O3S, the fused ring system is almost planar, the largest deviation from the mean plane being 0.023 (2) Å, and makes a dihedral angle of 47.92 (10)° with the benzene ring of the benzene-sulfonamide moiety. In the crystal, mol-ecules are connected through N-H⋯O hydrogen bonds and weak C-H⋯O contacts, forming a two-dimensional network which is parallel to (010).

N-(3-Chloro-1H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-10-12

In the title compound, C14H12ClN3O3S, the fused five- and six-membered rings are folded slightly along the common edge, forming a dihedral angle of 3.2 (1)°. The mean plane through the indazole system makes a dihedral angle of 30.75 (7)° with the distant benzene ring. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules, forming a two-dimensional network parallel to (001).

Synthesis of Tricyclo[4,3,1,0(1,5)]decane Core of Plumisclerin A Using Pauson-Khand Annulation and SmI2-Mediated Radical Cyclization.

PubMed

Chen, Ji-Peng; He, Wei; Yang, Zhen-Yu; Yao, Zhu-Jun

2015-07-17

An efficient synthesis of the tricyclo[4,3,1,0(1, 5)]decane core (B/C/D rings) of plumisclerin A, a unique cytotoxic marine diterpenoid, is described. A Pauson-Khand reaction and a SmI2-mediated radical 1,4-conjugate addition successfully served as key reactions for construction of the fully functionalized 5,6-fused rings and the highly strained cyclobutanol moiety with correct relative stereochemistries, respectively.

Implementation of GPC characterization of asphalt binders at Louisiana materials laboratory : tech summary.

DOT National Transportation Integrated Search

2013-10-01

Asphalt is a mixture of a wide variety of chemical compounds that include aliphatic hydrocarbons and highly fused : aromatic ring systems. They are classi ed as asphaltenes (medium molecular weight) and maltenes (low molecular : weight). To improv...

4,5,7,8,17-Penta-hydr-oxy-14,18-dimethyl-6-methyl-ene-3,10-dioxapenta-cyclo-[9.8.0.0.0.0]nona-dec-14-ene-9,16-dione methanol solvate dihydrate.

PubMed

Teh, Chin Hoe; Teoh, Siew Chin; Yeap, Chin Sing; Chan, Kit Lam; Fun, Hoong-Kun

2009-03-28

The title quassinoid compound, C(20)H(24)O(9)·CH(3)OH·2H(2)O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The mol-ecules contain a fused five-ring system, with one tetra-hydro-furan ring adopting an envelope conformation, one tetra-hydro-pyran-2-one ring in a screw boat conformation, one cyclo-hexenone ring in a half-chair conformation and two cyclo-hexane rings in chair conformations. Intra-molecular C-H⋯O inter-actions generate S(5) ring motifs and an O-H⋯O inter-action generates an S(7) ring motif. In the crystal, mol-ecules are linked via inter-molecular O-H⋯O inter-actions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, R.; Nelson, P.A.; Shimotake, H.; Battles, J.E.

1983-07-26

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Hermetically sealed electrical feedthrough for high temperature secondary cells

DOEpatents

Knoedler, Reinhard; Nelson, Paul A.; Shimotake, Hiroshi; Battles, James E.

1985-01-01

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Catalytic asymmetric synthesis of chiral propargylic alcohols for the intramolecular Pauson-Khand cycloaddition.

PubMed

Turlington, Mark; Yue, Yang; Yu, Xiao-Qi; Pu, Lin

2010-10-15

Several methods for the catalytic asymmetric alkyne addition to aldehydes are used to prepare the propargylic alcohol-based chiral en-ynes. Protection of the propargylic alcohols with either an acetyl or a methyl group allows the resulting en-ynes to undergo the intramolecular Pauson-Khand reaction to form the corresponding optically active 5,5- and 5,6-fused bicyclic products with high diastereoselectivity and high enantiomeric purity. In the major product, the propargylic substituent and the bridgehead hydrogen are cis with respect to each other on the fused bicyclic rings. The enantiomeric purity of the propargylic alcohols generated from the asymmetric alkyne addition is maintained in the cycloaddition products. The allylic ethers of the chiral propargylic alcohols are prepared which can also undergo the highly diastereoselective Pauson-Khand cycloaddition with retention of the high enantiomeric purity. This study has shown that the size of the substituents at the propargylic position as well as on the alkyne is important for the diastereoselectivity with the greater bulkiness of the substituents giving higher diastereoselectivity.

Modulation of α-synuclein fibrillization by ring-fused 2-pyridones: templation and inhibition involve oligomers with different structure.

PubMed

Horvath, Istvan; Sellstedt, Magnus; Weise, Christoph; Nordvall, Lina-Maria; Krishna Prasad, G; Olofsson, Anders; Larsson, Göran; Almqvist, Fredrik; Wittung-Stafshede, Pernilla

2013-04-15

In a recent study we discovered that a ring-fused 2-pyridone compound triggered fibrillization of a key protein in Parkinson's disease, α-synuclein. To reveal how variations in compound structure affect protein aggregation, we now prepared a number of strategic analogs and tested their effects on α-synuclein amyloid fiber formation in vitro. We find that, in contrast to the earlier templating effect, some analogs inhibit α-synuclein fibrillization. For both templating and inhibiting compounds, the key species formed in the reactions are α-synuclein oligomers that contain compound. Despite similar macroscopic appearance, the templating and inhibiting oligomers are distinctly different in secondary structure content. When the inhibitory oligomers are added in seed amounts, they inhibit fresh α-synuclein aggregation reactions. Our study demonstrates that small chemical changes to the same central fragment can result in opposite effects on protein aggregation. Copyright © 2013 Elsevier Inc. All rights reserved.

Estimating the densities of benzene-derived explosives using atomic volumes.

PubMed

Ghule, Vikas D; Nirwan, Ayushi; Devi, Alka

2018-02-09

The application of average atomic volumes to predict the crystal densities of benzene-derived energetic compounds of general formula C a H b N c O d is presented, along with the reliability of this method. The densities of 119 neutral nitrobenzenes, energetic salts, and cocrystals with diverse compositions were estimated and compared with experimental data. Of the 74 nitrobenzenes for which direct comparisons could be made, the % error in the estimated density was within 0-3% for 54 compounds, 3-5% for 12 compounds, and 5-8% for the remaining 8 compounds. Among 45 energetic salts and cocrystals, the % error in the estimated density was within 0-3% for 25 compounds, 3-5% for 13 compounds, and 5-7.4% for 7 compounds. The absolute error surpassed 0.05 g/cm 3 for 27 of the 119 compounds (22%). The largest errors occurred for compounds containing fused rings and for compounds with three -NH 2 or -OH groups. Overall, the present approach for estimating the densities of benzene-derived explosives with different functional groups was found to be reliable. Graphical abstract Application and reliability of average atom volume in the crystal density prediction of energetic compounds containing benzene ring.

N-(1-Allyl-1H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Abderrafia, Hafid; Saadi, Mohamed; El Ammari, Lahcen

2013-11-30

The asymmetric unit of the title compound, C17H17N3O2S, contains two independent mol-ecules linked by an N-H⋯O hydrogen bond. The mol-ecules show different conformations. In the first mol-ecule, the fused five- and six-membered ring system is almost perpendicular to the plane through the atoms forming the allyl group, as indicated by the dihedral angle of 85.1 (4)°. The dihedral angle with the methyl-benzene-sulfonamide group is 78.8 (1)°. On the other hand, in the second mol-ecule, the dihedral angles between the indazole plane and the allyl and methyl-benzene-sulfonamide groups are 80.3 (3) and 41.5 (1)°, respectively. In the crystal, mol-ecules are further linked by N-H⋯N and C-H⋯O hydrogen bonds, forming a three-dimensional network.

Fused dithienogermolodithiophene low band gap polymers for high-performance organic solar cells without processing additives.

PubMed

Zhong, Hongliang; Li, Zhe; Deledalle, Florent; Fregoso, Elisa Collado; Shahid, Munazza; Fei, Zhuping; Nielsen, Christian B; Yaacobi-Gross, Nir; Rossbauer, Stephan; Anthopoulos, Thomas D; Durrant, James R; Heeney, Martin

2013-02-13

We report the synthesis of a novel ladder-type fused ring donor, dithienogermolodithiophene, in which two thieno[3,2-b]thiophene units are held coplanar by a bridging dialkyl germanium. Polymerization of this extended monomer with N-octylthienopyrrolodione by Stille polycondensation afforded a polymer, pDTTG-TPD, with an optical band gap of 1.75 eV combined with a high ionization potential. Bulk heterojunction solar cells based upon pDTTG-TPD:PC(71)BM blends afforded efficiencies up to 7.2% without the need for thermal annealing or processing additives.

The 1:1 inclusion compounds zolmitriptan-benzene and zolmitriptan-phenol.

PubMed

Swamy, G Y S K; Sridhar, B; Ravikumar, K; Krishnan, Harihara

2007-07-01

In the benzene and phenol solvates of (S)-4-{3-[2-(dimethylamino)ethyl]-1H-indol-5-ylmethyl}oxazolidin-2-one, viz. C(16)H(21)N(3)O(2) x C(6)H(6), (I), and C(16)H(21)N(3)O(2) x C(6)H(5)OH, (II), the host molecule has three linked residues, namely a planar indole ring system, an ethylamine side chain and an oxazolidinone system. It has comparable features to that of sumatriptan, although the side-chain orientations of (I) and (II) differ from those of sumatriptan. Both (I) and (II) have host-guest-type structures. The host molecule in (I) and (II) has an L-shaped form, with the oxazolidinone ring occupying the base and the remainder of the molecule forming the upright section. In (I), each benzene guest molecule is surrounded by four host molecules, and these molecules are linked by a combination of N-H...N, N-H...O and C-H...O hydrogen bonds into chains of edge-fused R(4)(4)(33) rings. In (II), two independent molecules are present in the asymmetric unit, with similar conformations. The heterocyclic components are connected through N-H...N, N-H...O and C-H...O interactions to form chains of edge-fused R(6)(4)(38) rings, from which the phenol guest molecules are pendent, linked by O-H...O hydrogen bonds. The structures are further stabilized by extensive C-H...pi interactions.

Monolithic optofluidic ring resonator lasers created by femtosecond laser nanofabrication.

PubMed

Chandrahalim, Hengky; Chen, Qiushu; Said, Ali A; Dugan, Mark; Fan, Xudong

2015-05-21

We designed, fabricated, and characterized a monolithically integrated optofluidic ring resonator laser that is mechanically, thermally, and chemically robust. The entire device, including the ring resonator channel and sample delivery microfluidics, was created in a block of fused-silica glass using a 3-dimensional femtosecond laser writing process. The gain medium, composed of Rhodamine 6G (R6G) dissolved in quinoline, was flowed through the ring resonator. Lasing was achieved at a pump threshold of approximately 15 μJ mm(-2). Detailed analysis shows that the Q-factor of the optofluidic ring resonator is 3.3 × 10(4), which is limited by both solvent absorption and scattering loss. In particular, a Q-factor resulting from the scattering loss can be as high as 4.2 × 10(4), suggesting the feasibility of using a femtosecond laser to create high quality optical cavities.

Contemplating the ultimate sacrifice: identity fusion channels pro-group affect, cognition, and moral decision making.

PubMed

Swann, William B; Gómez, Angel; Buhrmester, Michael D; López-Rodríguez, Lucía; Jiménez, Juan; Vázquez, Alexandra

2014-05-01

Although most people acknowledge the moral virtue in sacrificing oneself to save others, few actually endorse self-sacrifice. Seven experiments explored the cognitive and emotional mechanisms that underlie such endorsements. Participants responded to 1 of 2 moral dilemmas in which they could save 5 members of their country only by sacrificing themselves. Over 90% of participants acknowledged that the moral course of action was to sacrifice oneself to save others (Experiment 1), yet only those who were strongly fused with the group preferentially endorsed self-sacrifice (Experiments 2-7). The presence of a concern with saving group members rather than the absence of a concern with self-preservation motivated strongly fused participants to endorse sacrificing themselves for the group (Experiment 3). Analyses of think aloud protocols suggested that saving others was motivated by emotional engagement with the group among strongly fused participants but by utilitarian concerns among weakly fused participants (Experiment 4). Hurrying participants' responses increased self-sacrifice among strongly fused participants but decreased self-sacrifice among weakly fused participants (Experiment 5). Priming the personal self increased endorsement of self-sacrifice among strongly fused participants but further reduced endorsement of self-sacrifice among weakly fused participants (Experiment 6). Strongly fused participants ignored utilitarian considerations, but weakly fused persons endorsed self-sacrifice more when it would save more people (Experiment 7). Apparently, the emotional engagement with the group experienced by strongly fused persons overrides the desire for self-preservation and compels them to translate their moral beliefs into self-sacrificial behavior.

Efficient approach to androstene-fused arylpyrazolines as potent antiproliferative agents. Experimental and theoretical studies of substituent effects on BF(3)-catalyzed intramolecular [3 + 2] cycloadditions of olefinic phenylhydrazones.

PubMed

Frank, Eva; Mucsi, Zoltán; Zupkó, István; Réthy, Borbála; Falkay, George; Schneider, Gyula; Wölfling, János

2009-03-25

Highly diastereoselective Lewis acid induced intramolecular 1,3-dipolar cycloadditions of alkenyl phenylhydrazones (containing various substituents on the aromatic ring) obtained from a d-secopregnene aldehyde were carried out under fairly mild conditions to furnish androst-5-ene-fused arylpyrazolines in good to excellent yields. The ability of phenylhydrazones to undergo cyclization was found to be affected significantly by the electronic features of the substituents on the aromatic moiety. The rates of the ring-closure reactions were observed to be increased by electron-donating and decreased by electron-withdrawing groups. The experimental findings on the BF(3)-catalyzed transformations were supported by calculations of the proposed mechanism at the BLYP/6-31G(d) level of theory, indicating a noteworthy dependence, mainly of the initial complexation step, and hence of the whole process, on the character of the substituent. The cycloaddition was estimated to occur via a zwitterionic intermediate rather than involving a pure concerted mechanism. The antiproliferative activities of the structurally related pyrazoline derivatives were tested in vitro on three malignant human cell lines (HeLa, MCF7, and A431): the microculture tetrazolium assay revealed that several compounds exerted marked cell growth-inhibitory effects. The highest cytotoxic activities, displayed by the p-methoxyphenylpyrazoline derivative 7d (IC(50) values: 2.01, 2.16, and 1.41 microM on HeLa, MCF7, and A341 cells, respectively), were better than those of cisplatin (IC(50) values: 12.43, 9.63, and 2.84 microM, respectively).

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

Brennan, Mathew D.; Spencer, Michelle J. S., E-mail: t-morishita@aist.go.jp, E-mail: michelle.spencer@rmit.edu.au; Morishita, Tetsuya, E-mail: t-morishita@aist.go.jp, E-mail: michelle.spencer@rmit.edu.au

Silicene is a relatively new material consisting of a two-dimensional sheet of silicon atoms. Functionalisation of silicene with different chemical groups has been suggested as a way to tune its electronic properties. In this work, density functional theory calculations and ab initio molecular dynamics simulations are used to examine the effects of functionalisation with naphthyl or anthracyl groups, which are two examples of small polycyclic aromatic hydrocarbons (PAHs). Different attachment positions on the naphthyl and anthracyl groups were compared, as well as different thicknesses of the silicene nanosheet. It was found that the carbon attachment position farthest from the bondmore » fusing the aromatic rings gave the more stable structures for both functional groups. All structures showed direct band gaps, with tuning of the band gap being achievable by increasing the length of the PAH or the thickness of the silicene. Hence, modifying the functional group or thickness of the silicene can both be used to alter the electronic properties of silicene making it a highly promising material for use in future electronic devices and sensors.« less

Crystal structure of (E)-13-{4-[(Z)-2-cyano-2-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]phen-yl}parthenolide methanol hemisolvate.

PubMed

Penthala, Narsimha Reddy; Bommagani, Shobanbabu; Janganati, Venumadhav; Parkin, Sean; Crooks, Peter A

2014-10-01

The title compound, C33H35NO6 [systematic name: (Z)-3-(4-{(E)-[(E)-1a,5-dimethyl-9-oxo-2,3,7,7a-tetra-hydro-oxireno[2',3':9,10]cyclo-deca-[1,2-b]furan-8(1aH,6H,9H,10aH,10bH)-yl-idene]meth-yl}phen-yl)-2-(3,4,5-tri-meth-oxy-phen-yl)acrylo-ni-trile methanol hemisolvate], C33H35NO6·0.5CH3OH, was prepared by the reaction of (Z)-3-(4-iodo-phen-yl)-2-(3,4,5-tri-meth-oxy-phen-yl)acrylo-nitrile with parthenolide [systematic name: (E)-1a,5-dimethyl-8-methyl-ene-2,3,6,7,7a,8,10a,10b-octa-hy-dro-oxireno[2',3':9,10]cyclo-deca-[1,2-b]furan-9(1aH)-one] under Heck reaction conditions. The mol-ecule is built up from fused ten-, five- (lactone) and three-membered (epoxide) rings with a {4-[(Z)-2-cyano-2-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]phen-yl}methyl-idene group as a substituent. The 4-[(Z)-2-cyano-2-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]phenyl group on the parthenolide exocyclic double bond is oriented in a trans position to the lactone ring to form the E isomer. The dihedral angle between the benzene ring of the phenyl moiety and the lactone ring mean plane is 21.93 (4)°.

Heterobimetallic Pd-Sn catalysis: a Suzuki, tandem ring-closing sequence toward indeno[2,1-b]thiophenes and indeno[2,1-b]indoles.

PubMed

Das, Debjit; Pratihar, Sanjay; Roy, Sujit

2012-09-21

Indeno[2,1-b]thiophene and indeno[1,2-b]indole motifs have been obtained in moderate to good yields from easily available substituted boronic acids, 2-bromo aryl/vinyl aldehydes, and nucleophiles such as arenes/heteroarenes and others using a catalytic combination of bimetallic "Pd-Sn" and AgPF(6). This formal three-component coupling involves a Suzuki reaction followed by nucleophile assisted tandem ring closure. The sequential synthesis of substituted heterocycle-fused indenes, benzofluorene, and fluorenes was also accomplished.

Development of Tricyclic Hydroxy-1H-pyrrolopyridine-trione Containing HIV-1 Integrase Inhibitors

PubMed Central

Zhao, Xue Zhi; Maddali, Kasthuraiah; Metifiot, Mathieu; Smith, Steven J.; Vu, B. Christie; Marchand, Christophe; Hughes, Stephen H.; Pommier, Yves; Burke, Terrence R.

2011-01-01

New tricyclic HIV-1 integrase (IN) inhibitors were prepared that combined structural features of bicyclic pyrimidinones with recently disclosed 4,5-dihydroxy-1H-isoindole-1,3(2H)-diones. This combination resulted in the introduction of a nitrogen into the aryl ring and the addition of a fused third ring to our previously described inhibitors. The resulting analogues showed low micromolar inhibitory potency in in vitro HIV-1 integrase assays, with good selectivity for strand transfer relative to 3′-processing. PMID:21493066

Synthesis and profiling of a diverse collection of azetidine-based scaffolds for the development of CNS-focused lead-like libraries.

PubMed

Lowe, Jason T; Lee, Maurice D; Akella, Lakshmi B; Davoine, Emeline; Donckele, Etienne J; Durak, Landon; Duvall, Jeremy R; Gerard, Baudouin; Holson, Edward B; Joliton, Adrien; Kesavan, Sarathy; Lemercier, Berenice C; Liu, Haibo; Marié, Jean-Charles; Mulrooney, Carol A; Muncipinto, Giovanni; Welzel-O'Shea, Morgan; Panko, Laura M; Rowley, Ann; Suh, Byung-Chul; Thomas, Meryl; Wagner, Florence F; Wei, Jingqiang; Foley, Michael A; Marcaurelle, Lisa A

2012-09-07

The synthesis and diversification of a densely functionalized azetidine ring system to gain access to a wide variety of fused, bridged, and spirocyclic ring systems is described. The in vitro physicochemical and pharmacokinetic properties of representative library members are measured in order to evaluate the use of these scaffolds for the generation of lead-like molecules to be used in targeting the central nervous system. The solid-phase synthesis of a 1976-membered library of spirocyclic azetidines is also described.

4-Methyl-N-(1-methyl-1H-indazol-5-yl)benzene-sulfonamide.

PubMed

Chicha, Hakima; Oulemda, Bassou; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C15H15N3O2S, the fused ring system is close to planar, the largest deviation from the mean plane being 0.030 (2) Å, and makes a dihedral angle of 48.84 (9)° with the benzene ring belonging to the methyl-benzene-sulfonamide moiety. In the crystal, mol-ecules are -connected through N-H⋯N hydrogen bonds and weak C-H⋯O contacts, forming a two-dimensional network parallel to (001).

4-Methyl-N-(1-methyl-1H-indazol-5-yl)benzene­sulfonamide

PubMed Central

Chicha, Hakima; Oulemda, Bassou; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C15H15N3O2S, the fused ring system is close to planar, the largest deviation from the mean plane being 0.030 (2) Å, and makes a dihedral angle of 48.84 (9)° with the benzene ring belonging to the methyl­benzene­sulfonamide moiety. In the crystal, mol­ecules are ­connected through N—H⋯N hydrogen bonds and weak C—H⋯O contacts, forming a two-dimensional network parallel to (001). PMID:24427093

N-(3-Chloro-1H-indazol-5-yl)-4-meth­oxy­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C14H12ClN3O3S, the fused five- and six-membered rings are folded slightly along the common edge, forming a dihedral angle of 3.2 (1)°. The mean plane through the indazole system makes a dihedral angle of 30.75 (7)° with the distant benzene ring. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules, forming a two-dimensional network parallel to (001). PMID:24454078

N-(1H-Indazol-5-yl)-4-meth­oxy­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C14H13N3O3S, the fused ring system is almost planar, the largest deviation from the mean plane being 0.023 (2) Å, and makes a dihedral angle of 47.92 (10)° with the benzene ring of the benzene­sulfonamide moiety. In the crystal, mol­ecules are connected through N—H⋯O hydrogen bonds and weak C—H⋯O contacts, forming a two-dimensional network which is parallel to (010). PMID:24454128

Enantioselective Copper-Catalyzed Carboetherification of Unactivated Alkenes**

PubMed Central

Bovino, Michael T.; Liwosz, Timothy W.; Kendel, Nicole E.; Miller, Yan; Tyminska, Nina

2014-01-01

Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein is reported a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols that terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition state calculations support a cis-oxycupration stereochemistry-determining step. PMID:24798697

Microwave-assisted one-pot synthesis of ring-fused aminals under catalyst- and solvent-free conditions

EPA Science Inventory

Heterocyclic compounds hold a special place in drug discovery and variety of techniques such as combinatorial synthesis, parallel synthesis, and automated library production to increase the output of these entities has been developed. Although most of these techniques are rapid a...

2-Hy-droxy-16-[(E)-4-methyl-benzyl-idene]-13-(4-methyl-phen-yl)-12-phenyl-1,11-diaza-penta-cyclo-[12.3.1.0.0.0]octa-deca-3(8),4,6-triene-9,15-dione.

PubMed

Kumar, Raju Suresh; Osman, Hasnah; Abdul Rahim, Aisyah Saad; Goh, Jia Hao; Fun, Hoong-Kun

2010-07-24

In the title compound, C(37)H(32)N(2)O(3), an intra-molecular O-H⋯N hydrogen bond generates a five-membered ring, producing an S(5) motif. The piperidone ring adopts a half-chair conformation. The two fused pyrrolidine rings have similar envelope conformations. The interplanar angles between the benzene rings A/B and C/D are 75.68 (7) and 30.22 (6)°, respectively. In the crystal structure, adjacent mol-ecules are inter-connected into chains propagating along the [010] direction via inter-molecular C-H⋯O hydrogen bonds. Further stabilization is provided by weak C-H⋯π inter-actions.

Design of high birefringence and low confinement loss photonic crystal fibers with five rings hexagonal and octagonal symmetry air-holes in fiber cladding

NASA Astrophysics Data System (ADS)

Yang, Kuang-Yu; Chau, Yuan-Fong; Huang, Yao-Wei; Yeh, Hsiao-Yu; Ping Tsai, Din

2011-05-01

We present a new cladding design for high birefringence and low confinement loss photonic crystal fibers (PCFs) using a full-vector finite element method with anisotropic perfectly matched boundary layer. Six cases of PCFs are proposed for comparison. The proposed cladding in PCFs is composed of five rings of air-holes. Air-holes on the inner two rings are arranged in a hexagonal symmetry whereas, air-holes on the outer three rings are arranged in an octagonal symmetry in fused silica. Results show that suitable design air-holes on the inner two rings will significantly increase the birefringence, whereas, elliptical holes with major axis along x-axis on the outer three rings will provide strong confinement ability. The highest modal birefringence and lowest confinement loss of our proposed case five structure at the excitation wavelength of λ = 1550 nm can be achieved at a magnitude of 0.87 × 10-2 and less than 0.01 dB/km with only five rings of air-holes in fiber cladding.

Pressure derivatives of elastic moduli of fused quartz to 10 kb

USGS Publications Warehouse

Peselnick, L.; Meister, R.; Wilson, W.H.

1967-01-01

Measurements of the longitudinal and shear moduli were made on fused quartz to 10 kb at 24??5??C. The anomalous behavior of the bulk modulus K at low pressure, ???K ???P 0, at higher pressures. The pressure derivative of the rigidity modulus ???G ???P remains constant and negative for the pressure range covered. A 15-kb hydrostatic pressure vessel is described for use with ultrasonic pulse instrumentation for precise measurements of elastic moduli and density changes with pressure. The placing of the transducer outside the pressure medium, and the use of C-ring pressure seals result in ease of operation and simplicity of design. ?? 1967.

An Unfused-Core-Based Nonfullerene Acceptor Enables High-Efficiency Organic Solar Cells with Excellent Morphological Stability at High Temperatures.

PubMed

Li, Shuixing; Zhan, Lingling; Liu, Feng; Ren, Jie; Shi, Minmin; Li, Chang-Zhi; Russell, Thomas P; Chen, Hongzheng

2018-02-01

Most nonfullerene acceptors developed so far for high-performance organic solar cells (OSCs) are designed in planar molecular geometry containing a fused-ring core. In this work, a new nonfullerene acceptor of DF-PCIC is synthesized with an unfused-ring core containing two cyclopentadithiophene (CPDT) moieties and one 2,5-difluorobenzene (DFB) group. A nearly planar geometry is realized through the F···H noncovalent interaction between CPDT and DFB for DF-PCIC. After proper optimizations, the OSCs with DF-PCIC as the acceptor and the polymer PBDB-T as the donor yield the best power conversion efficiency (PCE) of 10.14% with a high fill factor of 0.72. To the best of our knowledge, this efficiency is among the highest values for the OSCs with nonfullerene acceptors owning unfused-ring cores. Furthermore, no obvious morphological changes are observed for the thermally treated PBDB-T:DF-PCIC blended films, and the relevant devices can keep ≈70% of the original PCEs upon thermal treatment at 180 °C for 12 h. This tolerance of such a high temperature for so long time is rarely reported for fullerene-free OSCs, which might be due to the unique unfused-ring core of DF-PCIC. Therefore, the work provides new idea for the design of new nonfullerene acceptors applicable in commercial OSCs in the future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and SAR of novel imidazoquinoxaline-based Lck inhibitors: improvement of cell potency.

PubMed

Chen, Ping; Iwanowicz, Edwin J; Norris, Derek; Gu, Henry H; Lin, James; Moquin, Robert V; Das, Jagabandhu; Wityak, John; Spergel, Steven H; de Fex, Henry; Pang, Suhong; Pitt, Sydney; Shen, Ding Ren; Schieven, Gary L; Barrish, Joel C

2002-11-04

A series of anilino(imidazoquinoxaline) analogues bearing solubilizing side chains at the 6- and 7-positions of the fused phenyl ring has been prepared and evaluated for inhibition against Lck enzyme and of T-cell proliferation. Significant improvement of the cellular activity was achieved over the initial lead, compound 2.

CLONING AND CHARACTERIZATION OF THE PHTHALATE CATABOLISM REGION OF PRE1 OF ARTHROBACTER KEYSERI 12B

EPA Science Inventory

o-Phthalate (benzene-1,2-dicarboxylate) is a central intermediate in the bacterial degradation of phthalate ester plasticizers as well as of a number of fused-ring polycyclic aromatic hydrocarbons found in fossil fuels. In Arthrobacter keyseri 12B, the genes encoding catabolism o...

Experimental study of the competitive adsorption of HNO3 and H2O on surfaces by using Brewster angle cavity ring-down spectroscopy in the 295-345 nm region.

PubMed

Du, Juan; Keesee, Robert G; Zhu, Lei

2014-09-18

The competitive adsorption of HNO3 and H2O from the gas phase onto fused silica surfaces is investigated. Brewster angle cavity ring-down spectroscopy is used to measure absorption of a laser probe beam by the HNO3/H2O coadsorbed on fused silica surfaces as a function of the mixture pressure. The laser absorption measurements were made in the 295-345 nm region. Langmuir adsorption constants for nitric acid and water were found to be 107 ± 17 and 562 ± 21 Torr(-1), respectively. A method has been developed for calculating absorption by HNO3 and H2O codeposited on the surface as a function of the HNO3/H2O mixture pressure using multicomponent Langmuir adsorption isotherms and absorption cross-sections at a given wavelength for surface-adsorbed HNO3 and H2O. The validity of this treatment has been evaluated both as a function of wavelength and as a function of mixing ratio.

Improving Photovoltaic Performance of a Fused-Ring Azepinedione Copolymer via a D-A-A Design.

PubMed

Zhang, Honghong; Li, Ting; Xiao, Zuo; Lei, Zhongli; Ding, Liming

2018-04-01

Two conjugated copolymer donors, PTTABDT and PBTTABDT, based on a fused-ring azepinedione acceptor unit, 5-(2-octyldodecyl)-4H-thieno[2',3':4,5]thieno[3,2-c]thieno[2',3':4,5]thieno[2,3-e]azepine-4,6(5H)-dione (TTA), are prepared. PTTABDT possesses a conventional donor-acceptor (D-A) structure with one TTA in the repeat unit, while PBTTABDT has a D-A-A structure with two TTAs in the repeat unit. Compared with PTTABDT, PBTTABDT shows a deeper highest occupied molecular orbital (HOMO) level, a narrower bandgap, and a higher hole mobility, and exhibits better performance in bulk heterojunction solar cells. Power conversion efficiencies of 6.18% and 7.81% are achieved from PTTABDT:PC 71 BM and PBTTABDT:PC 71 BM solar cells, respectively. The higher performance of PBTTABDT:PC 71 BM solar cells results from the enhanced open-circuit voltage (V oc ) and short-circuit current density (  J sc ). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of novel heterocyclic ring-fused 18β-glycyrrhetinic acid derivatives with antitumor and antimetastatic activity.

PubMed

Gao, Cheng; Dai, Fu-Jun; Cui, Hai-Wei; Peng, Shi-Hong; He, Yuan; Wang, Xue; Yi, Zheng-Fang; Qiu, Wen-Wei

2014-08-01

Glycyrrhetinic acid (GA) is one of the most important triterpenoic acids shows many pharmacological effects, especially antitumor activity. GA triggers apoptosis in various tumor cell lines. However, the antitumor activity of GA is weak, thus the synthesis of new synthetic analogs with enhanced potency is needed. By introducing various five-member fused heterocyclic rings at C-2 and C-3 positions, 18 novel GA derivatives were obtained. These compounds were evaluated for their inhibitory activity against the growth of eight different tumor cell lines using a SRB assay. The most active compound 37 showed IC50 between 5.19 and 11.72 μm, which was about 11-fold more potent than the lead compound GA. An apoptotic effect of GA and 37 was determined using flow cytometry and trypan blue exclusion assays. We also demonstrated here for the first time that GA and the synthetic derivatives exhibited inhibitory effect on migration of the tested tumor cells, especially 37 which was about 20-fold more potent than GA on antimetastatic activity. © 2014 John Wiley & Sons A/S.

Energetic factors determining the binding of type I inhibitors to c-Met kinase: experimental studies and quantum mechanical calculations.

PubMed

Yu, Zhe; Ma, Yu-chi; Ai, Jing; Chen, Dan-qi; Zhao, Dong-mei; Wang, Xin; Chen, Yue-lei; Geng, Mei-yu; Xiong, Bing; Cheng, Mao-sheng; Shen, Jing-Kang

2013-11-01

To decipher the molecular interactions between c-Met and its type I inhibitors and to facilitate the design of novel c-Met inhibitors. Based on the prototype model inhibitor 1, four ligands with subtle differences in the fused aromatic rings were synthesized. Quantum chemistry was employed to calculate the binding free energy for each ligand. Symmetry-adapted perturbation theory (SAPT) was used to decompose the binding energy into several fundamental forces to elucidate the determinant factors. Binding free energies calculated from quantum chemistry were correlated well with experimental data. SAPT calculations showed that the predominant driving force for binding was derived from a sandwich π-π interaction with Tyr-1230. Arg-1208 was the differentiating factor, interacting with the 6-position of the fused aromatic ring system through the backbone carbonyl with a force pattern similar to hydrogen bonding. Therefore, a hydrogen atom must be attached at the 6-position, and changing the carbon atom to nitrogen caused unfavorable electrostatic interactions. The theoretical studies have elucidated the determinant factors involved in the binding of type I inhibitors to c-Met.

Fluorescent aromatic sensors and their methods of use

NASA Technical Reports Server (NTRS)

Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

2012-01-01

Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

Fusion of Renewable Ring Resonator Lasers and Ultrafast Laser Inscribed Photonic Waveguides

PubMed Central

Chandrahalim, Hengky; Rand, Stephen C.; Fan, Xudong

2016-01-01

We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator – waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3′-Diethyloxacarbocyanine iodide (CY3) as exemplary gain media. In all above cases, the waveguide was able to couple out and guide the laser emission. This work opens a door to reconfigurable active and passive photonic devices for on-chip coherent light sources, optical signal processing, and the investigation of new optical phenomena. PMID:27600872

Fused thiophene-based conjugated polymers and their use in optoelectronic devices

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

Facchetti, Antonio; Marks, Tobin J.; Takai, Atsuro

The present teachings relate to polymeric compounds and their use as organic semiconductors in organic and hybrid optical, optoelectronic, and/or electronic devices such as photovoltaic cells, light emitting diodes, light emitting transistors, and field effect transistors. The disclosed compounds generally include as repeating units at least one annulated thienyl-vinylene-thienyl (TVT) unit and at least one other pi-conjugated unit. The annulated TVT unit can be represented by the formula: ##STR00001## where Cy.sup.1 and Cy.sup.2 can be a five- or six-membered carbocyclic ring. The annulated TVT unit can be optionally substituted at any available ring atom(s), and can be covalently linked tomore » the other pi-conjugated unit via either the thiophene rings or the carbocyclic rings Cy.sup.1 and Cy.sup.2. The other pi-conjugated unit can be a conjugated linear linker including one or more unsaturated bonds, or a conjugated cyclic linker including one or more carbocyclic and/or heterocyclic rings.« less

Fusion of Renewable Ring Resonator Lasers and Ultrafast Laser Inscribed Photonic Waveguides.

PubMed

Chandrahalim, Hengky; Rand, Stephen C; Fan, Xudong

2016-09-07

We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator - waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3'-Diethyloxacarbocyanine iodide (CY3) as exemplary gain media. In all above cases, the waveguide was able to couple out and guide the laser emission. This work opens a door to reconfigurable active and passive photonic devices for on-chip coherent light sources, optical signal processing, and the investigation of new optical phenomena.

Sesquiterpene lactone stereochemistry influences herbivore resistance and plant fitness in the field

PubMed Central

Ahern, Jeffrey R.; Whitney, Kenneth D.

2014-01-01

Background and Aims Stereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant–herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field. Methods Natural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness. Key Results The stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide. Conclusions To our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing extensive stereochemical variation. PMID:24380844

Sesquiterpene lactone stereochemistry influences herbivore resistance and plant fitness in the field.

PubMed

Ahern, Jeffrey R; Whitney, Kenneth D

2014-03-01

Stereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant-herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field. Natural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness. The stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide. To our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing extensive stereochemical variation.

Enantioselective copper-catalyzed carboetherification of unactivated alkenes.

PubMed

Bovino, Michael T; Liwosz, Timothy W; Kendel, Nicole E; Miller, Yan; Tyminska, Nina; Zurek, Eva; Chemler, Sherry R

2014-06-16

Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein reported is a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols which terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, thus yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition-state calculations support a cis-oxycupration stereochemistry-determining step. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical study of geometrical and electronic structures of various thiophene-based tricyclic polymers

NASA Astrophysics Data System (ADS)

Hong, Sung Y.; Song, Jung M.

1997-12-01

A theoretical study of a variety of tricyclic polymers [-(C8H2X2Y)n-] with two different types of bridging groups was performed, X=S and Y=CH2, SiH2, C=O, C=S, or C=CH2 for the fused bithiophene system and vice versa for the thieno-bicyclic system. These two types of the bridging groups are different from each other in that S favors the aromatic form of a cyclic polymer and the other groups prefer the quinonoid form. Geometrical structures of the polymers were obtained from semiempirical self-consistent-field (SCF) band calculations and the electronic properties from the modified extended Hückel band calculations. It is found that the ground-state geometrical structures of the tricyclic polymers are determined by the bridging groups in the outer rings. That is, the fused bithiophene system is aromatic in the ground state and the thieno-bicyclic system is quinonoid. The ground-state band gaps (which correspond to the absorption peaks of π-π* band transition) of the polymers were estimated to be in the range of 0.7-2.0 eV. The band gaps were analyzed in terms of the bond-length alternation along the conjugated carbon backbone, the C1-C4 interactions, and the electronic effect of the bridging groups. We also investigated the geometrical and electronic structures of polydicyanomethylene-cyclopenta-dicyclopentadiene (PDICNCY). Unlike the theoretical predictions of Toussaint and Bredas [Synth. Met. 69, 637 (1995)], PDICNCY in the ground state was estimated to be of the quinonoid form and to possess a large band gap (2.55 eV) comparable with the gap of polythiophene.

4,5,7,8,17-Penta­hydr­oxy-14,18-dimethyl-6-methyl­ene-3,10-dioxapenta­cyclo­[9.8.0.01,7.04,19.013,18]nona­dec-14-ene-9,16-dione methanol solvate dihydrate

PubMed Central

Teh, Chin Hoe; Teoh, Siew Chin; Yeap, Chin Sing; Chan, Kit Lam; Fun, Hoong-Kun

2009-01-01

The title quassinoid compound, C20H24O9·CH3OH·2H2O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The mol­ecules contain a fused five-ring system, with one tetra­hydro­furan ring adopting an envelope conformation, one tetra­hydro­pyran-2-one ring in a screw boat conformation, one cyclo­hexenone ring in a half-chair conformation and two cyclo­hexane rings in chair conformations. Intra­molecular C—H⋯O inter­actions generate S(5) ring motifs and an O—H⋯O inter­action generates an S(7) ring motif. In the crystal, mol­ecules are linked via inter­molecular O—H⋯O inter­actions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues. PMID:21582604

X-Ray study of hetero ring flexibility in norbornane, norbornene-fused 1,3-oxazin-2-thiones Structure of 5,8-methano- r-4-phenyl-c-4a, c-5,6,7, c-8, c- 8a-hexahydro-4H- 1 ,3-benzoxazin-2 (3H)-thione

NASA Astrophysics Data System (ADS)

Kálmán, A.; Argay, Gy.; Stájer, G.; Bernáth, G.

1991-08-01

The structure of S,8-methano- r-4-phenyl c4a, c5,6,7 c8 c8ahexahydro4 H 1,3 -benzoxazin- 2 (3 H)-thione (C 15H 17N0S, M r=259.37) has been established by X-ray crystallography from diffractometer data: it crystallizes in the monoclinic space group P2 1/n with a=6.150(2) Å, b=9.655(1) Å, c=22.093(4) Å,β=96.75(2)† V=1302.7(8) Å 3,4,D c=1.32gcm -3and p( Cu K) =20.4cm -. The structure has been solved by direct methods, refined to R=0.050 for 2193 observed reflections. The X-ray analysis substantiated the structure: the NMR spectra in- dicated that the 4-phenyl group assumes an exo-equatorial position. The puckering parameters of D. Cremer, J.A. Pople, J. Am. Chem. Soc., 97 (1975), 1354 (ref.1), of the distorted hetero ring (a transitional form between E 4-envelope, ( 5S 4-screw-boat) show that, depending on the positions of the hetero atoms, both the norbornane, norbornene skeletons markedly alter the characteristic transitional ( 5E/ 5H 6) shape of the 1,3-oxazine ring observed in other saturated, partly saturated l,3-benzoxazin-2-ones, analogous thiones.

[Effects of laser welding on bond of porcelain fused cast pure titanium].

PubMed

Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

2006-04-01

To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

N-(1-Allyl-1H-indazol-5-yl)-4-methyl­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Abderrafia, Hafid; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The asymmetric unit of the title compound, C17H17N3O2S, contains two independent mol­ecules linked by an N—H⋯O hydrogen bond. The mol­ecules show different conformations. In the first mol­ecule, the fused five- and six-membered ring system is almost perpendicular to the plane through the atoms forming the allyl group, as indicated by the dihedral angle of 85.1 (4)°. The dihedral angle with the methyl­benzene­sulfonamide group is 78.8 (1)°. On the other hand, in the second mol­ecule, the dihedral angles between the indazole plane and the allyl and methyl­benzene­sulfonamide groups are 80.3 (3) and 41.5 (1)°, respectively. In the crystal, mol­ecules are further linked by N—H⋯N and C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:24454264

Chiral cavity ring down polarimetry: Chirality and magnetometry measurements using signal reversals.

PubMed

Bougas, Lykourgos; Sofikitis, Dimitris; Katsoprinakis, Georgios E; Spiliotis, Alexandros K; Tzallas, Paraskevas; Loppinet, Benoit; Rakitzis, T Peter

2015-09-14

We present the theory and experimental details for chiral-cavity-ring-down polarimetry and magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by the presence of both chiral and Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. We present the measurement of the specific rotation at 800 nm of vapors of α-pinene, 2-butanol, and α-phellandrene, the measurement of optical rotation of sucrose solutions in a flow cell, the measurement of the Verdet constant of fused silica, and measurements and theoretical treatment of evanescent-wave optical rotation at a prism surface. Therefore, these signal-enhancing and signal-reversing methods open the way for ultrasensitive polarimetry measurements in gases, liquids and solids, and at surfaces.

The Pauson-Khand reaction of medium sized trans-cycloalkenes.

PubMed

Lledó, Agustí; Fuster, Aida; Revés, Marc; Verdaguer, Xavier; Riera, Antoni

2013-04-14

Medium sized trans-cycloalkenes are unusually reactive in the intermolecular Pauson-Khand reaction (PKR) with regard to typical monocyclic alkenes. This is due to the ring strain imparted by the E stereochemistry. The PKR of these alkenes offers a modular, regioselective and straightforward entry to trans fused [n.3.0] bicyclic scaffolds (n = 6-8).

Monolithic Cylindrical Fused Silica Resonators with High Q Factors

PubMed Central

Pan, Yao; Wang, Dongya; Wang, Yanyan; Liu, Jianping; Wu, Suyong; Qu, Tianliang; Yang, Kaiyong; Luo, Hui

2016-01-01

The cylindrical resonator gyroscope (CRG) is a typical Coriolis vibratory gyroscope whose performance is determined by the Q factor and frequency mismatch of the cylindrical resonator. Enhancing the Q factor is crucial for improving the rate sensitivity and noise performance of the CRG. In this paper, for the first time, a monolithic cylindrical fused silica resonator with a Q factor approaching 8 × 105 (ring-down time over 1 min) is reported. The resonator is made of fused silica with low internal friction and high isotropy, with a diameter of 25 mm and a center frequency of 3974.35 Hz. The structure of the resonator is first briefly introduced, and then the experimental non-contact characterization method is presented. In addition, the post-fabrication experimental procedure of Q factor improvement, including chemical and thermal treatment, is demonstrated. The Q factor improvement by both treatments is compared and the primary loss mechanism is analyzed. To the best of our knowledge, the work presented in this paper represents the highest reported Q factor for a cylindrical resonator. The proposed monolithic cylindrical fused silica resonator may enable high performance inertial sensing with standard manufacturing process and simple post-fabrication treatment. PMID:27483263

A Metal-Free Regioselective Multicomponent Approach for the Synthesis of Free Radical Scavenging Pyrimido-Fused Indazoles and Their Fluorescence Studies.

PubMed

Palaniraja, Jeyakannu; Mohana Roopan, Selvaraj; Mokesh Rayalu, G; Abdullah Al-Dhabi, Naif; Valan Arasu, Mariadhas

2016-11-18

This study deals with a new and efficient metal-free regioselective synthesis of pyrimido-fused indazoles with nitrogen ring junction motifs. We have developed a metal-free domino type reaction between 3-aminoindazole, aryl aldehydes and aceotophenones in the presence of KOH/DMF that leads to pyrimido[1,2- b ]indazole analogues. Response Surface Methodology (RSM) coupled with a Box-Behnken design (BBD) were utilized for exploring the effect of base used (A), temperature of reaction (B) and (C), reaction time. This approach can allow access to a variety of pyrimidoindazole fluorophores and related compounds. The compound N,N -dimethyl-4-(2-phenylpyrimido[1,2- b ]indazol-4-yl)aniline ( 4e ) displays the maximum fluorescence intensity at 518 nm and shows a fluorescence quantum yield of 0.068. The synthesized pyramido-fused indazoles have been evaluated for their free radical scavenging activity and compound 4f showed good antioxidant activity.

[Study on content of nickel in saliva released from the nickel-chromium and the nickel-chromium-titanium porcelain alloy].

PubMed

Wang, Wen-Jie; Zhang, Tai-Qiang; Wei, Hong

2010-02-01

The purpose of the study was to investigate the content of nickel (Ni) ion in patients' saliva after wearing the porcelain-fused-to nickel-chromium (Ni-Cr) crown or the porcelain-fused-to nickel-chromium-titanium(Ni-Cr-Ti) crown. 50 patients who had one molar or premolar needed repairing were selected and divided into two groups randomly. Patients in one group were fabricated with porcelain-fused-to Ni-Cr crown and the patients in the other group were fabricated with porcelain-fused-to Ni-Cr-Ti crown. Collect the patients' saliva before wearing, 1 week, 3 months, and 6 months after wearing. The content of Ni ion in saliva was detected by inductively coupled plasma mass spectrometry (ICP-MS). The content of Ni ion in both groups increased at the first week, and go back after 6 months. There were no significant differences before wearing, 1 week, 3 months, and 6 months after wearing. There were no significant differences between the two groups. Wearing the porcelain-fused-to Ni-Cr crown or the porcelain-fused-to Ni-Cr-Ti crown has no significant influence on the content of Ni ion in saliva.

Application of MCD spectroscopy and TD-DFT to a highly non-planar porphyrinoid ring system. New insights on red-shifted porphyrinoid spectral bands.

PubMed

Mack, John; Asano, Yoshiaki; Kobayashi, Nagao; Stillman, Martin J

2005-12-21

The first magnetic circular dichroism (MCD) spectra are reported for tetraphenyltetraacenaphthoporphyrin (TPTANP). The impact on the electronic structure of steric interactions between the fused acenaphthalene rings and the meso-tetraphenyl substituents is explored based on an analysis of the optical spectra of the Zn(II) complex (ZnTPTANP) and the free base dication species ([H4TPTANP]2+). In the case of ZnTPTANP, significant folding of the porphyrinoid ligand induces a highly unusual MCD-sign reversal providing the first direct spectroscopic evidence of ligand nonplanarity. Density functional theory (DFT) geometry optimizations for a wide range of Zn(II) porphyrinoids based on the B3LYP functional and TD-DFT calculations of the associated UV-visible absorption spectra are reported, allowing a complete assessment of the MCD data. TPTANP complexes are found to fall into a class of cyclic polyenes, termed as soft MCD chromophores by Michl (J. Pure Appl. Chem. 1980, 52, 1549.), since the signs of the Faraday A1 terms observed in the MCD spectrum are highly sensitive to slight structural changes. The origin of an unusually large red shift of the main B (or Soret) band of MTPTANP (the most red shifted ever reported for fused-ring-expanded metal porphines) and of similar red shifts observed in the spectra of other peripherally crowded porphyrinoid complexes is also explored and explained on this basis.

African Baobabs with False Inner Cavities: The Radiocarbon Investigation of the Lebombo Eco Trail Baobab

PubMed Central

Patrut, Adrian; Woodborne, Stephan; von Reden, Karl F.; Hall, Grant; Hofmeyr, Michele; Lowy, Daniel A.; Patrut, Roxana T.

2015-01-01

The article reports the radiocarbon investigation results of the Lebombo Eco Trail tree, a representative African baobab from Mozambique. Several wood samples collected from the large inner cavity and from the outer part of the tree were investigated by AMS radiocarbon dating. According to dating results, the age values of all samples increase from the sampling point with the distance into the wood. For samples collected from the cavity walls, the increase of age values with the distance into the wood (up to a point of maximum age) represents a major anomaly. The only realistic explanation for this anomaly is that such inner cavities are, in fact, natural empty spaces between several fused stems disposed in a ring-shaped structure. We named them false cavities. Several important differences between normal cavities and false cavities are presented. Eventually, we dated other African baobabs with false inner cavities. We found that this new architecture enables baobabs to reach large sizes and old ages. The radiocarbon date of the oldest sample was 1425 ± 24 BP, which corresponds to a calibrated age of 1355 ± 15 yr. The dating results also show that the Lebombo baobab consists of five fused stems, with ages between 900 and 1400 years; these five stems build the complete ring. The ring and the false cavity closed 800–900 years ago. The results also indicate that the stems stopped growing toward the false cavity over the past 500 years. PMID:25621989

A fused-ring acceptor unit in d-a copolymers benefits photovoltaic performance.

PubMed

Zuo, Chuantian; Cao, Jiamin; Ding, Liming

2014-08-01

Pentacyclic lactam acceptor unit TPTI invented by our group is proved to be a good building block for efficient D-A copolymers used in organic solar cells. Here, two D-A copolymers PBTTPTI and PTTTPTI are developed by copolymerizing TPTI with 2,2'-bithiophene (BT) or thieno[3,2-b]thiophene (TT). PBTTPTI and PTTTPTI exhibit good solubility and strong interchain π-π interaction even in dilute solution. They possess deep HOMO levels (ca. -5.3 eV), partial crystallinity, and good hole mobilities. Blending with PC71 BM, PBTTPTI and PTTTPTI give decent power conversion efficiencies (PCE) up to 6.83% and 5.86%, with outstanding fill factors (FF) of 74.3% and 71.3%, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Seven papers on fused-ring heterocyclic ketones containing an N-tosyl­pyrrolo­[3,4-c]pyrano moiety. Corrigenda

PubMed Central

Chinnakali, K.; Jayagobi, M.; Fun, Hoong-Kun

2008-01-01

Corrections are made to the name of an author in seven papers by Chinnakali et al. [Acta Cryst. (2007), E63, o4363, o4364, o4434–o4435, o4436–o4437, o4438, o4489–o4490 and o4491–o4492]. PMID:21200448

Expeditious Preparation of Open-Cage Fullerenes by Rhodium(I)-Catalyzed [2+2+2] Cycloaddition of Diynes and C60: an Experimental and Theoretical Study.

PubMed

Artigas, Albert; Pla-Quintana, Anna; Lledó, Agustí; Roglans, Anna; Solà, Miquel

2018-06-04

A novel methodology to transform C60 into a variety of open-cage fullerene derivatives employing rhodium(I) catalysis has been developed. This transformation encompasses a partially intermolecular [2+2+2] cycloaddition reaction between diynes 1 and C60 to deliver a cyclohexadiene-fused fullerene, which concomitantly undergoes a formal [4+4]/retro-[2+2+2] rearrangement to deliver open-cage fullerenes 2. Most notably, this process occurs without the need of photoexcitation. The complete mechanism of this transformation has been rationalized by DFT calculations, which indicate that, after [2+2+2] cycloaddition, the cyclohexadiene-fused intermediate evolves into the final product through a Rh-catalyzed di-π-methane rearrangement followed by a retro-[2+2+2] cycloaddition. The obtained open-cage fullerenes can be derivatized by Suzuki-Miyaura cross-coupling, or subjected to ring expansion to deliver a 12-membered ring orifice in the fullerene structure. Overall, the methodology presented constitutes a straightforward entry to functional open-cage C60-fullerene derivatives employing catalytic methods. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energetic factors determining the binding of type I inhibitors to c-Met kinase: experimental studies and quantum mechanical calculations

PubMed Central

Yu, Zhe; Ma, Yu-chi; Ai, Jing; Chen, Dan-qi; Zhao, Dong-mei; Wang, Xin; Chen, Yue-lei; Geng, Mei-yu; Xiong, Bing; Cheng, Mao-sheng; Shen, Jing-kang

2013-01-01

Aim: To decipher the molecular interactions between c-Met and its type I inhibitors and to facilitate the design of novel c-Met inhibitors. Methods: Based on the prototype model inhibitor 1, four ligands with subtle differences in the fused aromatic rings were synthesized. Quantum chemistry was employed to calculate the binding free energy for each ligand. Symmetry-adapted perturbation theory (SAPT) was used to decompose the binding energy into several fundamental forces to elucidate the determinant factors. Results: Binding free energies calculated from quantum chemistry were correlated well with experimental data. SAPT calculations showed that the predominant driving force for binding was derived from a sandwich π–π interaction with Tyr-1230. Arg-1208 was the differentiating factor, interacting with the 6-position of the fused aromatic ring system through the backbone carbonyl with a force pattern similar to hydrogen bonding. Therefore, a hydrogen atom must be attached at the 6-position, and changing the carbon atom to nitrogen caused unfavorable electrostatic interactions. Conclusion: The theoretical studies have elucidated the determinant factors involved in the binding of type I inhibitors to c-Met. PMID:24056705

Evaluation of certain food additives.

PubMed

2017-01-01

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, with a view to concluding as to safety concerns and to preparing specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation of and assessment of dietary exposure to food additives, including flavouring agents. A summary follows of the Committee’s evaluations of technical, toxicological and dietary exposure data for 10 food additives (Allura Red AC; carob bean gum; lutein esters from Tagetes erecta; octenyl succinic acid (OSA)– modified gum arabic; pectin; Quinoline Yellow; rosemary extract; steviol glycosides; tartrazine; and xanthan gum) and five groups of flavouring agents (alicyclic, alicyclic-fused and aromatic-fused ring lactones; aliphatic and aromatic amines and amides; aliphatic secondary alcohols, ketones and related esters; cinnamyl alcohol and related substances; and tetrahydrofuran and furanone derivatives). Specifications for the following food additives were revised: aspartame; cassia gum; citric and fatty acid esters of glycerol (CITREM); modified starches; octanoic acid; starch sodium octenyl succinate; and total colouring matters. Annexed to the report are tables summarizing the Committee’s recommendations for dietary exposures to and toxicological evaluations of all of the food additives, including flavouring agents, considered at this meeting.

Probes for Narcotic Receptor Mediated Phenomena. 37.1 Synthesis and Opioid Binding Affinity of the Final Pair of Oxide-Bridged Phenylmorphans, the ortho- and para-b Isomers and Their N-Phenethyl Analogues, and the Synthesis of the N-Phenethyl Analogues of the ortho- and para-d Isomers

PubMed Central

Kurimura, Muneaki; Liu, Hehua; Sulima, Agnieszka; Hashimoto, Akihiro; Przybyl, Anna K.; Ohshima, Etsuo; Kodato, Shinichi; Deschamps, Jeffrey R.; Dersch, Christina M.; Rothman, Richard B.; Lee, Yong Sok; Jacobson, Arthur E.; Rice, Kenner C.

2008-01-01

In the isomeric series of 12 racemic topologically rigid N-methyl analogues of oxide-bridged phenylmorphans, all but two of the racemates, the ortho- and para-b-oxide-bridged phenylmorphansa 20 and 12, have remained to be synthesized. The b-isomers were very difficult to synthesize because of the highly strained 5,6-trans-fused ring junction that had to be formed. Our successful strategy required functionalization of the position para (or ortho) to a fluorine atom on the aromatic ring using an electron-withdrawing nitro group to activate that fluorine. The racemic N-phenethyl analogues 24 and 16 were moderately potent κ-receptor antagonists in the [35S]GTPγS assay. We synthesized the N-phenethyl-substituted oxide-bridged phenylmorphans in the ortho- and para-d oxide-bridged phenylmorphana series (51 and 52) which had not been previously evaluated using contemporary receptor binding assays to see whether they also have higher affinity for opioid receptors than their N-methyl relatives 46 and 47. PMID:19053757

Use of Silica-Encapsulated Pseudomonas sp. Strain NCIB 9816-4 in Biodegradation of Novel Hydrocarbon Ring Structures Found in Hydraulic Fracturing Waters

PubMed Central

Aukema, Kelly G.; Kasinkas, Lisa; Aksan, Alptekin

2014-01-01

The most problematic hydrocarbons in hydraulic fracturing (fracking) wastewaters consist of fused, isolated, bridged, and spiro ring systems, and ring systems have been poorly studied with respect to biodegradation, prompting the testing here of six major ring structural subclasses using a well-characterized bacterium and a silica encapsulation system previously shown to enhance biodegradation. The direct biological oxygenation of spiro ring compounds was demonstrated here. These and other hydrocarbon ring compounds have previously been shown to be present in flow-back waters and waters produced from hydraulic fracturing operations. Pseudomonas sp. strain NCIB 9816-4, containing naphthalene dioxygenase, was selected for its broad substrate specificity, and it was demonstrated here to oxidize fundamental ring structures that are common in shale-derived waters but not previously investigated with this or related enzymes. Pseudomonas sp. NCIB 9816-4 was tested here in the presence of a silica encasement, a protocol that has previously been shown to protect bacteria against the extremes of salinity present in fracking wastewaters. These studies demonstrate the degradation of highly hydrophobic compounds by a silica-encapsulated model bacterium, demonstrate what it may not degrade, and contribute to knowledge of the full range of hydrocarbon ring compounds that can be oxidized using Pseudomonas sp. NCIB 9816-4. PMID:24907321

Laser-Gyro Materials Studies

DTIC Science & Technology

1986-03-01

mean-square (rms) have been measured on fused quartz and Zerodur surfaces polished by manufacturers of ring- laser gyros. The measurements were made...Sizes and Percent Crystallinity of Laser Gyro Materials. Crystallite Crystallinity, Material size, :-100 A ±10 vol% Zerodur 800 79 Quartz 500 53...Based on t data presented in this rel ort, Cervit, Zerodur , and RLA 559,122 from Corning Glass Works have acceptable material properties for laser

C–H Functionalization of Cyclic Amines: Redox-Annulations with α,β-Unsaturated Carbonyl Compounds

PubMed Central

Kang, YoungKu; Richers, Matthew T.; Sawicki, Conrad H.; Seidel, Daniel

2015-01-01

Cyclic amines such as pyrrolidine and 1,2,3,4-tetrahydroisoquinoline undergo redox-annulations with α,β-unsaturated aldehydes and ketones. Carboxylic acid promoted generation of a conjugated azomethine ylide is followed by 6π-electrocylization, and, in some cases, tautomerization. The resulting ring-fused pyrrolines are readily oxidized to the corresponding pyrroles or reduced to pyrrolidines. PMID:26051897

Supramolecular complex of a fused zinc phthalocyanine-zinc porphyrin dyad assembled by two imidazole-C60 units: ultrafast photoevents.

PubMed

Follana-Berná, Jorge; Seetharaman, Sairaman; Martín-Gomis, Luis; Charalambidis, Georgios; Trapali, Adelais; Karr, Paul A; Coutsolelos, Athanassios G; Fernández-Lázaro, Fernando; D'Souza, Francis; Sastre-Santos, Ángela

2018-03-14

A new zinc phthalocyanine-zinc porphyrin dyad (ZnPc-ZnP) fused through a pyrazine ring has been synthesized as a receptor for imidazole-substituted C 60 (C 60 Im) electron acceptor. Self-assembly via metal-ligand axial coordination and the pertinent association constants in solution were determined by 1 H-NMR, UV-Vis and fluorescence titration experiments at room temperature. The designed host was able to bind up to two C 60 Im electron acceptor guest molecules to yield C 60 Im:ZnPc-ZnP:ImC 60 donor-acceptor supramolecular complex. The spectral data showed that the two binding sites behave independently with binding constants similar in magnitude. Steady-state fluorescence studies were indicative of an efficient singlet-singlet energy transfer from zinc porphyrin to zinc phthalocyanine within the fused dyad. Accordingly, the transient absorption studies covering a wide timescale of femto-to-milli seconds revealed ultrafast energy transfer from 1 ZnP* to ZnPc (k EnT ∼ 10 12 s -1 ) in the fused dyad. Further, a photo induced electron transfer was observed in the supramolecularly assembled C 60 Im:ZnPc-ZnP:ImC 60 donor-acceptor complex leading to charge separated states, which persisted for about 200 ns.

Crystal structure of 1,2,3,4-di-O-methyl­ene-α-d-galacto­pyran­ose

PubMed Central

Tiritiris, Ioannis; Tussetschläger, Stefan; Kantlehner, Willi

2015-01-01

The title compound, C8H12O6, was synthesized by de­acetyl­ation of 6-acetyl-1,2,3,4-di-O-methyl­ene-α-d-galactose with sodium methoxide. The central part of the mol­ecule consists of a six-membered C5O pyran­ose ring with a twist-boat conformation. Both fused dioxolane rings adopt an envelope conformation with C and O atoms as the flap. In the crystal, O—H⋯O and C—H⋯O hydrogen bonds are present between adjacent mol­ecules, generating a three-dimensional network. PMID:26870551

14-Meth­oxy-4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-di­aza­tetra­cyclo­[8.8.0.02,7.013,18]octa­deca-2(7),13,15,17-tetra­ene-3,5,11-trione

PubMed Central

Jagadeesan, G; Jayashree, S.; Kannan, D.; Bakthadoss, M.; Aravindhan, S.

2013-01-01

The title compound, C23H20N2O6, crystallizes with two mol­ecules in the asymmetric unit in which the dihedral angles between the mean planes of the pyran and phenyl rings are 66.6 (1) and 61.9 (1) °. The fused pyrone and pyran rings each adopts a sofa conformation. In the crystal, C—H⋯O hydrogen bonds link the mol­ecules, forming a two-dimensional network parallel to [001]. PMID:24109298

14-Eth­oxy-4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-diaza­tetra­cyclo­[8.8.0.02,7.013,18]octa­deca-2(7),13,15,17-tetra­ene-3,5,11-trione

PubMed Central

Jagadeesan, G.; Kannan, D.; Bakthadoss, M.; Aravindhan, S.

2013-01-01

In the title compound, C23H20N2O6, the fused pyrone and pyran rings each adopt a sofa conformation. The dihedral angle between the mean planes of the pyran and phenyl rings is 61.9 (1)°. In the crystal, mol­ecules are linked by two pairs of C—H⋯O hydrogen bonds, forming dimers. These dimers are linked via a third C—H⋯O hydrogen bond, forming a two-dimensional network parallel to (10-2). PMID:23476462

7-Chloro-5-cyclo­propyl-9-methyl-5H-4,5,6,10-tetra­aza­dibenzo[a,d]cyclo­hepten-11(10H)-one

PubMed Central

Naveen, S.; Thimmegowda, N. R.; Manjunath, H. R.; Sridhar, M. A.; Prasad, J. Shashidhara; Rangappa, K. S.

2011-01-01

In the title compound, C15H13ClN4O, which is a chloro derivative of the drug Nevirapine, the diazepine ring is in a twisted boat conformation. The pyridine rings fused to the diazepine fragment form a dihedral angle of 58.44 (10)° and the mol­ecule adopts a butterfly shape. The mol­ecules are joined via N—H⋯N hydrogen bonding into polymeric chains down the b axis. All weaker C—H⋯O inter­actions involve the carbonyl O atom as acceptor. PMID:21754822

Recent advances in isoxazole chemistry

NASA Astrophysics Data System (ADS)

Galenko, A. V.; Khlebnikov, A. F.; Novikov, M. S.; Pakalnis, V. V.; Rostovskii, N. V.

2015-04-01

The preparation methods and reactions of isoxazoles are described and systematized on the basis of analysis of the literature published from 2005 to present. In the discussion of synthesis, major attention is focused on the most efficient approaches: condensation of hydroxylamine with 1,3-dielectrophiles and reactions of nitrile oxides with alkenes and alkynes. Five-membered ring opening reactions leading to acyclic functionalized or other heterocyclic compounds are considered. The transformations of isoxazole derivatives that occur without ring cleavage to form fused heterocyclic systems, as well as reactions that lead to the introduction of C-substituents into isoxazoles, are considered. Data on the biological activity of some isoxazole derivatives are reported. The bibliography includes 439 references.

Filamentation and light bullet formation dynamics in solid-state dielectric media with weak, moderate and strong anomalous group velocity dispersion

NASA Astrophysics Data System (ADS)

Gražulevičiūtė, I.; Garejev, N.; Majus, D.; Jukna, V.; Tamošauskas, G.; Dubietis, A.

2016-02-01

We present a series of measurements, which characterize filamentation dynamics of intense ultrashort laser pulses in the space-time domain, as captured by means of three-dimensional imaging technique in sapphire and fused silica, in the wavelength range of 1.45-2.25 μm, accessing the regimes of weak, moderate and strong anomalous group velocity dispersion (GVD). In the regime of weak anomalous GVD (at 1.45 μm), pulse splitting into two sub-pulses producing a pair of light bullets with spectrally shifted carrier frequencies in both nonlinear media is observed. In contrast, in the regimes of moderate (at 1.8 μm) and strong (at 2.25 μm) anomalous GVD we observe notably different transient dynamics, which however lead to the formation of a single self-compressed quasistationary light bullet with an universal spatiotemporal shape comprised of an extended ring-shaped periphery and a localized intense core that carries the self-compressed pulse.

A comparative study on the crystal structure of bicycle analogues to the natural phytotoxin helminthosporins

NASA Astrophysics Data System (ADS)

Barbosa, Luiz Cláudio de Almeida; Teixeira, Robson Ricardo; Nogueira, Leonardo Brandão; Maltha, Celia Regina Alvares; Doriguetto, Antônio Carlos; Martins, Felipe Terra

2016-02-01

Herein we described structural insights of a series of analogues to helminthosporin phytotoxins. The key reaction used to prepare the compounds corresponded to the [3 + 4] cycloaddition between the oxyallyl cation generated from 2,4-dibromopentan-3-one and different furans. Their structures were confirmed upon IR, NMR and X-ray diffraction analyses. While bicycles 7, 8 and 9 crystallize in the centrosymmetric monoclinic space group P21/c, compound 10 was solved in the noncentrosymmetric orthorhombic space group P212121. The solid materials obtained were shown to be racemic crystals (7, 8, 9) or racemic conglomerate (10). In all compounds, there is formation of a bicycle featured by fused tetrahydropyranone and 2,5-dihydrofuran rings. They adopt chair and envelope conformations, respectively. Crystal packing of all compounds is stabilized through C-H•••O contacts. Conformational aspects as well as similarities and differences among the crystal structures of the synthesized analogues are discussed.

8-Chloro-6-iodo-2-phenyl­chromeno[4,3-c]pyrazol-4(2H)-one N,N-dimethyl­formamide monosolvate

PubMed Central

Lokhande, Pradeep; Hasanzadeh, Kamal; Khaledi, Hamid; Mohd Ali, Hapipah

2011-01-01

In the title compound, C16H8ClIN2O2·C3H7NO, the fused tricyclic pyrazolo­coumarin ring and the N-phenyl ring are almost coplanar, the dihedral angle between them being 1.86 (9)°. In the crystal, these rings stack on top of each other via π–π inter­actions [centroid–centroid distances = 3.489 (2), 3.637 (2), 3.505 (2) and 3.662 (2) Å], forming infinite chains along the a axis. The chains are connected into layers parallel to ac plane through I⋯O inter­actions [3.0011 (18) Å] between pairs of symmetry-related mol­ecules. The DMF solvent mol­ecules are C—H⋯O bonded to this network. PMID:21837089

Measurement of temperature and concentration influence on the dispersion of fused silica glass photonic crystal fiber infiltrated with water-ethanol mixture

NASA Astrophysics Data System (ADS)

Van, Hieu Le; Buczynski, Ryszard; Long, Van Cao; Trippenbach, Marek; Borzycki, Krzysztof; Manh, An Nguyen; Kasztelanic, Rafal

2018-01-01

We present experimental and simulation results of the zero-dispersion shift in photonics crystal fibers infiltrated with water-ethanol mixture. The fiber based on the fused silica glass with a hexagonal lattice consists of seven rings of air-holes filled by liquid. We show that it is possible to shift the zero-dispersion wavelength by 35 ps/nm/km when changing the temperature by 60 °C, and by 42 ps/nm/km when changing the concentration of ethanol from 0 to 100%. The results also show that for the optical fiber filed with pure ethanol the flattened part of the dispersion shifts from anomalous to the normal regime at temperatures below -70 °C.

The Pauson-Khand Reaction as a New Entry to the Synthesis of Bridged Bicyclic Heterocycles: Application to the Enantioselective Total Synthesis of (−)-Alstonerine

PubMed Central

Miller, Kenneth A.; Shanahan, Charles S.; Martin, Stephen F.

2008-01-01

The first application of the Pauson-Khand reaction (PKR) to the synthesis of azabridged bicyclic structures is described. Compounds containing azabicyclo[3.3.1]nonane and azabicyclo[3.2.1]octane rings fused to cyclopentenones were efficiently constructed via the PKR of cis-2,6-disubstituted N-acyl piperidine enyne substrates, many of which can be readily prepared from 4-methoxypyridine in a few steps. Moreover, the PKR of cis-2,6-disubstituted piperazine enynes allowed the preparation of diazabicyclo[3.3.1]nonanes fused to cyclopentenones. This new strategy for the synthesis of azabridged bicyclic frameworks was exploited as a key step in a concise, enantioselective total synthesis of the macroline alklaoid (−)-alstonerine. PMID:19122869

The Pauson-Khand Reaction as a New Entry to the Synthesis of Bridged Bicyclic Heterocycles: Application to the Enantioselective Total Synthesis of (-)-Alstonerine.

PubMed

Miller, Kenneth A; Shanahan, Charles S; Martin, Stephen F

2008-01-01

The first application of the Pauson-Khand reaction (PKR) to the synthesis of azabridged bicyclic structures is described. Compounds containing azabicyclo[3.3.1]nonane and azabicyclo[3.2.1]octane rings fused to cyclopentenones were efficiently constructed via the PKR of cis-2,6-disubstituted N-acyl piperidine enyne substrates, many of which can be readily prepared from 4-methoxypyridine in a few steps. Moreover, the PKR of cis-2,6-disubstituted piperazine enynes allowed the preparation of diazabicyclo[3.3.1]nonanes fused to cyclopentenones. This new strategy for the synthesis of azabridged bicyclic frameworks was exploited as a key step in a concise, enantioselective total synthesis of the macroline alklaoid (-)-alstonerine.

Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy-droxy-7-meth-oxy-meth-oxy-11,15,18,18-tetra-methyl-3-oxo-2,4-dioxa-tetra-cyclo-[12.3.1.0(1,5).0(6,11)]octa-dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative.

PubMed

Oishi, Takeshi; Fukaya, Keisuke; Yamaguchi, Yu; Sugai, Tomoya; Watanabe, Ami; Sato, Takaaki; Chida, Noritaka

2015-05-01

The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra-cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (A), there are two independent benzoate mol-ecules (A and A') and a half mol-ecule of solvent pentane disordered about an inversion center. The mol-ecular conformations of (A), (B) and (C) are similar except for the flexible meth-oxy-meth-oxy group. The cyclo-hexane, cyclo-hexene and central cyclo-octane rings adopt chair, half-chair and chair-chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A' is slightly twisted from the mean plane. In the crystal of (A), inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol-ecules are linked through O-H⋯O and C-H⋯π inter-actions, and C-H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter-molecular C-H⋯O inter-actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).

Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 15. Effects of the pyridyl substituents and fused exocyclic rings on the UV-visible spectroscopic properties of Mg(II)-porphyrazines: a combined experimental and DFT/TDDFT study.

PubMed

Donzello, Maria Pia; De Mori, Giorgia; Viola, Elisa; Ercolani, Claudio; Ricciardi, Giampaolo; Rosa, Angela

2014-08-04

Two new Mg(II) porphyrazine macrocycles, the octakis(2-pyridyl)porphyrazinato-magnesium(II), [Py8PzMg(H2O)], and the tetrakis-[6,7-di(2-pyridyl)quinoxalino]porphyrazinato-magnesium(II), [Py8QxPzMg(H2O)], were prepared by Mg-template macrocyclization processes, and their general physicochemical properties were examined. The previously reported porphyrazine analog, the tetrakis-2,3-[5,6-di(2-pyridyl)-pyrazino]porphyrazinato-magnesium(II), [Py8PyzPzMg(H2O)], has been also considered in the present work. The UV-visible solution spectra in nonaqueous solvents of this triad of externally octapyridinated Mg(II) complexes exhibit the usual profile observed for phthalocyanine and porphyrazine macrocycles, with intense absorptions in the Soret (300-450 nm) and Q band (600-800 nm) regions. It is observed that the Q band maximum sensibly shifts toward the red with peak values at 635 → 658 → 759 nm along the series [Py8PzMg(H2O)], [Py8PyzPzMg(H2O)], and [Py8QxPzMg(H2O)], as the extension of the macrocycle π-system increases. TDDFT calculations of the electronic absorption spectra were performed for the related water-free model compounds [Py8PzMg], [Py8PyzPzMg], and [Py8QxPzMg] to provide an interpretation of the UV-visible spectral changes occurring upon introduction of the pyrazine and quinoxaline rings at the periphery of the Pz macrocycle. To discriminate the electronic effects of the fused exocyclic rings from those of the appended 2-pyridyl rings, the UV-visible spectra of [PzMg] and [PyzPzMg] were also theoretically investigated. The theoretical results prove to agree very well with the experimental data, providing an accurate description of the UV-visible spectra. The observed spectral changes are interpreted on the basis of the electronic structure changes occurring along the series.

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

NASA Astrophysics Data System (ADS)

Chandrahalim, Hengky; Fan, Xudong

2015-12-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3‧-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3‧-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

PubMed Central

Chandrahalim, Hengky; Fan, Xudong

2015-01-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip. PMID:26674508

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers.

PubMed

Chandrahalim, Hengky; Fan, Xudong

2015-12-17

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3'-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3'-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm(2) per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm(2) per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

Identification and quantification of seven fused aromatic rings C26H14 peri-condensed benzenoid polycyclic aromatic hydrocarbons in a complex mixture of polycyclic aromatic hydrocarbons from coal tar.

PubMed

Oña-Ruales, Jorge O; Ruiz-Morales, Yosadara; Wise, Stephen A

2016-04-15

A methodology for the characterization of groups of polycyclic aromatic hydrocarbons (PAHs) using a combination of normal phase liquid chromatography with ultraviolet-visible spectroscopy (NPLC/UV-vis) and gas chromatography with mass spectrometry (GC/MS) was used for the identification and quantification of seven fused aromatic rings C26H14 peri-condensed benzenoid polycyclic aromatic hydrocarbons, PAHs, in standard reference material (SRM) 1597a, complex mixture of PAHs from coal tar. The NPLC/UV-vis isolated the fractions based on the number of aromatic carbons and the GC/MS allowed the identification and quantification of five of the nine C26H14 PAH isomers; naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[b,pqr]perylene, naphtho[8,1,2-bcd]perylene, and dibenzo[cd,lm]perylene using a retention time comparison with authentic reference standards. For the other four benzenoid isomers with no available reference standards the following two approaches were used. First, the annellation theory was used to achieve the potential identification of benzo[qr]naphtho[3,2,1,8-defg]chrysene, and second, the elution distribution in the GC fractions was used to support the potential identification of benzo[qr]naphtho[3,2,1,8-defg]chrysene and to reach the tentative identifications of dibenzo[a,ghi]perylene, naphtho[7,8,1,2,3-pqrst]pentaphene, and anthra[2,1,9,8-opqra]naphthacene. It is the first time that naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[b,pqr]perylene, naphtho[8,1,2-bcd]perylene, and dibenzo[cd,lm]perylene are quantified, and the first time that benzo[qr]naphtho[3,2,1,8-defg]chrysene is potentially identified, in any sample, in any context. Copyright © 2016 Elsevier B.V. All rights reserved.

The Basicity of Unsaturated Hydrocarbons as probed by H-Bond Acceptor Ability. Bifurcated N–H+⋯π Hydrogen Bonding

PubMed Central

Stoyanov, Evgenii S.; Stoyanova, Irina V.; Reed, Christopher A.

2009-01-01

The competitive substitution of the anion in contact ion pairs of the type [Oct3NH+]B(C6F5)4− by unsaturated hydrocarbons L in accordance with the equilibrium Oct3NH+⋯Anion− + nL ↔ [Oct3NH+⋯Ln]Anion− has been studied in CCl4 solution. On the basis of equilibrium constants K and shifts of νNH to low frequency, it is established that complexed Oct3NH+⋯Ln cations with n = 1 and 2 are formed, having unidentate and bifurcated N–H+⋯π hydrogen bonds, respectively. Bifurcated H-bonds to unsaturated hydrocarbons have not been observed previously. The unsaturated hydro-carbons studied include benzene and methylbenzenes, fused-ring aromatics, alkenes, conjugated dienes, and alkynes. From the magnitude of the red shifts in N-H stretching frequencies, ΔνNH, a new scale for ranking the π-basicity of unsaturated hydrocarbons is proposed: fused-ring aromatics ≤ benzene < toluene < xylene < mesitylene < durene < conjugated dienes ∼ 1-alkynes < pentamethylbenzene < hexamethyl-benzene < internal alkynes ∼ cyclo-alkenes < 1-methylcycloalkenes. This scale is relevant to the discussion of π complexes for incipient protonation reactions and to understanding N–H+⋯π hydrogen bonding in proteins and molecular crystals. PMID:18637650

Synthesis and characterization of triangulene

NASA Astrophysics Data System (ADS)

Pavliček, Niko; Mistry, Anish; Majzik, Zsolt; Moll, Nikolaj; Meyer, Gerhard; Fox, David J.; Gross, Leo

2017-05-01

Triangulene, the smallest triplet-ground-state polybenzenoid (also known as Clar's hydrocarbon), has been an enigmatic molecule ever since its existence was first hypothesized. Despite containing an even number of carbons (22, in six fused benzene rings), it is not possible to draw Kekulé-style resonant structures for the whole molecule: any attempt results in two unpaired valence electrons. Synthesis and characterization of unsubstituted triangulene has not been achieved because of its extreme reactivity, although the addition of substituents has allowed the stabilization and synthesis of the triangulene core and verification of the triplet ground state via electron paramagnetic resonance measurements. Here we show the on-surface generation of unsubstituted triangulene that consists of six fused benzene rings. The tip of a combined scanning tunnelling and atomic force microscope (STM/AFM) was used to dehydrogenate precursor molecules. STM measurements in combination with density functional theory (DFT) calculations confirmed that triangulene keeps its free-molecule properties on the surface, whereas AFM measurements resolved its planar, threefold symmetric molecular structure. The unique topology of such non-Kekulé hydrocarbons results in open-shell π-conjugated graphene fragments that give rise to high-spin ground states, potentially useful in organic spintronic devices. Our generation method renders manifold experiments possible to investigate triangulene and related open-shell fragments at the single-molecule level.

Antifungal activity of fused Mannich ketones triggers an oxidative stress response and is Cap1-dependent in Candida albicans.

PubMed

Rossignol, Tristan; Kocsis, Béla; Bouquet, Orsolya; Kustos, Ildikó; Kilár, Ferenc; Nyul, Adrien; Jakus, Péter B; Rajbhandari, Kshitij; Prókai, László; d'Enfert, Christophe; Lóránd, Tamás

2013-01-01

We investigated the antifungal activity of fused Mannich ketone (FMK) congeners and two of their aminoalcohol derivatives. In particular, FMKs with five-membered saturated rings were shown to have minimum inhibitory concentration (MIC90s) ranging from 0.8 to 6 µg/mL toward C. albicans and the closely related C. parapsilosis and C. krusei while having reduced efficacy toward C. glabrata and almost no efficacy against Aspergillus sp. Transcript profiling of C. albicans cells exposed for 30 or 60 min to 2-(morpholinomethyl)-1-indanone, a representative FMK with a five-membered saturated ring, revealed a transcriptional response typical of oxidative stress and similar to that of a C. albicans Cap1 transcriptional activator. Consistently, C. albicans lacking the CAP1 gene was hypersensitive to this FMK, while C. albicans strains overexpressing CAP1 had decreased sensitivity to 2-(morpholinomethyl)-1-indanone. Quantitative structure-activity relationship studies revealed a correlation of antifungal potency and the energy of the lowest unoccupied molecular orbital of FMKs and unsaturated Mannich ketones thereby implicating redox cycling-mediated oxidative stress as a mechanism of action. This conclusion was further supported by the loss of antifungal activity upon conversion of representative FMKs to aminoalcohols that were unable to participate in redox cycles.

Kinetically E-selective macrocyclic ring-closing metathesis

NASA Astrophysics Data System (ADS)

Shen, Xiao; Nguyen, Thach T.; Koh, Ming Joo; Xu, Dongmin; Speed, Alexander W. H.; Schrock, Richard R.; Hoveyda, Amir H.

2017-01-01

Macrocyclic compounds are central to the development of new drugs, but preparing them can be challenging because of the energy barrier that must be surmounted in order to bring together and fuse the two ends of an acyclic precursor such as an alkene (also known as an olefin). To this end, the catalytic process known as ring-closing metathesis (RCM) has allowed access to countless biologically active macrocyclic organic molecules, even for large-scale production. Stereoselectivity is often critical in such cases: the potency of a macrocyclic compound can depend on the stereochemistry of its alkene; alternatively, one isomer of the compound can be subjected to stereoselective modification (such as dihydroxylation). Kinetically controlled Z-selective RCM reactions have been reported, but the only available metathesis approach for accessing macrocyclic E-olefins entails selective removal of the Z-component of a stereoisomeric mixture by ethenolysis, sacrificing substantial quantities of material if E/Z ratios are near unity. Use of ethylene can also cause adventitious olefin isomerization—a particularly serious problem when the E-alkene is energetically less favoured. Here, we show that dienes containing an E-alkenyl-B(pinacolato) group, widely used in catalytic cross-coupling, possess the requisite electronic and steric attributes to allow them to be converted stereoselectively to E-macrocyclic alkenes. The reaction is promoted by a molybdenum monoaryloxide pyrrolide complex and affords products at a yield of up to 73 per cent and an E/Z ratio greater than 98/2. We highlight the utility of the approach by preparing recifeiolide (a 12-membered-ring antibiotic) and pacritinib (an 18-membered-ring enzyme inhibitor), the Z-isomer of which is less potent than the E-isomer. Notably, the 18-membered-ring moiety of pacritinib—a potent anti-cancer agent that is in advanced clinical trials for treating lymphoma and myelofibrosis—was prepared by RCM carried out at a substrate concentration 20 times greater than when a ruthenium carbene was used.

Carbazole Scaffold in Medicinal Chemistry and Natural Products: A Review from 2010-2015.

PubMed

Tsutsumi, Lissa S; Gündisch, Daniela; Sun, Dianqing

2016-01-01

9H-carbazole is an aromatic molecule that is tricyclic in nature, with two benzene rings fused onto a 5-membered pyrrole ring. Obtained from natural sources or by synthetic routes, this scaffold has gained much interest due to its wide range of biological activity upon modifications, including antibacterial, antimalarial, anticancer, and anti-Alzheimer properties. This review reports a survey of the literature on carbazole-containing molecules and their medicinal activities from 2010 through 2015. In particular, we focus on their in vitro and in vivo activities and summarize structure-activity relationships (SAR), mechanisms of action, and/or cytotoxicity/selectivity findings when available to provide future guidance for the development of clinically useful agents from this template.

Reflectance spectroscopy (350-2500 nm) of solid-state polycyclic aromatic hydrocarbons (PAHs)

NASA Astrophysics Data System (ADS)

Izawa, M. R. M.; Applin, D. M.; Norman, L.; Cloutis, E. A.

2014-07-01

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds based on fused aromatic rings, and are formed in a variety of astrophysical, solar nebula and planetary processes. Polycyclic aromatic hydrocarbons are known or suspected to occur in a wide variety of planetary settings including icy satellites, Titan’s hazes, carbonaceous meteorites, comet nuclei, ring particles; and terrestrial organic-rich lithologies such as coals, asphaltites, and bituminous sands. Relatively few measurements of the visible and near-infrared spectra of PAHs exist, yet this wavelength region (350-2500 nm) is widely used for remote sensing. This study presents detailed analyses of the 350-2500 nm reflectance spectra of 47 fine-grained powders of different high-purity solid-state PAHs. Spectral properties of PAHs change with variations in the number and connectivity of linked aromatic rings and the presence and type of side-groups and heterocycles. PAH spectra are characterized by three strong features near ∼880 nm, ∼1145 nm, and ∼1687 nm due to overtones of νCH fundamental stretching vibrations. Some PAHs are amenable to remote detection due to the presence of diagnostic spectral features, including: Nsbnd H stretching overtones at 1490-1515 nm in NH- and NH2-bearing PAHs, aliphatic or saturated bond Csbnd H overtone vibrations at ∼1180-1280 nm and ∼1700-1860 nm; a broad asymmetric feature between ∼1450 nm and ∼1900 nm due to Osbnd H stretching overtones in aromatic alcohols, Csbnd H and Cdbnd O combinations near ∼2000-2010 nm and ∼2060-2270 nm in acetyl and carboxyl-bearing PAHs. Other substituents such as sulphonyl, thioether ether and carboxyl heterocycles, or cyano, nitrate, and aromatic side groups, do not produce well-resolved diagnostic spectral features but do cause shifts in the positions of the aromatic Csbnd H vibrational overtone features. Fluorescence is commonly suppressed by the presence of heterocycles, side-groups and in many non-alternant PAHs. The spectral characteristics of PAHs offer the potential, under suitable circumstances, for remote characterization of the classes of PAH present and in some cases, identification of particular heterocyclic or side-group substituents.

Focusing experiments in plasma coaxial railguns

NASA Astrophysics Data System (ADS)

Driga, M. D.; Cook, R. W.; Thelen, R. F.

1986-11-01

Results are reported from experiments on focusing of plasma fired from a coaxial electromagnetic gun (CEMG). The plasma used, obtained by exploding a metallic fuse at the gun breech, comprised metal vapor, metallic liquid droplets and small chunks of solid metal. An azimuthal current, and thereby an axial field, was introduced at the breech of the CEMG by a solenoid. Previous studies indicated that the field would cause vaporized metal to form into a self-stabilizing toroidal plasma. Test shots instrumented with Languir probes and pick-up coils did not reveal the presence of toroidal plasma rings. However, post-mortem of the 30 cm rail showed that only one-third of the 3 mg Al fuse metal remained in the bore. Further, a toroidal hole was punched in a diagnostic screen at the bore exit after one shot.

Asymmetric synthesis of a potent, aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV inhibitor.

PubMed

Xu, Feng; Corley, Edward; Zacuto, Michael; Conlon, David A; Pipik, Brenda; Humphrey, Guy; Murry, Jerry; Tschaen, David

2010-03-05

A practical asymmetric synthesis of a novel aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV (DPP-4) inhibitor 1 has been developed. Application of a unique three-component cascade coupling with chiral nitro diester 7, which is easily accessed via a highly enantioselective Michael addition of dimethyl malonate to a nitrostyrene, allows for the assembly of the functionalized piperidinone skeleton in one pot. Through a base-catalyzed, dynamic crystallization-driven process, the cis-piperidionone 16a is epimerized to the desired trans isomer 16b, which is directly crystallized from the crude reaction stream in high yield and purity. Isomerization of the allylamide 16b in the presence of RhCl(3) is achieved without any epimerization of the acid/base labile stereogenic center adjacent to the nitro group on the piperidinone ring, while the undesired enamine intermediate is consumed to <0.5% by utilizing a trace amount of HCl generated from RhCl(3). The amino lactam 4, obtained through hydrogenation and hydrolysis, is isolated as its crystalline pTSA salt from the reaction solution directly, as such intramolecular transamidation has been dramatically suppressed via kinetic control. Finally, a Cu(I) catalyzed coupling-cyclization allows for the formation of the tricyclic structure of the potent DPP-4 inhibitor 1. The synthesis, which is suitable for large scale preparation, is accomplished in 23% overall yield.

1-(Hydroxy­meth­yl)pyrene

PubMed Central

Gruber, Tobias; Seichter, Wilhelm; Weber, Edwin

2010-01-01

The asymmetric unit of the title compound, C17H12O, contains two molecules, in which the fused aromatic ring systems are almost planar [maximum deviations = 0.0529 (9) and 0.0256 (9) Å]. In the crystal, aromatic π–π stacking inter­actions (perpendicular distance of centroids of about 3.4 Å) and strong O—H⋯O hydrogen bonds result in a helical arrangement of pyrenyl dimers. PMID:21579858

An efficient route for annulation of pyrimidines to steroids and non-steroids via a base catalyzed one-pot three component reaction.

PubMed

Saikia, Pallabi; Gogoi, Shyamalee; Gogoi, Sanjib; Boruah, Romesh C

2014-10-01

A facile strategy for the synthesis of steroidal A- and D-ring fused pyrimidines has been accomplished in high yields via a one-pot reaction of steroidal ketones, aromatic aldehydes and amidine derivatives in presence of potassium tert-butoxide in refluxing ethanol. The generality of the reaction was also extended to non-steroidal ketones. Copyright © 2014 Elsevier Inc. All rights reserved.

Filters for Submillimeter Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Berdahl, C. M.

1986-01-01

New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.

Uncertainties of polynuclear aromatic hydrocarbon and carbonyl measurements in heavy-duty diesel emission.

PubMed

Mabilia, Rosanna; Cecinato, Angelo; Guerriero, Ettore; Possanzini, Massimiliano

2006-02-01

In this note we describe the speciated particle-phase PM2.5 polynuclear aromatic hydrocarbon (PAH) and gas-phase carbonyl emissions as collected from a heavy-duty diesel bus outfitted with an oxidation catalyst for exhaust after-treatment. The vehicle was run on a chassis dynamometer during a transient cycle test reproducing a typical city bus route (Azienda Tramviaria Municipalizzata cycle). The diluted tailpipe emissions were sampled for PAH using a 2.5 microm cut size cyclone glass fiber filter assembly, while carbonyls were absorbed onto dinitrophenyl hydrazine-coated silica cartridges. The former compounds were analysed by CGC-MS, the latter by HPLC-UV. Combining the two sets of speciation data resulting from 15 identical dynamometer tests provided a profile of both unregulated organic emissions. PAH emission rates decreased with the number of benzene fused rings. Fluoranthene and pyrene amounted to 90% of total PAHs quantified; six-ring PAHs accounted only for 0.5%. Similarly, formaldehyde and acetaldehyde accounted for approximately 80% of the total carbonyl emissions. Uncertainties of the method in the determination of individual emission factors were calculated. Statistical data processing revealed that all the measurements were quite unaffected by systematic errors and repeatability percentages did not exceed 50% for the majority of components of both groups.

Rejected and excluded forevermore, but even more devoted: irrevocable ostracism intensifies loyalty to the group among identity-fused persons.

PubMed

Gómez, Angel; Morales, J Francisco; Hart, Sonia; Vázquez, Alexandra; Swann, William B

2011-12-01

When people are ostrasized (i.e., rejected and excluded) by either an outgroup or an ingroup, they may either withdraw or engage in compensatory activities designed to reaffirm their social identity as a group member. The authors proposed here that individual differences in identity fusion (an index of familial orientation toward the group) would moderate the tendency for people to display such compensatory activity. Consistent with this reasoning, the results of four experiments showed that irrevocable ostracism increased endorsement of extreme, pro-group actions (fighting and dying for the ingroup) among fused persons but not among nonfused persons. This effect emerged when an outgroup ostracized fused individuals due either to their nationality (Experiment 1) or their personal preferences (Experiment 2). Similarly, ostracism by the ingroup amplified the tendency for fused persons to both endorse extreme pro-group actions, refuse to leave the group (Experiment 3), and donate money to an ingroup member (Experiment 4). Finally, compensatory activities emerged even when ostracism was based on being "too good" for the group, suggesting that a desire for self-enhancement does not mediate such activities (Experiment 4).

Sources, fate, and effects of PAHs in shallow water environments: a review with special reference to small watercraft

USGS Publications Warehouse

Albers, P.H.; Kennish, Michael J.

2002-01-01

Polycyclic aromatic hydrocarbons (PAHs) are aromatic hydrocarbons with two to seven fused carbon (benzene) rings that can have substituted groups attached. Shallow coastal, estuarine, lake, and river environments receive PAHs from treated wastewater, stormwater runoff, petroleum spills and natural seeps, recreational and commercial boats, natural fires, volcanoes, and atmospheric deposition of combustion products. Abiotic degradation of PAHs is caused by photooxidation, photolysis in water, and chemical oxidation. Many aquatic microbes, plants, and animals can metabolize and excrete ingested PAHs; accumulation is associated with poor metabolic capabilities, high lipid content, and activity patterns or distributions that coincide with high concentrations of PAHs. Resistance to biological transformation increases with increasing number of carbon rings. Four- to seven-ring PAHs are the most difficult to metabolize and the most likely to accumulate in sediments. Disturbance by boating activity of sediments, shorelines, and the surface microlayer of water causes water column re-entry of recently deposited or concentrated PAHs. Residence time for PAHs in undisturbed sediment exceeds several decades. Toxicity of PAHs causes lethal and sublethal effects in plants and animals, whereas some substituted PAHs and metabolites of some PAHs cause mutations, developmental malformations, tumors, and cancer. Environmental concentrations of PAHs in water are usually several orders of magnitude below levels that are acutely toxic, but concentrations can be much higher in sediment. The best evidence for a link between environmental PAHs and induction of cancerous neoplasms is for demersal fish in areas with high concentrations of PAHs in the sediment.

Bioinspired synthesis of pentalene-based chromophores from an oligoketone chain.

PubMed

Saito, Yuki; Higuchi, Masayuki; Yoshioka, Shota; Senboku, Hisanori; Inokuma, Yasuhide

2018-04-24

We report a bioinspired synthesis of 2,5-dihydropentalene-based chromophores from an aliphatic oligoketone bearing 1,3- and 1,4-diketone subunits. Unlike the natural polyketone sequence, fused five-membered rings were formed via an intramolecular aldol condensation. A subsequent Knoevenagel condensation reaction with malononitrile furnished a multiply cross-conjugated π-system with low-lying LUMO levels. Furthermore, pentalenes obtained from a non-conjugated aliphatic chain exhibited visible absorption and solid-state fluorescence.

2,2'-(Carbono-thio-yldisulfanedi-yl)bis-(2-methyl-propanoic acid).

PubMed

Moreno-Fuquen, Rodolfo; Grande, Carlos; Advincula, Rigoberto C; Tenorio, Juan C; Ellena, Javier

2013-05-01

The mol-ecular structure of the title compound, C9H14O4S3, exhibits intra-molecular C-H⋯S hydrogen bonds. In the crystal, pairs of O-H⋯O hydrogen bonds lead to the formation of centrosymmetric dimers, which are in turn connected by weak C-H⋯O inter-actions. The combination of these inter-actions generates edge-fused R 2 (2)(8) and R 2 (2)(20) rings running along [211].

Dynamics and three-dimensional localization of ribosomal RNA within the nucleolus.

PubMed Central

Thiry, M; Cheutin, T; O'Donohue, M F; Kaplan, H; Ploton, D

2000-01-01

Although rRNA synthesis, maturation, and assembly into preribosomal particles occur within the nucleolus, the route taken by pre-rRNAs from their synthetic sites toward the cytoplasm remains largely unexplored. Here, we employed a nondestructive method for the incorporation of BrUTP into the RNA of living cells. By using pulse-chase experiments, three-dimensional image reconstructions of confocal optical sections, and electron microscopy analysis of ultrathin sections, we were able to describe topological and spatial dynamics of rRNAs within the nucleolus. We identified the precise location and the volumic organization of four typical subdomains, in which rRNAs are successively moving towards the nucleolar periphery during their synthesis and processing steps. The incorporation of BrUTP takes place simultaneously within several tiny spheres, centered on the fibrillar centers. Then, the structures containing the newly synthesized RNAs enlarge and appear as compact ringlets disposed around the fibrillar centers. Later, they form hollow spheres surrounding the latter components and begin to fuse together. Finally, these structures widen and form large rings reaching the limits of the nucleoli. These results clearly show that the transport of pre-rRNAs within the nucleolus does not occur randomly, but appears as a radial flow starting from the fibrillar centers that form concentric rings, which finally fuse together as they progress toward the nucleolar periphery. PMID:11142375

Imidazopyridine/Pyrrole and hydroxybenzimidazole/pyrrole pairs for DNA minor groove recognition.

PubMed

Renneberg, Dorte; Dervan, Peter B

2003-05-14

The DNA binding properties of fused heterocycles imidazo[4,5-b]pyridine (Ip) and hydroxybenzimidazole (Hz) paired with pyrrole (Py) in eight-ring hairpin polyamides are reported. The recognition profile of Ip/Py and Hz/Py pairs were compared to the five-membered ring pairs Im/Py and Hp/Py on a DNA restriction fragment at four 6-base pair recognition sites which vary at a single position 5'-TGTNTA-3', where N = G, C, T, A. The Ip/Py pair distinguishes G.C from C.G, T.A, and A.T, and the Hz/Py pair distinguishes T.A from A.T, G.C, and C.G, affording a new set of heterocycle pairs to target the four Watson-Crick base pairs in the minor groove of DNA.

Fusion with the Cross-Gender Group Predicts Genital Sex Reassignment Surgery.

PubMed

Swann, William B; Gómez, Ángel; Vázquez, Alexandra; Guillamón, Antonio; Segovia, Santiago; Carrillo, Beatriz; Carillo, Beatriz

2015-07-01

Transsexuals vary in the sacrifices that they make while transitioning to their cross-gender group. We suggest that one influence on the sacrifices they make is identity fusion. When people fuse with a group, a visceral and irrevocable feeling of oneness with the group develops. The personal self (the sense of "I" and "me") remains potent and combines synergistically with the social self to motivate behavior. We hypothesized that transsexuals who felt fused with the cross-gender group would be especially willing to make sacrifices while transitioning to that group. Our sample included 22 male-to-female (MtF) and 16 female-to-male (FtM) transsexuals. Consistent with expectation, those who were fused with their cross-gender group (1) expressed more willingness to sacrifice close relationships in the process of changing sex than non-fused transsexuals and (2) actually underwent irreversible surgical change of their primary sexual characteristics (vaginoplasty for MtF transsexuals and hysterectomy for FtM transsexuals). These outcomes were not predicted by a measure of "group identification," which occurs when membership in the group eclipses the personal self (the "I" and "me" is subsumed by the group; in the extreme case, brainwashing occurs). These findings confirm and extend earlier evidence that identity fusion is uniquely effective in tapping a propensity to make substantial sacrifices for the group. We discuss identity fusion as a social psychological determinant of the choices of transsexuals.

Histological characteristics of collagen denaturation and injuries in bipolar radiofrequency-induced colonic anastomoses.

PubMed

Zhao, Lingxi; Zhuo, Changhua; Song, Chengli; Li, Xinxiang; Zhou, Yu; Shi, Debing

2015-03-01

Bipolar radiofrequency-induced thermo-fusion has been explored as an advanced surgical method for intestinal anastomoses; however, the histological characteristics of collagen denaturation and injuries arising from this process remain unclear. The aim of this study was to investigate the microcosmic changes and tissue damage of fusion regions with various parameters of injury. Ex vivo colons of pigs were fused serosa-serosa on two carrier rings, which were installed on a homemade anastomotic device. Five levels of compressive pressure from 171 to 313 kPa were applied for 5s to fuse the colons under radiofrequency power of 160 W, and then the collagen denaturation of the fused region was examined by transmission electron microscopy. Light microscopy was utilized to observe histological slices that were stained with picrosirius red in order to visualize the tissue injuries under two levels of radiofrequency power (120 vs. 140 W) and operation time (5 vs. 10s). Transmission electron micrographs showed that increased compressive pressure led to thicker denatured collagen fibrils and wider gaps between each collagen fibril. Serosa adhesion regions appeared abundant in collagen. No histological differences were observed when 120 W of power was applied for 5 and 10s. Significant muscle cracking occurred when colons were fused using 140 W for 5s. When the operation time was extended to 10s, 140 W led to tight fusion and less splitting on muscles. These results suggest that higher compressive pressure results in more severe collagen unfolding and also reduces collagen crosslinking in fused colons. Improved radiofrequency power along with operation time could avoid tissue injury upon radiofrequency-induced colonic anastomoses. Copyright © 2014 Elsevier GmbH. All rights reserved.

Sum Frequency Generation Spectroscopy and Molecular Dynamics Simulations Reveal a Rotationally Fluid Adsorption State of α-Pinene on Silica

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

Ho, Junming; Psciuk, Brian T.; Chase, Hilary M.

2016-06-16

A rotationally fluid state of α-pinene at fused silica/vapor interfaces is revealed by computational and experimental vibrational sum frequency generation (SFG) studies. We report the first assignment of the vibrational modes in the notoriously congested C-H stretching region of α-pinene and identify its bridge methylene group on the four-membered ring ("βCH2") as the origin of its dominant spectral feature. We find that the spectra are perfused with Fermi resonances that need to be accounted for explicitly in the computation of vibrational spectra of strained hydrocarbons such α-pinene. The preferred orientations of α-pinene are consistent with optimization of van der Waalsmore » contacts with the silica surface that results in a bimodal distribution of highly fluxional orientations in which the βCH2 group points "towards" or "away from” the surface. The reported findings are particularly relevant to the exposure of α-pinene to primary oxidants in heterogeneous catalytic pathways that exploit α-pinene as a sustainable feedstock for fine chemicals and polymers.« less

The structure study of thin semiconductor and dielectric films by diffraction of synchrotron radiation

NASA Astrophysics Data System (ADS)

Yurjev, G. S.; Fainer, N. I.; Maximovskiy, E. A.; Kosinova, M. L.; Sheromov, M. A.; Rumyantsev, Yu. M.

1998-02-01

The structure of semiconductor and dielectric thin (100-300 nm) films was studied by diffraction of synchrotron radiation. The diffraction experiments were performed at both the station "Anomalous scattering" of the storage ring synchrotron facility VEPP-3 and DRON-4 diffractometer. The structure of CdS thin films grown on fused silica, single Si(100) and InP(100) substrates was investigated. The structure of Cu 2S thin films grown on fused silica, single Si(100) substrates and CdS/Si(100)-heterostructure was studied. The structure study was performed on Si 3N 4 films grown on GaAs(100) substrates. The structure of thin BN layers grown on single Si(100) substrates was studied. It was established that structural parameters of above-mentioned thin films coincide on the parameters of JCPDS International Centre for Diffraction Data.

Probing the Reverse Shock in an Oxygen-Rich Supernova Remnant

NASA Technical Reports Server (NTRS)

Sonneborn, George (Technical Monitor); Gaetz, Terrance J.

2003-01-01

The aim of this proposal was to examine the O VI emission at three positions around the X-ray bright ring of the remnant in order to investigate the relation between the O VI emission, the X-ray O VII and O VIII emission, and the optical [O III] emission, and how these vary around the rim of the remnant. So far, only one Far Ultraviolet Spectroscopic Explorer (FUSE) pointing at the remnant has been performed, together with the background pointing needed to subtract the diffuse scattered light from nearby O stars. The data were recalibrated using the CalFUSE calibration pipeline, but the emission is faint enough that hand processing will be needed for this pointing to optimize the extraction. Rereduction of the data is underway. A postdoctoral fellow has also been hired, and in part she will assist with the analysis.

Regio- and stereoselective synthesis of pregnane-fused isoxazolines by nitril-oxide/alkene 1,3-dipolar cycloaddition and an evaluation of their cell-growth inhibitory effect in vitro

NASA Astrophysics Data System (ADS)

Mótyán, Gergő; Baji, Ádám; Zupkó, István; Frank, Éva

2016-04-01

Efficient syntheses of some pregnane-fused isoxazolines from 16-dehydropregnenolone acetate with different arylnitrile oxides were carried out by 1,3-dipolar cycloadditions. The intermolecular ring-closures occurred in a highly regio- and stereoselective manner permitting the formation of a single 16α,17α-condensed diastereomer in which the O terminus of the nitrile oxide dipole is attached to C-17 of the sterane core. The conversions were found to be affected significantly by the electronic character of the substituents on the aromatic moiety of the 1,3-dipoles. Deacetylation of the primary products resulted in the corresponding 3β-OH analogs. All of the synthesized compounds were subjected to in vitro pharmacological studies for the determination of their antiproliferative effects on four breast cancer cell lines (MCF7, T47D, MDA-MB-231 and MDA-MB-361).

C-H Activation and Alkyne Annulation via Automatic or Intrinsic Directing Groups: Towards High Step Economy.

PubMed

Zheng, Liyao; Hua, Ruimao

2018-06-01

Direct transformation of carbon-hydrogen bond (C-H) has emerged to be a trend for construction of molecules from building blocks with no or less prefunctionalization, leading high atom and step economy. Directing group (DG) strategy is widely used to achieve higher reactivity and selectivity, but additional steps are usually needed for installation and/or cleavage of DGs, limiting step economy of the overall transformation. To meet this challenge, we proposed a concept of automatic DG (DG auto ), which is auto-installed and/or auto-cleavable. Multifunctional oxime and hydrazone DG auto were designed for C-H activation and alkyne annulation to furnish diverse nitrogen-containing heterocycles. Imidazole was employed as an intrinsic DG (DG in ) to synthesize ring-fused and π-extended functional molecules. The alkyne group in the substrates can also be served as DG in for ortho-C-H activation to afford carbocycles. In this account, we intend to give a review of our progress in this area and brief introduction of other related advances on C-H functionalization using DG auto or DG in strategies. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shoulder balance in Lenke type 2 adolescent idiopathic scoliosis: Should we fuse to the second thoracic vertebra?

PubMed

Yang, Huiliang; Im, Gi Hye; Hu, Bowen; Wang, Lei; Zhou, Chunguang; Liu, Limin; Song, Yueming

2017-12-01

There are many different systems recommending upper instrumented vertebra (UIV) for Lenke type 2 adolescent idiopathic scoliosis (AIS), several of which suggest that all Lenke type 2 AIS patients should be fused to the second thoracic vertebra (T2). However, all previously proposed UIV selecting systems do not accurately predict postoperative shoulder balance. We investigated whether fusing to T2 could prevent postoperative shoulder imbalance and identified circumstances under which to fuse up to T2. We retrospectively collected all patients with typical Lenke type 2 AIS who received surgery by one spine surgeon in our hospital from 2010 to 2014. Lateral shoulder balance was assessed utilizing radiographic shoulder height difference (RSH), coracoid height difference (CHD), clavicle-rib intersection difference (CRID), and clavicle angle (CA). Medial shoulder balance was assessed by T1 tilt angle and first rib angle (FRA). Lateral shoulders were considered to be level if the absolute value of RSH was less than 10 millimeters. All patients were divided into two groups as follows: 1) T2 group: UIV of T2 (n=49); and 2) below-T2 group: UIV of T3 (n=24) or T4 (n=6). Patients were assessed before surgery and at final follow-up with a minimum follow-up duration of 24 months. Seventy-nine typical Lenke type 2 AIS patients were identified. Preoperative CHD and CA were significantly associated with postoperative lateral shoulder imbalance (both p=0.045), whereas the UIV level was not significantly associated with it. Both fusing to T2 and to below T2 could improve RSH (p<0.001 and p=0.001, respectively). Fusing to T2 slightly worsened CHD, CRID, and CA at last follow-up (all p<0.001), while fusing to below T2 improved these lateral shoulder balance parameters (p=0.042, p<0.001, and p=0.007, respectively). For medial shoulder balance, fusing to below T2 worsened T1 tilt angle and FRA at last follow-up (p=0.025 and p<0.001, respectively), while fusing to T2 effectively kept these medial shoulder parameters in balance. In addition, for patients with an elevated left border of T1, the T2 group had worse preoperative T1 tilt angle but gained better postoperative T1 tilt angle than the below-T2 group (p<0.001 and p=0.040, respectively). Preoperative lateral shoulder balance, more so than the UIV level, can strongly influence postoperative lateral shoulder balance. Fusing to T2 can only effectively improve medial shoulder balance, not lateral shoulder balance (CHD, CRID, and CA). Moreover, a positive T1 tilt angle is an indicator for fusing to T2 to improve medial shoulder balance. Copyright © 2017 Elsevier B.V. All rights reserved.

Duplicate origin of the posterior communicating artery diagnosed by magnetic resonance angiography.

PubMed

Uchino, Akira; Kamiya, Kouhei; Suzuki, Chihiro

2013-10-01

Extremely rarely, a posterior communicating artery (PCoA) of "duplicate origin" occurs when two branches of the PCoA arise separately from the supraclinoid segment of the internal carotid artery (ICA) and quickly fuse to form an arterial ring. Three such cases previously reported were described as "fenestration." We report the case of this rare variation diagnosed by magnetic resonance angiography and discuss the differentiation of PCoA of duplicate origin from PCoA fenestration, supraclinoid ICA fenestration, and hyperplastic anterior choroidal artery.

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

Wu, Fu-Peng; Un, Hio-Ieng; Li, Yongxi

A new electron-deficient unit with fused 5-heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with cyclohepta- 4,6-diene-1,3-diimde unit. The imide bridging endows BBI with fixed planar configuration and both low the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbit (LUMO) energy levels. Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm2 V-1 s-1, which indicates that the BBI is a promising ntype semiconductor for optoelectronics.

Mathematics of Periodic Tables for Benzenoid Hydrocarbons.

PubMed

Dias, Jerry Ray

2007-01-01

The upper and lower bounds for invariants of polyhex systems based on the Harary and Harborth inequalities are studied. It is shown that these invariants are uniquely correlated by the Periodic Table for Benzenoid Hydrocarbons. A modified periodic table for total resonant sextet (TRS) benzenoids based on the invariants of Ds and r(empty) is presented; Ds is the number of disconnections among the empty rings for fused TRS benzenoid hydrocarbons. This work represents a contribution toward deciphering the topological information content of benzenoid formulas.

Rigidifying Nonplanar Perylene Diimides by Ring Fusion Toward Geometry-Tunable Acceptors for High-Performance Fullerene-Free Solar Cells.

PubMed

Zhong, Hongliang; Wu, Chen-Hao; Li, Chang-Zhi; Carpenter, Joshua; Chueh, Chu-Chen; Chen, Jung-Yao; Ade, Harald; Jen, Alex K-Y

2016-02-03

Rigid fused perylene diimide (PDI) dimers bridged with heterocycles exhibit superior photovoltaic performance compared to their unfused semiflexible analogues. Changing the chalcogen atoms in the aromatic bridges gradually increases the twist angles between the two PDI planes, leading to a varied morphology in which the one bridged by thiophene achieves a balance and shows the best efficiency of 6.72%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antiandrogenic steroidal sulfonyl heterocycles. Utility of electrostatic complementarity in defining bioisosteric sulfonyl heterocycles.

PubMed

Mallamo, J P; Pilling, G M; Wetzel, J R; Kowalczyk, P J; Bell, M R; Kullnig, R K; Batzold, F H; Juniewicz, P E; Winneker, R C; Luss, H R

1992-05-15

Complementarity of electrostatic potential surface maps was utilized in defining bioisosteric steroidal androgen receptor antagonists. Semiempirical and ab initio level calculations performed on a series of methanesulfonyl heterocycles indicated the requirement for a partial negative charge at the heteroatom attached to C-3 of the steroid nucleus to attain androgen receptor affinity. Synthesis and testing of six heterocycle A-ring-fused dihydroethisterone derivatives support this hypothesis, and we have identified two new androgen receptor antagonists of this class.

MORPHOLOGICAL TRANSFORMATION AND DNA ADDUCT FORMATION BY BENZ[J]ACEANTHRYLENE AND ITS METABOLITES IN C3H1OT1/2CL8 CELLS: EVIDENCE FOR BOTH CYCLOPENTA-RING AND BAY REGION METABOLIC ACTIVATION PATHWAYS

EPA Science Inventory

Benz[j]aceanthrylene (B[j]A), a cyclopenta-fused polycyclic aromatic hydrocarbon (CP-PAH) related to 3-methylcholanthrene, has been studied to identify the major routes of metabolic activation in transformable C3H1OT1/2CLB (C3H1OT1/2) mouse embryo fibroblasts in culture. he morph...

Crystal structure of (2R*,3aR*)-2-phenyl-sulfonyl-2,3,3a,4,5,6-hexa-hydro-pyrrolo-[1,2-b]isoxazole.

PubMed

Hernández, Yaiza; Marcos, Isidro; Garrido, Narciso M; Sanz, Francisca; Diez, David

2017-01-01

The title compound, C 12 H 15 NO 3 S, was prepared by 1,3-dipolar cyclo-addition of 3,4-di-hydro-2 H -pyrrole 1-oxide and phenyl vinyl sulfone. In the mol-ecule, both fused five-membered rings display a twisted conformation. In the crystal, C-H⋯O hydrogen bonds link neighbouring mol-ecules, forming chains running parallel to the b axis.

Total Syntheses of (-)-Mersicarpine, (-)-Scholarisine G, (+)-Melodinine E, (-)-Leuconoxine, (-)-Leuconolam, (-)-Leuconodine A, (+)-Leuconodine F, and (-)-Leuconodine C: Self-Induced Diastereomeric Anisochronism (SIDA) Phenomenon for Scholarisine G and Leuconodines A and C.

PubMed

Xu, Zhengren; Wang, Qian; Zhu, Jieping

2015-05-27

Enantioselective total syntheses of title natural products from a common cyclohexenone derivative (S)-18 were reported. Ozonolysis of (S)-18 afforded a stable diketo ester (R)-17 that was subsequently converted to two skeletally different natural products, i.e., (-)-mersicarpine (8) with a [6.5.6.7] fused tetracyclic ring system and (-)-scholarisine G (9) with a [6.5.6.6.5] fused pentacyclic skeleton, respectively. The postcyclization diversification was realized by taking advantage of the facile conversion of (+)-melodinine E (6) to N-acyliminium ion 7, from which a hydroxy group was selectively introduced to the C6, C7, C10 and the central C21 position of diazafenestrane system, leading to (-)-leuconodine A (11), (+)-leuconodine F (12), (-)-scholarisine G (9), (-)-leuconodine C (13), and skeletally different (-)-leuconolam (5). Furthermore, an unprecedented non-natural oxabridged oxadiazafenestrane 68 was formed by oxidation of (+)-melodinine E (6). During the course of this study, a strong self-induced diastereomeric anisochronism (SIDA) phenomenon was observed for scholarisine G (9), leuconodines A (11) and C (13). X-ray structures of both the racemic and the enantiopure natural products 9, 11, and 13 were obtained. The different crystal packing of these two forms nicely explained the chemical shift differences observed in the (1)H NMR spectra of the racemic and the enantio-enriched compounds in an achiral environment.

Nonlinear femtosecond near infrared laser structuring in oxide glasses

NASA Astrophysics Data System (ADS)

Royon, Arnaud

Three-dimensional femtosecond laser structuring has a growing interest because of its ease of implementation and the numerous possible applications in the domain of photonic components. Structures such as waveguides, diffraction gratings, optical memories or photonic crystals can be fabricated thanks to this technique. Its use with oxide glasses is promising because of several advantages; they are resistant to flux and ageing, their chemical composition can easily be changed to fit the well-defined requirements of an application. They can already be found in Raman amplifiers, optical fibers, fiber lasers, and other devices. This thesis is based on two axes. The first axis consists in characterizing the linear and nonlinear optical properties of bulk vitreous materials in order to optimize their composition with a particular application in view. Within this context, the nonlinear optical properties, their physical origins (electronic and nuclear) as well as their characteristic response times (from a few femtoseconds to a few hundreds of picoseconds) are described within the Born-Oppenheimer approximation. Fused silica and several sodium-borophosphate glasses containing different concentrations in niobium oxide have been studied. Results show that the nonlinear optical properties of fused silica are mainly from electronic origin, whereas in the sodium-borophosphate glasses, the contribution from nuclear origin becomes predominant when the concentration of niobium oxide exceeds 30%. The second axis is based on the structuring of materials. Three commercially available fused silica samples presenting different fabrication conditions (therefore distinct impurity levels) and irradiated with a near infrared femtosecond laser have been studied. The laser induced defects have been identified by means of several spectroscopic techniques. They show the formation of color centers as well as a densification inside the irradiated area. Their linear refractive index and nonlinear third-order susceptibility properties have been measured. Moreover, the structuring of fused silica at the subwavelength scale into "nanogratings" is observed and the form of birefringence induced by these structures is discussed. In addition to the fused silica samples, several oxide glasses presenting very distinct chemical compositions have been studied. A sodium-borophosphate glass containing niobium oxide exhibits micro-cracks and nano-crystallites following irradiation. A silicate glass with or without a silver component reveals fluorescent rings or "nanograting" structures. A zinc phosphate glass containing silver also presents fluorescent ring structures, with a size of the order of 80 nm, well below the diffraction limit. Pump-probe microscope techniques have been performed on this glass to investigate the laser-glass interaction. The absorption mechanism is determined to be four-photon absorption. The generated free electron density is ˜ 1017 cm-3, which suggests the conclusion that an electron gas rather than a plasma is formed during the laser irradiation.

Total Synthesis of Purported Cephalosporolides H and I, Penisporolide B, and Their Stereoisomers.

PubMed

Wang, Jian; Tong, Rongbiao

2016-05-20

Development of a unified, bioinspired synthetic strategy to access four possible diastereomers of unique 2,2-dimethyl-[5,5]-spiroacetal-cis-fused-γ-lactone (Me2SAFL) is reported, featuring pyridinium chlorochromate (PCC)-promoted oxidative ring expansion of β-hydroxy cyclic ethers and dehydrative ring-contraction rearrangement of 10-membered lactones. Synthetic utility of this strategy was demonstrated by total syntheses of 12 Me2SAFLs, corresponding to the purported cephalosporolide H (CesH), cephalosporolide I (CesI), and penisporolide B (PenB) and their possible diastereomers. Comprehensive NMR data analysis suggested that the tricyclic Me2SAFL core of CesH, CesI, and PenB should be revised to the same relative (3R*, 4R*, 6S*, 9R*) configuration and that the side chains required an unknown constitutional structure revision.

Antivirulence Isoquinolone Mannosides: Optimization of the Biaryl Aglycone for FimH Lectin Binding Affinity and Efficacy in the Treatment of Chronic UTI.

PubMed

Jarvis, Cassie; Han, Zhenfu; Kalas, Vasilios; Klein, Roger; Pinkner, Jerome S; Ford, Bradley; Binkley, Jana; Cusumano, Corinne K; Cusumano, Zachary; Mydock-McGrane, Laurel; Hultgren, Scott J; Janetka, James W

2016-02-17

Uropathogenic E. coli (UPEC) employ the mannose-binding adhesin FimH to colonize the bladder epithelium during urinary tract infection (UTI). Previously reported FimH antagonists exhibit good potency and efficacy, but low bioavailability and a short half-life in vivo. In a rational design strategy, we obtained an X-ray structure of lead mannosides and then designed mannosides with improved drug-like properties. We show that cyclizing the carboxamide onto the biphenyl B-ring aglycone of biphenyl mannosides into a fused heterocyclic ring, generates new biaryl mannosides such as isoquinolone 22 (2-methyl-4-(1-oxo-1,2-dihydroisoquinolin-7-yl)phenyl α-d-mannopyranoside) with enhanced potency and in vivo efficacy resulting from increased oral bioavailability. N-Substitution of the isoquinolone aglycone with various functionalities produced a new potent subseries of FimH antagonists. All analogues of the subseries have higher FimH binding affinity than unsubstituted lead 22, as determined by thermal shift differential scanning fluorimetry assay. Mannosides with pyridyl substitution on the isoquinolone group inhibit bacteria-mediated hemagglutination and prevent biofilm formation by UPEC with single-digit nanomolar potency, which is unprecedented for any FimH antagonists or any other antivirulence compounds reported to date. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pharmacological and Nutritional Effects of Natural Coumarins and Their Structure-Activity Relationships.

PubMed

Zhu, Jing-Jing; Jiang, Jian-Guo

2018-05-11

Coumarins are fused benzene and pyrone ring systems with a wide spectrum of bioactivities including anti-tumor, anti-inflammation, antiviral and antibacterial effects. In this paper, the current development of coumarins-based drugs is introduced, and their structure-activity relationship is discussed by reviewing the relevant literatures published in the past twenty years. Coumarin molecules can be customized by the target site to prevent systemic side effects by virtue of structural modification. The ortho-phenolic hydroxyl on the benzene ring had remarkable antioxidant and anti-tumor activities. Coumarins with aryl groups at the C-4 position have good activities in anti-HIV, anti-tumor, anti-inflammation and analgesia. C-3 phenylcoumarins have strong anti-HIV and antioxidant effects. Tetracycline pyranocoumarins can significantly inhibit the HIV, osthol structural analogues have antimicrobial activity. Praeruptorin C and its derivatives play an important role in lowering blood pressure and dilating coronary arteries, and khellactone derivatives have significant inhibitory effects on AIDS, cancer and cardiovascular diseases. It is concluded that the specific site on the core structure of coumarin exhibits one or more activities due to the electronic or steric effects of the substituents. This review is designed to be conducive to rational design and development of more active and less toxic agents with a coumarin scaffold. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Ring Bubbles of Dolphins

NASA Technical Reports Server (NTRS)

Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)

1996-01-01

The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since centrifugal force has to be balanced by a lift-like force. She then re-traces her path and injects air into the vortex from her blowhole. She can even make a ring reconnect from the helix. In the second technique, demonstrated a few times, she again swims in a curved path, releases a cloud or group of bubbles from her blowhole and turns sharply away (Which presumably strengthens the vortex). As the bubbles encounter the vortex, they travel to the center of the vortex, merge and, in a flash, elongate along the core of the vortex. In all the three types, the air-water interface is shiny smooth and stable because the pressure gradient in the vortex flow around the bubble stabilizes it. A lot of the interesting physics still remains to be explored.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, D.P.; Massey, R.T.

1985-07-18

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, Daniel P.; Massey, Richard T.

1986-01-01

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Improving solar-pumped laser efficiency by a ring-array concentrator

NASA Astrophysics Data System (ADS)

Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.

2018-01-01

We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.

Regiospecific Synthesis of Ring A Fused Withaferin A Isoxazoline Analogues: Induction of Premature Senescence by W-2b in Proliferating Cancer Cells.

PubMed

Rasool, Faheem; Nayak, Debasis; Katoch, Archana; Faheem, Mir Mohd; Yousuf, Syed Khalid; Hussain, Nazar; Belawal, Chetan; Satti, N K; Goswami, Anindya; Mukherjee, Debaraj

2017-10-23

Induction of premature senescence represents a novel functional strategy to curb the uncontrolled proliferation of malignant cancer cells. This study unveils the regiospecific synthesis of novel isoxazoline derivatives condensed to ring A of medicinal plant product Withaferin-A. Intriguingly, the cis fused products with β-oriented hydrogen exhibited excellent cytotoxic activities against proliferating human breast cancer MCF7 and colorectal cancer HCT-116 cells. The most potent derivative W-2b triggered premature senescence along with increase in senescence-associated β-galactosidase activity, G2/M cell cycle arrest, and induction of senescence-specific marker p21 Waf1/Cip1 at its sub-toxic concentration. W-2b conferred a robust increase in phosphorylation of mammalian checkpoint kinase-2 (Chk2) in cancer cells in a dose-dependent manner. Silencing of endogenous Chk2 by siRNA divulged that the amplification of p21 expression and senescence by W-2b was Chk2-dependent. Chk2 activation (either by ectopic overexpression or through treatment with W-2b) suppressed NM23-H1 signaling axis involved in cancer cell proliferation. Finally, W-2b showed excellent in vivo efficacy with 83.8% inhibition of tumor growth at a dose of 25 mg/kg, b.w. in mouse mammary carcinoma model. Our study claims that W-2b could be a potential candidate to limit aberrant cellular proliferation rendering promising improvement in the treatment regime in cancer patients.

Synthesis and Optical Properties of Excited-State Intramolecular Proton Transfer Active π-Conjugated Benzimidazole Compounds: Influence of Structural Rigidification by Ring Fusion.

PubMed

Takagi, Koji; Ito, Kaede; Yamada, Yoshihiro; Nakashima, Takuya; Fukuda, Ryoichi; Ehara, Masahiro; Masu, Hyuma

2017-12-01

Two excited-state intramolecular proton transfer (ESIPT) active benzimidazole derivatives (1 and 2) were synthesized by acid-catalyzed intramolecular cyclization. The steady-state fluorescence spectrum in THF revealed that ring-fused derivative 1 exhibits a dual emission, namely, the major emission was from the K* (keto) form (ESIPT emission) at 515 nm with a large Stokes shift of 11 100 cm -1 and the minor emission was from the E* (enol) form at below 400 nm. In contrast, the normal emission from the E* form was dominant and the fluorescence quantum yield was very low (Φ ∼ 0.002) for nonfused derivative 2. The time-resolved fluorescence spectroscopy of 1 suggested that ESIPT effectively occurs due to the restricted conformational transition to the S 1 -T ICT state, and the averaged radiative and nonradiative decay rate constants were estimated as ⟨k f ⟩ = 0.15 ns -1 and ⟨k nr ⟩ = 0.60 ns -1 , respectively. The fluorescence emission of 1 was influenced by the measurement conditions, such as solvent polarity and basicity, as well as the presence of Lewis base. The ESIPT process and solvatochromic behavior were nicely reproduced by the DFT/TDDFT calculation using the PCM model. In the single-crystal fluorescent spectra, the ESIPT emissions were exclusively observed for both fused and nonfused compounds as a result of hydrogen-bonding interactions.

A DSC and FTIR spectroscopic study of the effects of the epimeric 4-cholesten-3-ols and 4-cholesten-3-one on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes: comparison with their 5-cholesten analogues.

PubMed

Benesch, Matthew G K; Mannock, David A; Lewis, Ruthven N A H; McElhaney, Ronald N

2014-01-01

We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five of its analogues on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (βOH, αOH or C=O) and in the position of the double bond (C4-C5 in ring A or C5-C6 in ring B). In the three Δ(5) sterols/steroid series, the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases in the order βOH>αOH>C=O and these differences in concentration are significant. However, in the Δ(4) series, these concentrations are more similar, regardless of polar head group nature or stereochemistry. Similarly, the residual enthalpy of the main phase transition of DPPC at 50 mol.% sterol/steroid, which is inversely related to the miscibility of these compounds in the DPPC bilayer, also increases in the order βOH>αOH>C=O, but this effect is attenuated in the Δ(4) as opposed to the Δ(5) series. Both of these results indicate that the presence of a double bond at C4-C5 in ring A, as compared to a C5-C6 double bond in ring B, reduces the effect of variations in the structure of the polar group at C3 on the properties of the host DPPC bilayer. The movement of the double bond from C5 to C4 in the two sterol pairs results in a greater decrease in the temperature and enthalpy of both the pretransition and the main phase transition, whereas the opposite result is observed in the ketosteroid pair. Similarly, the ability of these compounds to order the DPPC hydrocarbon chains decreases in the order βOH>αOH>C=O in both series of compounds, but in the two sterol pairs, hydrocarbon chain ordering is greater for the Δ(5) than the Δ(4) sterols, whereas the opposite is the case for the steroid pair. All of these results indicate that the typical effects of sterols/steroids in increasing the packing density and thermal stability of fluid lipid bilayers are optimal when an OH group rather than C=O group is present at C3, and that this OH group is more effective in the equatorial rather than the axial orientation. We can explain all of our sterol results by noting that the shift of the double bond from Δ(5) to Δ(4) introduces of a bend in ring A, which in turn destroys the coplanarity of the steroid fused ring system and reduces the goodness of sterol packing in the host DPPC bilayer. However, this conformational change should also occur in the ketosteroid pair, yet our experimental results indicate that the presence of the Δ(4) double bond is less disruptive than a double bond at Δ(5). We suggest that the presence of keto-enol tautomerism in the conjugated Δ(4) ketosteroid, but not in the nonconjugated Δ(5) compound, may provide additional H-bonding opportunities to adjacent DPPC molecules in the bilayer, which can overcome the unfavourable conformational change in ring A induced by the Δ(4) double bond. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Studies of New Fused Benzazepine as Selective Dopamine D3 Receptor Antagonists Using 3D-QSAR, Molecular Docking and Molecular Dynamics

PubMed Central

Liu, Jing; Li, Yan; Zhang, Shuwei; Xiao, Zhengtao; Ai, Chunzhi

2011-01-01

In recent years, great interest has been paid to the development of compounds with high selectivity for central dopamine (DA) D3 receptors, an interesting therapeutic target in the treatment of different neurological disorders. In the present work, based on a dataset of 110 collected benzazepine (BAZ) DA D3 antagonists with diverse kinds of structures, a variety of in silico modeling approaches, including comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), homology modeling, molecular docking and molecular dynamics (MD) were carried out to reveal the requisite 3D structural features for activity. Our results show that both the receptor-based (Q2 = 0.603, R2ncv = 0.829, R2pre = 0.690, SEE = 0.316, SEP = 0.406) and ligand-based 3D-QSAR models (Q2 = 0.506, R2ncv =0.838, R2pre = 0.794, SEE = 0.316, SEP = 0.296) are reliable with proper predictive capacity. In addition, a combined analysis between the CoMFA, CoMSIA contour maps and MD results with a homology DA receptor model shows that: (1) ring-A, position-2 and R3 substituent in ring-D are crucial in the design of antagonists with higher activity; (2) more bulky R1 substituents (at position-2 of ring-A) of antagonists may well fit in the binding pocket; (3) hydrophobicity represented by MlogP is important for building satisfactory QSAR models; (4) key amino acids of the binding pocket are CYS101, ILE105, LEU106, VAL151, PHE175, PHE184, PRO254 and ALA251. To our best knowledge, this work is the first report on 3D-QSAR modeling of the new fused BAZs as DA D3 antagonists. These results might provide information for a better understanding of the mechanism of antagonism and thus be helpful in designing new potent DA D3 antagonists. PMID:21541053

Studies of new fused benzazepine as selective dopamine D3 receptor antagonists using 3D-QSAR, molecular docking and molecular dynamics.

PubMed

Liu, Jing; Li, Yan; Zhang, Shuwei; Xiao, Zhengtao; Ai, Chunzhi

2011-02-18

In recent years, great interest has been paid to the development of compounds with high selectivity for central dopamine (DA) D3 receptors, an interesting therapeutic target in the treatment of different neurological disorders. In the present work, based on a dataset of 110 collected benzazepine (BAZ) DA D3 antagonists with diverse kinds of structures, a variety of in silico modeling approaches, including comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), homology modeling, molecular docking and molecular dynamics (MD) were carried out to reveal the requisite 3D structural features for activity. Our results show that both the receptor-based (Q(2) = 0.603, R(2) (ncv) = 0.829, R(2) (pre) = 0.690, SEE = 0.316, SEP = 0.406) and ligand-based 3D-QSAR models (Q(2) = 0.506, R(2) (ncv) =0.838, R(2) (pre) = 0.794, SEE = 0.316, SEP = 0.296) are reliable with proper predictive capacity. In addition, a combined analysis between the CoMFA, CoMSIA contour maps and MD results with a homology DA receptor model shows that: (1) ring-A, position-2 and R(3) substituent in ring-D are crucial in the design of antagonists with higher activity; (2) more bulky R(1) substituents (at position-2 of ring-A) of antagonists may well fit in the binding pocket; (3) hydrophobicity represented by MlogP is important for building satisfactory QSAR models; (4) key amino acids of the binding pocket are CYS101, ILE105, LEU106, VAL151, PHE175, PHE184, PRO254 and ALA251. To our best knowledge, this work is the first report on 3D-QSAR modeling of the new fused BAZs as DA D3 antagonists. These results might provide information for a better understanding of the mechanism of antagonism and thus be helpful in designing new potent DA D3 antagonists.

Extreme oxatriquinanes and a record C-O bond length

NASA Astrophysics Data System (ADS)

Gunbas, Gorkem; Hafezi, Nema; Sheppard, William L.; Olmstead, Marilyn M.; Stoyanova, Irini V.; Tham, Fook S.; Meyer, Matthew P.; Mascal, Mark

2012-12-01

Oxatriquinanes are fused, tricyclic oxonium ions that are known to have exceptional stability compared to simple alkyl oxonium salts. C-O bonds in ethers are generally ˜1.43 Å in length, but oxatriquinane has been found to have C-O bond lengths of 1.54 Å. A search of the Cambridge Structural Database turned up no bona fide C-O bond length exceeding this value. Computational modelling of oxatriquinane alongside other alkyl oxonium ions indicated that the electronic consequences of molecular strain were primarily responsible for the observed bond elongation. We also show that substitution of the oxatriquinane ring system with alkyl groups of increasing steric demand pushes the C-O bond to unheard of distances, culminating in a tert-butyl derivative at a predicted 1.60 Å. Chemical synthesis and an X-ray crystallographic study of these compounds validated the results of the modelling work and, finally, an extraordinary 1.622 Å C-O bond was observed in 1,4,7-tri-tert-butyloxatriquinane.

[Color stability of porcelain-fused-to-titanium restorations after repeated firings].

PubMed

Wu, Xiao-min; Zhou, Zheng

2004-08-01

To study the effect of repeated firings on color of porcelain-fused-to-titanium restorations. Twenty standard porcelain-fused-to-titanium specimens were made with Dentsply DETREY TiBond C3 and Dentaurum rematitan Til. Then they were fired 1, 2, 4, 7, and 10 times. Color measurement was done after each firing. Most of the color parameters had no significant difference after firing except for a* and Hab. All the color difference among groups were smaller than 1.0 (deltaE < 1.0). Repeated firings will not affect the color stability of porcelain-fused-to-titanium restorations.

13C chemical-shift anisotropy of alkyl-substituted aromatic carbon in anthracene derivatives.

PubMed

Hoop, Cody L; Iuliucci, Robbie J

2013-06-01

The (13)C chemical-shift anisotropy in anthracene derivatives (9,10-dimethylanthracene, 9,10-dihydroanthracene, dianthracene, and triptycene) has been measured by the 2D FIREMAT timed pulse sequence and the corresponding set of principal values has been determined by the TIGER processing method. These molecules expand the data base of (13)C CSA measurements of fused aromatic rings some bridged by sp(3) carbon resulting in an unusual bonding configuration, which leads to distinctive aromatic (13)C CSA values. Crystal lattice distortions to the CSA were observed to change the isotropic shift by 2.5 to 3.3 ppm and changes as large as 8.3 ppm in principal components. Modeling of the CSA data by GIPAW DFT (GGA-PBE/ultrafine) shielding calculations resulted in an rms chemical-shift distance of 2.8 ppm after lattice including geometry optimization of the diffraction structures by the GIPAW method at GGA-PBE/ultrafine level. Attention is given to the substituted aromatic carbon in the phenyl groups (here forth referred to as the α-carbon) with respect to CSA modeling with electronic methods. The (13)C CSA of this position is accurately determined due to its spectral isolation of the isotropic shift that limits overlap in the FIREMAT spectrum. In cases where the bridging ring is sp(3) carbon, the current density is reduced from extending beyond the peripheral phenyl groups; this plays a significant role in the magnetic shielding of the α-position. Nuclear independent chemical-shift calculations based on GIAO DFT (B3LYP/6-31G(d)) shielding calculations were used to model the intramolecular π-interactions in dianthracene and triptycene. These NICS results estimate the isotropic shift of the α-position in dianthracene to be insignificantly affected by the presence of the neighboring aromatic rings. However, a notable change in isotropic shielding, Δσ(iso)=-2.1 ppm, is predicted for the α- position of triptycene. Experimentally, the δ22 principal component at the α-position for both dianthracene and triptycene increases by at least 12 ppm compared to 9,10-dihydroanthracene. To rationalize this change, shielding calculations in idealized structures are explored. The spatial position of the bicyclic scaffolding of the bridging ring plays a key role in the large increase in δ22 for the α-carbon. Copyright © 2013 Elsevier Inc. All rights reserved.

[A comparative study of marginal microleakage using different cements in porcelain-fused-to-metal crown].

PubMed

Jiang, Ming-Xin; Huang, Ke-Qiang; Li, Zhi-Gang; Gao, Xiu-Qiu; Li, Chun-Shan

2011-04-01

To evaluate the marginal microleakage of porcelain-fused-to-metal crown using four different cements. Sixteen porcelain-fused-to-metal crowns were built and randomly divided into 4 group, luted onto standard prepared human forward molars using four different cements (glass ionomer cement, resin-modified glass ionomer cement, PanaviaF, Super-Bond C&B adhesive luting system). After temperature cycling test, all the crowns were then submerged in 2% fuchsin for 24 h. The marginal microleakage at tooth cement interfaces was observed using light stereomicroscopy and evaluated in classification index. The marginal microleakage grade of 4 groups were analyzed by SPSS 13.0. The PanaviaF demonstrated the least marginal microleakage, Super-Bond C&B adhesive luting system, resin-modified glass ionomer cement showed an intermediate level of marginal microleakage, glass ionomer cement was associated with severe marginal microleakage (total, Chi2 = 157.60, P < 0.01; among the different groups, P<0.05). Adhesive resin luting system which is the first selection in clinical is better than glass ionomer cement and is good at porcelain-fused-to-metal crown.

Synthesis of isochromene-type scaffolds via single-flask Diels-Alder-[4 + 2]-annulation sequence of a silyl-substituted diene with menadione.

PubMed

Lee, Jihoon; Panek, James S

2014-06-20

A sequential Diels-Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels-Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an aldehyde and the TBS protected alcohol resulted in the formation of a cis-fused hydroisochromene 13.

2,2′-(Carbono­thio­yldisulfanedi­yl)bis­(2-methyl­propanoic acid)

PubMed Central

Moreno-Fuquen, Rodolfo; Grande, Carlos; Advincula, Rigoberto C.; Tenorio, Juan C.; Ellena, Javier

2013-01-01

The mol­ecular structure of the title compound, C9H14O4S3, exhibits intra­molecular C—H⋯S hydrogen bonds. In the crystal, pairs of O—H⋯O hydrogen bonds lead to the formation of centrosymmetric dimers, which are in turn connected by weak C—H⋯O inter­actions. The combination of these inter­actions generates edge-fused R 2 2(8) and R 2 2(20) rings running along [211]. PMID:23723918

Crystal structure of ochraceolide A isolated from Elaeodendron trichotomum (Turcz.) Lundell

PubMed Central

Herrera-España, Angel D.; Mena-Rejón, Gonzalo J.; Hernández-Ortega, Simón; Quijano, Leovigildo; Mirón-López, Gumersindo

2017-01-01

The title compound, C30H44O3 [systematic name: 6aR,6 bR,8aS,9aR,12aR,14bR)-4,4,6a,6;b,8a,14b-hexa­methyl-12-methyl­eneicosa­hydro-3H-phenanthro[1′,2′:6,7]indeno­[2,1-b]furan-3,11(2H)-dione], is a triterpene lactone, which was isolated from di­chloro­methane extract of Elaeodendron trichotomum (Turcz.) Lundell (celastraceae) stem bark. The compound has a lupane skeleton and consists of four fused six-membered rings and two five-membered rings. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds into a three-dimensional network. The configuration of ochraceolide A was proposed based on analogue compounds which belong to the lupane type. PMID:29250361

The ability of multimerized cyclophilin A to restrict retrovirus infection

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

Javanbakht, Hassan; Diaz-Griffero, Felipe; Yuan Wen

2007-10-10

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

Catalytic hydrogenation rate of polycyclic aromatic hydrocarbons in supercritical carbon dioxide containing polymer-stabilized palladium nanoparticles.

PubMed

Liao, Weisheng; Liu, Hsin-Wang; Chen, Hsing-Jung; Chang, Wen-Yen; Chiu, Kong-Hwa; Wai, Chien M

2011-01-01

Catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs) with up to four fused benzene rings over high-density-polyethylene-stabilized palladium nanoparticles in supercritical carbon dioxide via in situ UV/Vis spectroscopy is presented. PAHs can be efficiently converted to saturated polycyclic hydrocarbons using this green technique under mild conditions at 20 MPa of CO₂ containing 1 MPa of H₂ at 40-50°C. Kinetic studies based on in situ UV/Vis spectra of the CO₂ phase reveal that the initial hydrogenation of a given PAH and the subsequent hydrogenations of its intermediates are pseudo-first-order. The hydrogenation rate of the latter is always much smaller than that of the former probably due to increasing steric hindrance introduced by the hydrogenated benzene rings of PAHs which impedes the adsorption process and hydrogen access to PAHs on catalyst surfaces. Copyright © 2010 Elsevier Ltd. All rights reserved.

Synthesis and biological evaluation of new 2-(4,5-dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives.

PubMed

Touzeau, Frédérique; Arrault, Axelle; Guillaumet, Gérald; Scalbert, Elizabeth; Pfeiffer, Bruno; Rettori, Marie-Claire; Renard, Pierre; Mérour, Jean-Yves

2003-05-08

2-(4,5-Dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives and tricyclic analogues with a fused additional ring on the nitrogen atom of the benzoxazine moiety have been prepared and evaluated for their cardiovascular effects as potential antihypertensive agents. The imidazoline ring was generated by reaction of the corresponding ethyl ester with ethylenediamine. Affinities for imidazoline binding sites (IBS) I(1) and I(2) and alpha(1) and alpha(2) adrenergic receptors were evaluated as well as the effects on mean arterial blood pressure (MAP) and heart rate (HR) of spontaneously hypertensive rats. With few exceptions the most active compounds on MAP were those with high affinities for IBS and alpha(2) receptor. Among these, compound 4h was the most interesting and is now, together with its enantiomers, under complementary pharmacological evaluation.

The dynamics and regulation of mesenchymal cell fusion in the sea urchin embryo.

PubMed

Hodor, P G; Ettensohn, C A

1998-07-01

Cell-cell fusion occurs in a wide variety of developmental contexts, yet the mechanisms involved are just beginning to be elucidated. In the sea urchin embryo, primary mesenchyme cells (PMCs) fuse to form syncytial filopodial cables within which skeletal spicules are deposited. Taking advantage of the optical transparency and ease of micromanipulation of sea urchin embryos, we have developed methods for directly observing the dynamics of PMC fusion in vivo. A fraction of the PMCs was labeled with fluorescent dextran and transfer of the dye to unlabeled PMCs was followed by time-lapse, fluorescence microscopy. Fusion was first detected about 2 h after PMCs began to migrate within the blastocoel. Fusion proceeded in parallel with the assembly of the PMC ring pattern and was complete by the early gastrula stage. The formation of a single, extensive PMC syncytium was confirmed by DiI labeling of fixed embryos. When single micromeres were isolated and cultured in unsupplemented seawater, they divided and their progeny underwent fusion. This shows that the capacity to fuse is autonomously programmed in the micromere-PMC lineage by the 16-cell stage. PMC transplantations at late embryonic stages revealed that these cells remain fusion-competent long after their fusion is complete. At late stages, other mesenchyme cells (blastocoelar cells) are also present within the blastocoel and are migrating and fusing with one another. Fusion-competent blastocoelar cells and PMCs come into contact but do not fuse with one another, indicating that these two cell types fuse by distinct mechanisms. When secondary mesenchyme cells convert to a skeletogenic fate they alter their fusogenic properties and join the PMC syncytium, as shown by transfer of fluorescent dextran. Our analysis has provided a detailed picture of the cellular basis and regulation of mesodermal cell fusion and has important implications regarding molecular mechanisms that underlie fusion.

A Fusion Architecture for Tracking a Group of People Using a Distributed Sensor Network

DTIC Science & Technology

2013-07-01

Determining the composition of the group is done using several classifiers. The fusion is done at the UGS level to fuse information from all the modalities to...to classification and counting of the targets. Section III also presents the algorithms for fusion of distributed sensor data at the UGS level and...ultrasonic sensors. Determining the composition of the group is done using several classifiers. The fusion is done at the UGS level to fuse

Crystallographic study of three coronary vasodilators of the nitrate ester type: 1,4- trans-cyclohexanedimethanol dinitrate, 1,4:3,6-dianhydro- D-glucitol-2,5-dinitrate and 1,4:3,6-dianhydro- D-glucitol-2-mononitrate

NASA Astrophysics Data System (ADS)

Kanters, J. A.; Schouten, A.; Sterk, G. J.; de Jong, M. H.

1993-10-01

The crystal structures of three vasodilators of the nitrate ester type have been determined by X-ray diffraction. Compound I, 1,4- trans-cyclohexanedimethanol dinitrate (CDDN), C 8H 14N 2O 6, is a recently developed nitrate ester with a promising haemodynamic profile in the treatment of ischaemic heart diseases. CDDN crystallizes in space group P2 1/a with a = 5.9443(4), b = 16.7052(9), c = 6.2022(2) Å, β = 116.669(4)°, Z = 2 and T = 295 K. The molecule lies on a centre of inversion and the structure refined to R = 0.042 for 991 reflections with I > 2.5σ( I). The cyclohexane ring approaches an ideal chair conformation and the C-O-NO 2 fragment is strictly planar. Compound II is the widely applied vasodilator in angina pectoris, isosorbide dinitrate or 1,4:3,6-dianhydro- D-glucitol-2,5-dinitrate (ISDN), C 6H 8N 2O 8. ISDN crystallizes in space group P22 12 1 with a = 5.7535(2), b = 10.9393(5), c = 14.6599(5)Å, Z = 4 and T = 295 K. The structure refined to R = 0.033 for 1104 reflections with I > 2.5σ( I). The molecular skeleton consists of two cis-fused five-membered rings, which each adopt an envelope conformation such that the torsion angels about the central CC bond are 0.3(2) and -7.8(2)°. The angle between the rings is 60.8(1)° and the two nitrate groups are planar. Compound III, isosorbide-2-mononitrate or 1,4:3,6-dianhydro- D-glucitol-2-mononitrate (IS-2MN), C 6H 9NO 6, is an active metabolite of II and crystallizes in space group P2 12 12 1 with a = 6.4318(4), b = 7.5273(4), c = 15.866(1)Å Z = 4 and T = 100 K. The structure refined to R = 0.031 for 1488 reflections with I > 2.5σ( I). The skeleton of III is very similar to that of II. The torsion angles about the central CC bond are 2.4(2) and -3.1(2)°, the interplanar angle is 61.5(1)° and the nitrate group is strictly planar.

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

Li, Yang; Tu, Xingchen; Wang, Hao

The electronic efficiency and binding energy of contacts formed between graphene electrodes and poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium Green’s function formalism combined with density functional theory. Our calculations show that PAH molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and that the binding energy increases following the increase of the number of carbon and hydrogen atoms constituting the PAH molecule. When we move to analyzing the electronic transport properties of molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic efficiency ofmore » the graphene-PAH contacts is found to depend on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the corresponding PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap of the PAH anchoring group, the higher is the electronic efficiency of the graphene-PAH contact. Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap.« less

Crystal structure of rac-(3aR,4S,5aR,6S,9R,10aS,10bR)-3a,5a,9-tri­methyl­tetra­deca­hydro-6,9-ep­oxy­cyclo­hepta­[e]inden-4-ol monohydrate

PubMed Central

Schäfer, Andreas; Golz, Christopher; Preut, Hans; Strohmann, Carsten; Hiersemann, Martin

2015-01-01

The title hydrate, C17H28O2·H2O, was synthesized in order to determine the relative configuration of the tetra­cyclic framework. The fused 5,6,7-tricarbocyclic core exhibits an entire cis-annulation, featuring a 1,4-cis-relation of the angular methyl groups in the six-membered ring. The oxa bridge of the ep­oxy­cyclo­heptane moiety is oriented towards the concave face of the boat-shaped mol­ecule, whereas the angular methyl groups are directed towards the convex face. The asymmetric unit of the crystal contains two nearly identical formula units, which are related via a pseudo-centre of symmetry. The structure could be solved in the space groups I-4 and I41/a. The refinement in the acentric space group, however, gave significantly better results and these are used in this paper. O—H⋯O hydrogen bonds are observed between the organic mol­ecules, between the organic mol­ecules and the water mol­ecules, and between the water mol­ecules, forming a chain along the c-axis direction. PMID:26396907

Di-epoxides of the three isomeric dicyclopenta-fused pyrenes: ultimate mutagenic active agents.

PubMed

Otero-Lobato, María José; Kaats-Richters, Veronica E M; Havenith, Remco W A; Jenneskens, Leonardus W; Seinen, Willem

2004-11-14

To rationalize the high bacterial mutagenic response recently found for the (di-) cyclopenta-fused pyrene congeners, viz. cyclopenta[cd]-(1), dicyclopenta[cd,mn]-(2), dicyclopenta[cd,fg]-(3) and dicyclopenta[cd,jk]pyrene (4), in the presence of a metabolic activation mixture (S9-mix), their (di-)epoxides at the externally fused unsaturated five-membered rings were previously proposed as the ultimate mutagenic active forms. In this study, cyclopenta[cd]pyrene-3,4-epoxide (5) and the novel dicyclopenta[cd,mn]pyrene-1,2,4,5-di-epoxide (6), dicyclopenta[cd,fg]pyrene-5,6,7,8-di-epoxide (7) and dicyclopenta[cd,jk]pyrene-1,2,6,7-di-epoxide (8) were synthesised from 1 to 4, respectively, and subsequently assayed for bacterial mutagenicity in the standard microsomal/histidine reverse mutation assay (Ames-assay with Salmonella typhimurium strain TA98). The di-epoxides 6-8 are present as a mixture of their cis- and trans-stereo-isomers in a close to 1:1 ratio ((1)H NMR spectroscopy and ab initio IGLO/III//RHF/6-31G** calculations). The direct-acting mutagenic activity and the strong cytotoxicity exerted by 5-8 both in the absence or presence of an exogenous metabolic activation system (+/-S9-mix) demonstrate that the ultimate mutagenic active forms are the proposed (di-)epoxides of 1-4.

Fracture strength of all-ceramic lithium disilicate and porcelain-fused-to-metal bridges for molar replacement after dynamic loading.

PubMed

Chitmongkolsuk, Somsak; Heydecke, Guido; Stappert, Christian; Strub, Joerg R

2002-03-01

The replacement of missing posterior teeth using all-ceramic bridges remains a challenge. This study compares the fracture resistance of all-ceramic 3-unit bridges for the replacement of first molars to conventional porcelain-fused-to-metal bridges. Human premolars and molars were used to create two test groups and one control group of 16 specimens each. To simulate clinical parameters, the specimens were exposed to cyclic fatigue loading in an artificial mouth with simultaneous thermocycling. All samples were thereafter exposed to fracture strength testing. Porcelain-fused-to-metal bridges showed significantly higher fracture strengths than all-ceramic bridges. However, the fracture strength of the all-ceramic bridges was higher than peak physiological chewing forces.

Synthesis and Structural Data of Tetrabenzo[8]circulene

PubMed Central

Miller, Robert W.; Duncan, Alexandra K.; Schneebeli, Severin T.; Gray, Danielle L.; Whalley, Adam C.

2015-01-01

In 1976, the first attempted synthesis of the saddle-shaped molecule [8]circulene was reported. The next 37 years produced no advancement towards the construction of this complicated molecule. Remarkably, however, over the last six months a flurry of progress has been made with two groups reporting independent and strikingly different strategies for the synthesis of [8]circulene derivatives. Herein, we present a third synthetic method in which we target tetrabenzo[8]circulene. Our approach employs a Diels-Alder reaction and a palladium-catalyzed arylation reaction as the key steps. Despite calculations describing the instability of [8]circulene, coupled with the reported instability of synthesized derivatives of the parent molecule, the addition of four fused benzenoid rings around the periphery of the molecule provides a highly stable structure. This increased stability over the parent [8]circulene was predicted using Clar’s theory of aromatic sextets and is a result of the compound becoming fully benzenoid upon incorporation of these additional rings. The synthesized compound exhibits remarkable stability under ambient conditions – even at elevated temperatures – with no signs of decomposition over several months. The solid-state structure of this compound is significantly twisted compared to the calculated structure primarily as a result of crystal packing forces in the solid state. Despite this contortion from the lowest energy structure, a range of structural data is presented confirming the presence of localized aromaticity in this large polycyclic aromatic hydrocarbon. PMID:24615957

Assembly interdependence among the S. cerevisiae bud neck ring proteins Elm1p, Hsl1p and Cdc12p.

PubMed

Thomas, Courtney L; Blacketer, Melissa J; Edgington, Nicholas P; Myers, Alan M

2003-07-15

In Saccharomyces cerevisiae, a complex comprising more than 20 different polypeptides assembles in a ring at the neck between the mother cell and the bud. This complex functions to coordinate cell morphology with cell division. Relatively little is known about this control system, including the physical relationships between the components of the neck ring. This study addressed the assembly interactions of three components of the ring, specifically the protein kinases Elm1p and Hsl1p and the septin Cdc12p. Specific amino acid substitutions in each of these three proteins were identified that either cause or suppress a characteristic phenotype of abnormally elongated cells and delay in the G(2)-M transition. Each protein was fused to green fluorescent protein, and its ability to localize at the neck was monitored in vivo in cells of various genotypes. Localization of Hsl1p to the neck requires Elm1p function. Elm1p localized normally in the absence of Hsl1p, although a specific point mutation in Hsl1p clearly affected Elm1p localization. The cdc12-122 mutation prevented assembly of Elm1p or Hsl1p into the neck ring. Normal assembly of Cdc12p at the neck was dependent upon Elm1p and also, to a smaller extent, on Hsl1p. Ectopic localization of Cdc12p at the bud tip was observed frequently in elm1 mutants and also, to a lesser extent, in hsl1 mutants. Thus, Elm1p is a key factor in the assembly and/or maintenance of Hsl1p, as well as at least one septin, into the bud neck ring. Copyright 2003 John Wiley & Sons, Ltd.

Reconstructing the anterior part of the nervous system of Gordius aquaticus (Nematomorpha, cycloneuralia) by a multimethodological approach.

PubMed

Henne, Stephan; Friedrich, Frank; Hammel, Jörg U; Sombke, Andy; Schmidt-Rhaesa, Andreas

2017-01-01

The Nematomorpha (horsehair worms) and Nematoda (round worms) are sister taxa (together Nematoida) and closely related to Scalidophora (Priapulida, Kinorhyncha, Loricifera). To date, all species were assumed to possess a specific brain type, i.e., the "cycloneuralian" brain that forms a ring-shaped neuropil around the pharynx and is composed of anteriorly and posteriorly located somata. However, descriptions of the nematomorph nervous system are rare and somewhat variable, calling in to question the validity of the cycloneuralian condition. To clarify whether there is a typical cycloneuralian pattern in the nematomorph brain, we investigated the anterior end of Gordius aquaticus with different methods: histology, immunohistochemistry and micro-CT analysis. Three-dimensional reconstructions were made from histological serial sections. The brain is composed of a central neuropil and a ring-shaped structure with associated somata. The unpaired ventral nerve cord emerges from the posteroventral part of the brain. A pharynx/esophagus is absent. In addition to the brain, a peripheral nerve plexus was detected. In summary, we interpret the architecture of the brain as potentially derived from a cycloneuralian structure, but being highly modified. The central position of the neuropil is possibly a consequence of the reduction of the anterior intestinal system as a result of the parasitic lifestyle. The ring-shaped arrangement of the somata may be a remnant of a cycloneuralian arrangement, after the two rings of somata (= cycloneuralian condition) either fused or one ring was reduced to form one massive ring-shaped structure in G. aquaticus. J. Morphol. 278:106-118, 2017. ©© 2016 Wiley Periodicals,Inc. © 2016 Wiley Periodicals, Inc.

Electron tomography study of isolated human centrioles.

PubMed

Ibrahim, Rana; Messaoudi, Cédric; Chichon, Francisco Javier; Celati, Claude; Marco, Sergio

2009-01-01

Centrioles are components of the centrosome, which is present in most eukaryotic cells (from protozoa to mammals). They organize the microtubule skeleton during interphase and the mitotic spindle during cell division. In ciliate cells, centrioles form basal bodies that are involved in cellular motility. Despite their important roles in biology, the detailed structure of centrioles remains obscure. This work contributes to a more complete model of centriole structure. The authors used electron tomography of isolated centrosomes from the human lymphoblast KE37 to explore the details of subdistal appendages and centriole lumen organization in mother centrioles. Their results reveal that each of the nine subdistal appendages is composed of two halves (20 nm diameter each) fused in a 40 nm tip that extends 100 nm from where it anchors to microtubules. The centriole lumen is filled at the distal domain by a 45 nm periodic stack of rings. Each ring has a 30 nm diameter, is 15 nm thick, and appears to be tilted at 53 degrees perpendicular to the centriole axis. The rings are anchored to microtubules by arms. Based on their results, the authors propose a model of the mother centriole distal structure. Copyright 2008 Wiley-Liss, Inc.

Neutron Diffraction Structure of Melampodin: Its Role in the Reclassification of the Germacranolides

PubMed Central

Watkins, Steven F.; Fischer, Nikolaus H.; Bernal, Ivan

1973-01-01

The precise crystal and molecular structure of melampodin, C21H24O9, was determined from three-dimensional neutron diffraction data collected by counter techniques and phases by direct statistical methods. Crystals are orthorhombic, P212121, a = 8,990(9), b = 14.352(14), c = 16.294(16) Å, V = 2102 Å3, d(calc.) = 1.328 g·cm-3, Z = 4 molecules per unit cell. The structural model was refined by full matrix least-squares of 2303 observed independent reflections, with all 54 atoms treated anisotropically, to R(F) = 5.0%. Hydrogen bonds link melampodin molecules together in the solid state. The conformation of the cyclodeca-1,5-diene ring is such that one intraannular hydrogen atom interacts strongly with one double bond, but there is little or no transannular interaction between double bonds. Strain in the ten-membered ring and in the trans-fused lactone ring is discussed, as are chemical implications of the unsymmetric epoxide in the epoxyangelic acid side chain. The previously suggested reclassification of germacranolide sesquiterpene lactones into four subgroups is supported, and a new convention for configurational representations of the four subgroups is proposed. PMID:16592106

Synthesis of conformationally North-locked pyrimidine nucleosides built on an oxabicyclo[3.1.0]hexane scaffold.

PubMed

Ludek, Olaf R; Marquez, Victor E

2012-01-20

Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in 11 steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases.

Reductive ring closure methodology toward heteroacenes bearing a dihydropyrrolo[3,2-b]pyrrole core: scope and limitation.

PubMed

Qiu, Li; Wang, Xiao; Zhao, Na; Xu, Shiliang; An, Zengjian; Zhuang, Xuhui; Lan, Zhenggang; Wen, Lirong; Wan, Xiaobo

2014-12-05

A newly developed reductive ring closure methodology to heteroacenes bearing a dihydropyrrolo[3,2-b]pyrrole core was systematically studied for its scope and limitation. The methodology involves (i) the cyclization of an o-aminobenzoic acid ester derivative to give an eight-membered cyclic dilactam, and (ii) the conversion of the dilactams into the corresponding diimidoyl chloride, which undergoes (iii) reductive ring closure to install the dihydropyrrolo[3,2-b]pyrrole core. The first step of the methodology plays the key role due to its substrate limitation, which suffers from the competition of oligomerization and hydrolysis. All the dilactams could successfully convert to the corresponding diimidoyl chlorides, most of which succeeded to give the dihydropyrrolo[3,2-b]pyrrole core. The influence of the substituents and the elongation of conjugated length on the photophysical properties of the obtained heteroacenes were then investigated systematically using UV-vis spectroscopy and cyclic voltammetry. It was found that chlorination and fluorination had quite a different effect on the photophysical properties of the heteroacene, and the ring fusing pattern also had a drastic influence on the band gap of the heteroacene. The successful preparation of a series of heteroacenes bearing a dihydropyrrolo[3,2-b]pyrrole core would provide a wide variety of candidates for further fabrication of organic field-effect transistor devices.

The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants.

PubMed

Archie, Elizabeth A; Moss, Cynthia J; Alberts, Susan C

2006-03-07

Many social animals live in stable groups. In contrast, African savannah elephants (Loxodonta africana) live in unusually fluid, fission-fusion societies. That is, 'core' social groups are composed of predictable sets of individuals; however, over the course of hours or days, these groups may temporarily divide and reunite, or they may fuse with other social groups to form much larger social units. Here, we test the hypothesis that genetic relatedness predicts patterns of group fission and fusion among wild, female African elephants. Our study of a single Kenyan population spans 236 individuals in 45 core social groups, genotyped at 11 microsatellite and one mitochondrial DNA (mtDNA) locus. We found that genetic relatedness predicted group fission; adult females remained with their first order maternal relatives when core groups fissioned temporarily. Relatedness also predicted temporary fusion between social groups; core groups were more likely to fuse with each other when the oldest females in each group were genetic relatives. Groups that shared mtDNA haplotypes were also significantly more likely to fuse than groups that did not share mtDNA. Our results suggest that associations between core social groups persist for decades after the original maternal kin have died. We discuss these results in the context of kin selection and its possible role in the evolution of elephant sociality.

The source and distribution of thermogenic dissolved organic matter in the ocean

NASA Astrophysics Data System (ADS)

Dittmar, T.; Suryaputra, I. G. N. A.; Paeng, J.

2009-04-01

Thermogenic organic matter (ThOM) is abundant in the environment. ThOM is produced at elevated temperature and pressure in deep sediments and earth's crust, and it is also a residue of fossil fuel and biomass burning ("black carbon"). Because of its refractory character, it accumulates in soils and sediments and, therefore, may sequester carbon from active cycles. It was hypothesized that a significant component of marine dissolved organic matter (DOM) might be thermogenic. Here we present a detailed data set on the distribution of thermogenic DOM in major water masses of the deep and surface ocean. In addition, several potential sources of thermogenic DOM to the ocean were investigated: active seeps of brine fluids in the deep Gulf of Mexico, rivers, estuaries and submarine groundwaters. Studies on deep-sea hydrothermal vents and aerosol deposition are ongoing. All DOM samples were isolated from seawater via solid phase extraction (SPE-DOM). ThOM was quantified in the extracts as benzene-polycarboxylic acids (BPCAs) after nitric acid oxidation via high-performance liquid chromatography and diode array detection (HPLC-DAD). BPCAs are produced exclusively from fused ring systems and are therefore unambiguous molecular tracers for ThOM. In addition to BPCA determination, the molecular composition and structure of ThOM was characterized in detail via ultrahigh resolution mass spectrometry (FT-ICR-MS). All marine and river DOM samples yielded significant amounts of BPCAs. The cold seep system in the deep Gulf of Mexico, but also black water rivers (like the Suwannee River) were particularly rich in ThOM. Up to 10% of total dissolved organic carbon was thermogenic in both systems. The most abundant BPCA was benzene-pentacarboxylic acid (B5CA). The molecular composition of BPCAs and the FT-ICR-MS data indicate a relatively small number (5-8) of fused aromatic rings per molecule. Overall, the molecular BPCA patterns were very similar independent of the source of ThOM. Petroleum-derived ThOM in the deep Gulf of Mexico had very similar structures than fused ring systems in asphaltenes, but also ThOM in the rivers and groundwaters was similar. First data on aerosols, on the other had, show a clear difference between particulate and dissolved samples. ThOM from aerosols and most soils was characterized by an abundance of benzene-hexacarboxylic acid (B6CA), different from thermogenic DOM. Dissolution processes may cause partial breakdown of larger fused ring systems and thus cause similar structural units in all DOM samples. In the deep ocean, the distribution of thermogenic DOM was relatively homogeneous throughout the water column. The concentration of carbon that resides in thermogenic polycyclic aromatic hydrocarbon varied between 610 and 800 nM (1.5-2% of total dissolved organic carbon). The total amount of thermogenic DOM in the deep ocean is approx. one Peta mole carbon globally. The relatively homogenous distribution of thermogenic DOM in the abyssal ocean indicates that thermogenic DOM behaves virtually inert in the abyssal environment. One of the most striking features is that the oldest water masses, which are not enriched in industrial products (such as the Freon CFC-12) showed highest concentrations of thermogenic DOM. The younger water masses such as Antarctic bottom and intermediate waters are not particularly enriched in thermogenic DOM. This distribution suggests a preindustrial origin of ThOM in the deep ocean. Rivers and deep-sea seep systems were both identified as potential sources of ThOM to the deep ocean. Radiocarbon dating on BPCAs will provide further evidence for the origin of BC in the deep ocean.

Reduced 3,4'-bipyrazoles from a simple pyrazole precursor: synthetic sequence, molecular structures and supramolecular assembly.

PubMed

Cuartas, Viviana; Insuasty, Braulio; Cobo, Justo; Glidewell, Christopher

2017-10-01

The reaction of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and N-benzylmethylamine under microwave irradiation gives 5-[benzyl(methyl)amino]-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, C 19 H 19 N 3 O, (I). Subsequent reactions under basic conditions, between (I) and a range of acetophenones, yield the corresponding chalcones. These undergo cyclocondensation reactions with hydrazine to produce reduced bipyrazoles which can be N-formylated with formic acid or N-acetylated with acetic anhydride. The structures of (I) and of representative examples from this reaction sequence are reported, namely the chalcone (E)-3-{5-[benzyl(methyl)amino]-3-methyl-1-phenyl-1H-pyrazol-4-yl}-1-(4-bromophenyl)prop-2-en-1-one, C 27 H 24 BrN 3 O, (II), the N-formyl derivative (3RS)-5'-[benzyl(methyl)amino]-3'-methyl-1',5-diphenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole]-2-carbaldehyde, C 28 H 27 N 5 O, (III), and the N-acetyl derivative (3RS)-2-acetyl-5'-[benzyl(methyl)amino]-5-(4-methoxyphenyl)-3'-methyl-1'-phenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole], which crystallizes as the ethanol 0.945-solvate, C 30 H 31 N 5 O 2 ·0.945C 2 H 6 O, (IV). There is significant delocalization of charge from the benzyl(methyl)amino substituent onto the carbonyl group in (I), but not in (II). In each of (III) and (IV), the reduced pyrazole ring is modestly puckered into an envelope conformation. The molecules of (I) are linked by a combination of C-H...N and C-H...π(arene) hydrogen bonds to form a simple chain of rings; those of (III) are linked by a combination of C-H...O and C-H...N hydrogen bonds to form sheets of R 2 2 (8) and R 6 6 (42) rings, and those of (IV) are linked by a combination of O-H...N and C-H...O hydrogen bonds to form a ribbon of edge-fused R 2 4 (16) and R 4 4 (24) rings.

Phthalocyanine based metal containing porous carbon sheet

NASA Astrophysics Data System (ADS)

Honda, Z.; Sakaguchi, Y.; Tashiro, M.; Hagiwara, M.; Kida, T.; Sakai, M.; Fukuda, T.; Kamata, N.

2017-03-01

Highly-ordered fused-ring poly copper phthalocyanine (PCuPc) was prepared using copper octacyanophthalocyanine as a building block, and two-dimensional (2D) square superlattices were directly observed by the transmission electron microscopy. Remarkably, we have found a formation of polymer network that consists of a 2D porous PCuPc sheet in which the centers of phthalocyanine units are alternately occupied by Cu atom and vacancy. Using this "half-filling" PCuPc, it must be possible to create alternating arrangements for transition metal centers, and therefore control the magnetic properties of the 2D carbon sheets.

Recent New Methodologies for Acetylenic Polymers with Advanced Functionalities.

PubMed

Qiu, Zijie; Han, Ting; Lam, Jacky W Y; Tang, Ben Zhong

2017-08-01

Polymers synthesized from acetylenic monomers often possess electronically unsaturated fused rings and thus show versatile optoelectronic properties and advanced functionalities. To expand the family of acetylenic polymers, development of new catalyst systems and synthetic routes is critically important. We summarize herein recent research progress on development of new methodologies towards functional polymers using alkyne building blocks since 2014. The polymerizations are categorized by the number of monomer components, namely homopolymerizations, two-component polymerizations, and multicomponent polymerizations. The properties and applications of acetylenic polymers, such as aggregation-induced emission, fluorescent photopatterning, light refraction, chemosensing, mechanochromism, chain helicity, etc., are also discussed.

Pd-Catalyzed regioselective intramolecular dehydrogenative C-5 cross coupling in an N-substituted pyrrole-azole system.

PubMed

Tripathi, Krishna N; Ray, Devalina; Singh, Ravi P

2017-12-06

Functionalized polycyclic pyrrole-azole structures possessing fused six membered and seven membered rings were directly synthesized via ligand-enabled, Pd-catalyzed, site selective, intramolecular cross couplings of N-substituted pyrrole-azoles. C5-H activation in the presence of a reactive C2-H remains a challenge that needs to be addressed and this was targeted to be resolved through the present approach by specifically generating the cyclized products with 83-100% selectivity. The featured methodology provides a novel disconnection for the synthesis of pyrrole containing alkaloids and medicinal compounds.

Studies toward brevisulcenal F via convergent strategies for marine ladder polyether synthesis.

PubMed

Katcher, Matthew; Jamison, Timothy F

2018-03-15

Shortly after the initial isolation of marine ladder polyether natural products, biomimetic epoxide-opening cascade reactions were proposed as an efficient strategy for the synthesis of these compounds. However, difficulties in assembling the cascade precursors have limited the realization of these cascades. In this report, we describe strategies that provide convergent access to cascade precursors via regioselective allylation and efficient fragment coupling. We then investigate epoxide-opening cascades promoted by strong bases for the formation of fused tetrahydropyrans. These strategies are evaluated in the context of the synthesis of rings CDEFG of brevisulcenal F.

Process Parameter-Growth Environment-Film Property Relationships for Reactive Sputter Deposited Metal (V, Nb, Zr, Y, Au) Oxide, Nitride, and Oxynitride Films

DTIC Science & Technology

1993-09-30

speed of light in vac- ring within the first 5 min of exposure. In a separate ex- uum, and g(A) is the detected fraction of emitted radia- periment...fold: film growth by reactive sputter deposition, in situ discharge diagnostics, film charcterization. A radio frequency diode apparatus was used to...l-’ZrO, films is reported.)3 1) Films were grown on Supers!]I II fused silica in a hot-oil pumped rf diode sputter deposition system using a 13-cm

Partial hammock valve: surgical repair in adulthood.

PubMed

Aramendi, José I; Rodríguez, Miguel A; Voces, Roberto; Pérez, Pedro; Rodrigo, David

2006-09-01

We describe a forme frustrée of hammock valve involving only the posterior mitral leaflet. Three adult patients were referred to surgery with the diagnosis of severe mitral regurgitation due to fibrosis of the posterior mitral leaflet. The final diagnosis was done intraoperatively. In all of them the posterior leaflet was attached to some accessory papillary muscles arranged en palisade, with three to four fused muscle heads producing restrictive leaflet motion in systole. Repair consisted in division of the papillary muscles, patch augmentation, and ring annuloplasty. This previously unreported lesion is congenital but manifests itself in adulthood.

Formation of Fused-Ring 2′-Deoxycytidine Adducts from 1-Chloro-3-buten-2-one, an in Vitro 1,3-Butadiene Metabolite, under in Vitro Physiological Conditions

PubMed Central

Sun, Liang; Pelah, Avishay; Zhang, Dong-Ping; Zhong, Yu-Fang; An, Jing; Yu, Ying-Xin; Zhang, Xin-Yu; Elfarra, Adnan A.

2013-01-01

1-Chloro-3-buten-2-one (CBO) is a potential metabolite of 1,3-butadiene (BD), a carcinogenic air pollutant. CBO is a bifunctional alkylating agent that readily reacts with glutathione (GSH) to form mono-GSH and di-GSH adducts. Recently, CBO and its precursor 1-chloro-2-hydroxy-3-butene (CHB) were found to be cytotoxic and genotoxic in human liver cells in culture with CBO being approximately 100-fold more potent than CHB. In the present study, CBO was shown to react readily with 2′-deoxycytidine (dC) under in vitro physiological conditions (pH 7.4, 37 °C) to form four dC adducts with the CBO moieties forming fused rings with the N3 and N4 atoms of dC. The four products were structurally characterized as 2-hydroxy-2-hydroxymethyl-7-(2-deoxy-β-D-erythro-pentofuranosyl)-1,2,3,4-tetrahy dro-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-1 and dC-2, a pair of diastereomers), 4-chloromethyl-4-hydroxy-7-(2-deoxy-β-D-erythro-pentofuranosyl)-1,2,3,4-tetrahydr o-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-3), and 2-chloromethyl-2-hydroxy-7-(2-deoxy-β-D-erythro-pentofuranosyl)-1,2,3,4-tetrahydr o-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-4). Interestingly, dC-1 and dC-2 were stable under our experimental conditions (pH 7.4, 37 °C, 6 h) and existed in equilibrium as indicated by HPLC analysis, whereas dC-3 and dC-4 were labile with the half-lives being 3.0 ± 0.36 and 1.7 ± 0.06 h, respectively. Decomposition of dC-4 produced both dC-1 and dC-2, whereas acid hydrolysis of dC-1/dC-2 and dC-4 in 1 M HCl at 100 °C for 30 min yielded the deribosylated adducts dC-1H/dC-2H and dC-4H, respectively. Because fused-ring dC adducts of other chemicals are mutagenic, the characterized CBO-dC adducts could be mutagenic and play a role in the cytotoxicity and genotoxicity of CBO and its precursors, CHB and BD. The CBO-dC adducts may also be used as standards to characterize CBO-DNA adducts and to develop potential biomarkers for CBO formation in vivo. PMID:24020501

Comparison of cycle control with a combined contraceptive vaginal ring and oral levonorgestrel/ethinyl estradiol.

PubMed

Bjarnadóttir, Ragnheidur I; Tuppurainen, Marjo; Killick, Stephen R

2002-03-01

The purpose of this study was to compare cycle control and tolerability of the NuvaRing (NV Organon, Oss, The Netherlands), a novel combined contraceptive vaginal ring, with a standard combined oral contraceptive pill. Healthy women aged 18 to 40 years who requested contraception received either NuvaRing or a combined oral contraceptive containing 30 microg ethinyl estradiol and 150 microg levonorgestrel for 6 cycles in 3 similarly designed studies. Each cycle comprised 3 weeks of ring or pill use, followed by 1 ring- or pill-free week. Two hundred forty-seven women began the studies, 121 women with NuvaRing and 126 women with the combined oral contraceptive. Withdrawal bleeding occurred in virtually all cycles in both groups. In the NuvaRing groups, the incidence of irregular bleeding was < or =5% in all cycles; this was lower than the combined oral contraceptive groups (5.4%-38.8%). Furthermore, the incidence of a normal intended bleeding pattern was significantly higher in the NuvaRing groups than in the combined oral contraceptive groups (P <.01). Both contraceptives were well tolerated. NuvaRing has excellent cycle control and is well tolerated.

Morphological evaluation of maxillary second molars with fused roots: a micro-CT study.

PubMed

Ordinola-Zapata, R; Martins, J N R; Bramante, C M; Villas-Boas, M H; Duarte, M H; Versiani, M A

2017-12-01

To evaluate the internal and external morphologies of fused-rooted maxillary second molars by means of micro-computed tomography (micro-CT) analysis. A total of 100 fused-rooted maxillary second molars from a Brazilian subpopulation were divided into six groups according to the root morphology. The samples were scanned at a resolution of 19.6 μm and evaluated with regard to the external morphology of the roots, the root canal configuration, the percentage frequency of C-shaped canals and isthmuses, as well as the morphology of the root canal system at 1, 2 and 3 mm from the anatomical apex of the fused roots. The most prevalent root canal fusions were type 1, mesiobuccal root fused with distobuccal root (32%), followed by type 3, DB root fused with P root (27%), and type 4, MB root fused with DB root, and P root fused with MB or DB roots (21%). The prevalence of C-shaped root canal systems were 22%. Depending on the type of root fusion, the percentage frequency of isthmuses in the apical level varied from 9.3% to 42.8%, whilst the presence of apical deltas ranged from 18.5% to 57.1% of teeth. The root canal system of maxillary second molars with fused roots may have a high incidence of merging canals, isthmuses, apical deltas and C-shaped configurations. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Quinonoid compounds via reactions of lawsone and 2-aminonaphthoquinone with α-bromonitroalkenes and nitroallylic acetates: Structural diversity by C-ring modification and cytotoxic evaluation against cancer cells.

PubMed

Baiju, Thekke V; Almeida, Renata G; Sivanandan, Sudheesh T; de Simone, Carlos A; Brito, Lucas M; Cavalcanti, Bruno C; Pessoa, Claudia; Namboothiri, Irishi N N; da Silva Júnior, Eufrânio N

2018-05-10

Morita-Baylis-Hillman acetates and α-bromonitroalkenes have been employed in cascade reactions with lawsone and 2-aminonaphthoquinone for the one-pot synthesis of heterocycle fused quinonoid compounds. The reactions reported here utilized the 1,3-binucleophilic potential of hydroxy- and aminonaphthoquinones and the 1,2/1,3-bielectrophilic potential of bromonitroalkenes and Morita-Baylis-Hillman acetates for the synthesis of pyrrole and furan fused naphthoquinones. The synthesized compounds were evaluated against HCT-116 (human colon carcinoma cells), PC3 (human prostate cancer cells), HL-60 (human promyelocytic leukemia cells), SF295 (human glioblastoma cells) and NCI-H460 (human lung cancer cells) and exhibited antitumor activity with IC 50 values as low as < 2 μM. Selected compounds were also evaluated against OVCAR-8 (ovary), MX-1 (breast) and JURKAT (leukemia) cell lines. The cytotoxic potential of the quinones evaluated was also assayed using non-tumor cells, exemplified by peripheral blood mononuclear (PBMC) and L929 cells. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Anti-acne activities of pulsaquinone, hydropulsaquinone, and structurally related 1, 4-quinone derivatives.

PubMed

Cho, Soon-Chang; Sultan, Md Zakir; Moon, Surk-Sik

2009-04-01

Quinone type compound, pulsaquinone 1, isolated from the aqueous ethanol extract of the roots of Pulsatilla koreana exhibited antimicrobial activities against an anaerobic non-spore-forming gram-positive bacillus, Propionibacterium acnes, which is related with the pathogenesis of the inflamed lesions in a common skin disease, acne vulgaris. Compound 1 was unstable on standing and thus converted to more stable compound 2, namely hydropulsaquinone by hydrogenation, whose activity was comparable to mother compound 1 (MIC for 1 and 2 against P. acnes: 2.0 and 4.0 microg/mL, respectively). Other structurally-related quinone derivatives (3-13) were also tested for structure-activity relationship against anaerobic and aerobic bacteria, and fungi. The antimicrobial activity was fairly good when the quinone moiety was fused with a nonpolar 6- or 7-membered ring on the right side whether or not conjugated (1,4-naphtoquinone derivatives 3-5), while simple quinone compounds 6-9 showed poor activity. It seems that the methoxy groups at the left side of the quinone function deliver no considerable antimicrobial effect.

Simultaneous MRI and PET imaging of a rat brain

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan K.; Sendhil Velan, S.; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Zorn, Carl; Marano, Gary D.

2006-12-01

Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI will allow the correlation of form with function. Our group is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode. Each MRI-PET detector module consists of an array of LSO detector elements coupled through a long fibre optic light guide to a single Hamamatsu flat panel position-sensitive photomultiplier tube (PSPMT). The use of light guides allows the PSPMTs to be positioned outside the bore of a 3T MRI scanner where the magnetic field is relatively small. To test the device, simultaneous MRI and PET images of the brain of a male Sprague Dawley rat injected with FDG were successfully obtained. The images revealed no noticeable artefacts in either image set. Future work includes the construction of a full ring PET scanner, improved light guides and construction of a specialized MRI coil to permit higher quality MRI imaging.

Three-chain B{sub 6n+14} cages as possible precursors for the syntheses of boron fullerenes

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

Lu, Haigang, E-mail: luhg@sxu.edu.cn; Li, Si-Dian

Using the first principle methods, we proposed a series of three-chain boron cages B{sub 6n+14} (n = 1–12) which are mainly built by fusing three boron semi-double-rings. Their simple geometric structures (approximate D{sub 3} or C{sub 3} symmetry) facilitate their bottom-up syntheses from the hexagonal B{sub 7} and the double-chain boron clusters, such as B{sub 2}, B{sub 4}, B{sub 6}, B{sub 8}H{sub 2}, B{sub 10}H{sub 2}, B{sub 12}H{sub 2}, and the double ring B{sub 20}. The spherical shapes of these three-chain boron cages show that they could be taken as the possible precursors to further synthesize the boron fullerenes, suchmore » as B{sub 80}. Therefore, these three-chain boron cages provide a possible synthesis pathway of the boron fullerenes from the experimentally synthesized small planar boron clusters.« less

Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

NASA Technical Reports Server (NTRS)

Chang, A. Y.; Battles, B. E.; Hanson, R. K.

1990-01-01

In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.

Demonstration of versatile whispering-gallery micro-lasers for remote refractive index sensing.

PubMed

Wan, Lei; Chandrahalim, Hengky; Zhou, Jian; Li, Zhaohui; Chen, Cong; Cho, Sangha; Zhang, Hui; Mei, Ting; Tian, Huiping; Oki, Yuji; Nishimura, Naoya; Fan, Xudong; Guo, L Jay

2018-03-05

We developed chip-scale remote refractive index sensors based on Rhodamine 6G (R6G)-doped polymer micro-ring lasers. The chemical, temperature, and mechanical sturdiness of the fused-silica host guaranteed a flexible deployment of dye-doped polymers for refractive index sensing. The introduction of the dye as gain medium demonstrated the feasibility of remote sensing based on the free-space optics measurement setup. Compared to the R6G-doped TZ-001, the lasing behavior of R6G-doped SU-8 polymer micro-ring laser under an aqueous environment had a narrower spectrum linewidth, producing the minimum detectable refractive index change of 4 × 10 -4 RIU. The maximum bulk refractive index sensitivity (BRIS) of 75 nm/RIU was obtained for SU-8 laser-based refractive index sensors. The economical, rapid, and simple realization of polymeric micro-scale whispering-gallery-mode (WGM) laser-based refractive index sensors will further expand pathways of static and dynamic remote environmental, chemical, biological, and bio-chemical sensing.

Reconstitution and structure of a bacterial Pnkp1RnlHen1 RNA repair complex

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

Wang, Pei; Selvadurai, Kiruthika; Huang, Raven H.

Ribotoxins cleave essential RNAs for cell killing, and RNA repair neutralizes the damage inflicted by ribotoxins for cell survival. We report a new bacterial RNA repair complex that performs RNA repair linked to immunity. This new RNA repair complex is a 270-kDa heterohexamer composed of three proteins—Pnkp1, Rnl and Hen1—that are required to repair ribotoxin-cleaved RNA in vitro. The crystal structure of the complex reveals the molecular architecture of the heterohexamer as two rhomboid-shaped ring structures of Pnkp1–Rnl–Hen1 heterotrimer fused at the Pnkp1 dimer interface. The four active sites required for RNA repair are located on the inner rim ofmore » each ring. Furthermore, the architecture and the locations of the active sites of the Pnkp1–Rnl–Hen1 heterohexamer suggest an ordered series of repair reactions at the broken RNA ends that confer immunity to recurrent damage.« less

Nuclear pore assembly proceeds by an inside-out extrusion of the nuclear envelope

PubMed Central

Otsuka, Shotaro; Bui, Khanh Huy; Schorb, Martin; Hossain, M Julius; Politi, Antonio Z; Koch, Birgit; Eltsov, Mikhail; Beck, Martin; Ellenberg, Jan

2016-01-01

The nuclear pore complex (NPC) mediates nucleocytoplasmic transport through the nuclear envelope. How the NPC assembles into this double membrane boundary has remained enigmatic. Here, we captured temporally staged assembly intermediates by correlating live cell imaging with high-resolution electron tomography and super-resolution microscopy. Intermediates were dome-shaped evaginations of the inner nuclear membrane (INM), that grew in diameter and depth until they fused with the flat outer nuclear membrane. Live and super-resolved fluorescence microscopy revealed the molecular maturation of the intermediates, which initially contained the nuclear and cytoplasmic ring component Nup107, and only later the cytoplasmic filament component Nup358. EM particle averaging showed that the evagination base was surrounded by an 8-fold rotationally symmetric ring structure from the beginning and that a growing mushroom-shaped density was continuously associated with the deforming membrane. Quantitative structural analysis revealed that interphase NPC assembly proceeds by an asymmetric inside-out extrusion of the INM. DOI: http://dx.doi.org/10.7554/eLife.19071.001 PMID:27630123

Fe3O4 Nanoparticles Mediated Synthesis of Novel Isatin-dihydropyrimidinone Hybrid Molecules as Antioxidant and Cytotoxic Agents.

PubMed

Maddela, Srinubabu; Makula, Ajitha; Jayarambabu, N

2017-01-01

The present study emphasizes on designing a new series of isatin-dihydropyrimidinone derivatives by adopting a hybrid pharmacophore approach. Fe3O4 nanoparticles (Fe3O4 NP) are magnetically recoverable and are effective catalysts adequately used to synthesize Isatin-dihydropyrimidinones. Individual derivatives of Isatin and dihydropyrimidinone are equipotent to treat cytotoxicity. The present work was planned to fuse two pharmacophores (Isatin, dihydropyrimidinone) and to examine any synergistic effect in the anticancer activity. The individual compounds are synthesized by adopting appropriate synthetic routes like sandmayers and biginellis reaction and are fused together by using glacial acetic acid and Methanolic KOH to form novel Isatindihydropyrimidinone hybrids. All the new series of hybrids 7a-l were characterized by FT-IR, 1H NMR, 13C NMR, elemental analysis and Mass spectroscopy. The antioxidant activity of the synthesized compounds was assessed by using two models: 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) and Hydrogen peroxide (H2O2) scavenging assay. From the results it can be inferred that nearly all the synthesized compounds have shown antioxidant activity at the tested dose as correlated with the standard ascorbic acid. The in vitro cytotoxic activity was assayed by using MTT assay. Compound 7l with IC50 values 22.13, 25.68 and 35.59 μM has significantly greater potency against MCF- 7, HeLa and IMR-32 cell lines. The compounds with halogen and electron withdrawing groups at the C-5 position of isatin ring exhibited significant antioxidant and cytotoxic activity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Clinical acceptability of an ethylene-vinyl-acetate nonmedicated vaginal ring.

PubMed

Roumen, F J; Dieben, T O

1999-01-01

In an open study the acceptability of a newly designed vaginal ring was evaluated. The ring being developed for contraceptive purposes was made of ethylene-vinyl-acetate copolymer (EVA). In this study the ring did not contain active medication. Three groups of 20 healthy female volunteers were asked to use rings--with a diameter of 54 mm--for 21 consecutive days; each group was assigned rings with a different cross-sectional thickness of 3, 3.5, or 4 mm. Subjects were given diary cards to report on insertion and removal of the ring and on complaints. Of the 65 women who participated, 59 completed the study and used the ring for at least 21 days, giving an acceptability of 91% (59/65). No major differences were found between the three types of rings except for a sensation of expulsion, which was reported more often in the group assigned the smallest cross-sectional-thickness ring. Expulsion was reported once during intercourse in the 3.5-mm group. Insertion and removal of the rings were judged to be easy by the overall majority of the women. The ring was felt by the partner during intercourse in 35%-50% of couples. Further development of an active combined contraceptive EVA ring with a cross-sectional thickness of 4 mm seems a reasonable option. In future studies with the active ring, allowance for temporary removal of the ring during intercourse, if preferred, may be suggested.

Co-fuse: a new class discovery analysis tool to identify and prioritize recurrent fusion genes from RNA-sequencing data.

PubMed

Paisitkriangkrai, Sakrapee; Quek, Kelly; Nievergall, Eva; Jabbour, Anissa; Zannettino, Andrew; Kok, Chung Hoow

2018-06-07

Recurrent oncogenic fusion genes play a critical role in the development of various cancers and diseases and provide, in some cases, excellent therapeutic targets. To date, analysis tools that can identify and compare recurrent fusion genes across multiple samples have not been available to researchers. To address this deficiency, we developed Co-occurrence Fusion (Co-fuse), a new and easy to use software tool that enables biologists to merge RNA-seq information, allowing them to identify recurrent fusion genes, without the need for exhaustive data processing. Notably, Co-fuse is based on pattern mining and statistical analysis which enables the identification of hidden patterns of recurrent fusion genes. In this report, we show that Co-fuse can be used to identify 2 distinct groups within a set of 49 leukemic cell lines based on their recurrent fusion genes: a multiple myeloma (MM) samples-enriched cluster and an acute myeloid leukemia (AML) samples-enriched cluster. Our experimental results further demonstrate that Co-fuse can identify known driver fusion genes (e.g., IGH-MYC, IGH-WHSC1) in MM, when compared to AML samples, indicating the potential of Co-fuse to aid the discovery of yet unknown driver fusion genes through cohort comparisons. Additionally, using a 272 primary glioma sample RNA-seq dataset, Co-fuse was able to validate recurrent fusion genes, further demonstrating the power of this analysis tool to identify recurrent fusion genes. Taken together, Co-fuse is a powerful new analysis tool that can be readily applied to large RNA-seq datasets, and may lead to the discovery of new disease subgroups and potentially new driver genes, for which, targeted therapies could be developed. The Co-fuse R source code is publicly available at https://github.com/sakrapee/co-fuse .

Stress corrosion cracking of Zircaloys in unirradiated and irradiated CsI

NASA Astrophysics Data System (ADS)

Cox, B.; Surette, B. A.; Wood, J. C.

1986-03-01

Unirradiated split-ring specimens of Zircaloy fuel cladding, coated with CsI, cracked when stressed at elevated temperatures. The specimens have been reexamined fractographically and metallographically in order to confirm that the cause of cracking was stress corrosion (SCC) and not delayed hydride cracking (DHC). Further specimens have been cracked at 350°C by a solution of CsI in a fused mixture of nitrates of rubidium, cesium, strontium and barium, by a similar mechanism. CsI dissolved in a fused molybdate melt was not stable at 400°C, and rapidly evolved iodine, leaving a melt that was incapable of causing SCC. Irradiation of stressed split-ring specimens of Zircaloy fuel cladding in a γ-irradiator of 10 6 R/h and in the U-5 loop in the NRU reactor at an estimated 10 9 R/h caused SCC when the specimens were packed in dry CsI powder. Care had to be taken to dry the CsI, otherwise cracking occurred by a DHC mechanism from hydrogen absorbed from residual moisture in the CsI. Fractography showed that the crack surfaces obtained with dry CsI were typical of iodine-induced SCC rather than cesium-induced metal vapour embrittlement. Thus, if a transport process is provided for the iodide to obtain access to the zirconium surface, CsI is capable of causing SCC of Zircaloy. This transport process might be ionic diffusion in a fission product oxide melt in the fuel-clad gap, however, radiolysis of CsI to form a volatile iodine species in a radiation field is the more probable explanation of PCI failures.

Regulation by a TGFβ-ROCK-actomyosin axis secures a non-linear lumen expansion that is essential for tubulogenesis.

PubMed

Denker, Elsa; Sehring, Ivonne M; Dong, Bo; Audisso, Julien; Mathiesen, Birthe; Jiang, Di

2015-05-01

Regulation of lumen growth is crucial to ensure the correct morphology, dimensions and function of a tubular structure. How this is controlled is still poorly understood. During Ciona intestinalis notochord tubulogenesis, single extracellular lumen pockets grow between pairs of cells and eventually fuse into a continuous tube. Here, we show that lumen growth exhibits a lag phase, during which the luminal membranes continue to grow but the expansion of the apical/lateral junction pauses for ∼30 min. Inhibition of non-muscle myosin II activity abolishes this lag phase and accelerates expansion of the junction, resulting in the formation of narrower lumen pockets partially fusing into a tube of reduced size. Disruption of actin dynamics, conversely, causes a reversal of apical/lateral junction expansion, leading to a dramatic conversion of extracellular lumen pockets to intracellular vacuoles and a tubulogenesis arrest. The onset of the lag phase is correlated with a de novo accumulation of actin that forms a contractile ring at the apical/lateral junctions. This actin ring actively restricts the opening of the lumen in the transverse plane, allowing sufficient time for lumen growth via an osmotic process along the longitudinal dimension. The dynamics of lumen formation is controlled by the TGFβ pathway and ROCK activity. Our findings reveal a TGFβ-ROCK-actomyosin contractility axis that coordinates lumen growth, which is powered by the dynamics of luminal osmolarity. The regulatory system may function like a sensor/checkpoint that responds to the change of luminal pressure and fine-tunes actomyosin contractility to effect proper tubulogenesis. © 2015. Published by The Company of Biologists Ltd.

The marriage of peripherally metallated and directly linked porphyrins: bromidobis(phosphine)platinum(II) as a cation-stabilizing substituent on directly linked and fused triply linked diporphyrins.

PubMed

Hartnell, Regan D; Yoneda, Tomoki; Mori, Hirotaka; Osuka, Atsuhiro; Arnold, Dennis P

2013-11-01

A meso-bromidoplatiniobis(triphenylphosphine) η(1)-organometallic porphyrin monomer was prepared by the oxidative addition of meso-bromoZnDPP (DPP=dianion of 5,15-diphenylporphyrin) to a platinum(0) species. The meso-meso directly linked dimeric porphyrin (5) was prepared from this monomer by silver(I)-promoted oxidative coupling and planarized to give a triply linked dizinc(II) porphyrin dimer (8). Acidic demetallation of 8 afforded the bis(free base) 9. Dimer 5 was demetallated then remetallated with nickel(II) to give the dinickel(II) analogue 10, the X-ray crystal structure of which showed a twisted molecule with ruffled, orthogonal NiDPP rings, terminated by square-planar trans-[Pt(PPh3)2Br] units. New compounds were fully characterized spectroscopically, and the fused diporphyrin exhibited a broad, low-energy, near-IR electronic absorption band near 1100 nm. Electrochemical measurements of this series indicate that the organometallic fragment is a strong electron donor towards the porphyrin ring. The triply linked organometallic diporphyrin has a substantially lowered first one-electron oxidation potential (-0.35 V versus the ferrocene/ferrocenium couple (Fc/Fc(+))) and a narrow HOMO-LUMO gap of 0.96 V. Solutions prepared for NMR spectroscopy slowly decompose with degradation of the signals, which is attributed to partial oxidation to the cation radical. This paramagnetic species can be reduced in situ by hydrazine to restore the NMR spectrum to its former appearance. The combined influence of the two [Pt(PPh3)2Br] electron-donating substituents is sufficient to make dimer too aerobically unstable to allow further elaboration. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

29 CFR 1926.907 - Use of safety fuse.

Code of Federal Regulations, 2014 CFR

2014-07-01

... separated sufficiently to prevent one charge from dislodging other shots in the blast. (m) When blasting... ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The... lighting devices are used. However, when two or more safety fuses in a group are lighted as one by means of...

29 CFR 1926.907 - Use of safety fuse.

Code of Federal Regulations, 2013 CFR

2013-07-01

... separated sufficiently to prevent one charge from dislodging other shots in the blast. (m) When blasting... ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The... lighting devices are used. However, when two or more safety fuses in a group are lighted as one by means of...

29 CFR 1926.907 - Use of safety fuse.

Code of Federal Regulations, 2011 CFR

2011-07-01

... separated sufficiently to prevent one charge from dislodging other shots in the blast. (m) When blasting... ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The... lighting devices are used. However, when two or more safety fuses in a group are lighted as one by means of...

29 CFR 1926.907 - Use of safety fuse.

Code of Federal Regulations, 2012 CFR

2012-07-01

... separated sufficiently to prevent one charge from dislodging other shots in the blast. (m) When blasting... ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The... lighting devices are used. However, when two or more safety fuses in a group are lighted as one by means of...

29 CFR 1926.907 - Use of safety fuse.

Code of Federal Regulations, 2010 CFR

2010-07-01

... separated sufficiently to prevent one charge from dislodging other shots in the blast. (m) When blasting... ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The... lighting devices are used. However, when two or more safety fuses in a group are lighted as one by means of...

Acute and chronic pain in calves after different methods of rubber-ring castration.

PubMed

Becker, Johanna; Doherr, Marcus G; Bruckmaier, Rupert M; Bodmer, Michèle; Zanolari, Patrik; Steiner, Adrian

2012-12-01

The goal of the present study was to evaluate the effect of different methods of rubber-ring castration on acute and chronic pain in calves. Sixty-three 4-6 week-old calves were randomly and sequentially allocated to one of five groups: Group RR (traditional rubber ring castration); group BRR (combination of one rubber ring with Burdizzo); group Rcut (one rubber ring applied with the scrotal tissue and rubber ring removed on day 9); group 3RR (three rubber rings placed one above the other around the scrotal neck); and group CO (controls; sham-castrated). All calves received 0.2 mL/kg bodyweight lidocaine 2%, injected into the spermatic cords and around the scrotal neck 15 min before castration. The presence of acute and chronic pain was assessed using plasma cortisol concentrations, response to palpation of scrotal area, time from castration until complete wound healing, and behavioural signs. Calves of group 3RR showed severe swelling and inflammation, and licking of the scrotal area occurred significantly more often than in groups Rcut and CO. Technique 3RR was discontinued for welfare reasons before the end of the study. All castration groups had significantly more pain upon palpation than calves of group CO, but palpation elicited markedly less pain in group Rcut than in the other castration groups. The most rapid healing time and shortest duration of chronic pain after castration was achieved in group Rcut. For welfare reasons, the Rcut technique should be considered as a valuable alternative to traditional rubber ring castration of calves at 4-6 weeks of age. Copyright © 2012 Elsevier Ltd. All rights reserved.

CYP63A2, a catalytically versatile fungal P450 monooxygenase capable of oxidizing higher-molecular-weight polycyclic aromatic hydrocarbons, alkylphenols, and alkanes.

PubMed

Syed, Khajamohiddin; Porollo, Aleksey; Lam, Ying Wai; Grimmett, Paul E; Yadav, Jagjit S

2013-04-01

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbon n-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized n-alkanes with various chain lengths (C9 to C12 and C15 to C19), as well as alkyl side chains (C3 to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills).

CYP63A2, a Catalytically Versatile Fungal P450 Monooxygenase Capable of Oxidizing Higher-Molecular-Weight Polycyclic Aromatic Hydrocarbons, Alkylphenols, and Alkanes

PubMed Central

Syed, Khajamohiddin; Porollo, Aleksey; Lam, Ying Wai; Grimmett, Paul E.

2013-01-01

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbon n-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized n-alkanes with various chain lengths (C9 to C12 and C15 to C19), as well as alkyl side chains (C3 to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills). PMID:23416995

A Versatile Platform for Nanotechnology Based on Circular Permutation of a Chaperonin Protein

NASA Technical Reports Server (NTRS)

Paavola, Chad; McMillan, Andrew; Trent, Jonathan; Chan, Suzanne; Mazzarella, Kellen; Li, Yi-Fen

2004-01-01

A number of protein complexes have been developed as nanoscale templates. These templates can be functionalized using the peptide sequences that bind inorganic materials. However, it is difficult to integrate peptides into a specific position within a protein template. Integrating intact proteins with desirable binding or catalytic activities is an even greater challenge. We present a general method for modifying protein templates using circular permutation so that additional peptide sequence can be added in a wide variety of specific locations. Circular permutation is a reordering of the polypeptide chain such that the original termini are joined and new termini are created elsewhere in the protein. New sequence can be joined to the protein termini without perturbing the protein structure and with minimal limitation on the size and conformation of the added sequence. We have used this approach to modify a chaperonin protein template, placing termini at five different locations distributed across the surface of the protein complex. These permutants are competent to form the double-ring structures typical of chaperonin proteins. The permuted double-rings also form the same assemblies as the unmodified protein. We fused a fluorescent protein to two representative permutants and demonstrated that it assumes its active structure and does not interfere with assembly of chaperonin double-rings.

Engineering bioartificial tracheal tissue using hybrid fibroblast-mesenchymal stem cell cultures in collagen hydrogels.

PubMed

Naito, Hiroshi; Tojo, Takashi; Kimura, Michitaka; Dohi, Yoshiko; Zimmermann, Wolfram-Hubertus; Eschenhagen, Thomas; Taniguchi, Shigeki

2011-02-01

We aimed at providing the first in vitro and in vivo proof-of-concept for a novel tracheal tissue engineering technology. We hypothesized that bioartificial trachea (BT) could be generated from fibroblast and collagen hydrogels, mechanically supported by osteogenically-induced mesenchymal stem cells (MSC) in ring-shaped 3D-hydrogel cultures, and applied in an experimental model of rat trachea injury. Tube-shaped tissue was constructed from mixtures of rat fibroblasts and collagen in custom-made casting molds. The tissue was characterized histologically and mechanically. Ring-shaped tissue was constructed from mixtures of rat MSCs and collagen and fused to the tissue-engineered tubes to function as reinforcement. Stiffness of the biological reinforcement was enhanced by induction of osteogeneic differentiation in MSCs. Osteogenic differentiation was evaluated by assessment of osteocalcin (OC) secretion, quantification of calcium (Ca) deposit, and mechanical testing. Finally, BT was implanted to bridge a surgically-induced tracheal defect. A three-layer tubular tissue structure composed of an interconnected network of fibroblasts was constructed. Tissue collapse was prevented by the placement of MSC-containing ring-shaped tissue reinforcement around the tubular constructs. Osteogenic induction resulted in high OC secretion, high Ca deposit, and enhanced construct stiffness. Ultimately, when BT was implanted, recipient rats were able to breathe spontaneously.

Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxa-bicyclo[3.1.0]hexane Scaffold

PubMed Central

Ludek, Olaf R.; Marquez, Victor E.

2011-01-01

Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in eleven steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases. PMID:22026578

Exploring the relevance of thiophene rings as bridge unit in acceptor-bridge-donor dyes on self-aggregation and performance in DSSCs.

PubMed

Zarate, Ximena; Saavedra-Torres, Mario; Rodriguez-Serrano, Angela; Gomez, Tatiana; Schott, Eduardo

2018-04-30

The possibility of dye charge recombination in DSSCs remains a challenge for the field. This consists of: (a) back-transfer from the TiO 2 to the oxidized dye and (b) intermolecular electron transfer between dyes. The latter is attributed to dye aggregation due to dimeric conformations. This leads to poor electron injection which decreases the photocurrent conversion efficiency. Most organic sensitizers are characterized by an Acceptor-Bridge-Donor (A-Bridge-D) arrangement that is commonly employed to provide charge separation and, therefore, lowering the unwanted back-transfer. Here, we address the intermolecular electron transfer by studying the dimerization and photovoltaic performance of a group of A-Bridge-D structured dyes. Specifically, eight famous sulfur containing π-bridges were analyzed (A and D remained fixed). Through quantum mechanical and molecular dynamics approaches, it was found that the formation of weakly stabilized dimers is allowed. The dyes with covalently bonded and fused thiophene rings as Bridges, 6d and 7d as well as 8d with a fluorene, would present high aggregation and, therefore, high probability of recombination processes. Conversely, using TiO 2 cluster and surface models, delineated the shortest bridges to improve the adsorption energy and the stability of the system. Finally, the elongation of the bridge up to 2 and 3 units and their photovoltaic parameters were studied. These results showed that all the sensitizers are able to provide similar photocurrent outcomes, regardless of whether the bridge is elongated. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Comparison of disposable sutureless silicone ring and traditional metal ring in 23-gauge vitrectomy combined with cataract surgery

PubMed Central

Wu, Jian-Guo; Wei, Rui-Hua; Liu, Ai-Hua; Zhou, Xiao-Xu; Sun, Guo-Ling; Li, Xiao-Rong

2011-01-01

Background: The purpose of this prospective, interventional, comparative case series was to evaluate the efficiency and feasibility of a disposable sutureless silicone lens ring for corneal contact lens stabilization during combined 23-gauge vitrectomy and cataract surgery. Methods: We developed a ring consisting of a single silicone component with three footplates along the ring margin to fit cannulae for holding conventional contact lenses. Thirty eyes from 30 patients with cataract and vitreoretinal disease were included, and divided into two matched groups according to disease type and ring used. In Group A, we used a 23-gauge transconjunctival vitrectomy system and a disposable sutureless silicone lens ring (n = 15). In Group B, we used a 23-gauge transconjunctival vitrectomy system and a conventional metal lens ring (n = 15). The main outcome measures were: time required for vitrectomy preparation, rate of intraoperative corneal limbus bleeding, and limbus scar rate at the final follow-up visit. Results: Thirty cases were successfully completed. The average vitrectomy preparation time was less in Group A than in Group B (P < 0.01), and the average preparation time saved was 3.94 minutes. None of the Group A patients had intraoperative bleeding or postoperative scarring, whereas all 15 Group B cases had bleeding and five had scarring. There was a statistically significant difference between Group A and Group B for these complications (P ≤ 0.05). Conclusion: This report demonstrates the advantages of using a sutureless silicone ring during combined 23-gauge vitrectomy and cataract surgery. Using this method could allow extra time for the surgeon to pay more attention to complex vitreoretinal procedures. PMID:21760720

Comparison of disposable sutureless silicone ring and traditional metal ring in 23-gauge vitrectomy combined with cataract surgery.

PubMed

Wu, Jian-Guo; Wei, Rui-Hua; Liu, Ai-Hua; Zhou, Xiao-Xu; Sun, Guo-Ling; Li, Xiao-Rong

2011-01-01

The purpose of this prospective, interventional, comparative case series was to evaluate the efficiency and feasibility of a disposable sutureless silicone lens ring for corneal contact lens stabilization during combined 23-gauge vitrectomy and cataract surgery. We developed a ring consisting of a single silicone component with three footplates along the ring margin to fit cannulae for holding conventional contact lenses. Thirty eyes from 30 patients with cataract and vitreoretinal disease were included, and divided into two matched groups according to disease type and ring used. In Group A, we used a 23-gauge transconjunctival vitrectomy system and a disposable sutureless silicone lens ring (n = 15). In Group B, we used a 23-gauge transconjunctival vitrectomy system and a conventional metal lens ring (n = 15). The main outcome measures were: time required for vitrectomy preparation, rate of intraoperative corneal limbus bleeding, and limbus scar rate at the final follow-up visit. Thirty cases were successfully completed. The average vitrectomy preparation time was less in Group A than in Group B (P < 0.01), and the average preparation time saved was 3.94 minutes. None of the Group A patients had intraoperative bleeding or postoperative scarring, whereas all 15 Group B cases had bleeding and five had scarring. There was a statistically significant difference between Group A and Group B for these complications (P ≤ 0.05). This report demonstrates the advantages of using a sutureless silicone ring during combined 23-gauge vitrectomy and cataract surgery. Using this method could allow extra time for the surgeon to pay more attention to complex vitreoretinal procedures.

Discrete Optimization in Chemical Space Reference Manual

DTIC Science & Technology

2012-10-01

ChemGroup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 6.3 vanilla -rings.inp...Examples: carbazoles.inp, and vanilla -rings.inp. 4.8.2 Constructor & Destructor Documentation 4.8.2.1 ChemGroup::ChemGroup () 4.8.2.2 ChemGroup::ChemGroup...also: carbazoles.inp and vanilla -rings.inp in the examples section. Read the connector. Read the connector. 4.9.2.6 ChemIdent::ChemIdent (istream & in

Consistent Orientation of Moduli Spaces

NASA Astrophysics Data System (ADS)

Freed, Daniel S.; Hopkins, Michael J.; Teleman, Constantin

In a series of papers by Freed, Hopkins, and Teleman (2003, 2005, 2007a) the relationship between positive energy representations of the loop group of a compact Lie group G and the twisted equivariant K-theory Kτ+dimGG (G) was developed. Here G acts on itself by conjugation. The loop group representations depend on a choice of ‘level’, and the twisting τ is derived from the level. For all levels the main theorem is an isomorphism of abelian groups, and for special transgressed levels it is an isomorphism of rings: the fusion ring of the loop group andKτ+dimGG (G) as a ring. For G connected with π1G torsionfree, it has been proven that the ring Kτ+dimGG (G) is a quotient of the representation ring of G and can be calculated explicitly. In these cases it agrees with the fusion ring of the corresponding centrally extended loop group. This chapter explicates the multiplication on the twisted equivariant K-theory for an arbitrary compact Lie group G. It constructs a Frobenius ring structure on Kτ+dimGG (G). This is best expressed in the language of topological quantum field theory: a two-dimensional topological quantum field theory (TQFT) is constructed over the integers in which the abelian group attached to the circle is Kτ+dimGG (G).

An Experimental Investigation of the Long-Term Stability of Triple-Point-of-Water Cells

NASA Astrophysics Data System (ADS)

Hill, K. D.

2014-04-01

Contamination of triple-point-of-water (TPW) cells by the chemical components of the borosilicate glass that contains the water is now widely recognized as the principal contributor to long-term drift of the cell temperature. To add to the available experimental data, a comparison of 24 TPW cells of various ages (from 10 years to 59 years), manufacturers (NRC, Jarrett, Isotech), and materials (borosilicate glass and fused quartz) was undertaken in 2013. Twelve cells from this group were compared to one another in 1997. By comparing the current inter-cell temperature differences to those determined 16 years earlier, it was found that some cells have remained stable, others have become colder (as might be expected from ongoing dissolution of the glass), and one or two show an apparent increase in temperature that seems anomalous. Also included among the 24 cells are five cells of borosilicate glass and five of fused quartz that were purchased 10 years ago. By comparing the relative temperature differences among this group of borosilcate and fused-quartz-encapsulated cells to the values obtained when they were last compared 6 years ago, it was found that the average temperature of the borosilcate group of cells decreases by , in reasonable agreement with an average drift of suggested 12 years ago. It was concluded that fused quartz is the superior container for TPW cells.

Synthesis, anticonvulsant, sedative and anxiolytic activities of novel annulated pyrrolo[1,4]benzodiazepines.

PubMed

Sorra, Kumaraswamy; Chen, Chien-Shu; Chang, Chi-Fen; Pusuluri, Srinivas; Mukkanti, Khagga; Wu, Chi-Rei; Chuang, Ta-Hsien

2014-09-18

Four new pentacyclic benzodiazepine derivatives (PBDTs 13-16) were synthesized by conventional thermal heating and microwave-assisted intramolecular cyclocondensation. Their anticonvulsant, sedative and anxiolytic activities were evaluated by drug-induced convulsion models, a pentobarbital-induced hypnotic model and an elevated plus maze in mice. PBDT 13, a triazolopyrrolo[2,1-c][1,4]benzodiazepin-8-one fused with a thiadiazolone ring, exhibited the best anticonvulsant, sedative and anxiolytic effects in our tests. There was no significant difference in potency between PBDT 13 and diazepam, and we proposed that the action mechanism of PBDT 13 could be similar to that of diazepam via benzodiazepine receptors.

Scaffold Diversity Synthesis Delivers Complex, Structurally, and Functionally Distinct Tetracyclic Benzopyrones

PubMed Central

Sankar, Muthukumar G.; Roy, Sayantani; Tran, Tuyen Thi Ngoc; Wittstein, Kathrin; Bauer, Jonathan O.; Strohmann, Carsten; Ziegler, Slava

2018-01-01

Abstract Complexity‐generating chemical transformations that afford novel molecular scaffolds enriched in sp 3 character are highly desired. Here, we present a highly stereoselective scaffold diversity synthesis approach that utilizes cascade double‐annulation reactions of diverse pairs of zwitterionic and non‐zwitterionic partners with 3‐formylchromones to generate highly complex tetracyclic benzopyrones. Each pair of annulation partners adds to the common chroman‐4‐one scaffold to build two new rings, supporting up to four contiguous chiral centers that include an all‐carbon quaternary center. Differently ring‐fused benzopyrones display different biological activities, thus demonstrating their immense potential in medicinal chemistry and chemical biology research. PMID:29721402

Two Marine Cyanobacterial Aplysiatoxin Polyketides, Neo-debromoaplysiatoxin A and B, with K+ Channel Inhibition Activity.

PubMed

Han, Bing-Nan; Liang, Ting-Ting; Keen, Lawrence Jordan; Fan, Ting-Ting; Zhang, Xiao-Dan; Xu, Lin; Zhao, Qi; Wang, Shu-Ping; Lin, Hou-Wen

2018-02-02

The isolation and structure elucidation of two cyanobacterial debromoaplysiatoxin (DAT) analogues, neo-debromoaplysiatoxin A (1) and neo-debromoaplysiatoxin B (2), were reported and found to possess 6/10/6 and 6/6/6 fused-ring systems, respectively, which are rarely seen among aplysiatoxins. Both compounds exhibited potent blocking activity against Kv1.5 with IC 50 values of 6.94 ± 0.26 and 0.30 ± 0.05 μM, respectively. These findings suggest the potential of aplysiatoxin analogues in modulating ionic channels and also provide links between the DAT target, protein kinase C, and cell regulation.

An Imide-Based Pentacyclic Building Block for n-Type Organic Semiconductors

DOE PAGES

Wu, Fu-Peng; Un, Hio-Ieng; Li, Yongxi; ...

2017-10-09

For this study a new electron-deficient unit with fused 5-heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with cyclohepta-4,6-diene-1,3-diimde unit. The imide bridging endows BBI with fixed planar configuration and both low the highest occupied molecular orbital (HOMO) (-6.24 eV) and the lowest unoccupied molecular orbit (LUMO) (-2.57 eV) energy levels. Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm 2 V -1 s -1, which indicates that the BBI is a promising n-type building block for optoelectronics.

Rh(I)-catalyzed Pauson-Khand-type cycloaddition reaction of ene-vinylidenecyclopropanes with carbon monoxide (CO).

PubMed

Yuan, Wei; Dong, Xiang; Shi, Min; McDowell, Patrick; Li, Guigen

2012-11-02

An intramolecular Pauson-Khand type cycloaddition reaction of ene-vinylidenecyclopropanes with carbon monoxide has been established by using [Rh(COD)Cl](2) as the catalyst. The reaction was found to be highly efficient in solvents of 1,2-dichloroethane and 1,1,2,2-tetrachloroethane to give excellent yields of 90-99%. The reaction provides easy access to a series of fused 6,5-ring structures containing spiro-cyclopropane units that are useful for drug design and development. A mechanism of this cycloaddition process has been proposed accounting for structures of resulting products that were unambiguously assigned by X-ray diffractional analysis.

Total synthesis of (+/-)-taiwaniaquinol B via a domino intramolecular friedel-crafts acylation/carbonyl alpha-tert-alkylation reaction.

PubMed

Fillion, Eric; Fishlock, Dan

2005-09-28

The first synthesis of taiwaniaquinol B, a 6-nor-5(6-->7)abeoabietane-type diterpenoid exhibiting the uncommon fused 6-5-6 tricyclic carbon skeleton, was accomplished in 15 steps. A Lewis acid-promoted tandem intramolecular Friedel-Crafts/carbonyl alpha-tert-alkylation reaction was exploited as the core strategy for the synthesis of the sterically congested 1-indanone-containing tricyclic structure. This multiple carbon-carbon bond forming reaction exploits the unique reactivity of Meldrum's acid. The facile precursor synthesis makes this a useful methodology for the expedient modification and assembly of sterically congested 1-indanone-containing ring systems.

Rhodomollanol A, a Highly Oxygenated Diterpenoid with a 5/7/5/5 Tetracyclic Carbon Skeleton from the Leaves of Rhododendron molle.

PubMed

Zhou, Junfei; Zhan, Guanqun; Zhang, Hanqi; Zhang, Qihua; Li, Ying; Xue, Yongbo; Yao, Guangmin

2017-07-21

A novel diterpenoid with an unprecedented carbon skeleton, rhodomollanol A (1), and a new grayanane diterpenoid, rhodomollein XXXI (2), were isolated from the leaves of Rhododendron molle. Their structures were elucidated using comprehensive spectroscopic methods and single-crystal X-ray diffraction. Compound 1 possesses a unique cis/trans/trans/cis/cis-fused 3/5/7/5/5/5 hexacyclic ring system featuring a rare 7-oxabicyclo[4.2.1]nonane core decorated with three cyclopentane units. The plausible biosynthetic pathway for 1 was proposed. Compound 1 exhibited moderate PTP1B inhibitory activity.

Rhodium-catalyzed enantioselective intramolecular C-H silylation for the syntheses of planar-chiral metallocene siloles.

PubMed

Zhang, Qing-Wei; An, Kun; Liu, Li-Chuan; Yue, Yuan; He, Wei

2015-06-01

Reported herein is the rhodium-catalyzed enantioselective C-H bond silylation of the cyclopentadiene rings in Fe and Ru metallocenes. Thus, in the presence of (S)-TMS-Segphos, the reactions took place under very mild conditions to afford metallocene-fused siloles in good to excellent yields and with ee values of up to 97%. During this study it was observed that the steric hindrance of chiral ligands had a profound influence on the reactivity and enantioselectivity of the reaction, and might hold the key to accomplishing conventionally challenging asymmetric C-H silylations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Imide-Based Pentacyclic Building Block for n-Type Organic Semiconductors

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

Wu, Fu-Peng; Un, Hio-Ieng; Li, Yongxi

For this study a new electron-deficient unit with fused 5-heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with cyclohepta-4,6-diene-1,3-diimde unit. The imide bridging endows BBI with fixed planar configuration and both low the highest occupied molecular orbital (HOMO) (-6.24 eV) and the lowest unoccupied molecular orbit (LUMO) (-2.57 eV) energy levels. Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm 2 V -1 s -1, which indicates that the BBI is a promising n-type building block for optoelectronics.

Rotationally asymmetric multifocal IOL implantation with and without capsular tension ring: refractive and visual outcomes and intraocular optical performance.

PubMed

Alió, Jorge L; Plaza-Puche, Ana B; Piñero, David P

2012-04-01

To ascertain whether the refractive, visual, and intraocular optical quality outcomes of a rotationally asymmetric multifocal intraocular lens (IOL) are enhanced by the use of a capsular tension ring. Ninety consecutive eyes from 53 patients (age range: 36 to 82 years) were divided into two groups: the no ring group comprised 43 eyes implanted with the multifocal rotationally asymmetric Lentis Mplus LS-312 (Oculentis GmbH) without a capsular tension ring; and the ring group comprised 47 eyes with the same IOL with a capsular tension ring. Distance and near visual acuity and refractive outcomes were evaluated pre- and postoperatively. Contrast sensitivity, intraocular aberrations, and defocus curve were evaluated postoperatively. Significant postoperative differences between groups were found in sphere, spherical equivalent refraction, and near addition (P<.02). Regarding defocus curve, significantly better visual acuity was present in eyes with the capsular tension ring for intermediate vision conditions (P<.05). Intraocular aberrometry did not differ significantly between groups (P<.09). Refractive predictability and intermediate visual outcomes with the Lentis Mplus LS-312 IOL improved significantly when implanted in combination with a capsular tension ring. Copyright 2012, SLACK Incorporated.

Annular dynamics after mitral valve repair with different prosthetic rings: A real-time three-dimensional transesophageal echocardiography study.

PubMed

Nishi, Hiroyuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Fukushima, Satsuki; Kawamura, Masashi; Yoshioka, Daisuke; Saito, Tetsuya; Ueno, Takayoshi; Kuratani, Toru; Sawa, Yoshiki

2016-09-01

We assessed the effects of different types of prosthetic rings on mitral annular dynamics using real-time three-dimensional echocardiography (RT3DE). RT3DE was performed in 44 patients, including patients undergoing mitral annuloplasty using the Cosgrove-Edwards flexible band (Group A, n = 10), the semi-rigid Sorin Memo 3D ring (Group B, n = 17), the semi-rigid Edwards Physio II ring (Group C, n = 7) and ten control subjects. Various annular diameters were measured throughout the cardiac cycle. We observed flexible anterior annulus motion in all of the groups except Group C. A flexible posterior annulus was only observed in Group B and the Control group. The mitral annular area changed during the cardiac cycle by 8.4 ± 3.2, 6.3 ± 2.0, 3.2 ± 1.3, and 11.6 ± 5.0 % in Group A, Group B, Group C, and the Control group, respectively. The dynamic diastolic to systolic change in mitral annular diameters was lost in Group C, while it was maintained in Group A, and to a good degree in Group B. In comparison to the Control group, the mitral annulus shape was more ellipsoid in Group B and Group C, and more circular in Group A. Although mitral regurgitation was well controlled by all of the types of rings that were utilized in the present study, we demonstrated that the annulus motion and annulus shape differed according to the type of prosthetic ring that was used, which might provide important information for the selection of an appropriate prosthetic ring.

2,4 Diamino benzonitrile

NASA Technical Reports Server (NTRS)

Frost, Lawrence W. (Inventor)

1980-01-01

Deep curable polymers having heterocyclic ring systems such as isoindoloquinazolinedione ring systems prepared from novel cyanoimide polymers, most desirably 2'-cyanoimide polymers. Preferably the cyanoimide polymers are prepared from a diamine having at least one nitrile group in the two position to an amine group and a dianhydride having at least two cyclic anhydride groups. Copolymers may be prepared having other linkages, notably imide linkages, in addition to isoindoloquinazolinedione ring systems and/or other similar heterocyclic ring systems. The copolymers can be prepared by use of diamines containing one or more cyanoimide groupings and/or imide groups in their structure.

Chemical Interactions of Polyethylene Glycols (PEG) and Glycerol with Protein Functional Groups: Applications to PEG, Glycerol Effects on Protein Processes

PubMed Central

Knowles, DB; Shkel, Irina A; Phan, Noel M; Sternke, Matt; Lingeman, Emily; Cheng, Xian; Cheng, Lixue; O’Connor, Kevin; Record, M. Thomas

2015-01-01

Here we obtain the data needed to predict chemical interactions of polyethylene glycols (PEGs) and glycerol with proteins and related organic compounds, and thereby interpret or predict chemical effects of PEGs on protein processes. To accomplish this we determine interactions of glycerol and tetraEG with >30 model compounds displaying the major C, N, and O functional groups of proteins. Analysis of these data yields coefficients (α-values) quantifying interactions of glycerol, tetraEG and PEG end (-CH2OH) and interior (-CH2OCH2-) groups with these groups, relative to interactions with water. TetraEG (strongly) and glycerol (weakly) interact favorably with aromatic C, amide N, and cationic N, but unfavorably with amide O, carboxylate O and salt ions. Strongly unfavorable O and salt anion interactions help make both small and large PEGs effective protein precipitants. Interactions of tetraEG and PEG interior groups with aliphatic C are quite favorable, while interactions of glycerol and PEG end groups with aliphatic C are not. Hence tetraEG and PEG 300 favor unfolding of the DNA-binding domain of lac repressor (lacDBD) while glycerol, di- and mono-ethylene glycol are stabilizers. Favorable interactions with aromatic and aliphatic C explain why PEG400 greatly increases the solubility of aromatic hydrocarbons and steroids. PEG400-steroid interactions are unusually favorable, presumably because of simultaneous interactions of multiple PEG interior groups with the fused ring system of the steroid. Using α-values reported here, chemical contributions to PEG m-values can be predicted or interpreted in terms of changes in water-accessible surface area (ΔASA), and separated from excluded volume effects. PMID:25962980

Ring-diameter Ratios for Multi-ring Basins Average 2.0(0.5)D

NASA Technical Reports Server (NTRS)

Pike, R. J.; Spudis, P. D.

1985-01-01

The spacing of the concentric rings of planetary impact basins was studied. It is shown that a radial increment of x (sup 0.5) D, where x is about 2.0 and D = ring diameter, separates both (1) adjacent least-squares groups of rings and arcs of multi-ring basins on Mars, Mercury, and the Moon; and (2) adjacent rings of individual basins on the three planets. Statistics for ratios of ring diameters are presented, the first and most-applied parameter of ring spacing. It is found that ratios excluding rings flanking the main ring also have a mean spacing increment of about 2.0. Ratios including such rings, as for the least-squares groups, and (1) above, have a larger increment, averaging 2.1. The F-test indicates, that these spacings of basin ring locations, and mode of ring formation are controlled by the mechanics of the impact event itself, rather than by crustal properties.

Four-point bending as a method for quantitatively evaluating spinal arthrodesis in a rat model.

PubMed

Robinson, Samuel T; Svet, Mark T; Kanim, Linda A; Metzger, Melodie F

2015-02-01

The most common method of evaluating the success (or failure) of rat spinal fusion procedures is manual palpation testing. Whereas manual palpation provides only a subjective binary answer (fused or not fused) regarding the success of a fusion surgery, mechanical testing can provide more quantitative data by assessing variations in strength among treatment groups. We here describe a mechanical testing method to quantitatively assess single-level spinal fusion in a rat model, to improve on the binary and subjective nature of manual palpation as an end point for fusion-related studies. We tested explanted lumbar segments from Sprague-Dawley rat spines after single-level posterolateral fusion procedures at L4-L5. Segments were classified as 'not fused,' 'restricted motion,' or 'fused' by using manual palpation testing. After thorough dissection and potting of the spine, 4-point bending in flexion then was applied to the L4-L5 motion segment, and stiffness was measured as the slope of the moment-displacement curve. Results demonstrated statistically significant differences in stiffness among all groups, which were consistent with preliminary grading according to manual palpation. In addition, the 4-point bending results provided quantitative information regarding the quality of the bony union formed and therefore enabled the comparison of fused specimens. Our results demonstrate that 4-point bending is a simple, reliable, and effective way to describe and compare results among rat spines after fusion surgery.

Supra­molecular inter­actions in 2,6-di­amino-4-chloro­pyrimidin-1-ium 5-chloro­salicylate and bis­(2,6-di­amino-4-chloro­pyrimidin-1-ium) naphthalene-1,5-di­sulfonate

PubMed Central

Swinton Darious, Robert; Thomas Muthiah, Packianathan

2018-01-01

The crystals of two new salts, 2,6-di­amino-4-chloro­pyrimidin-1-ium 5-chloro­salicylate, C4H6ClN4 +·C7H4ClO3 −, (I), and bis­(2,6-di­amino-4-chloro­pyrimidin-1-ium) naphthalene-1,5-di-sulfonate, 2C4H6ClN4 +·C10H6O6S2 2−, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both compounds, the N atom of the pyrimidine group in between the amino substituents is protonated and the pyrimidinium cation forms a pair of N—H⋯O hydrogen bonds with the carboxyl­ate/sulfonate ion, leading to a robust R 2 2(8) motif (supra­molecular heterosynthon). In compound (I), a self-complementary base pairing involving the other pyrimidinium ring nitro­gen atom and one of the amino groups via a pair of N—H⋯N hydrogen bonds [R 2 2(8) homosynthon] is also present. In compound (II), the crystallographic inversion centre coincides with the inversion centre of the naphthalene-1,5-di­sulfonate ion and all the sulfonate O atoms are hydrogen-bond acceptors, generating fused-ring motifs and a quadruple DDAA array. A halogen-bond (Cl⋯Cl) inter­action is present in (I) with a distance and angle of 3.3505 (12) Å and 151.37 (10)°, respectively. In addition, a C—Cl⋯π inter­action and a π–π inter­action in (I) and a π–π inter­action in (II) further stabilize these crystal structures. PMID:29850062

Investigation of intermolecular interactions in finasteride drug crystals in view of X-ray and Hirshfeld surface analysis

NASA Astrophysics Data System (ADS)

Bojarska, Joanna; Maniukiewicz, Waldemar

2015-11-01

The N,N-dimethylformamide (DMF) solvate hemihydrate (1) of finasteride, has been structurally characterized by single-crystal X-ray diffraction at 100 K and compared with previously reported finasteride crystalline forms. In addition, in order to resolve ambiguity concerning H-bond interactions, the crystal structure of finasteride hemihydrate, (2), originally reported by Schultheiss et al. in 2009, has been redetermined with higher precision. The (1) and (2) pseudopolymorphs of finasteride crystallize as orthorhombic in chiral P212121 space group with two very similar host molecules in the asymmetric unit. The conformation of fused 6-membered rings are screw-boat, chair and chair for both molecules, while 5-membered rings assume chair in (1), and half-chair in (2). There is a fairly close resemblance of the molecular geometry for all analyzed compounds, arising due to the rigid host molecule. Inter- and intramolecular host-host, host-guest strong O-H⋯O, N-H⋯O hydrogen bonds and weak C-H⋯O interactions form 3D net conferring stability to the crystal packing. Finasterides can be classified as synthon pseudopolymorphs. Isostructural solvates crystallizing in the orthorhombic space group P212121, with Z‧ = 2, exhibit R22(8) C22(15) network, monoclinic solvate (Z‧ = 1) possess D11(2), while both orthorhombic and monoclinic polymorphs have C(4) motifs, respectively. The structural similarities and subtle differences have been interpreted in view of the 3D Hirshfeld surface analysis and associated 2D fingerprint plots, which enabled detailed qualitative and quantitative insight into the intermolecular interactions. The 97-100% of Hirshfeld surface areas are due to H···H, O···H/H⋯O, C···H/H⋯C and N⋯H/H⋯N contacts. Furthermore, the electrostatic potential has been mapped over the Hirshfeld surfaces to decode the electrostatic complementarities, which exist in the crystal packing.

The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings.

PubMed

Haralur, Satheesh B; Hamdi, Osama A; Al-Shahrani, Abdulaziz A; Alhasaniah, Sultan

2017-01-01

To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings. The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups ( n = 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukey post hoc statistical analysis with Statistical Package for the Social Sciences version 20 software. The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukey post hoc analysis between group V and group VI with all the other groups with regards to marginal adaptation. The dry cellulose ring liners provided better marginal adaptation in comparison to prewet cellulose ring liners. Accurate cuspal height was obtained with shorter ring liner in comparison to full-length cellulose ring liners.

The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings

PubMed Central

Haralur, Satheesh B.; Hamdi, Osama A.; Al-Shahrani, Abdulaziz A.; Alhasaniah, Sultan

2017-01-01

Aim: To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings. Materials and Methods: The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups (n = 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukey post hoc statistical analysis with Statistical Package for the Social Sciences version 20 software. Results: The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukey post hoc analysis between group V and group VI with all the other groups with regards to marginal adaptation. Conclusion: The dry cellulose ring liners provided better marginal adaptation in comparison to prewet cellulose ring liners. Accurate cuspal height was obtained with shorter ring liner in comparison to full-length cellulose ring liners. PMID:28316950

Comparison of outcomes of tricuspid annuloplasty with 3D-rigid versus flexible prosthetic ring for functional tricuspid regurgitation secondary to rheumatic mitral valve disease.

PubMed

Wang, Haiping; Liu, Xiancheng; Wang, Xin; Lv, Zhenqian; Liu, Xiaojun; Xu, Ping

2016-11-01

Annuloplasty bands and rings are widely used for repairing functional tricuspid regurgitation (FTR). However, the question regarding which is the ideal annuloplasty device remains unclear. The aim of this study was to compare the efficacy and mid-term durability of tricuspid ring annuloplasty for FTR secondary to rheumatic mitral valve disease using flexible Cosgrove-Edwards band and the rigid Edwards MC3 ring (Edwards Lifesciences, LLC, Irvine, CA, USA). We retrospectively collected the clinical data of those who underwent mitral valve replacement (MVR) in concomitant with tricuspid ring annuloplasty from 2009 to 2013. The flexible band was used in 46 patients (flexible group), and the 3D rigid ring was used in 60 patients (rigid group). Echocardiographic evaluation of tricuspid function was performed preoperatively and postoperatively. The grade of TR was significantly improved compared to preoperative values in two groups. There was no significant difference regarding postoperative TR grade between the two groups at 1 week and 2-3 months but there was statistical significant difference at postoperative 6-12 months, and 2-3 years. During the follow up period, 25 of 46 patients (54.3%) in flexible group and 22 of 60 patients (30.3%) in rigid group developed recurrent TR. Freedom from recurrent TR in flexible group is significant lower than rigid group in each postoperative follow up period. These findings suggest that 3D rigid ring annuloplasty might be more effective for tricuspid ring annuloplasty in FTR in mid-term postoperative periods when compared to flexible band.

Ring versus 'Mercedes-Benz' cartilage-perichondrium graft tympanoplasty in management of pars tensa cholesteatoma.

PubMed

Albirmawy, O A

2011-12-01

To compare anatomical and audiological outcomes of ring versus 'Mercedes-Benz' cartilage-perichondrium graft tympanoplasty in patients with pars tensa cholesteatoma. Prospective clinical study. Otolaryngology department, Tanta University Hospital, Egypt. Over three years, 60 ears in 60 patients underwent surgery for either sinus or tensa retraction cholesteatoma, reconstructed using either a ring-shaped (30 ears) or Mercedes-Benz symbol shaped (30 ears) cartilage-perichondrium graft, with at least two years' follow up. Post-operative drum perforation and retraction, cholesteatoma residue and recurrence, middle-ear effusion, and hearing acuity were monitored. Anatomical outcomes were equivalent in both groups, but slightly better in the Mercedes group. Hearing improved significantly in both groups (pre- vs post-operative results), but significantly more so in the ring group. Within-group hearing outcomes were unaffected by cholesteatoma type or tympanoplasty type. The Mercedes-Benz technique may be superior to the ring technique in preventing neodrum retraction. However, the ring graft technique had better hearing outcomes, perhaps due to its more physiological design.

Multiscale image fusion using the undecimated wavelet transform with spectral factorization and nonorthogonal filter banks.

PubMed

Ellmauthaler, Andreas; Pagliari, Carla L; da Silva, Eduardo A B

2013-03-01

Multiscale transforms are among the most popular techniques in the field of pixel-level image fusion. However, the fusion performance of these methods often deteriorates for images derived from different sensor modalities. In this paper, we demonstrate that for such images, results can be improved using a novel undecimated wavelet transform (UWT)-based fusion scheme, which splits the image decomposition process into two successive filtering operations using spectral factorization of the analysis filters. The actual fusion takes place after convolution with the first filter pair. Its significantly smaller support size leads to the minimization of the unwanted spreading of coefficient values around overlapping image singularities. This usually complicates the feature selection process and may lead to the introduction of reconstruction errors in the fused image. Moreover, we will show that the nonsubsampled nature of the UWT allows the design of nonorthogonal filter banks, which are more robust to artifacts introduced during fusion, additionally improving the obtained results. The combination of these techniques leads to a fusion framework, which provides clear advantages over traditional multiscale fusion approaches, independent of the underlying fusion rule, and reduces unwanted side effects such as ringing artifacts in the fused reconstruction.

A case of annular pancreas with Wirsung's duct encircling the duodenum: embryological hypothesis based on cholangiopancreatographic and immunohistochemical findings.

PubMed

Fukai, Manami; Kamisawa, Terumi; Horiguchi, Shin-Ichirou; Hishima, Tsunekazu; Kuruma, Sawako; Chiba, Kazuro; Koizumi, Satomi; Tabata, Taku; Nagao, Sayaka; Kikuyama, Masataka; Honda, Goro; Kurata, Masanao

2017-06-01

We present a resected case of annular pancreas in which Wirsung's duct encircled the duodenum and continued directly to the main pancreatic duct in the body and tail. Furthermore, Wirsung's duct coursed along the right side of the lower bile duct near the major duodenal papilla. Histologically, the islets of Langerhans in the annular pancreas were irregular in shape and were characterized by a striking abundance of pancreatic polypeptide (PP)-positive cells. The PP-rich area that encircled the duodenum was fused with the PP-poor area in the head of the pancreas. The following embryological hypothesis is proposed. The tip of the ventral pancreatic anlage adhered to the duodenal wall and stretched to form a ring during clockwise rotation. The rotation was incomplete, and the pancreatic duct did not cross over the lower bile duct. Since there was adequate ventral anlage in the lower part of the head of the pancreas, fusion between the ducts of the ventral and dorsal anlagen did not occur. The tip of the ventral anlage overgrew and adhered to the dorsal anlage, and the annular duct fused with the main duct of the dorsal anlage.

Cartilage canals in the distal intermediate ridge of the tibia of fetuses and foals are surrounded by different types of collagen.

PubMed

Hellings, Ingunn Risnes; Dolvik, Nils Ivar; Ekman, Stina; Olstad, Kristin

2017-10-01

Some epiphyseal growth cartilage canals are surrounded by a ring of hypereosinophilic matrix consisting of collagen type I. Absence of the collagen type I ring may predispose canal vessels to failure and osteochondrosis, which can lead to fragments in joints (osteochondrosis dissecans). It is not known whether the ring develops in response to programming or biomechanical force. The distribution that may reveal the function of the ring has only been described in the distal femur of a limited number of foals. It is also not known which cells are responsible for producing the collagen ring. The aims of the current study were to examine fetuses and foals to infer whether the ring forms in response to biomechanical force or programming, to describe distribution and to investigate which cell type produces the ring. The material consisted of 46 fetuses and foals from 293 days of gestation to 142 days old, of both sexes and different breeds, divided into three groups, designated the naïve group up to and including the day of birth, the adapting group from 2 days up to and including 14 days old, and the loaded group from 15 days and older. The distal tibia was sawn into parasagittal slabs and the cranial half of the central slab from the intermediate ridge was examined by light microscopy and immunohistochemical staining for collagen type I. Presence, completeness and location of the collagen ring was compared, as was the quantity of perivascular mesenchymal cells. An eosinophilic ring present on HE-stained sections was seen in every single fetus and foal examined, which corresponded to collagen type I in immunostained sections. A higher proportion of cartilage canals were surrounded by an eosinophilic ring in the naïve and adapting groups at 73 and 76%, respectively, compared with the loaded group at 51%. When considering only patent canals, the proportion of canals with an eosinophilic ring was higher in the adapting and loaded than the naïve group of foals. The ring was present around 90 and 81% of patent canals in the deep and middle layers, respectively, compared with 58% in the superficial layer, and the ring was more often complete around deep compared with superficial canals. The ring was absent or partial around chondrifying canals. When an eosinophilic ring was present around patent canals, it was more common for the canal to contain one or more layers of perivascular mesenchymal cells rather than few to no layers. It was also more common for the collagen ring to be more complete around canals that contained many as opposed to few mesenchymal cells. In conclusion, the proportion of cartilage canals that had an eosinophilic ring was similar in all three groups of fetuses and foals, indicating that the presence of the collagen ring was mostly programmed, although some adaptation was evident. The ring was more often present around deep, compared with superficial canals, indicating a role in preparation for ossification. The collagen ring appeared to be produced by perivascular mesenchymal cells. © 2017 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.

Frequency and management of breakthrough bleeding with continuous use of the transvaginal contraceptive ring: a randomized controlled trial.

PubMed

Sulak, Patricia J; Smith, Virginia; Coffee, Andrea; Witt, Iris; Kuehl, Alicia L; Kuehl, Thomas J

2008-09-01

To assess bleeding patterns with continuous use of the transvaginal contraceptive ring. We did a prospective analysis of daily menstrual flow during a 21/7 cycle followed by 6 months of continuous use and institution of a randomized protocol to manage breakthrough bleeding/spotting. Seventy-four women completed the baseline 21/7 phase and were randomized equally into two groups during the continuous phase. Group 1 was instructed to replace the ring monthly on the same calendar day with no ring-free days. Group 2 was instructed to use the same process, but if breakthrough bleeding/spotting occurred for 5 days or more, they were to remove the ring for 4 days, store it, and then reinsert that ring. Sixty-five women completed the continuous phase with reduced average flow scores in the continuous phase compared with the 21/7 phase (P<.02). Most patients had no to minimal bleeding during continuous use, with group 2 experiencing a statistically greater percentage of days without breakthrough bleeding or spotting (95%) compared with group 1 (89%) (P=.016). Instituting a 4-day hormone-free interval was more (P<.001) effective in resolving breakthrough bleeding/spotting than continuing ring use. A reduction in bleeding occurred during continuous use with replacement of the transvaginal ring compared with baseline 21/7 use. Continuous vaginal ring use resulted in an acceptable bleeding profile in most patients, reduction in flow, reduction in pelvic pain, and a high continuation rate.

Comparison of outcomes of tricuspid annuloplasty with 3D-rigid versus flexible prosthetic ring for functional tricuspid regurgitation secondary to rheumatic mitral valve disease

PubMed Central

Wang, Haiping; Wang, Xin; Lv, Zhenqian; Liu, Xiaojun

2016-01-01

Background Annuloplasty bands and rings are widely used for repairing functional tricuspid regurgitation (FTR). However, the question regarding which is the ideal annuloplasty device remains unclear. The aim of this study was to compare the efficacy and mid-term durability of tricuspid ring annuloplasty for FTR secondary to rheumatic mitral valve disease using flexible Cosgrove-Edwards band and the rigid Edwards MC3 ring (Edwards Lifesciences, LLC, Irvine, CA, USA). Methods We retrospectively collected the clinical data of those who underwent mitral valve replacement (MVR) in concomitant with tricuspid ring annuloplasty from 2009 to 2013. The flexible band was used in 46 patients (flexible group), and the 3D rigid ring was used in 60 patients (rigid group). Echocardiographic evaluation of tricuspid function was performed preoperatively and postoperatively. Results The grade of TR was significantly improved compared to preoperative values in two groups. There was no significant difference regarding postoperative TR grade between the two groups at 1 week and 2–3 months but there was statistical significant difference at postoperative 6–12 months, and 2–3 years. During the follow up period, 25 of 46 patients (54.3%) in flexible group and 22 of 60 patients (30.3%) in rigid group developed recurrent TR. Freedom from recurrent TR in flexible group is significant lower than rigid group in each postoperative follow up period. Conclusions These findings suggest that 3D rigid ring annuloplasty might be more effective for tricuspid ring annuloplasty in FTR in mid-term postoperative periods when compared to flexible band. PMID:28066587

How a RING finger protein and a steroid hormone control autophagy.

PubMed

Lindmo, Karine; Stenmark, Harald

2006-01-01

Previous work in our laboratory has indicated that the steroid hormone ecdysone triggers programmed autophagy in the fat body of Drosophila larvae by downregulating the class I phosphoinositide 3-kinase (PI3K) pathway. We recently found evidence that Deep orange (Dor), a Drosophila RING finger protein implicated in late-endosomal trafficking, controls ecdysone signaling as well as autolysosome fusion, thus exerting a dual regulation of autophagy. We found that dor mutants are defective in programmed autophagy. The mutant larvae showed impaired upregulation of ecdysone signaling during development, accompanied by a failure to downregulate the PI3K pathway. Downregulation of the PI3K pathway could be restored by feeding the dor mutants with ecdysone. Even though ecdysone signaling and autophagy were impaired in the dor mutants, we detected an accumulation of autophagosomes in dor mutant fat bodies. This could probably be attributed to the failure of autophagosomes to fuse with lysosomes. In this Addendum we review these findings and provide some speculations about how Dor may control both ecdysone signalling and autolysosomal fusion.

Acenes, Heteroacenes and Analogous Molecules for Organic Photovoltaic and Field Effect Transistor Applications

NASA Astrophysics Data System (ADS)

Granger, Devin Benjamin

Polycyclic aromatic hydrocarbons composed of benzenoid rings fused in a linear fashion comprise the class of compounds known as acenes. The structures containing three to six ring fusions are brightly colored and possess band gaps and charge transport efficiencies sufficient for semiconductor applications. These molecules have been investigated throughout the past several decades to assess their optoelectronic properties. The absorption, emission and charge transport properties of this series of molecules has been studied extensively to elucidate structure-property relationships. A wide variety of analogous molecules, incorporating heterocycles in place of benzenoid rings, demonstrate similar properties to the parent compounds and have likewise been investigated. Functionalization of acene compounds by placement of groups around the molecule affects the way in which molecules interact in the solid state, in addition to the energetics of the molecule. The use of electron donating or electron withdrawing groups affects the frontier molecular orbitals and thus affects the optical and electronic gaps of the molecules. The use of bulky side groups such as alkylsilylethynyl groups allows for crystal engineering of molecular aggregates, and changing the volume and dimensions of the alkylsilyl groups affects the intermolecular interactions and thus changes the packing motif. In chapter 2, a series of tetracene and pentacene molecules with strongly electron withdrawing groups is described. The investigation focuses on the change in energetics of the frontier molecular orbitals between the base acene and the nitrile and dicyanovinyl derivatives as well as the differences between the pentacene and tetracene molecules. The differences in close packing motifs through use of bulky alkylsilylethynyl groups is also discussed in relation to electron acceptor material design and bulk heterojunction organic photovoltaic characteristics. Chapter 3 focuses on molecular acceptor and donor molecules for bulk heterojunction organic photovoltaics based on anthrathiophene and benzo[1,2-b:4,5-b']dithiophene central units like literature molecules containing fluorene and dithieno[2,3-b:2',3'-d]silole cores. The synthetic strategies of developing reduced symmetry benzo[1,2-b:4,5-b']dithiophene to study the effect of substitution around the central unit is also described. The optical and electronic properties of the donors and acceptors are described along with the performance and characteristics of devices employing these molecules. The final two data chapters focus on new nitrogen containing polycyclic hydrocarbons containing indolizine and (2.2.2) cyclazine units. The optical, electronic and other physical properties of these molecules are explored, in addition to the synthetic strategies for incorporating the indolizine and cyclazine units. By use of alkylsilylethynyl groups, crystal engineering was investigated for the benzo[2,3-b:5,6-b']diindolizine chromophore described in chapter 4 to target the 2-D "brick-work" packing motif for application in field effect transistor devices. Optical and electronic properties of the cyclazine end-capped acene molecules described in chapter 5 were investigated and described in relation to the base acene molecules. In both cases, density functional theory calculations were conducted to better understand unexpected optical properties of these molecules, which are like the linear acene series despite the non-linear attachment.

Artist as Educator? Assessing the Pedagogic Role of Folly in the Early Work of the Anglo-Swiss Artist Henry Fuseli (1741-1825)

ERIC Educational Resources Information Center

Smith, Hester Camilla

2010-01-01

This article examines a group of five ink, pen and wash drawings produced by the Anglo-Swiss artist Henry Fuseli in the mid-eighteenth century in Zurich. The drawings were produced for a "Narrenbuch" (Book of Fools) uniting visual images of folly with humorous slogans. The drawings are significant in that they imitate sixteenth-century…

Immunomodulatory Polyketides from a Phoma-like Fungus Isolated from a Soft Coral.

PubMed

Sun, Yi-Zhe; Kurtán, Tibor; Mándi, Attila; Tang, Hua; Chou, Yalan; Soong, Keryea; Su, Li; Sun, Peng; Zhuang, Chun-Lin; Zhang, Wen

2017-11-22

Fourteen new polyketides with a trans-fused decalin ring system, libertalides A-N (3-16), together with two known analogues, aspermytin A and its acetate (1, 2), were isolated from the fermentation extract of a coral-derived Libertasomyces sp. fungus. Their relative configurations were elucidated on the basis of detailed spectroscopic analysis, and the absolute configurations were determined by TDDFT-ECD and optical rotation (OR) calculations. The OR of 1 and 2 were found to have opposite signs in CH 3 CN and CHCl 3 , which was in agreement with the OR calculations producing alternating signs for the optical rotation depending on the applied conditions. Because the signs of the OR for 1 and 2 showed high solvent dependence, they may not be used alone to correlate the absolute configurations. Compound 16 displayed structural novelty characterized by an α-enol ether bridge conjugated with an aldehyde group. In in vitro immunomodulatory screening, compounds 1, 4, and 10 significantly induced the proliferation of CD3 + T cells, while compounds 2, 7, 11, and 14 significantly increased the CD4 + /CD8 + ratio at 3 μM. A preliminary structure-activity analysis revealed a crucial role of Δ 7 and a terminal OH group in the regulation of CD3 + T cell proliferation. This is the first report of immunoregulatory activity for metabolites of this kind.

Reactions of Trimethylsilyl Fluorosulfonyldifluoroacetate with Purine and Pyrimidine Nucleosides

PubMed Central

Rapp, Magdalena; Cai, Xiaohong; Xu, Wei; Dolbier, William R.; Wnuk, Stanislaw F.

2008-01-01

Difluorocarbene, generated from trimethylsilyl fluorosulfonyldifluoroacetate (TFDA), reacts with the uridine and adenosine substrates preferentially at the enolizable amide moiety of the uracil ring and the 6-amino group of the purine ring. 2',3'-Di-O-acetyl-3'-deoxy-3'-methyleneuridine reacts with TFDA to produce 4-O-difluoromethyl product derived from an insertion of difluorocarbene into the 4-hydroxyl group of the enolizable uracil ring. Reaction of the difluorocarbene with the adenosine substrates having the unprotected 6-amino group in the purine ring produced the 6-N-difluoromethyl derivative, while reaction with 6-N-benzoyl protected adenosine analogues gave the difluoromethyl ether product derived from the insertion of difluorocarbene into the enol form of the 6-benzamido group. Treatment of the 6-N-phthaloyl protected adenosine analogues with TFDA resulted in the unexpected one-pot conversion of the imidazole ring of the purine into the corresponding N-difluoromethylthiourea derivatives. Treatment of the suitably protected pyrimidine and purine nucleosides bearing an exomethylene group at carbons 2', 3' or 4' of the sugar rings with TFDA afforded the corresponding spirodifluorocyclopropyl analogues but in low yields. PMID:20160856

Four new triterpenoids from the leaves of Psidium guajava.

PubMed

Shao, Meng; Wang, Ying; Huang, Xiao-Jun; Fan, Chun-Lin; Zhang, Qing-Wen; Zhang, Xiao-Qi; Ye, Wen-Cai

2012-01-01

Four new triterpenoids, psiguanins A-D (1-4), along with 13 known ones (5-17), were isolated from the leaves of Psidium guajava. The structures of new compounds were determined as 2α,3β-dihydroxy-taraxer-20-en-28-oic acid (1), 2α,3β,12α,13β-tetrahydroxy-urs-28-oic acid (2), 2α,3β,12β,13β-tetrahydroxy-urs-28-oic acid (3), and 2α,3β,12β,13α-tetrahydroxy-urs-28-oic acid (4), respectively, on the basis of comprehensive spectroscopic methods and molecular modeling calculation. Among them, compound 4 was characterized as an unusual ursane-type triterpenoid with cis-fused C/D ring system.

Unified Total Syntheses of Fawcettimine Class Alkaloids: Fawcettimine, Fawcettidine, Lycoflexine, and Lycoposerramine B

PubMed Central

Pan, Guojun; Williams, Robert M.

2012-01-01

The total syntheses of the lycopodium alkaloids: fawcettimine, fawcettidine, lycoflexine, and lycoposerramine B have been accomplished through an efficient, unified, and stereocontrolled strategy, which relies on a Diels-Alder reaction to construct the cis-fused 6,5-carbocycles with one all-carbon quaternary center. Access to the enantioselective syntheses of both antipodes of those alkaloids can be achieved by kinetic resolution of the earliest intermediate via a Sharpless asymmetric dihydroxylation (Sharpless AD). Compared to existing approaches to these alkaloids, our synthetic route possesses superior stereocontrol over the C-4 and C-15 stereogenic centers as well as allowing for more functional variation on the 6-membered ring. PMID:22519642

Switchable narrow linewidth fiber laser with LP11 transverse mode output

NASA Astrophysics Data System (ADS)

Shen, Ya; Ren, Guobin; Yang, Yuguang; Yao, Shuzhi; Wu, Yue; Jiang, Youchao; Xu, Yao; Jin, Wenxing; Zhu, Bofeng; Jian, Shuisheng

2018-01-01

We experimentally demonstrate a switchable narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser with LP11 transverse mode output. The laser is based on a mode selective all-fiber fused coupler which is composed of a single-mode fiber (SMF) and a two-mode fiber (TMF). By controlling the polarization state of the output light, the laser can provide narrow linewidth SLM output with LP11 transverse mode at two specific wavelengths, which correspond to two transmission peaks of the chirped moiré fiber grating (CMFBG). The 20 dB linewidth of the fiber laser for each wavelength is approximately 7.2 and 6.4 kHz.

Poly(sodium 4-styrenseulfonate)-modified monolayer graphene for anode applications of organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zhou, Yongfang; Wang, Min; Wang, Liang; Liu, Shuli; Chen, Shufen; Cao, Kun; Shang, Wenjuan; Mai, Jiangquan; Zhao, Baomin; Feng, Jing; Lu, Xinhui; Huang, Wei

2017-09-01

An insulated poly(sodium 4-styrenseulfonate) (PSS) was used to modify monolayer graphene for anode applications of organic photovoltaics (OPVs). With this PSS interfacial modification layer, the OPVs showed a significant increase of 56.4% in efficiency due to an improved work function and hydrophilic feature of graphene and an enlarged recombination resistance of carriers/excitons. Doping a highly contorted 1,2,5-thiadiazole-fused 12-ring polyaromatic hydrocarbon into the active layer to form ternary blended OPVs further enlarged the recombination resistance of carriers/excitons and improved light absorption of the active layer, with which a high power conversion efficiency of 6.29% was acquired.

Rh(I)-catalyzed Pauson-Khand-type cycloaddition reaction of ene-vinylidenecyclopropanes with carbon monoxide (CO)

PubMed Central

Yuan, Wei; Dong, Xiang; McDowell, Patrick

2012-01-01

An intramolecular Pauson-Khand type cycloaddition reaction of ene-vinylidenecyclopropanes with carbon monoxide has been established by using [Rh(COD)Cl]2 as the catalyst. The reaction was found to be highly efficient in solvents of 1,2-dichloroethane and 1,1,2,2-tetrachloroethane to give excellent yields of 90 – 99%. The reaction provides easy access to a series of fused 6,5-ring structures containing spiro-cyclopropane units that are useful for drug design and development. A mechanism of this cycloaddition process has been proposed accounting for structures of resulting products that were unambiguously assigned by X-ray diffractional analysis. PMID:23098194

Impact of a hands-on component on learning in the Fundamental Use of Surgical Energy™ (FUSE) curriculum: a randomized-controlled trial in surgical trainees.

PubMed

Madani, Amin; Watanabe, Yusuke; Vassiliou, Melina C; Fuchshuber, Pascal; Jones, Daniel B; Schwaitzberg, Steven D; Fried, Gerald M; Feldman, Liane S

2014-10-01

While energy devices are ubiquitous in the operating room, they remain poorly understood and can result in significant complications. The purpose of this study was to estimate the extent to which adding a novel bench-top component improves learning of SAGES' Fundamental Use of Surgical Energy™ (FUSE) electrosurgery curriculum among surgical trainees. Surgical residents participated in a 1-h didactic electrosurgery (ES) course, based on the FUSE curriculum. They were then randomized to one of two groups: an unstructured hands-on session where trainees used ES devices (control group) or a goal-directed hands-on training session (Sim group). Pre- and post-curriculum (immediate and at 3 months) assessments included knowledge of ES (multiple-choice examination), self-perceived competence for each of the 35 course objectives (questionnaire), and self-perceived comfort with performance of seven tasks related to safe use of ES. Data expressed as median[interquartile range], *p < 0.05. 56 (29 control; 27 Sim) surgical trainees completed the curriculum and assessments. Baseline characteristics, including pre-curriculum exam and questionnaire scores, were similar. Total score on the exam improved from 46%[40;54] to 84%[77;91]* for the entire cohort, with higher immediate post-curriculum scores in the Sim group compared to controls (89%[83;94] vs. 83%[71;86]*). At 3 months, performance on the exam declined in both groups, but remained higher in the Sim group (77%[69;90] vs 60%[51;80]*). Participants in both groups reported feeling greater comfort and competence post-curriculum (immediate and at 3 months) compared to baseline. This improvement was greater in the Sim group with a higher proportion feeling "Very Comfortable" or "Fully Competent" (Sim: 3/7 tasks and 28/35 objectives; control: 0/7 tasks and 10/35 objectives). A FUSE-based curriculum improved surgical trainees' knowledge and comfort in the safe use of electrosurgical devices. The addition of a structured interactive bench-top simulation component further improved learning and retention at 3 months.

In search of a new class of stable nitroxide: synthesis and reactivity of a peri-substituted N,N-bissulfonylhydroxylamine.

PubMed

Patel, Bhaven; Carlisle, Julie; Bottle, Steven E; Hanson, Graeme R; Kariuki, Benson M; Male, Louise; McMurtrie, John C; Spencer, Neil; Grainger, Richard S

2011-04-07

Acyclic bissulfonylnitroxides have never been isolated, and degrade through fragmentation. In an approach to stabilising a bissulfonylnitroxide radical, the cyclic, peri-substituted N,N-bissulfonylhydroxylamine, 2-hydroxynaphtho[1,8-de][1,3,2]dithiazine 1,1,3,3-tetraoxide (1), has been prepared by formal nitrogen insertion into the sulfur-sulfur bond of a sulfinylsulfone, naphtho[1,8-cd][1,2]dithiole 1,1,2-trioxide. The heterocyclic ring of 1 is shown to adopt a sofa conformation by X-ray crystallography, with a pseudo-axial hydroxyl group. N,N-Bissulfonylhydroxylamine 1 displays high thermal, photochemical and hydrolytic stability compared to acyclic systems. EPR analysis reveals formation of the corresponding bissulfonylnitroxide 2 upon oxidation of 1 with the Ce(IV) salts CAN and CTAN. Although 2 does not undergo fragmentation, it cannot be isolated, since hydrogen atom abstraction to reform 1 occurs in situ. The stability and reactivity of 1 and 2 are compared with the known cyclic benzo-fused N,N-bissulfonylhydroxylamine, N-hydroxy-O-benzenedisulfonimide (6), for which the X-ray data, and EPR of the corresponding nitroxide 10, are also reported for the first time.

Tetramethylpyrazine-Inducible Promoter Region from Rhodococcus jostii TMP1.

PubMed

Stanislauskienė, Rūta; Kutanovas, Simonas; Kalinienė, Laura; Bratchikov, Maksim; Meškys, Rolandas

2018-06-25

An inducible promoter region, P TTMP (tetramethylpyrazine [TTMP]), has been identified upstream of the tpdABC operon, which contains the genes required for the initial degradation of 2,3,5,6-tetramethylpyrazine in Rhodococcus jostii TMP1 bacteria. In this work, the promoter region was fused with the gene for the enhanced green fluorescent protein (EGFP) to investigate the activity of P TTMP by measuring the fluorescence of bacteria. The highest promoter activity was observed when bacteria were grown in a nutrient broth (NB) medium supplemented with 5 mM 2,3,5,6-tetramethylpyrazine for 48 h. Using a primer extension reaction, two transcriptional start sites for tpdA were identified, and the putative −35 and −10 promoter motifs were determined. The minimal promoter along with two 15 bp long direct repeats and two 7 bp inverted sequences were identified. Also, the influence of the promoter elements on the activity of P TTMP were determined using site-directed mutagenesis. Furthermore, P TTMP was shown to be induced by pyrazine derivatives containing methyl groups in the 2- and 5-positions of the heterocyclic ring, in the presence of the LuxR family transcriptional activator TpdR.

Anti-Amyloidogenic Properties of Some Phenolic Compounds

PubMed Central

Porzoor, Afsaneh; Alford, Benjamin; Hügel, Helmut M.; Grando, Danilla; Caine, Joanne; Macreadie, Ian

2015-01-01

A family of 21 polyphenolic compounds consisting of those found naturally in danshen and their analogues were synthesized and subsequently screened for their anti-amyloidogenic activity against the amyloid beta peptide (Aβ42) of Alzheimer’s disease. After 24 h incubation with Aβ42, five compounds reduced thioflavin T (ThT) fluorescence, indicative of their anti-amyloidogenic propensity (p < 0.001). TEM and immunoblotting analysis also showed that selected compounds were capable of hindering fibril formation even after prolonged incubations. These compounds were also capable of rescuing the yeast cells from toxic changes induced by the chemically synthesized Aβ42. In a second assay, a Saccharomyces cerevisiae AHP1 deletant strain transformed with GFP fused to Aβ42 was treated with these compounds and analyzed by flow cytometry. There was a significant reduction in the green fluorescence intensity associated with 14 compounds. We interpret this result to mean that the compounds had an anti-amyloid-aggregation propensity in the yeast and GFP-Aβ42 was removed by proteolysis. The position and not the number of hydroxyl groups on the aromatic ring was found to be the most important determinant for the anti-amyloidogenic properties. PMID:25898401

Quinoxaline-substituted chalcones as new inhibitors of breast cancer resistance protein ABCG2: polyspecificity at B-ring position

PubMed Central

Winter, Evelyn; Gozzi, Gustavo Jabor; Chiaradia-Delatorre, Louise Domeneghini; Daflon-Yunes, Nathalia; Terreux, Raphael; Gauthier, Charlotte; Mascarello, Alessandra; Leal, Paulo César; Cadena, Silvia M; Yunes, Rosendo Augusto; Nunes, Ricardo José; Creczynski-Pasa, Tania Beatriz; Di Pietro, Attilio

2014-01-01

A series of chalcones substituted by a quinoxaline unit at the B-ring were synthesized and tested as inhibitors of breast cancer resistance protein-mediated mitoxantrone efflux. These compounds appeared more efficient than analogs containing other B-ring substituents such as 2-naphthyl or 3,4-methylenedioxyphenyl while an intermediate inhibitory activity was obtained with a 1-naphthyl group. In all cases, two or three methoxy groups had to be present on the phenyl A-ring to produce a maximal inhibition. Molecular modeling indicated both electrostatic and steric positive contributions. A higher potency was observed when the 2-naphthyl or 3,4-methylenedioxyphenyl group was shifted to the A-ring and methoxy substituents were shifted to the phenyl B-ring, indicating preferences among polyspecificity of inhibition. PMID:24920885

Explicitly correlated benchmark calculations on C8H8 isomer energy separations: how accurate are DFT, double-hybrid, and composite ab initio procedures?

NASA Astrophysics Data System (ADS)

Karton, Amir; Martin, Jan M. L.

2012-10-01

Accurate isomerization energies are obtained for a set of 45 C8H8 isomers by means of the high-level, ab initio W1-F12 thermochemical protocol. The 45 isomers involve a range of hydrocarbon functional groups, including (linear and cyclic) polyacetylene, polyyne, and cumulene moieties, as well as aromatic, anti-aromatic, and highly-strained rings. Performance of a variety of DFT functionals for the isomerization energies is evaluated. This proves to be a challenging test: only six of the 56 tested functionals attain root mean square deviations (RMSDs) below 3 kcal mol-1 (the performance of MP2), namely: 2.9 (B972-D), 2.8 (PW6B95), 2.7 (B3PW91-D), 2.2 (PWPB95-D3), 2.1 (ωB97X-D), and 1.2 (DSD-PBEP86) kcal mol-1. Isomers involving highly-strained fused rings or long cumulenic chains provide a 'torture test' for most functionals. Finally, we evaluate the performance of composite procedures (e.g. G4, G4(MP2), CBS-QB3, and CBS-APNO), as well as that of standard ab initio procedures (e.g. MP2, SCS-MP2, MP4, CCSD, and SCS-CCSD). Both connected triples and post-MP4 singles and doubles are important for accurate results. SCS-MP2 actually outperforms MP4(SDQ) for this problem, while SCS-MP3 yields similar performance as CCSD and slightly bests MP4. All the tested empirical composite procedures show excellent performance with RMSDs below 1 kcal mol-1.

Compounds for neutron radiation detectors and systems thereof

DOEpatents

Payne, Stephen A; Stoeffl, Wolfgang; Zaitseva, Natalia P; Cherepy, Nerine J; Carman, M. Leslie

2014-05-27

A material according to one embodiment exhibits an optical response signature for neutrons that is different than an optical response signature for gamma rays, said material exhibiting performance comparable to or superior to stilbene in terms of distinguishing neutrons from gamma rays, wherein the material is not stilbene, the material comprising a molecule selected from a group consisting of: two or more benzene rings, one or more benzene rings with a carboxylic acid group, one or more benzene rings with at least one double bound adjacent to said benzene ring, and one or more benzene rings for which at least one atom in the benzene ring is not carbon.

Study of idempotents in cyclic group rings over F{sub 2}

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

Ong, Kai Lin, E-mail: i.am.kailin@hotmail.com; Ang, Miin Huey, E-mail: mathamh@usm.my

The existence of an idempotent generator for group codes or group ring codes in F{sub q}G plays a very important role in determining the minimal distance of the respective code. Some necessary and sufficient conditions for a group ring element to be an idempotent in F{sub 2}C{sub n} are investigated in this paper. The main result in this paper is the affirmation of the existence of finitely many basis idempotents which gives a full identification of all idempotents in every binary cyclic group ring F{sub 2}C{sub n}. All the basis idempotents in F{sub 2}C{sub n} are able to be foundmore » by partitioning the largest idempotent’s support.« less

Magnetic ring anastomosis of suprahepatic vena cava: novel technique for liver transplantation in rat.

PubMed

Shi, Yuan; Zhang, Wei; Deng, Yong-lin; Zhang, Ya-min; Zhang, Quan-sheng; Zhang, Wei-ye; Zheng, Hong; Pan, Cheng; Shen, Zhong-Yang

2015-01-01

To improve the technique of suprahepatic vena cava (SHVC) reconstruction in rat OLT, novel magnetic rings were designed and manufactured to facilitate reconstruction of SHVC and shorten the anhepatic time. One-hundred and twenty adult male Wistar rats were randomly divided into two groups: rings group (n = 30), using magnetic rings for SHVC reconstruction; suture group (n = 30), 7/0 prolene suture was used for SHVC running anastomosis as control. Cuff techniques were used for portal vein and infrahepatic vena cava reconstruction as Kamada and Calne described. The bile duct was reconnected with a stent. The hepatic re-arterialization was omitted. In the rings group, the SHVC reconstruction took 0.91 ± 0.24 (mean ± SD) min; the anhepatic phase and the recipient operation time were 5.63 ± 0.65 min and 36.02 ± 8.02 min, respectively. In suture group, the anastomotic time of SHVC was 10.40 ± 2.11 min; the anhepatic phase and the recipient operation time were 17.76 ± 2.51 and 49.38 ± 12.06 min, respectively, and there was statistically significant difference between the two groups. The ALT levels reached peak at 24 h post-OLT (186.2 ± 32.5 IU/l) and restored to normal level at 96 h gradually. In the rings group, 29 of 30 rats survived at day 7 and 28 of 30 rats survived at day 30. In contrast, only 25 of 30 recipients in suture group remained alive at day 7 and 22 of 30 remained alive at day 30 (P < 0.05). Better anastomotic healing was founded in rings group by pathology and scanning electron microscope. The magnetic rings technique provides a novel, simple method for SHVC reconstruction of OLT in rat. It significantly shortens anhepatic phase, while the success rate of the operation is satisfactory. © 2014 Steunstichting ESOT.

Rhodium(III)-catalyzed vinylic sp2 C-H bond functionalization: efficient synthesis of pyrido[1,2-α]benzimidazoles and imidazo[1,2-α]pyridines.

PubMed

Dong, Lin; Huang, Ji-Rong; Qu, Chuan-Hua; Zhang, Qian-Ru; Zhang, Wei; Han, Bo; Peng, Cheng

2013-09-28

A simple approach for synthesis of novel aza-fused scaffolds such as pyrido[1,2-α]benzimidazoles and imidazo[1,2-α]pyridines was developed by Rh(III)-catalyzed direct oxidative coupling between alkenes and unactivated alkynes without an extra directing group. The method would allow a broad substrate scope, providing fused heterocycles with potential biological properties.

Observation of changes in the metallurgical characteristics of Ni-Cr alloys using Nd:YAG laser welding

PubMed Central

Choi, SM

2014-01-01

This study aimed to determine the effect of hardness change according to penetration depth in the laser fusing zone and observed the correlation of the microstructure as an Nd:YAG laser was irradiated to Ni-Cr alloy for dental use by setting the spot diameter size to various conditions. In all groups, the hardness depth profiles in the laser fusing zone and heat-affected zone (HAZ) had larger values than those of the base metal. In addition, the hardness values in places beyond the fusing zone and the HAZ were measured as being quantitatively lower. The observation result of the diffusion of the constituent elements and microstructure using field emission scanning electron microscopy, energy-dispersive spectroscopy, and electron probe microanalyzer showed that the fusing zone revealed a much finer dendritic form than the base metal due to the self-quenching effect after welding, while no change in constituent elements was found although some evaporation of the main elements was observed. In addition, Mo- and Si-combined intermetallic compounds were formed on the interdendritic area. Through this study, the laser fusing zone had better hardenability due to the intermetallic compound and grain refinement effect. PMID:25342985

Comparison of combined hormonal vaginal ring and low dose combined oral hormonal pill for the treatment of idiopathic chronic pelvic pain: a randomised trial.

PubMed

Priya, Khushboo; Rajaram, Shalini; Goel, Neerja

2016-12-01

To compare the efficacy and acceptability of combined hormonal vaginal ring with combined oral hormonal pill in women with idiopathic chronic pelvic pain. Randomised prospective interventional trial conducted in 60 women with idiopathic chronic pelvic pain. Women were randomised into two groups of 30 each. In each group, treatment was given for 84 days using either combined vaginal ring or combined oral hormonal pill. Hormonal vaginal ring releases 15mcg of ethinyl estradiol and 120mcg of the etonogestrel per day while the hormonal pill contained 30mcg of ethinyl estradiol and 150mcg of levonorgestrel. There was no ring or pill free week. After every 28 days, pain relief was measured using visual analogue scale (VAS), and verbal rating score (VRS) calculated by summing dysmenorrhea, non-cyclic pelvic pain (NCCP) and deep dyspareunia scores. Side effects, compliance, satisfaction, and user acceptability were also measured. Data was analyzed using various parametric and non-parametric tests. Reduction in mean VAS score at end of treatment in ring group was 6.23 (95% confidence interval [CI], 5.45-7.01; p<0.001) as compared to 5.53 in pill group (95% CI, 4.83-6.23; p<0.001). Reduction in mean VRS score was 5.63 in ring users (95% CI, 4.84-6.42; p<0.001) versus 4.36 in pill users (95% CI, 3.63-5.10; p<0.001). A significantly higher persistent relief in NCPP score was observed in vaginal ring group as compared to oral pill group at end of one month after stopping treatment. Compliance, satisfaction, and user acceptability were higher in ring users (80%) than pill users (70%) and a higher incidence of nausea was seen in pill group. Present study demonstrates for first time that both vaginal and oral hormonal therapy are effective in treatment of idiopathic chronic pelvic pain and vaginal ring may be a better choice with higher satisfaction rate and fewer side effects. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Identification of the related substances of tilmicosin by liquid chromatography/ion trap mass spectrometry.

PubMed

Stoev, Georgi; Nazarov, Valeri

2008-06-01

Structures of seven impurities of the veterinary drug tilmicosin have been elucidated by multiple fragmentation with ion trap tandem mass spectrometry. All related compounds possess the main lactone ring of tilmicosin. The differences in their structures are due to the hydroxyl, mycaminose, 3,5-dimethylpiperidine and mycinose groups connected to C(3), C(5), C(6), C(14) of the lactone ring, respectively. The following compounds of the impurity profile of tilmicosin were identified: B - tilmicosin with a hydroxyl group at C(3); C - tilmicosin without a methyl group at the N-atom connected to C(3) of the mycaminose ring; D - tilmicosin with a hydroxyl group at C(6) of the mycaminose ring; E - tilmicosin with a methoxy group at C(3), F - desmicosin; G - 20-dihydrodesmicosin; and H - tilmicosin without a mycaminose ring. Isomers of the compounds B, C, D, E and H were identified by their mass chromatograms and retention times. The concentrations of the impurities varied in the range of 0.1% to 2.9%.

Azaquinolone dye lasers

DOEpatents

Hammond, Peter R.; Atkins, Ronald L.; Henry, Ronald A.; Fletcher, Aaron N.

1978-01-01

A dye laser comprising a laser dye solution of a compound having the general structure: ##STR1## wherein at least one of the 5, 6 and 8 ring positions is occupied by a nitrogen atom in lieu of the corresponding CR group and X is OH, alkoxy, or amino including amino substituted by at least one of the following: alkyl, aryl, acyl, aracyl, a group which taken together with the nitrogen atom of the amino group forms a heterocyclic ring, or part of one or two 5 or 6 membered aliphatic heterocyclic rings attached to ring A at positions 6 or 8 or both depending on where the N in ring A is located. R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.8 are hydrogen or other groups as defined below. The compounds lase in the blue to near ultraviolet region.

Azacoumarin dye lasers

DOEpatents

Hammond, Peter R.; Atkins, Ronald L.; Henry, Ronald A.; Fletcher, Aaron N.

1978-01-01

A dye laser comprising a laser dye solution of a compound having the general structure: ##STR1## wherein at least one of the 5, 6 and 8 ring positions is occupied by a nitrogen atom in lieu of the corresponding CR group and X is OH, alkoxy, or amino including amino substituted by at least one of the following: alkyl, aryl, acyl, aracyl, a group which taken together with the nitrogen atom of the amino group forms a heterocyclic ring, or part of one or two 5 or 6 membered aliphatic heterocyclic rings attached to ring A at positions 6 or 8 or both depending on where the N in ring A is located. R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.8 are hydrogen or other groups as defined below. The compounds lase in the blue-green to near ultraviolet region.

Quartz and feldspar glasses produced by natural and experimental shock.

NASA Technical Reports Server (NTRS)

Stoeffler, D.; Hornemann, U.

1972-01-01

Refractive index, density, and infrared absorption studies of naturally and experimentally shocked-produced glasses formed from quartz, plagioclase, and alkali-feldspar confirm the existence of two main groups of amorphous forms of the framework silicates: solid-state and liquid-state glasses. These were apparently formed as metastable release products of high-pressure-phases above and below the glass transition temperatures. Solid-state glasses exhibit a series of structural states with increasing disorder caused by increasing shock pressures and temperatures. They gradually merge into the structural state of fused minerals similar to that of synthetic glasses quenched from a melt. Shock-fused alkali feldspars can, however, be distinguished from their laboratory-fused counterparts by infrared absorption and by higher density.

Long-term outcomes of tricuspid annuloplasty for functional tricuspid regurgitation associated with degenerative mitral regurgitation: suture annuloplasty versus ring annuloplasty using a flexible band.

PubMed

Murashita, Takashi; Okada, Yukikatsu; Kanemitsu, Hideo; Fukunaga, Naoto; Konishi, Yasunobu; Nakamura, Ken; Koyama, Tadaaki

2014-01-01

We investigated the long-term outcomes of suture/ring tricuspid valve annuloplasty for functional tricuspid regurgitation associated with degenerative mitral regurgitation. We retrospectively reviewed patients who underwent flexible ring tricuspid valve annuloplasty (n = 120) or suture tricuspid valve annuloplasty (n = 42) for functional tricuspid regurgitation concomitant with surgery for degenerative mitral regurgitation (mean follow-up duration, 5.3 ± 5.1 years). The mean age of patients was 62.5 ± 13.1 years. Thirty-day mortality was zero in the suture group, and 0.8% in the ring group. Tricuspid regurgitation grade at discharge was lower in the ring group ( p = 0.002). No difference was observed between survival and freedom from major cardiac/cerebrovascular adverse events between the groups. However, freedom from ≥moderate tricuspid regurgitation was higher in the ring group (Log-rank p = 0.003). From univariate analysis, the risk factors for ≥moderate TR were suture annuloplasty and preoperative tricuspid regurgitation grade. No reoperation for recurrent tricuspid regurgitation occurred in either group because symptoms experienced by patients with recurrent tricuspid regurgitation were relatively insignificant. Concomitant tricuspid annuloplasty using flexible bands offered improved durability than suture annuloplasty for preventing postoperative tricuspid regurgitation progression.

Adolescent Scoliosis 1A001: Radiographic Results of Selecting the Touched Vertebra as the Lowest Instrumented Vertebra in Lenke Type 1 (Main Thoracic) & Type 2 (Double Thoracic) Curves at a Minimum 5-year Follow-up

PubMed Central

Lenke, Lawrence; Newton, Peter; Lehman, Ronald; Kelly, Michael; Clements, David; Errico, Thomas; Betz, Randall; Samdani, Amer; Blanke, Kathy

2017-01-01

Introduction: A prior study showed the touched vertebra (TV), defined as the most cephalad thoracolumbar/lumbar vertebra “touched” by the center sacral vertical line (CSVL), as a potential landmark vertebra & recommended lowest instrumented vertebra (LIV) as well. We evaluated a large cohort of Lenke type 1 & 2 cases to determine if selecting the TV as the LIV will produce optimal positioning at a min. 5 yrs postoperative. Our hypothesis was that it would and that fusing short of the TV would lead to a suboptimal result. Material and Methods: 299 pts with Lenke 1 (n = 207) or Lenke 2 (n = 92) AIS curves at a min. 5 yr f/u were evaluated. The TV was selected on the preoperative x-ray by 2 independent examiners & confirmed for agreement. The LIV selected was compared to the preoperative TV as well as the LIV-CSVL distance at min. 5 yr f/u. Comparison was made on the LIV-CSVL distance in pts fused short of the TV, to the TV or distal to the TV using standard statistical software. Results: When comparing the entire cohort, differences in 5 yr LIV-CSVL absolute values between the 3 groups approached, but did not reach, significance (P = .055). In a subanalysis of the lumbar A modifiers (n = 161), main effect ANOVA indicated a significant difference among the 3 groups (P = .002). Post hoc comparison revealed that pts fused short of the TV (TV-1) had significantly greater LIV-CSVL distance values than those fused to the TV (P = .006) & those fused distal to the TV (TV+1, P = .002). There was no significant difference among the 3 groups when looking at lumbar B (n = 76, p = 0.424) & lumbar C (n = 62, P = .326) modifiers. Conclusion: Selecting the touched vertebra (TV) as the LIV for Lenke type 1A & 2A curves produced optimal LIV positioning at a minimum 5 yrs postoperative, while fusing short of the TV showed statistically increased LIV- CSVL translation. Understanding & utilizing the TV rule assists the surgeon in proper LIV selection in Lenke type 1A & 2A curve patterns for AIS.

Morphology and Description of Bursaphelenchus platzeri n. sp. (Nematoda: Parasitaphelenchidae), an Associate of Nitidulid Beetles

PubMed Central

Giblin-Davis, Robin M.; Kanzaki, Natsumi; Ye, Weimin; Mundo-Ocampo, Manuel; Baldwin, James G.; Thomas, W. Kelley

2006-01-01

Bursaphelenchus platzeri n. sp., an associate of nitidulid beetles in southern California, is described and illustrated. Adult males and females of B. platzeri n. sp. were examined by scanning electron microscopy for ultrastructural comparisons with other members of the genus. Bursaphelenchus cocophilus (red ring nematode) appears to be the closest related taxon to B. platzeri n. sp. based upon shared morphological features of the fused spicules, female tail shape, phoresy with non-scolytid beetles, and molecular analysis of the near full-length small subunit (SSU) rDNA. Unfortunately, sequence data from the D2D3 expansion segments of the large subunit (LSU) rDNA and partial mitochondrial DNA COI did not help resolve the relationship of nearest relative. In addition to significant molecular sequence differences in SSU, LSU, and COI, B. platzeri n. sp., which is an obligate fungal feeder, can be differentiated from B. cocophilus because it is an obligate parasite of palms. Bursaphelenchus platzeri n. sp. can be differentiated from all other species of Bursaphelenchus by the length and shape of the female tail and spicule morphology. The spicules are fused along the ventral midline and possess unfused cucullae; the fused unit appears to function as a conduit for sperm. Population growth of B. platzeri n. sp. was measured in a time-course experiment at 25°C in the laboratory on cultures of the fungus Monilinia fructicola grown on 5% glycerol-supplemented potato dextrose agar (GPDA). Nematode population densities rapidly increased from 25 to approximately 200,000/culture within 14 d and then plateaued for up to 28 d. PMID:19259440

Creation and validation of a simulator for corneal rust ring removal.

PubMed

Mednick, Zale; Tabanfar, Reza; Alexander, Ashley; Simpson, Sarah; Baxter, Stephanie

2017-10-01

To create and validate a simulation model for corneal rust ring removal. Rust rings were created on cadaveric eyes with the use of small particles of metal. The eyes were mounted on suction plates at slit lamps and the trainees practiced rust ring removal. An inexperienced cohort of medical students and first year ophthalmology residents (n=11), and an experienced cohort of senior residents and faculty (n=11) removed the rust rings from the eyes with the use of a burr. Rust ring removal was evaluated based on removal time, percentage of rust removed and incidence of corneal perforation. A survey was administered to participants to determine face validity. Time for rust ring removal was longer in the inexperienced group at 187±93 seconds (range of 66-408 seconds), compared to the experienced group at 117±54 seconds (range of 55-240 seconds) (p=0.046). Removal speed was similar between groups, at 4847±4355 pixels/minute and 7206±5181 pixels/minute in the inexperienced and experienced groups, respectively (p=0.26). Removal percentage values were similar between groups, at 61±15% and 69±18% (p=0.38). There were no corneal perforations. 100% (22/22) of survey respondents believed the simulator would be a valuable practice tool, and 89% (17/19) felt the simulation was a valid representation of the clinical correlate. The corneal rust ring simulator presented here is a valid training tool that could be used by early trainees to gain greater comfort level before attempting rust ring removal on a live patient. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

[Effect of staining method and sintering temperature on the color of porcelain-fused-to-metal restorations].

PubMed

Wang, Yan; Yan, Wei-hao; Zhang, Xin-chun; Huang, Yue; Shen, Lin-han

2004-12-01

To investigate the effect of staining method and sintering temperature on the color of porcelain-fused-metal restorations. 40 cylindrical stained porcelain-metal specimens of 15 mm in diameter and 6 mm in height were fabricated with customized mould, consisting of 2 mm Ni-Cr metal, 1 mm opaque porcelain, 2 mm dentine porcelain and 1 mm enamel porcelain. The specimens were prepared by 5 techniques, 8 for each group. Group A: internal staining, Group B: external staining, 900 degrees centigrade sintering temperature was used in both A and B group; Group C to E: external staining, with the sintering temperature of 880 degrees centigrade, 900 degrees centigrade and 920 degrees centigrade respectively. Sofu A2 porcelain and Sofu 44 stain system were used for the study. Using standard white plate as a reference, colors (L*,a*,b* coordinates) of the specimens were measured with a computerized colorimeter. Student's t test and one way ANOVA were used to analyze the data. DeltaE, b* and Delta C(ab)* of Group B (external staining) and group A (internal staining) were 43.72 +/- 2.99/26.51 +/- 1.64/31.31 +/- 2.48 and 39.71 +/- 1.78/23.69 +/- 0.36/26.55 +/- 2.16, respectively. The values of the former group were significantly higher than that of the latter (P < 0.05); For Group C to E, there were no significant differences in all the color parameters. Staining method has a significant effect on the color parameters of porcelain-fused-to-metal restorations; For external staining, within the clinically-used range, changing the sintering temperature does not have an obvious effect on the color.

Atmospheric, Ionospheric, and Energetic Radiation Environments of Saturn's Rings

NASA Astrophysics Data System (ADS)

Cooper, J. F.; Kollmann, P.; Sittler, E. C., Jr.; Johnson, R. E.; Sturner, S. J.

2015-12-01

Planetary magnetospheric and high-energy cosmic ray interactions with Saturn's rings were first explored in-situ during the Pioneer 11 flyby in 1979. The following Voyager flybys produced a wealth of new information on ring structure and mass, and on spatial structure of the radiation belts beyond the main rings. Next came the Cassini Orbiter flyover of the rings during Saturn Orbital Insertion in 2004 with the first in-situ measurements of the ring atmosphere and plasma ionosphere. Cassini has since fully explored the radiation belt and magnetospheric plasma region beyond the main rings, discovering how Enceladus acts as a source of water group neutrals and water ions for the ion plasma. But do the main rings also substantially contribute by UV photolysis to water group plasma (H+, O+, OH+, H2O+, H3O+, O2+) and neutrals inwards from Enceladus? More massive rings, than earlier inferred from Pioneer 11 and Voyager observations, would further contribute by bulk ring ice radiolysis from interactions of galactic cosmic ray particles. Products of these interactions include neutron-decay proton and electron injection into the radiation belts beyond the main rings. How does radiolysis from moon and ring sweeping of the radiation belt particles compare with direct gas and plasma sources from the main rings and Enceladus? Can the magnetospheric ion and electron populations reasonably be accounted for by the sum of the ring-neutron-decay and outer magnetospheric inputs? Pioneer 11 made the deepest radial penetration into the C-ring, next followed by Cassini SOI. What might Cassini's higher-inclination proximal orbits reveal about the atmospheric, ionospheric, and energetic radiation environments in the D-ring and the proximal gap region? Recent modeling predicts a lower-intensity innermost radiation belt extending from the gap to the inner D-ring. Other remaining questions include the lifetimes of narrow and diffuse dust rings with respect to plasma and energetic particle irradiation processes, the mass flux of water group ions along planetary magnetic field lines into the Saturn planetary atmosphere, seasonal dust charging dynamics of the now-reappeared Saturn ring spokes, and the exchange of energy via energetic neutral atoms between the outer magnetosphere and the rings.

New phenethylamines in Europe.

PubMed

King, L A

2014-01-01

Sixteen phenethylamines are now included in Schedules I and II of the United Nations 1971 Convention on Psychotropic Substances. Most of the ring-substituted compounds are in Schedule I, whereas 2C-B, amphetamine, and methamphetamine are listed in Schedule II. Substances in Schedule IV (e.g. benzphetamine) are now regarded as obsolete pharmaceutical products. They all represent the 'old phenethylamines'. By 2013, nearly 100 illicit phenethylamines had been found in the European Union (EU). Of these, nine (MBDB, 4-MTA, PMMA, 2C-I, 2C-T-2, 2C-T-7, TMA-2, 5-IT and 4-MA) were submitted for risk assessment by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). All except MBDB were recommended for EU-wide control. Of the 'new phenethylamines', 2C-B was the most commonly reported, but other 2C compounds were widespread. Many of the ring-substituted phenethylamines are described in the 1991 book PIHKAL. Many fused ring phenethylamines have appeared in the past few years; they include further benzofurans (e.g. 5-and 6-APB), indanylalkylamines (e.g. 5-IAP), dibenzofurans (e.g. 2C-B-FLY) and 2-aminopropylindoles (e.g.5-IT). The recent and rapid rise of phenethylamines with bulky N-substituents (e.g. 25I-NBOMe) has been particularly significant. Although not phenethylamines, it is notable that the thiophene bioisosteres of amphetamine and methamphetamine as well as certain conformationally-restricted variants (e.g. aminoindanes) have been found in recent drug seizures. In the United Kingdom Misuse of Drugs Act, most ring-substituted phenethylamines are either listed by name or are covered by generic definitions dating from 1977. In 2013, temporary generic legislation included a number of benzofurans, indanylalkylamines and certain 'NBOMe' compounds. Copyright © 2013 John Wiley & Sons, Ltd.

Ontogenetic development of otoliths in Alligator Gar

USGS Publications Warehouse

Long, James M.; Snow, Richard A.

2016-01-01

The Alligator Gar Atractosteus spatula is a species of conservation concern throughout its range, and better definition of otoliths during early development would aid understanding its life history and ecology. We conducted X-ray computed tomography scans, scanning electron microscopy, and light microscopy to examine the three pairs of otoliths and how they developed over time in relation to fish size and age. The sagittae are the largest, possessing distinct dorsal and ventral lobes covered with small otoconia concentrated in the sulcul region. The sagittae exhibited allometric growth, increasing more rapidly in the ventral lobe than in the dorsal. The asterisci were smaller and also exhibited small otoconia on their surface, but much less than the sagittae. The lapilli were oriented laterally, in contrast to the sagittae and asterisci, which were oriented vertically, with a hump on the dorsum and very large otoconia on the lateral surface that appeared to fuse into the main otolith as the fish grew. Based on size measurements and ring counts in all three pairs of otoliths from 101 known-age Alligator Gar sampled weekly through 91 d after hatch, we developed regression models to examine otolith growth and predict age. All relationships were significant and highly explanatory, but the strongest relationships were between otolith and fish size (for measurements from sagittae) and for age predictions from the lapillus. Age prediction models all resulted in a slope near unity, indicating that ring deposition occurred approximately daily. The first ring in sagittae and lapilli corresponded to swim-up, whereas the first ring formed in asterisci approximately 8 d after swim-up. These results fill a gap in knowledge and can aid understanding of evolutionary processes as well as provide useful information for management and conservation.

Coupling of carboxylic groups onto the surface of polystyrene parts during fused filament fabrication

NASA Astrophysics Data System (ADS)

Nagel, Jürgen; Zimmermann, Philipp; Schubert, Oliver; Simon, Frank; Schlenstedt, Kornelia

2017-11-01

A method for the fabrication of polystyrene parts, modified with carboxylic groups during Fused Filament Fabrication (FFF), is being introduced. This method is based on the application of a thin layer of a reactive polymer carrying carboxylic groups on a substrate surface. A polystyrene film is printed on top of this layer. During contact between the hot melt and the reactive layer, a Friedel-Crafts type acylation using a green catalyst takes place, which attaches the reactive polymer to the polystyrene surface. The modified surface is homogeneous, hydrophilic and able to bind copper ions. The method could be used to fabricate unique parts of polystyrene with tailored surface functionalisation. It could be applied for laboratory use, e.g. for the manufacture of lab-on-a-chip devices.

Application of combinatorial biocatalysis for a unique ring expansion of dihydroxymethylzearalenone.

PubMed

Rich, Joseph O; Budde, Cheryl L; McConeghey, Luke D; Cotterill, Ian C; Mozhaev, Vadim V; Singh, Sheo B; Goetz, Michael A; Zhao, Annie; Michels, Peter C; Khmelnitsky, Yuri L

2009-06-01

Combinatorial biocatalysis was applied to generate a diverse set of dihydroxymethylzearalenone analogs with modified ring structure. In one representative chemoenzymatic reaction sequence, dihydroxymethylzearalenone was first subjected to a unique enzyme-catalyzed oxidative ring opening reaction that creates two new carboxylic groups on the molecule. These groups served as reaction sites for further derivatization involving biocatalytic ring closure reactions with structurally diverse bifunctional reagents, including different diols and diamines. As a result, a library of cyclic bislactones and bislactams was created, with modified ring structures covering chemical space and structure activity relationships unattainable by conventional synthetic means.

Novel fused oxazepino-indoles (FOIs) attenuate liver carcinogenesis via IL-6/JAK2/STAT3 signaling blockade as evidenced through data-based mathematical modeling.

PubMed

Singh, Ashok K; Bhadauria, Archana Singh; Kumar, Umesh; Raj, Vinit; Maurya, Vimal; Kumar, Dinesh; Maity, Biswanath; Prakash, Anand; De, Arnab; Samanta, Amalesh; Saha, Sudipta

2018-05-15

To potentiate the well-documented tumor protecting ability of paullones, literatures demand for rational modifications in paullone ring structure and exploration of a precise mechanism underlying their antitumor effects. Thus, recently we synthesized novel paullone-like scaffold, 5H-benzo [2, 3][1,4]oxazepino[5,6-b]indoles, where compounds 13a and 14a attenuated the growth of liver cancer specific Hep-G2 cells in vitro and formed stable binding complex with IL-6. Henceforth, we hypothesized that this action is probably due to the blockade of IL-6 mediated JAK2/STAT3 signaling cascade. A preclinical study was conducted using NDEA-induced HCC rat model by oral administration of FOIs at 10 mg/kg dose for 15 days. The molecular insights were confirmed through ELISA, qRT-PCR, western blot analyses. The study was further confirmed by data-based mathematical modeling using the quantitative data obtained from western blot analysis. 1 H NMR based metabolomics study was also performed to unveil metabolite discriminations among various studied groups. We identified that the HCC condition was produced due to the IL-6 induced activation of JAK2 and STAT3 which, in turn, was due to enhanced phosphorylation of JAK2 and STAT3. The treatment with FOIs led to the significant blockade of the IL-6 mediated JAK2/STAT3 signaling pathway. Besides, FOIs showed their potential ability in restoring perturbed metabolites linked to HCC. In particular, the anticancer efficacy of compound 13a was comparable or somewhat better than marketed chemotherapeutics, 5-flurouracil. These findings altogether opened up possibilities of developing fused oxazepino-indoles (FOIs) as new candidate molecule for plausible alternative of paullones to treat liver cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

Rod fracture in adult spinal deformity surgery fused to the sacrum: prevalence, risk factors, and impact on health-related quality of life in 526 patients.

PubMed

Lertudomphonwanit, Thamrong; Kelly, Michael P; Bridwell, Keith H; Lenke, Lawrence G; McAnany, Steven J; Punyarat, Prachya; Bryan, Timothy P; Buchowski, Jacob M; Zebala, Lukas P; Sides, Brenda A; Steger-May, Karen; Gupta, Munish C

2018-02-28

Risk factors associated with rod fracture (RF) following adult spinal deformity (ASD) surgery fused to the sacrum remain debatable, and the impact of RF on patient-reported outcomes (PROs) after ASD surgery has not been investigated. We aimed to evaluate the prevalence of and risk factors for RF and determine PROs changes associated with RF after ASD surgery fused to the sacrum. A retrospective single-center cohort study was performed. Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution by two senior spine surgeons from 2004 to 2014 were included. Patient demographics, radiographic parameters, and surgical factors were assessed for risk factors associated with RF. Oswestry Disability Index (ODI) and Scoliosis Research Society-30 (SRS-30) scores were assessed at baseline, 1 year postoperatively, and latest follow-up. Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and either development of RF or no development of RF with minimum 2-year follow-up. Patient characteristics, operative data, radiographic parameters, and PROs were analyzed at baseline and follow-up. Separate Cox proportional hazard models based on rod material and diameter were used to determine factors associated with RF. Five hundred twenty-six patients (80%) were available for analysis. RF occurred in 97 (18.4%) patients (unilateral RF n=61 [63%]; bilateral RF n=36 [37%]). Risk factors for fracture of 5.5 mm cobalt chromium (CC) instrumentation (CC 5.5 model) included preoperative sagittal vertical axis (hazard ratio [HR] 1.07, 95% confidence interval [95% CI] 1.02-1.14 per 1-cm increase), preoperative thoracolumbar kyphosis (HR 1.02, 95% CI 1.01-1.04 per 1-degree increase), and number of levels fused for patients who received rhBMP-2 <12 mg per level fused (HR 1.48, 95% CI 1.20-1.82 per 1-level increase). Implants that were 5.5-mm CC constructs were at a higher risk for fracture than 6.35-mm stainless steel (SS) constructs (HR 8.49, 95% CI 4.26-16.89). The RF group had less overall improvement in SRS Satisfaction (0.93 vs. 1.32; p=.007) and SRS Self-image domain scores (0.72 vs. 1.02; p=.01). The bilateral RF group had less overall improvement in ODI (8.1 vs. 15.8; p=.02), SRS Subscore (0.51 vs. 0.85; p=.03), and SRS Pain domain scores (0.48 vs. 0.95; p=.02) compared with the non-RF group at final follow-up. The prevalence of all RF after index procedures was 18.4%, 37% for bilateral RF. Greater preoperative sagittal vertical axis, greater preoperative thoracolumbar kyphosis, increased number of vertebrae fused for patients who received rhBMP-2 <12 mg per level fused, and CC 5.5-mm rod were associated with RF. Less improvement in patient satisfaction and self-image was noted in the RF group. Furthermore, bilateral RF significantly affected PROs as measured by ODI and SRS Subscore at final follow-up. Copyright © 2018 Elsevier Inc. All rights reserved.

Oxazolidinone antimicrobials: a patent review (2012-2015).

PubMed

Phillips, Oludotun A; Sharaf, Leyla H

2016-05-01

Antimicrobial resistance in Gram-positive bacteria is a major health care issue. This review summarizes patent publications from 2012 to 2015 that divulged novel oxazolidinones as antibacterial agents. A total of 25 patents obtained from Espacenet, WIPO Patentscope and FreePatentsOnline, and AcclaimIP search engines were reviewed. The patents were scrutinized based on the novelty of the compounds, their antibacterial activity (MIC, µg/mL), and the process of preparation. The oxazolidinones with promising antibacterial activity were classified according to the following structural diversities, as biaryl heterocyclic, fused heteroaryl rings containing oxazolidinones, and others. The biaryl heterocyclic, fused heteroaryl, benzoxazine, and the 1H-pyrazol-1-yl containing oxazolidinone derivatives demonstrated potent antibacterial activities superior to linezolid against Gram-positive bacteria. Some derivatives were effective against standard strains of Gram-negative bacteria, namely Moraxella catarrhalis ATCC A894, and Escherichia coli ATCC 25922. In addition, a patent disclosed a structural isomer of linezolid with marginal activity against the aerobic Gram-negative bacteria MDR Stenotrophomonas (Xanthomonas) maltophilia, while linezolid and vancomycin did not inhibit growth. Finally, some derivatives showed activity against respiratory infectious diseases' causative agents, such as B. anthracis, B. mallei, Y. pestis, and M. pneumoniae. Overall, there is limited in vivo data to support the potential clinical advancement of the currently reported novel derivatives.

Synthesis and anti-cancer activity of chiral tetrahydropyrazolo[1,5-a]pyridine-fused steroids.

PubMed

Lopes, Susana M M; Sousa, Emanuel P; Barreira, Luísa; Marques, Cátia; Rodrigues, Maria João; Pinho E Melo, Teresa M V D

2017-06-01

Regio- and stereoselective synthesis of novel chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused steroids via [8π+2π] cycloaddition of diazafulvenium methides with steroidal scaffolds is reported. The biological evaluation of the new family of hexacyclic steroids as anti-cancer agents was also carried out. Hexacyclic steroids bearing a benzyl group at C-22, derived from 16-dehydropregnenolone and 16-dehydroprogesterone, show considerable cytotoxicity against EL4 (murine T-lymphoma) in contrast with the corresponding C-22-unsubstituted derivatives showing low cytotoxicity. Thus, results indicate that the presence of the benzyl group is important to ensure cytotoxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

"Tie over ring" sutureless compression based gastrointestinal anastomotic method: experimental rat model.

PubMed

Hiradfar, Mehran; Shojaeian, Reza; Zabolinejad, Nona; Gharavifard, Mohammad; Sabzevari, Alireza; Joodi, Marjan; Yal, Nazila; Saeedi Sharifabad, Parisa; Hajian, Sara; Nazarzadeh, Reza; Lotfinejad, Nasim

2014-03-01

Giving the ever-rising trend of pediatric minimally invasive surgery besides early neonatal surgical interventions, intestinal anastomosis turns out to be a time consuming stage due to several anatomical as well as technical difficulties. A perfect bowel anastomosis method should be easy, rapid, safe and reliable in creation of bowel continuity with minimal tissue damage. In this light, sutureless anastomotic methods have been introduced, using compression based anastomosis with biofragmentable rings or powerful magnets. Accordingly, this experimental animal model study has evaluated the result of an easy, rapid intestinal sutureless anastomotic technique via simple tying over an intraluminal ring, in comparison with conventional handsewn bowel anastomosis. Thirty Wistar-Albino male rats were enrolled and small bowel was transected via a midline laparotomy. A grooved plastic ring was inserted into the ileal lumen and both intestinal cutting ends were fixed over the ring with a simple tie in the first group. On the other hand, enteroenterostomy was performed by the conventional method of handsewn anastomosis in the second group. After 14 days, rats were sacrificed to evaluate for intraperitoneal adhesion and abscess formation in addition to other evidences of anastomotic leakage. Furthermore, the anastomotic site integrity, tensile strength and healing stage were assessed microscopically. The mean operative time and intraoperative bleeding in the tie over ring group were significantly less than those in the handsewn anastomosis group. Anastomotic stricture was more common in the conventional anastomosis group while the anastomotic tensile strength was significantly higher in the tie over ring group. Histopathological healing parameters and final healing score were almost similar in both groups but mean inflammatory cell infiltration in handsewn anastomosis was significantly higher. "Tie over ring" is a simple method of anastomosis that is feasible, fast, safe and functionally effective for bowel reconstruction in animal models that could be reconsidered in human bowel anastomosis. © 2014.

A comparative study of the structures and electronic properties of graphene fragments: A DFT and MP2 survey

NASA Astrophysics Data System (ADS)

de Carvalho, E. F. V.; Lopez-Castillo, A.; Roberto-Neto, O.

2018-01-01

Graphene can be viewed as sheet of benzene rings fused together forming a variety of structures including the trioxotriangulenes (TOTs) which is a class of organic molecules with electro-active properties. In order to clarify such properties, structures and electronic properties of the graphene fragments phenalenyl, triangulene, 6-oxophenalenoxyl, and X3TOT (X = H, F, Cl) are computed. Validation of the methodologies are carried out using the density functionals B3LYP, M06-2X, B2PLYP-D, and the MP2 theory, giving equilibrium geometries of benzene, naphthalene, and anthracene with mean unsigned error (MUE) of only 0.003, 0.007, 0.004, and 0.007 Å, respectively in relation to experiment.

Anatomical variations of the thymus in relation to the left brachiocephalic vein, findings of necropsia.

PubMed

Plaza, Oscar Alonso; Moreno, Freddy

2018-04-01

Two cases of anatomical variations of the thymus are presented with respect to the anatomical relations with the left brachiocephalic vein and found during the necropsy process. Less than 2 days after birth with Noonan Syndrome, when the left brachiocephalic vein was scanning behind the upper thymus horns, there were other adjacent lesions consisting of three supernumerary spleens and three hepatic veins. The second case was an 8-year-old infant with child malpractice who died from urinary sepsis due to obstructive uropathy, in which case the upper lobes of the thymus were fused and formed a ring through which the left brachiocephalic vein passed. Copyright © 2018 Elsevier B.V. All rights reserved.

Transition-metal-free synthesis of imidazo[2,1-b]thiazoles and thiazolo[3,2-a]benzimidazoles via an S-propargylation/5-exo-dig cyclization/isomerization sequence using propargyl tosylates as substrates.

PubMed

Omar, Mohamed A; Frey, Wolfgang; Conrad, Jürgen; Beifuss, Uwe

2014-11-07

A transition-metal-free route for the synthesis of several N-fused heterocycles, including thiazolo[3,2-a]benzimidazoles and imidazo[2,1-b]thiazoles, is reported. The reaction between propargyl tosylates and 2-mercaptobenzimidazoles under basic conditions results in 3-substituted thiazolo[3,2-a]benzimidazoles, in yields up to 92% in a single synthesis step. With 2-mercaptoimidazoles as the substrate, the corresponding imidazo[2,1-b]thiazoles were exclusively obtained. The transformation is considered to proceed as an intermolecular S-propargylation that is followed by 5-exo-dig ring closure and double-bond isomerization.

Effect of Different Ceramic Crown Preparations on Tooth Structure Loss: An In Vitro Study

NASA Astrophysics Data System (ADS)

Ebrahimpour, Ashkan

Objective: To quantify and compare the amount of tooth-structure reduction following the full-coverage preparations for crown materials of porcelain-fused-to-metal, lithium disilicate glass-ceramic and yttria-stabilized tetragonal zirconia polycrystalline for three tooth morphologies. Methods: Groups of resin teeth of different morphologies were individually weighed to high precision, then prepared following the preparation guidelines. The teeth were re-weighed after preparation and the amount of structural reduction was calculated. Statistical analyses were performed to find out if there was a significant difference among the groups. Results: Amount of tooth reduction for zirconia crown preparations was the lowest and statistically different compared with the other two materials. No statistical significance was found between the amount of reduction for porcelain-fused-to-metal and lithium disilicate glass-ceramic crowns. Conclusion: Within the limitations of this study, more tooth structure can be saved when utilizing zirconia full-coverage restorations compared with lithium disilicate glass-ceramic and porcelain-fused-to-metal crowns in maxillary central incisors, first premolars and first molars.

N-(4,4′-Dibromo-[1,1′-biphen­yl]-2-yl)benzamide

PubMed Central

Novina, J. Josephine; Vasuki, G.; Baheti, Abhishek; Thomas, K. R. Justin

2013-01-01

In the title compound, C19H13Br2NO, the dihedral angle between the rings of the biphenyl group is 53.59 (14)°. The ring of the benzamide group is inclined to the phenyl rings of the biphenyl group by 23.87 (15) and 75.89 (15)°. There are no significant inter­molecular inter­actions in the crystal structure. PMID:23424503

Immersive virtual reality-based training improves response in a simulated operating room fire scenario.

PubMed

Sankaranarayanan, Ganesh; Wooley, Lizzy; Hogg, Deborah; Dorozhkin, Denis; Olasky, Jaisa; Chauhan, Sanket; Fleshman, James W; De, Suvranu; Scott, Daniel; Jones, Daniel B

2018-01-25

SAGES FUSE curriculum provides didactic knowledge on OR fire prevention. The objective of this study is to evaluate the impact of an immersive virtual reality (VR)-based OR fire training simulation system in combination with FUSE didactics. The study compared a control with a simulation group. After a pre-test questionnaire that assessed the baseline knowledge, both groups were given didactic material that consists of a 10-min presentation and reading materials about precautions and stopping an OR fire from the FUSE manual. The simulation group practiced on the OR fire simulation for one session that consisted of five trials within a week from the pre-test. One week later, both groups were reassessed using a questionnaire. A week after the post-test both groups also participated in a simulated OR fire scenario while their performance was videotaped for assessment. A total of 20 subjects (ten per group) participated in this IRB approved study. Median test scores for the control group increased from 5.5 to 9.00 (p = 0.011) and for the simulation group it increased from 5.0 to 8.5 (p = 0.005). Both groups started at the same baseline (pre-test, p = 0.529) and reached similar level in cognitive knowledge (post-test, p = 0.853). However, when tested in the mock OR fire scenario, 70% of the simulation group subjects were able to perform the correct sequence of steps in extinguishing the simulated fire whereas only 20% subjects in the control group were able to do so (p = 0.003). The simulation group was better than control group in correctly identifying the oxidizer (p = 0.03) and ignition source (p = 0.014). Interactive VR-based hands-on training was found to be a relatively inexpensive and effective mode for teaching OR fire prevention and management scenarios.

Revisiting shape selectivity in liquid chromatography for polycyclic aromatic hydrocarbons (PAHs) - six-ring and seven-ring Cata-condensed PAH isomers of molecular mass 328 Da and 378 Da.

PubMed

Oña-Ruales, Jorge O; Sander, Lane C; Wilson, Walter B; Wise, Stephen A

2018-01-01

The relationship of reversed-phase liquid chromatography (RPLC) retention on a polymeric C 18 stationary phase and the shape of polycyclic aromatic hydrocarbons (PAHs) was investigated for three-ring to seven-ring cata-condensed isomers. We report the first RPLC separation for six-ring and seven-ring cata-condensed PAH isomers. Correlations of LC retention and shape parameters (length-to-breath ratio, L/B and thickness, T) were investigated for 2 three-ring isomers (molecular mass 178 Da), 5 four-ring isomers (molecular mass 228 Da), 11 five-ring isomers (molecular mass 278 Da), 17 six-ring isomers (molecular mass 328 Da), and 20 seven-ring isomers (molecular mass 378 Da). Significant linear correlations were found for all isomer groups (r = 0.71 to 0.94). Nonplanarity of the PAH isomers was found to influence retention (i.e., nonplanar isomers eluting earlier than expected based on L/B) and linear correlations of retention vs. T for isomer groups containing nonplanar isomers were significant (r = 0.71 to 0.86). Graphical abstract.

Finite element analysis to compare complete denture and implant-retained overdentures with different attachment systems.

PubMed

Barão, Valentim Adelino Ricardo; Assunção, Wirley Gonçalves; Tabata, Lucas Fernando; Delben, Juliana Aparecida; Gomes, Erica Alves; de Sousa, Edson Antonio Capello; Rocha, Eduardo Passos

2009-07-01

This finite element analysis compared stress distribution on complete dentures and implant-retained overdentures with different attachment systems. Four models of edentulous mandible were constructed: group A (control), complete denture; group B, overdenture retained by 2 splinted implants with bar-clip system; group C, overdenture retained by 2 unsplinted implants with o'ring system; and group D, overdenture retained by 2 splinted implants with bar-clip and 2 distally placed o'ring system. Evaluation was performed on Ansys software, with 100-N vertical load applied on central incisive teeth. The lowest maximum general stress value (in megapascal) was observed in group A (64.305) followed by groups C (119.006), D (258.650), and B (349.873). The same trend occurred in supporting tissues with the highest stress value for cortical bone. Unsplinted implants associated with the o'ring attachment system showed the lowest maximum stress values among all overdenture groups. Furthermore, o'ring system also improved stress distribution when associated with bar-clip system.

Effects of repeated gas sterilization on closure rates of ameroid ring constrictors in vitro.

PubMed

Kimberlin, William W; Wardlaw, Jennifer L; Madsen, Richard W

2016-01-01

To determine the effect of repeated gas sterilization on rate of closure of ameroid ring constrictors in vitro. Twenty-four 3.5-mm ameroid ring constrictors. Ameroid ring constrictors were allocated to 1 of 4 treatment groups (6/group) to undergo gas sterilization 0, 1, 5, or 10 times. After sterilization, constrictors were incubated in canine plasma at a protein concentration of 3 g/dL for 27 days. A digital camera was used to obtain images of the constrictors prior to and at various points during incubation, and lumen diameter was measured. Mean ± SD percentage of lumen closure for all groups of ameroid ring constrictors combined was 85.2 ± 1.6% at day 0 (prior to plasma incubation) and 95.4 ± 0.8% at day 27. Mean lumen area was 3.64 ± 0.43 mm(2) (95% confidence interval, 2.67 to 4.77 mm(2)) at day 0 and 1.32 ± 0.25 mm(2) (95% confidence interval, 0.76 to 2.04 mm(2)) at day 27. None of the ameroid ring constrictors had closed completely by day 27. Overall closure rates for ameroid ring constrictors appeared to be unaffected by repeated gas sterilization up to 10 times. Findings suggested that veterinary surgeons can resterilize ameroid ring constrictors up to 10 times with confidence that ring properties would remain suitable for clinical use.

A fruitful decade from 2005 to 2014 for anthraquinone patents.

PubMed

Hussain, Hidayat; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Green, Ivan R; Csuk, René; Ahmed, Ishtiaq; Shah, Afzah; Abbas, Ghulam; Rehman, Najeeb Ur; Ullah, Riaz

2015-01-01

Anthraquinones are aromatic compounds whose structures are related to anthracene (parent structure: 9,10-dioxoanthracene) for which various methods for their synthesis have been developed. In the past decade (2005 - 2014), much work has been done regarding anthraquinone chemistry in order to discover new compounds related to this scaffold as anticancer, antibacterial, antidiabetic, antiviral, anti-HCV, antifibrotic, fungicidal and anti-inflammatory agents. This review covers the patents on therapeutic activities of anthraquinones and their derivatives in the years between 2005 and 2014. A large portion of the therapeutic applications that were reported in international patents will be presented and discussed. Although a large number of patents have been registered over the last decade, this review is focused on important patents related to cancer, inflammation, infectious diseases, diabetic conditions and hepatitis C. The tricyclic planar ring system of anthraquinones displays a wide range of important pharmaceutical properties. By linking active anthraquinone analogs to other important pharmacophores or conjugates such as oximes, N-heterocycles, benzodiazepines or glycosyl ethers, their anticancer potential is enhanced. The ability of anthraquinone analogs to become more prominent as novel pharmaceutical agents may further be enhanced by fusing functionalized heterocyclic rings onto established anthraquinone cores.

Chemistry of withaferin-A: chemo, regio, and stereoselective synthesis of novel spiro-pyrrolizidino-oxindole adducts of withaferin-A via one-pot three-component [3+2] azomethine ylide cycloaddition and their cytotoxicity evaluation.

PubMed

Bharitkar, Yogesh P; Kanhar, Satish; Suneel, Neradibilli; Mondal, Susanta Kumar; Hazra, Abhijit; Mondal, Nirup B

2015-05-01

Withaferin-A (WA) has attracted the attention of chemists as well as biologists due to its interesting structure and various bio-activities. In light of the promising biological importance of WA as well as pyrrolidine-2-spiro-3'-oxindole ring system, we became interested in the synthesis of a combined motif involving both the ring systems via the 1,3-dipolar cycloaddition of WA at Δ(2)-bond of the α,β-unsaturated carbonyl system. We now report a facile, atom-economic synthesis of novel spiro-pyrrolizidino-oxindole adducts of withaferin-A (10 compounds) via the intermolecular cycloaddition of azomethine ylides generated in situ from proline and isatins/acenaphthoquinone. The reaction is highly chemo, regio, and stereoselective affording the cis-fused products with β-orienting hydrogen. The structures were determined by 1D/2D NMR spectroscopic data analysis and unequivocally confirmed by X-ray crystallographic analysis in some cases. Bioevaluation of the compounds against six cancer lines (e.g., CHO, HepG2, HeLa, HEK 293, MDCK-II, and Caco-2) identified 4 promising potential anticancer compounds.

Structure of a BMI-1-Ring1B Polycomb Group Ubiquitin Ligase Complex

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

Li,Z.; Cao, R.; Wang, M.

2006-01-01

Polycomb group (PcG) proteins Bmi-1 and Ring1B are core subunits of the PRC1 complex which plays important roles in the regulation of Hox gene expression, X-chromosome inactivation, tumorigenesis and stem cell self-renewal. The RING finger protein Ring1B is an E3 ligase that participates in the ubiquitination of lysine 119 of histone H2A, and the binding of Bmi-1 stimulates the E3 ligase activity. We have mapped the regions of Bmi-1 and Ring1B required for efficient ubiquitin transfer and determined a 2.5 Angstroms structure of the Bmi-1-Ring1B core domain complex. The structure reveals that Ring1B 'hugs' Bmi-1 through extensive RING domain contactsmore » and its N-terminal tail wraps around Bmi-1. The two regions of interaction have a synergistic effect on the E3 ligase activity. Our analyses suggest a model where the Bmi-1-Ring1B complex stabilizes the interaction between the E2 enzyme and the nucleosomal substrate to allow efficient ubiquitin transfer.« less

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

PubMed

Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

2013-03-01

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of <15% (averaged for several metal ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

Effects on cycle control and bodyweight of the combined contraceptive ring, NuvaRing, versus an oral contraceptive containing 30 microg ethinyl estradiol and 3 mg drospirenone.

PubMed

Milsom, I; Lete, I; Bjertnaes, A; Rokstad, K; Lindh, I; Gruber, C J; Birkhäuser, M H; Aubeny, E; Knudsen, T; Bastianelli, C

2006-09-01

The objective of this study was to compare cycle control, cycle-related characteristics and bodyweight effects of NuvaRing with those of a combined oral contraceptive (COC) containing 30 microg of ethinyl estradiol and 3 mg of drospirenone. A randomized, multicentre, open-label trial in which 983 women were treated (intent-to-treat population) with NuvaRing or the COC for 13 cycles. Breakthrough bleeding or spotting during cycles 2-13 was in general less frequent with NuvaRing than that with the COC (4.7-10.4%) and showed a statistically significant odds ratio of 0.61 (95% confidence interval: 0.46, 0.80) with longitudinal analysis. Intended bleeding was significantly better for all cycles with NuvaRing (55.2-68.5%) than that with the COC (35.6-56.6%) (P < 0.01). Changes from baseline in mean bodyweight and body composition parameters were relatively small for both groups with no notable between-group differences. NuvaRing was associated with better cycle control than the COC, and there was no clinically relevant difference between the two groups in bodyweight.

Skin patch and vaginal ring versus combined oral contraceptives for contraception.

PubMed

Lopez, Laureen M; Grimes, David A; Gallo, Maria F; Stockton, Laurie L; Schulz, Kenneth F

2013-04-30

The delivery of combination contraceptive steroids from a transdermal contraceptive patch or a contraceptive vaginal ring offers potential advantages over the traditional oral route. The transdermal patch and vaginal ring could require a lower dose due to increased bioavailability and improved user compliance. To compare the contraceptive effectiveness, cycle control, compliance (adherence), and safety of the contraceptive patch or the vaginal ring versus combination oral contraceptives (COCs). Through February 2013, we searched MEDLINE, POPLINE, CENTRAL, LILACS, ClinicalTrials.gov, and ICTRP for trials of the contraceptive patch or the vaginal ring. Earlier searches also included EMBASE. For the initial review, we contacted known researchers and manufacturers to identify other trials. We considered randomized controlled trials comparing a transdermal contraceptive patch or a contraceptive vaginal ring with a COC. Data were abstracted by two authors and entered into RevMan. For dichotomous variables, the Peto odds ratio (OR) with 95% confidence intervals (CI) was calculated. For continuous variables, the mean difference was computed. We also assessed the quality of evidence for this review. We found 18 trials that met our inclusion criteria. Of six patch studies, five examined the marketed patch containing norelgestromin plus ethinyl estradiol (EE); one studied a patch in development that contains levonorgestrel (LNG) plus EE. Of 12 vaginal ring trials, 11 examined the same marketing ring containing etonogestrel plus EE; one studied a ring being developed that contains nesterone plus EE.Contraceptive effectiveness was not significantly different for the patch or ring versus the comparison COC. Compliance data were limited. Patch users showed better compliance than COC users in three trials. For the norelgestromin plus EE patch, ORs were 2.05 (95% CI 1.83 to 2.29) and 2.76 (95% CI 2.35 to 3.24). In the levonorgestrel plus EE patch report, patch users were less likely to have missed days of therapy (OR 0.36; 95% CI 0.25 to 0.51). Of four vaginal ring trials, one found ring users had more noncompliance (OR 3.99; 95% CI 1.87 to 8.52), while another showed more compliance with the regimen (OR 1.67; 95% CI 1.04 to 2.68).More patch users discontinued early than COC users. ORs from two meta-analyses were 1.59 (95% CI 1.26 to 2.00) and 1.56 (95% CI 1.18 to 2.06) and another trial showed OR 2.57 (95% CI 0.99 to 6.64). Patch users also had more discontinuation due to adverse events than COC users. Users of the norelgestromin-containing patch reported more breast discomfort, dysmenorrhea, nausea, and vomiting. In the levonorgestrel-containing patch trial, patch users reported less vomiting, headaches, and fatigue.Of 11 ring trials with discontinuation data, two showed the ring group discontinued less than the COC group: OR 0.32 (95% CI 0.16 to 0.66) and OR 0.52 (95% CI 0.31 to 0.88). Ring users were less likely to discontinue due to adverse events in one study (OR 0.32; 95% CI 0.15 to 0.70). Compared to the COC users, ring users had more vaginitis and leukorrhea but less vaginal dryness. Ring users also reported less nausea, acne, irritability, depression, and emotional lability than COC users.For cycle control, only one trial study showed a significant difference. Women in the patch group were less likely to have breakthrough bleeding and spotting. Seven ring studies had bleeding data; four trials showed the ring group generally had better cycle control than the COC group. Effectiveness was not significantly different for the methods compared. Pregnancy data were available from half of the patch trials but two-thirds of ring trials. The patch could lead to more discontinuation than the COC. The patch group had better compliance than the COC group. Compliance data came from half of the patch studies and one-third of the ring trials. Patch users had more side effects than the COC group. Ring users generally had fewer adverse events than COC users but more vaginal irritation and discharge.The quality of the evidence for this review was considered low for the patch and moderate for the ring. The main reasons for downgrading were lack of information on the randomization sequence generation or allocation concealment, the outcome assessment methods, high losses to follow up, and exclusions after randomization.

Nobiletin: a citrus flavonoid displaying potent physiological activity.

PubMed

Noguchi, Shuji; Atsumi, Haruka; Iwao, Yasunori; Kan, Toshiyuki; Itai, Shigeru

2016-02-01

Nobiletin [systematic name: 2-(3,4-dimethoxyphenyl)-5,6,7,8-tetramethoxy-4H-chromen-4-one; C21H22O8] is a flavonoid found in citrus peels, and has been reported to show a wide range of physiological properties, including anti-inflammatory, anticancer and antidementia activities. We have solved the crystal structure of nobiletin, which revealed that the chromene and arene rings of its flavone moiety, as well as the two methoxy groups bound to its arene ring, were coplanar. In contrast, the C atoms of the four methoxy groups bound to the chromene ring are out of the plane, making the molecule conformationally chiral. A comparison of the crystal structures of nobiletin revealed that it could adopt a variety of different conformations through rotation of the covalent bond between the chromene and arene rings, and the orientations of methoxy groups bound to the chromene ring.

Single-ring ablation compared with standard circumferential pulmonary vein isolation using remote magnetic catheter navigation.

PubMed

Sohns, Christian; Bergau, Leonard; Seegers, Joachim; Lüthje, Lars; Vollmann, Dirk; Zabel, Markus

2014-10-01

In ablation of atrial fibrillation, the single-ring method aims for isolation of the posterior wall of the left atrium (LA) including the pulmonary veins (PVs) but avoiding posterior LA lesions. The aim of this randomized prospective study was to evaluate safety and efficacy of remote magnetic navigation (RMN)-guided single-ring ablation strategy as compared to standard RMN-guided circumferential PV ablation (PVA). Eighty consecutive patients undergoing PVA were enrolled prospectively and randomized equally into two study groups. RMN using the Stereotaxis system and open-irrigated 3.5-mm ablation catheters were used with a 3D mapping system in all procedures. Forty patients underwent RMN-guided single-ring ablation, and 40 patients received RMN-guided circumferential PVA. In the circumferential group, 3.3 ± 1.1 PVs were successfully isolated at the end of the procedure as compared to 3.1 ± 1.3 in the single-ring (box) group (p=0.38). All patients in the box group required additional posterior lesions in order to achieve electrical isolation of the PVs. Single-ring ablation was associated with longer procedure duration (p=0.01) and ablation time (p=0.001). After a single procedure, the proportion of patients free of any atrial tachycardia (AT)/atrial fibrillation (AF) episode at 12-month follow-up was 57 % in the box group and 58 % in the circ group. Using RMN, only minor complications have been observed. RMN-guided single-ring PVA provides comparable acute and long-term success rates as compared to RMN-guided circumferential PVA but requires additional posterior lesions to achieve PV isolation and increased procedure and ablation time. Procedural complication rates are low when using RMN.

Simulation study on the effects of chemical structure and molecular size on the acceptor strength in poly(3-hexylthiophene)-based copolymer with alternating donor and acceptor for photovoltaic applications

NASA Astrophysics Data System (ADS)

Rassamesard, Areefen; Pengpan, Teparksorn

2017-02-01

This research assessed the effects of various chemical structures and molecular sizes on the simulated geometric parameters, electron structures, and spectroscopic properties of single-chain complex alternating donor-acceptor (D-A) monomers and copolymers that are intended for use as photoactive layer in a polymer solar cell by using Kohn-Sham density functional theory with B3LYP exchange-correlation functional. The 3-hexylthiophene (3HT) was selected for electron donor, while eight chemicals, namely thiazole (Z), thiadiazole (D), thienopyrazine (TP), thienothiadiazole (TD), benzothiadiazole (BT), thiadiazolothieno-pyrazine (TPD), oxadiazole (OXD) and 5-diphenyl-1,2,4-triazole (TAZ), were employed as electron acceptor functional groups. The torsional angle, bridge bond length, intramolecular charge transfer, energy levels, and molecular orbitals were analyzed. The simulation results reveal that the geometry and electron structure of donor-acceptor monomer and copolymer are significantly impacted by heterocyclic rings, heteroatoms, fused rings, degree of steric hindrance and coplanarity of the acceptor molecular structure. Planar conformation was obtained from the D copolymer, and a pseudo-planar structure with the TD copolymer. The TAZ acceptor exhibited strong steric hindrance due to its bulky structure and non-planarity of its structure. An analysis of the electron structures indicated that the degree of intramolecular electron-withdrawing capability had the rank order TAZ  <  Z  <  D  <  TPD  <  OXD  <  TP  <  BT  <  TD. The TD is indicated as the most effective acceptor among those that were simulated. However, the small energy gaps of TD as well as TPD copolymer indicate that these two copolymers can be used in transparent conducting materials. The copolymer based on BT acceptor exhibited good intramolecular charge transfer and absorbed at 656 nm wavelength which is close to the maximum flux of solar spectrum. Hence, the BT acceptor functional group provides a compromise in the characteristics of a donor-acceptor copolymer, useful in a polymeric candidate material for the photoactive layer in a polymer solar cell.

Stem cells with FGF4-bFGF fused gene enhances the expression of bFGF and improves myocardial repair in rats

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

Chen, Xiang-Qi; Chen, Liang-Long, E-mail: xhzlyx@126.com; Fan, Lin

Highlights: • BFGF exists only in the cytoplasm of live cells. • BFGF cannot be secreted into the extracellular space to promote cell growth. • We combine the secretion-promoting signal peptide of FGF4. • We successfully modified BMSCs with the fused genes of FGF4-bFGF. • We promoted the therapeutic effects of transplanted BMSCs in myocardial infarction. - Abstract: The aim of this study was to investigate whether the modification of bone marrow-derived mesenchymal stem cells (BMSCs) with the fused FGF4 (fibroblast growth factor 4)-bFGF (basic fibroblast growth factor) gene could improve the expression and secretion of BFGF, and increase themore » efficacies in repairing infarcted myocardium. We used In-Fusion technique to construct recombinant lentiviral vectors containing the individual gene of bFGF, enhanced green fluorescent protein (EGFP), or genes of FGF4-bFGF and EGFP, and then transfected these lentiviruses into rat BMSCs. We conducted an in vitro experiment to compare the secretion of bFGF in BMSCs infected by these lentiviruses and also examined their therapeutic effects in the treatment of myocardial infraction in a rodent study. Sixty rats were tested in the following five conditions: Group-SHAM received only sham operation as controls; Group-AMI received only injection of placebo PBS buffer; Group-BMSC, Group-bFGF and Group-FGF4-bFGF received implantation of BMSCs with empty lentivirus, bFGF lentivirus, and FGF4-bFGF lentivirus, respectively. Our results found out that the transplanted FGF4-bFGF BMSCs had the highest survival rate, and also the highest myocardial expression of bFGF and microvascular density as evidenced by Western blotting and immunohistochemistry, respectively. As compared to other groups, the Group-FGF4-BFGF rats had the lowest myocardial fibrotic fraction, and the highest left ventricular ejection fraction. These results suggest that the modification of BMSCs with the FGF4-bFGF fused gene can not only increase the expression of bFGF but also improve its secretion. The FGF4-bFGF BMSCs thus can enhance the survival of the transplanted cells, diminish myocardial fibrosis, promote myocardial angiogenesis, and improve cardiac functions.« less

Quantitative study of interactions between oxygen lone pair and aromatic rings: substituent effect and the importance of closeness of contact.

PubMed

Gung, Benjamin W; Zou, Yan; Xu, Zhigang; Amicangelo, Jay C; Irwin, Daniel G; Ma, Shengqian; Zhou, Hong-Cai

2008-01-18

Current models describe aromatic rings as polar groups based on the fact that benzene and hexafluorobenzene are known to have large and permanent quadrupole moments. This report describes a quantitative study of the interactions between oxygen lone pair and aromatic rings. We found that even electron-rich aromatic rings and oxygen lone pairs exhibit attractive interactions. Free energies of interactions are determined using the triptycene scaffold and the equilibrium constants were determined by low-temperature 1H NMR spectroscopy. An X-ray structure analysis for one of the model compounds confirms the close proximity between the oxygen and the center of the aromatic ring. Theoretical calculations at the MP2/aug-cc-pVTZ level corroborate the experimental results. The origin of attractive interactions was explored by using aromatic rings with a wide range of substituents. The interactions between an oxygen lone pair and an aromatic ring are attractive at van der Waals' distance even with electron-donating substituents. Electron-withdrawing groups increase the strength of the attractive interactions. The results from this study can be only partly rationalized by using the current models of aromatic system. Electrostatic-based models are consistent with the fact that stronger electron-withdrawing groups lead to stronger attractions, but fail to predict or rationalize the fact that weak attractions even exist between electron-rich arenes and oxygen lone pairs. The conclusion from this study is that aromatic rings cannot be treated as a simple quadrupolar functional group at van der Waals' distance. Dispersion forces and local dipole should also be considered.

Two polymorphs of 2,5-dichloro-3,6-bis(dibenzylamino)-p-hydroquinone with flexible dibenzylamino groups.

PubMed

Shin, In Sub; Shimada, Yuta; Horiguchi-Babamoto, Emi; Matsumoto, Shinya

2018-04-01

We obtained two conformational polymorphs of 2,5-dichloro-3,6-bis(dibenzylamino)-p-hydroquinone, C 34 H 30 Cl 2 N 2 O 2 . Both polymorphs have an inversion centre at the centre of the hydroquinone ring (Z' = 1/2), and there are no significant differences between their bond lengths and angles. The most significant structural difference in the molecular conformations was found in the rotation of the phenyl rings of the two crystallographically independent benzyl groups. The crystal structures of the polymorphs were distinguishable with respect to the arrangement of the hydroquinone rings and the packing motif of the phenyl rings that form part of the benzyl groups. The phenyl groups of one polymorph are arranged in a face-to-edge motif between adjacent molecules, with intermolecular C-H...π interactions, whereas the phenyl rings in the other polymorph form a lamellar stacking pattern with no significant intermolecular interactions. We suggest that this partial conformational difference in the molecular structures leads to the significant structural differences observed in their molecular arrangements.

Novel benzothiophene 1,1-dioxide deoxygenation path for the microwave-assisted synthesis of substituted benzothiophene-fused pyrrole derivatives.

PubMed

Karakuş, Hamza; Dürüst, Yaşar

2017-02-01

The reaction of C-(4-substituted-phenyl)-N-(benzoyl)-N-methylglycines with benzo[b]thiophene 1,1-dioxide unexpectedly gave benzothiophene-fused pyrrole derivatives in toluene under microwave irradiation via a cycloaddition and metal-free Pummerer-type sulfone deoxygenation path. In order to obtain the desired sulfone derivatives, the sulfide group underwent oxidation with m-CPBA to afford sulfones. The structures of all the new products were elucidated by spectroscopic/physical methods and, in two cases, by X-ray diffraction.

One- and Two-Photon Uncaging: Carbazole Fused o-Hydroxycinnamate Platform for Dual Release of Alcohols (Same or Different) with Real-Time Monitoring.

PubMed

Venkatesh, Yarra; Srivastava, Hemant Kumar; Bhattacharya, S; Mehra, Muneshwar; Datta, P K; Bandyopadhyay, S; Singh, N D Pradeep

2018-04-20

A one- and two-photon activated photoremovable protecting group (PRPG) was designed based on a carbazole fused o-hydroxycinnamate platform for the dual (same or different) release of alcohols. The mechanism for the dual release proceeds through a stepwise pathway and also monitors the first and second photorelease in real time by an increase in fluorescence intensity and color change, respectively. Further, its application in staining live neurons and ex vivo imaging with two-photon excitation is shown.

Influence of ring size on the cognition-enhancing activity of DM235 and MN19, two potent nootropic drugs.

PubMed

Guandalini, L; Martini, E; Di Cesare Mannelli, L; Dei, S; Manetti, D; Scapecchi, S; Teodori, E; Ghelardini, C; Romanelli, M N

2012-03-01

A series of analogs of DM235 and MN19, characterized by rings with different size, have been prepared and evaluated for their nootropic activity in the mouse passive-avoidance test. It was found that the optimal ring size for the analogs of DM235, showing endocyclic both amidic groups, is 6 or 7 atoms. For the compounds structurally related to MN19, carrying an exocyclic amide group, the piperidine ring is the moiety which gives the most interesting compounds. Copyright © 2012 Elsevier Ltd. All rights reserved.

A randomised trial of a contraceptive vaginal ring in women at risk of HIV infection in Rwanda: Safety of intermittent and continuous use

PubMed Central

Van Nuil, Jennifer Ilo; Uwineza, Mireille; Umulisa, Marie Michelle; Mwambarangwe, Lambert; Ndagijimana, Jean Claude; De Baetselier, Irith; Buyze, Jozefien; Delvaux, Thérèse; Crucitti, Tania; Jespers, Vicky

2018-01-01

Background Contraceptive vaginal rings could play a role in expanding the contraceptive method mix and in preparing communities for the introduction of HIV prevention and multipurpose rings. Methods We conducted an open label single-centre randomised clinical trial of intermittent versus continuous use of NuvaRing® in Kigali, Rwanda, in 2013–2014. We randomised 120 HIV-negative women 1:1 to intermittent use (three rings with a ring-free week in between rings) or continuous use (four rings without ring-free weeks). Women underwent an interview, counselling, and a speculum examination, and were tested for pregnancy, bacterial vaginosis (BV) by Nugent scoring, yeasts and trichomonads on wet mount, and sexually transmitted infections. Findings Only one woman withdrew early. Deliberate ring removals were rare, but spontaneous ring expulsions occurred during 14% of ring use periods. There were no incident pregnancies, serious adverse events, serious social harms, or early discontinuations for safety reasons. Systemic side effects were uncommon, and local side effects were not significantly differently distributed between groups except for lower abdominal pain (P = 0.013). The incidence of vaginal yeasts during ring use was high: 22% of intermittent users and 27% of continuous users had incident vaginal yeasts at one or multiple ring removal visits (P = 0.666), and symptomatic vaginal yeast cases were more common in the continuous than intermittent users (P = 0.031). In contrast, mean Nugent scores improved over time in both groups. Conclusions Intermittent and continuous NuvaRing® use were safe in Rwandan women and improved Nugent scores over time. However, attention should be paid to ring expulsions and to a potential increased risk of vaginal candidiasis. PMID:29856848

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

Custelcean, Radu; Bartsch, Richard A.

Two series of novel mono-ionizable calix[4]arene-benzocrown-6 ligands in 1,3-alternate conformations are synthesized. In one series, the proton-ionizable group (PIG) is attached to the para position of one aromatic ring in the calixarene framework, thereby positioning it over the polyether ring cavity. In the other series, the PIG is a substituent on the benzo group in the polyether ring. This orients the PIG away from the crown ether cavity. In addition to carboxylic acid functions, the PIGs include N-(X)sulfonyl carboxamide groups. With X group variation from methyl to phenyl to 4-nitrophenyl to trifluoromethyl, the acidity of the PIG is 'tuned'. Solventmore » extraction of Ag{sup +} from aqueous solutions into chloroform is used to probe the influence of structural variation within the mono-ionizable calixcrown ligand on metal ion extraction efficiency, including the identity and acidity of the PIG and its orientation with respect to the polyether ring.« less

Evaluation of quality of life in adolescent idiopathic scoliosis with different distal fusion level: a comparison of L3 versus L4.

PubMed

Ding, Ran; Liang, Jinqian; Qiu, Guixing; Shen, Jianxiong; Li, Zheng

2014-07-01

Retrospective case-control study. The aim of this study was to assess patients' quality of life with different fusion levels in posterior pedicle screw correction of idiopathic scoliosis. No previous study has demonstrated differences in health-related quality of life (HRQoL) between patients fused to L3 versus L4. A retrospective study was conducted on 30 scoliotic patients fused to L3 using complete pedicle screw instruments. Thirty age-matched and sex-matched scoliotic patients fused to L4 were in the control group. Radiologic parameters were assessed before surgery and at latest follow-up between the 2 groups. These 2 groups were compared for the Scoliosis Research Society 22 questionnaire (SRS-22), Oswestry Disability Index (ODI), visual analogue scale (VAS), and Short Form-36 (SF-36) questionnaires, which were administered preoperatively and at final follow-up. There were no significant differences in sex, age, follow-up duration, the distribution of curve patterns, the postoperative residual Cobb angle of the main curve, complications, or surgical method between the L3 and L4 groups (P>0.05). Preoperative scores were statistically similar in the L3 and L4 groups for all domains of all questionnaires. There was no difference between the L3 and L4 groups for ODI (P=0.527) and VAS (P=0.518). There were no significant differences in the scores on function/activity, self-image/appearance, pain, mental health, or satisfaction with treatment domains between the 2 groups. No significant differences between the 2 groups were found at the final follow-up in the SF-36 subscales/domain scores. This study attempted to elucidate the correlation between the length of fusion and functional outcome; however, it could not identify any difference between different fusion levels. On the basis of short-term results, there were no significant differences in the questionnaire scores between the 2 groups.

[Comparison of dorso-lateral and dorso-ventral stabilization procedures in the treatment of vertebral fractures].

PubMed

Bertram, R; Bessem, H; Diedrich, O; Wagner, U; Schmitt, O

2003-01-01

The radiological and clinical outcome of surgical treated thoracolumbal fractures were followed up after 6.7 years. The study encompassed 97 patients. The degrees of the bony deformation and the local kyphosis were measured on the lateral view X-ray at 4 different time points: post trauma, after the operation, before implant removal and at the follow up examination. The clinical outcome was evaluated by the Oswestry score. 74 fractures were treated with a fixateur intern and a dorsal fusion by apposition of autologous bone postero-laterally. 23 fractures were fused in a combined dorso-ventral manner by intervertebral fusion with tricortical autologous bone. The lateral X-rays showed a loss of correction up to 48 % in the dorsal fused group and 10 % loss of correction in the combined group. The local kyphosis increased up to 84 % in the dorsal operated group due to degeneration of the injured disk. The clinical Oswestry score showed no significant difference in both groups. The additional ventral surgery should be evaluated carefully.

Linear particle accelerator with seal structure between electrodes and insulators

DOEpatents

Broadhurst, John H.

1989-01-01

An electrostatic linear accelerator includes an electrode stack comprised of primary electrodes formed or Kovar and supported by annular glass insulators having the same thermal expansion rate as the electrodes. Each glass insulator is provided with a pair of fused-in Kovar ring inserts which are bonded to the electrodes. Each electrode is designed to define a concavo-convex particle trap so that secondary charged particles generated within the accelerated beam area cannot reach the inner surface of an insulator. Each insulator has a generated inner surface profile which is so configured that the electrical field at this surface contains no significant tangential component. A spark gap trigger assembly is provided, which energizes spark gaps protecting the electrodes affected by over voltage to prevent excessive energy dissipation in the electrode stack.

Origins of Stereoselectivity in the trans-Diels-Alder Paradigm

PubMed Central

Paton, Robert S.; Mackey, Joel L.; Kim, Woo Han; Lee, Jun Hee; Danishefsky, Samuel J.; Houk, K. N.

2010-01-01

The regioselectivity and stereoselectivity aspects of the Diels-Alder/radical hydrodenitration reaction sequence leading to trans-fused ring systems have been investigated with density functional calculations. A continuum of transition structures representing Diels-Alder and hetero-Diels-Alder cycloadditions as well as a sigmatropic rearrangement have been located, and they all lie very close in energy on the potential energy surface. All three pathways are found to be important in the formation of the Diels-Alder adduct. Reported regioselectivities are reproduced by the calculations. The stereoselectivity of radical hydrodenitration of the cis-Diels-Alder adduct is found to be related to the relative conformational stabilities of bicyclic radical intermediates. Overall, the computations provide understanding of the regioselectivities and stereoselectivities of the trans-Diels-Alder paradigm. PMID:20557046

Stabilizing Pentacene By Cyclopentannulation.

PubMed

Bheemireddy, Sambasiva R; Ubaldo, Pamela C; Rose, Peter W; Finke, Aaron D; Zhuang, Junpeng; Wang, Lichang; Plunkett, Kyle N

2015-12-21

A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anthranilate-Activating Modules from Fungal Nonribosomal Peptide Assembly Lines†

PubMed Central

Ames, Brian D.; Walsh, Christopher T.

2010-01-01

Fungal natural products containing benzodiazepinone- and quinazolinone-fused ring systems can be assembled by nonribosomal peptide synthetases (NRPS) using the conformationally restricted β-amino acid anthranilate as one of the key building blocks. We validated that the first module of the acetylaszonalenin synthetase of Neosartorya fischeri NRRL 181 activates anthranilate to anthranilyl-AMP. With this as starting point, we then used bioinformatic predictions about fungal adenylation domain selectivities to identify and confirm an anthranilate-activating module in the fumiquinazoline A producer Aspergillus fumigatus Af293 as well as a second anthranilate-activating NRPS in N. fischeri. This establishes an anthranilate adenylation domain code for fungal NRPS and should facilitate detection and cloning of gene clusters for benzodiazepine- and quinazoline-containing polycyclic alkaloids with a wide range of biological activities. PMID:20225828

RING1 is associated with the polycomb group protein complex and acts as a transcriptional repressor.

PubMed

Satijn, D P; Gunster, M J; van der Vlag, J; Hamer, K M; Schul, W; Alkema, M J; Saurin, A J; Freemont, P S; van Driel, R; Otte, A P

1997-07-01

The Polycomb (Pc) protein is a component of a multimeric, chromatin-associated Polycomb group (PcG) protein complex, which is involved in stable repression of gene activity. The identities of components of the PcG protein complex are largely unknown. In a two-hybrid screen with a vertebrate Pc homolog as a target, we identify the human RING1 protein as interacting with Pc. RING1 is a protein that contains the RING finger motif, a specific zinc-binding domain, which is found in many regulatory proteins. So far, the function of the RING1 protein has remained enigmatic. Here, we show that RING1 coimmunoprecipitates with a human Pc homolog, the vertebrate PcG protein BMI1, and HPH1, a human homolog of the PcG protein Polyhomeotic (Ph). Also, RING1 colocalizes with these vertebrate PcG proteins in nuclear domains of SW480 human colorectal adenocarcinoma and Saos-2 human osteosarcoma cells. Finally, we show that RING1, like Pc, is able to repress gene activity when targeted to a reporter gene. Our findings indicate that RING1 is associated with the human PcG protein complex and that RING1, like PcG proteins, can act as a transcriptional repressor.

Frameless stereotactic radiosurgery with a bite-plate: our experience with brain metastases.

PubMed

Furuse, M; Aoki, T; Takagi, T; Takahashi, J A; Ishikawa, M

2008-12-01

Non-invasive frameless stereotactic radiosurgical systems have recently been developed. We report our experience of frameless stereotactic radiosurgery (SRS) with a bite-plate for brain metastases. Between February 2002 and December 2005, 147 patients with brain metastases were treated with C-arm linear accelerator-based SRS and 122 patients were followed up by our institute. An optic tracking system with infrared light-emitting diodes was used for real-time monitoring. A bite-plate with fiducial markers was applied as a first-line method for frameless SRS. Head-ring fixation was used in patients lacking teeth. Lung carcinomas (63%) were the most common primary tumors, followed by breast carcinomas (13%). Ninety patients underwent radiosurgery with a bite-plate and 32 patients underwent fixation of a head ring. Males were significantly more predominant in the head-ring group (26 men and 6 women), compared with the bite-plate group (47 men and 43 women, p < 0.01). The average age (62 years) in the bite-plate group was significantly younger than that (68 years) in the head-ring group (p < 0.01). The median survival time was 12.0 months in the bite-plate group and 8.0 months in the head-ring group (p = 0.0621). Nine patients who had brain metastases in or close to the brain stem were treated with fractionated stereotactic radiotherapy. The frameless stereotactic radiosurgical system with a bite-plate is safe and effective for the treatment of brain metastasis. Elderly male patients sometimes are edentulous and require placement of a head ring for radiosurgery.

Crystal structure and Hirshfield analysis of the 4-(di-methyl-amino)-pyridine adduct of 4-meth-oxy-phenyl-borane.

PubMed

Shooter, Jesse; Allen, Caleb J; Tinsley, Colby W K; Zakharov, Lev N; Abbey, Eric R

2017-11-01

The title compound [systematic name: 4-(di-methyl-amino)-pyridine-4-meth-oxy-phenyl-borane (1/1)], C 14 H 19 BN 2 O, contains two independent mol-ecules in the asymmetric unit. Both molecules exhibit coplanar, mostly sp 2 -hybridized meth-oxy and di-methyl-amino substituents on their respective aromatic rings, consistent with π-donation into the aromatic systems. The B-H groups exhibit an intra-molecular close contact with a C-H group of the pyridine ring, which may be evidence of electrostatic attraction between the hydridic B-H and the electropositive aromatic C-H. There appears to be weak C-H⋯π(arene) inter-actions between two of the H atoms of an amino-methyl group and the meth-oxy-substituted benzene ring of the other independent mol-ecule, and another C-H⋯π (arene) inter-action between one of the pyridine ring H atoms and the same benzene ring.

Alleviating CYP and hERG liabilities by structure optimization of dihydrofuran-fused tricyclic benzo[d]imidazole series - Potent, selective and orally efficacious microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors: Part-2.

PubMed

Muthukaman, Nagarajan; Deshmukh, Sanjay; Tambe, Macchindra; Pisal, Dnyandeo; Tondlekar, Shital; Shaikh, Mahamadhanif; Sarode, Neelam; Kattige, Vidya G; Sawant, Pooja; Pisat, Monali; Karande, Vikas; Honnegowda, Srinivasa; Kulkarni, Abhay; Behera, Dayanidhi; Jadhav, Satyawan B; Sangana, Ramchandra R; Gudi, Girish S; Khairatkar-Joshi, Neelima; Gharat, Laxmikant A

2018-04-15

In an effort to identify CYP and hERG clean mPGES-1 inhibitors from the dihydrofuran-fused tricyclic benzo[d]imidazole series lead 7, an extensive structure-activity relationship (SAR) studies were performed. Optimization of A, D and E-rings in 7 afforded many potent compounds with human whole blood potency in the range of 160-950 nM. Selected inhibitors 21d, 21j, 21m, 21n, 21p and 22b provided selectivity against COX-enzymes and mPGES-1 isoforms (mPGES-2 and cPGES) along with sufficient selectivity against prostanoid synthases. Most of the tested analogs demonstrated required metabolic stability in liver microsomes, low hERG and CYP liability. Oral pharmacokinetics and bioavailability of lead compounds 21j, 21m and 21p are discussed in multiple species like rat, guinea pig, dog, and cynomolgus monkey. Besides, these compounds revealed low to moderate activity against human pregnane X receptor (hPXR). The selected lead 21j further demonstrated in vivo efficacy in acute hyperalgesia (ED 50 : 39.6 mg/kg) and MIA-induced osteoarthritic pain models (ED 50 : 106 mg/kg). Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis of Potential Trypanocides

DTIC Science & Technology

1987-12-01

0188 Ia. REPORT SECURITY CLASSIFICATION 1b RESTRICTIVE MARKINGS Unclassified 2a. SECURITY CLASSIFICATION AUTHORITY 3 . DISTRIBUTION /AVAILABILITY OF...and the phenyl ring, ring structures 2 and 3 , introduction of a -CH:CII- group between the phenyl ring and its 4’-substituent, ring structure 4...imidazole (9, 15) thiazole (11) and pyridine (12-14) into ether-linked and vinyl-linked structures. 3 t % SCHEME 1 HETEROAROMATIC RINGS OHw Ch3 CH3 +1 N% f

Synthesis of benzo-fused 1-azabicyclo[m.n.0]alkanes via the Schmidt reaction: a formal synthesis of gephyrotoxin.

PubMed

Pearson, W H; Fang, W

2000-10-20

The intramolecular capture of benzocyclobutyl, benzocyclopentyl, and benzocyclohexyl carbocations 7 by azides produces spirocyclic aminodiazonium ions 8, which undergo 1,2-C-to-N rearrangement with loss of dinitrogen to produce benzo-fused iminium ions resulting from either aryl (9) or alkyl (10) migration to the electron-deficient nitrogen atom. Reduction of the iminium ions affords regioisomeric benzo-fused 1-azabicyclo[m.n.0]alkanes, e.g., benzopyrrolizidines, benzoindolizidines, benzoquinolizidines, or perhydrobenzo[f]pyrrolo[1,2-a]azepines in two regioisomeric versions, anilines (e.g., 11-14) and benzylic amines (e.g., 15-18), the result of aryl and alkyl migrations, respectively. Generally, aryl migration is preferred, despite modeling that shows that the lowest energy aminodiazonium ions are those where the departing dinitrogen is preferentially antiperiplanar to the migrating alkyl group rather than the aryl group. The utility of this methodology was illustrated by a formal synthesis of the alkaloid gephyrotoxin 4. A dependence on the efficiency and regioselectivity of the Schmidt reaction upon subtle changes in the structure of the cation precursor was observed, necessitating the exploration of a variety of substrates. Fortunately, these materials were easily made. Ultimately, the azido-alkene 81 bearing a 2-bromoethyl side-chain was useful for the Schmidt reaction, producing the known benzo-fused indolizidine 49, which had been transformed by Ito et al. into gephyrotoxin 4. The synthesis of 49 required nine steps (five purifications) from commercially available 4-methoxy-1-indanone 60 and proceeded in 22% overall yield.

Interaction of Spin-Labeled Lipid Membranes with Transition Metal Ions

PubMed Central

2015-01-01

The large values of spin relaxation enhancement (RE) for PC spin-labels in the phospholipid membrane induced by paramagnetic metal salts dissolved in the aqueous phase can be explained by Heisenberg spin exchange due to conformational fluctuations of the nitroxide group as a result of membrane fluidity, flexibility of lipid chains, and, possibly, amphiphilic nature of the nitroxide label. Whether the magnetic interaction occurs predominantly via Heisenberg spin exchange (Ni) or by the dipole–dipole (Gd) mechanism, it is essential for the paramagnetic ion to get into close proximity to the nitroxide moiety for efficient RE. For different salts of Ni the RE in phosphatidylcholine membranes follows the anionic Hofmeister series and reflects anion adsorption followed by anion-driven attraction of paramagnetic cations on the choline groups. This adsorption is higher for chaotropic ions, e.g., perchlorate. (A chaotropic agent is a molecule in water solution that can disrupt the hydrogen bonding network between water molecules.) However, there is no anionic dependence of RE for model membranes made from negatively charged lipids devoid of choline groups. We used Ni-induced RE to study the thermodynamics and electrostatics of ion/membrane interactions. We also studied the effect of membrane composition and the phase state on the RE values. In membranes with cholesterol a significant difference is observed between PC labels with nitroxide tethers long enough vs not long enough to reach deep into the membrane hydrophobic core behind the area of fused cholesterol rings. This study indicates one must be cautious in interpreting data obtained by PC labels in fluid membranes in terms of probing membrane properties at different immersion depths when it can be affected by paramagnetic species at the membrane surface. PMID:26490692

High resolution interrogation system for fiber Bragg grating (FBG) sensor application using radio frequency spectrum analyser

NASA Astrophysics Data System (ADS)

Muhammad, F. D.; Zulkifli, M. Z.; Harun, S. W.; Ahmad, H.

2013-05-01

In this paper, we propose a fiber Bragg grating (FBG) interrogation system for high resolution sensor application based on radio frequency (RF) generation technique by beating a single longitudinal mode (SLM) fiber ring laser with an external tunable laser source (TLS). The external TLS provides a constant wavelength (CW), functioning as the reference signal for the frequency beating technique. The TLS used has a constant output power and wavelength over time. The sensor signal is provided by the reflected wavelength of a typical fiber Bragg grating (FBG) in the SLM fiber ring laser, which consists of a 1 m long highly doped Erbium doped fiber as the gain medium. The key to ensure the SLM laser oscillation is the role of graphene as saturable absorber which is opposed to the commonly used unpumped erbiumdoped fiber and this consequently contributes to the simple and short cavity design of our proposed system. The signal from the SLM fiber ring laser, which is generated by the FBG in response to external changes, such as temperature, strain, air humidity and air movement, is heterodyned with the CW signal from the TLS at a 6 GHz photodetector using a 3-dB fused coupler to generate the frequency beating. This proposed system is experimentally demonstrated as a temperature sensor and the results shows that the frequency response of the system towards the changes in temperature is about 1.3 GHz/°C, taking into account the resolution bandwidth of 3 MHz of the radio frequency spectrum analyzer (RFSA).

Quantum chemical molecular dynamics simulation of single-walled carbon nanotube cap nucleation on an iron particle.

PubMed

Ohta, Yasuhito; Okamoto, Yoshiko; Page, Alister J; Irle, Stephan; Morokuma, Keiji

2009-11-24

The atomic scale details of single-walled carbon nanotube (SWNT) nucleation on metal catalyst particles are elusive to experimental observations. Computer simulation of metal-catalyzed SWNT nucleation is a challenging topic but potentially of great importance to understand the factors affecting SWNT diameters, chirality, and growth efficiency. In this work, we use nonequilibrium density functional tight-binding molecular dynamics simulations and report nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms. One C(2) molecule was placed every 1.0 ps around an Fe(38) cluster for 30 ps, after which a further 410 ps of annealing simulation without carbon supply was performed. We find that sp(2)-carbon network nucleation and annealing processes occur in three sequential and repetitive stages: (A) polyyne chains on the metal surface react with each other to evolve into a Y-shaped polyyne junction, which preferentially form a five-membered ring as a nucleus; (B) polyyne chains on the first five-membered ring form an additional fused five- or six-membered ring; and (C) pentagon-to-hexagon self-healing rearrangement takes place with the help of short-lived polyyne chains, stabilized by the mobile metal atoms. The observed nucleation process resembles the formation of a fullerene cage. However, the metal particle plays a key role in differentiating the nucleation process from fullerene cage formation, most importantly by keeping the growing cap structure from closing into a fullerene cage and by keeping the carbon edge "alive" for the addition of new carbon material.

Biological dosimetry of ionizing radiation: Evaluation of the dose with cytogenetic methodologies by the construction of calibration curves

NASA Astrophysics Data System (ADS)

Zafiropoulos, Demetre; Facco, E.; Sarchiapone, Lucia

2016-09-01

In case of a radiation accident, it is well known that in the absence of physical dosimetry biological dosimetry based on cytogenetic methods is a unique tool to estimate individual absorbed dose. Moreover, even when physical dosimetry indicates an overexposure, scoring chromosome aberrations (dicentrics and rings) in human peripheral blood lymphocytes (PBLs) at metaphase is presently the most widely used method to confirm dose assessment. The analysis of dicentrics and rings in PBLs after Giemsa staining of metaphase cells is considered the most valid assay for radiation injury. This work shows that applying the fluorescence in situ hybridization (FISH) technique, using telomeric/centromeric peptide nucleic acid (PNA) probes in metaphase chromosomes for radiation dosimetry, could become a fast scoring, reliable and precise method for biological dosimetry after accidental radiation exposures. In both in vitro methods described above, lymphocyte stimulation is needed, and this limits the application in radiation emergency medicine where speed is considered to be a high priority. Using premature chromosome condensation (PCC), irradiated human PBLs (non-stimulated) were fused with mitotic CHO cells, and the yield of excess PCC fragments in Giemsa stained cells was scored. To score dicentrics and rings under PCC conditions, the necessary centromere and telomere detection of the chromosomes was obtained using FISH and specific PNA probes. Of course, a prerequisite for dose assessment in all cases is a dose-effect calibration curve. This work illustrates the various methods used; dose response calibration curves, with 95% confidence limits used to estimate dose uncertainties, have been constructed for conventional metaphase analysis and FISH. We also compare the dose-response curve constructed after scoring of dicentrics and rings using PCC combined with FISH and PNA probes. Also reported are dose response curves showing scored dicentrics and rings per cell, combining PCC of lymphocytes and CHO cells with FISH using PNA probes after 10 h and 24 h after irradiation, and, finally, calibration data of excess PCC fragments (Giemsa) to be used if human blood is available immediately after irradiation or within 24 h.

Methyl 2-methyl-4-(oxiran-2-ylmeth-oxy)-2H-1,2-benzothia-zine-3-carboxyl-ate 1,1-dioxide.

PubMed

Ahmad, Matloob; Siddiqui, Hamid Latif; Zia-Ur-Rehman, Muhammad; Elsegood, Mark R J; Weaver, George W

2010-01-09

In the title compound, C(14)H(15)NO(6)S, the thia-zine ring adopts a distorted half-chair conformation. The structure displays several cooperative weak inter-molecular C-H⋯O hydrogen-bonding inter-actions, giving rise to a two-dimensional sheet packing motif. The CH(2) group in the meth-oxy linker to the oxirane ring, and the CH group in that ring, exhibit twofold positional disorder. The three-membered oxirane ring is twisted approximately perpendicular with respect to thia-zine ring (dihedral angle = 60/86° for the major/minor disorder components). 1,2-Benzothia-zines of this kind have a wide range of biological activities and are mainly used as medicines in the treatment of inflammation and rheumatoid arthritis.

Report of the eRHIC Ring-Ring Working Group

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

Aschenauer, E. C.; Berg, S.; Blaskiewicz, M.

2015-10-13

This report evaluates the ring-ring option for eRHIC as a lower risk alternative to the linac-ring option. The reduced risk goes along with a reduced initial luminosity performance. However, a luminosity upgrade path is kept open. This upgrade path consists of two branches, with the ultimate upgrade being either a ring-ring or a linac-ring scheme. The linac-ring upgrade could be almost identical to the proposed linac-ring scheme, which is based on an ERL in the RHIC tunnel. This linac-ring version has been studied in great detail over the past ten years, and its significant risks are known. On the othermore » hand, no detailed work on an ultimate performance ring-ring scenario has been performed yet, other than the development of a consistent parameter set. Pursuing the ring-ring upgrade path introduces high risks and requires significant design work that is beyond the scope of this report.« less

Recurrent Tricuspid Insufficiency

PubMed Central

Kara, Ibrahim; Koksal, Cengiz; Cakalagaoglu, Canturk; Sahin, Muslum; Yanartas, Mehmet; Ay, Yasin; Demir, Serdar

2013-01-01

This study compares the medium-term results of De Vega, modified De Vega, and ring annuloplasty techniques for the correction of tricuspid insufficiency and investigates the risk factors for recurrent grades 3 and 4 tricuspid insufficiency after repair. In our clinic, 93 patients with functional tricuspid insufficiency underwent surgical tricuspid repair from May 2007 through October 2010. The study was retrospective, and all the data pertaining to the patients were retrieved from hospital records. Functional capacity, recurrent tricuspid insufficiency, and risk factors aggravating the insufficiency were analyzed for each patient. In the medium term (25.4 ± 10.3 mo), the rates of grades 3 and 4 tricuspid insufficiency in the De Vega, modified De Vega, and ring annuloplasty groups were 31%, 23.1%, and 6.1%, respectively. Logistic regression analysis revealed that chronic obstructive pulmonary disease, left ventricular dysfunction (ejection fraction, < 0.50), pulmonary artery pressure ≥60 mmHg, and the De Vega annuloplasty technique were risk factors for medium-term recurrent grades 3 and 4 tricuspid insufficiency. Medium-term survival was 90.6% for the De Vega group, 96.3% for the modified De Vega group, and 97.1% for the ring annuloplasty group. Ring annuloplasty provided the best relief from recurrent tricuspid insufficiency when compared with DeVega annuloplasty. Modified De Vega annuloplasty might be a suitable alternative to ring annuloplasty when rings are not available. PMID:23466680

Recurrent tricuspid insufficiency: is the surgical repair technique a risk factor?

PubMed

Kara, Ibrahim; Koksal, Cengiz; Cakalagaoglu, Canturk; Sahin, Muslum; Yanartas, Mehmet; Ay, Yasin; Demir, Serdar

2013-01-01

This study compares the medium-term results of De Vega, modified De Vega, and ring annuloplasty techniques for the correction of tricuspid insufficiency and investigates the risk factors for recurrent grades 3 and 4 tricuspid insufficiency after repair. In our clinic, 93 patients with functional tricuspid insufficiency underwent surgical tricuspid repair from May 2007 through October 2010. The study was retrospective, and all the data pertaining to the patients were retrieved from hospital records. Functional capacity, recurrent tricuspid insufficiency, and risk factors aggravating the insufficiency were analyzed for each patient. In the medium term (25.4 ± 10.3 mo), the rates of grades 3 and 4 tricuspid insufficiency in the De Vega, modified De Vega, and ring annuloplasty groups were 31%, 23.1%, and 6.1%, respectively. Logistic regression analysis revealed that chronic obstructive pulmonary disease, left ventricular dysfunction (ejection fraction, < 0.50), pulmonary artery pressure ≥60 mmHg, and the De Vega annuloplasty technique were risk factors for medium-term recurrent grades 3 and 4 tricuspid insufficiency. Medium-term survival was 90.6% for the De Vega group, 96.3% for the modified De Vega group, and 97.1% for the ring annuloplasty group. Ring annuloplasty provided the best relief from recurrent tricuspid insufficiency when compared with DeVega annuloplasty. Modified De Vega annuloplasty might be a suitable alternative to ring annuloplasty when rings are not available.

Reasons for nonadherence to the dapivirine vaginal ring: narrative explanations of objective drug-level results.

PubMed

Montgomery, Elizabeth T; Stadler, Jonathan; Naidoo, Sarita; Katz, Ariana W K; Laborde, Nicole; Garcia, Morgan; Reddy, Krishnaveni; Mansoor, Leila E; Etima, Juliane; Zimba, Chifundo; Chitukuta, Miria; Soto-Torres, Lydia

2018-07-17

MTN-020/ASPIRE trial and IPM-027/Ring Study recently proved the dapivirine vaginal ring was safe and effective with consistent use. To optimize the ring's impact, the barriers and facilitators to ring adherence must be understood and addressed. Former ASPIRE participants were stratified by age group (18-21; 22-45) and randomly selected at seven sites in Malawi, South Africa, Uganda and Zimbabwe, 12-17 months after trial exit. Using in-depth interviews or focus group discussions, ring use barriers were explored using structured guides and visual tools including individual-level depictions of dapivirine levels detected in plasma and returned rings. A total of 187 were enrolled; 37% were 18-21 years when they began ASPIRE. Most (75%) had drug-level results, suggesting inconsistent ring use throughout ASPIRE. Participants viewed themselves as adherent, while simultaneously describing regular instances and reasons for ring removal (e.g. for sex or menses). Less adherent women reported fears that partners would oppose the ring or feel it during sex. High adherers expressed altruistic motivations for ring use. Women of all ages attributed young women's nonadherence to their tendency to be less 'serious' about the future, HIV prevention and the study; motivated predominantly by benefits; more fearful of fertility-related consequences; and to having less relationship control. When presented with objective adherence data, participants provided reasons for intermittent ring use, while simultaneously portraying themselves as consistent ring users. Further research is needed to understand how women could use the ring in a way that fits into the context of their relationships and their lives while still conferring adequate HIV prophylaxis.

TMPRSS2-ERG gene fusions are infrequent in prostatic ductal adenocarcinomas.

PubMed

Lotan, Tamara L; Toubaji, Antoun; Albadine, Roula; Latour, Mathieu; Herawi, Mehsati; Meeker, Alan K; DeMarzo, Angelo M; Platz, Elizabeth A; Epstein, Jonathan I; Netto, George J

2009-03-01

Ductal adenocarcinoma of the prostate is an unusual subtype that may be associated with a more aggressive clinical course, and is less responsive to conventional therapies than the more common prostatic acinar adenocarcinoma. However, given its frequent association with an acinar component at prostatectomy, some have challenged the concept of prostatic ductal adenocarcinoma as a distinct clinicopathologic entity. We studied the occurrence of the TMPRSS2-ERG gene fusion, in 40 surgically resected ductal adenocarcinoma cases, and in their associated acinar component using fluorescence in situ hybridization. A group of 38 'pure' acinar adenocarcinoma cases matched with the ductal adenocarcinoma group for pathological grade and stage was studied as a control. Compared with the matched acinar adenocarcinoma cases, the TMPRSS2-ERG gene fusion was significantly less frequently observed in ductal adenocarcinoma (45 vs 11% of cases, P=0.002, Fisher's exact test). Here, of the ductal adenocarcinoma cases with the gene fusion, 75% were fused through deletion, and the remaining case was fused through translocation. The TMPRSS2-ERG gene fusion was also rare in the acinar component of mixed ductal-acinar tumors when compared with the pure acinar adenocarcinoma controls (5 vs 45%, P=0.001, Fisher's exact test). In 95% of the ductal adenocarcinoma cases in which a concurrent acinar component was analyzed, there was concordance for presence/absence of the TMPRSS2-ERG gene fusion between the different histologic subtypes. In the control group of pure acinar adenocarcinoma cases, 59% were fused through deletion and 41% were fused through translocation. The presence of the TMPRSS2-ERG gene fusion in some cases of prostatic ductal adenocarcinoma supports the concept that ductal adenocarcinoma and acinar adenocarcinoma may be related genetically. However, the significantly lower rate of the gene fusion in pure ductal adenocarcinoma cases underscores the fact that genetic and biologic differences exist between these two tumors that may be important for future therapeutic strategies.

Influence of rhBMP-2 on Guided Bone Regeneration for Placement and Functional Loading of Dental Implants: A Radiographic and Histologic Study in Dogs.

PubMed

Ben Amara, Heithem; Lee, Jung-Won; Kim, Jung-Ju; Kang, Yun-Mi; Kang, Eun-Jung; Koo, Ki-Tae

Evidence on the outcomes of functional loading placed in recombinant human bone morphogenetic protein 2 (rhBMP-2)/acellular collagen sponge (ACS)-induced bone is lacking. The aim of this study was to verify whether guided bone regeneration (GBR) with rhBMP-2/ACS enhances regeneration of missing bone and osseointegration of dental implants subject to functional loading. Two bilateral standardized large saddle-type defects (≈10 × 10 × 6 mm) were surgically created in each mandible of seven beagle dogs 2 months after tooth extraction. Defects were immediately reconstructed randomly using rhBMP-2 (O-BMP or InFuse) soaked in ACS, deproteinized bovine bone mineral (DBBM) granules, or ACS alone as surgical control and subsequently covered with collagen membrane. Screw-type sand-blasted, acid-etched dental implants were placed 3 months later into the reconstructed defects and into adjacent bone. Osseointegration was allowed to progress for 3 months before functional loading of 3 months until sacrifice. Significantly more bone fill was radiographically observed for GBR with rhBMP-2/ACS (O-BMP: 92.5%, InFuse: 79%) in comparison to the DBBM (52%) and ACS alone groups (56.6%). Osseointegration was achieved and maintained in all experimental defects challenged by prostheses-driven functional load. The bone density ranged from 37.49% in the ACS group to 64.9% in the rhBMP-2/ACS (InFuse) group with no significance. The highest mean percentage of BIC was found in rhBMP-2/ACS (InFuse: 52.98%) with no statistical difference. Crestal bone resorption was observed around implants placed in reconstructed areas without any significant difference. GBR with rhBMP-2/ACS provided the greatest bone fill among the three treatment procedures. GBR with rhBMP-2/ACS showed efficacy for placement, osseointegration, and functional loading of titanium implants in alveolar ridge defects.

Influence of plate fixation on cervical height and alignment after one- or two-level anterior cervical discectomy and fusion.

PubMed

Yu, Jaecheon; Ha, Yoon; Shin, Jun Jae; Oh, Jae Keun; Lee, Chang Kyu; Kim, Keung Nyun; Yoon, Do Heum

2017-10-26

To evaluate the efficacy of plate fixation on cervical alignment after anterior cervical discectomy and fusion (ACDF) using a stand-alone cage (ACDF-CA), compared to ACDF performed using a cage and plate fixation (ACDF-CP) and ACDF using autologous iliac bone graft and plate fixation (ACDF-AP), for the treatment of one- or two-level cervical degenerative disease. A second objective was to assess the clinical and radiological outcomes between the groups. A total of 247 patients underwent ACDF and were divided into three groups: those who underwent ACDF-CA (n = 76), ACDF-CP (n = 82) or ACDF-AP (n = 89). Fusion rate and time-to-fusion, global cervical and segmental angle, fused segment height, subsidence rate, and clinical outcomes, were measured using the visual analogue scale (VAS), Oswestry Neck Disability Index (NDI), and Robinson's criteria, assessed preoperatively, immediately postoperatively, and at least 24 months, postoperatively. ACDF-AP was associated with the shortest mean time-to-fusion, followed by ACDF-CP and ACDF-CA. Compared to the preoperative status, the fused segment height and segmental angle increased in all groups immediately postoperatively, being well-maintained in patients who underwent ACDF-AP, while decreasing in those who underwent ACDF-CP and ACDF-CA procedures. Global cervical lordosis increased with ACDF-AP, but decreased immediately postoperatively with ACDF-CP and ACDF-CA, and at the final follow-up. Univariate analysis confirmed that a change in fused segment height was positively associated with a change in both segmental and global cervical angles. Clinical outcomes, namely VAS and NDI scores, as well as Robinson's criteria, were comparable among the three techniques. Supplementation with plate fixation, especially using autologous iliac bone graft, is beneficial for maintaining the fused segment height and cervical spine curvature, as well as reducing time-to-fusion and subsidence rate.

Reasons for non-adherence to the dapivirine vaginal ring: results of the MTN-032/ AHA study.

PubMed

Montgomery, Elizabeth T; Stadler, Jonathan; Naidoo, Sarita; Katz, Ariana; Laborde, Nicole; Garcia, Morgan; Reddy, Krishnaveni; Mansoor, Leila; Etima, Juliane; Zimba, Chifundo; Chitukuta, Miria; Soto-Torres, Lydia

2018-05-11

METHODS:: Former ASPIRE participants were stratified by age group (18-21; 22-45) and randomly selected at seven sites in Malawi, South Africa, Uganda and Zimbabwe, 12-17 months after trial exit. Using in-depth interviews or focus group discussions, ring use barriers were explored using structured guides and visual tools including individual-level depictions of dapivirine levels detected in plasma and returned rings. 187 were enrolled; 37% were 18-21 when they began ASPIRE. Most (75%) had drug-level results suggesting inconsistent ring use throughout ASPIRE. Participants viewed themselves as adherent, while simultaneously describing regular instances and reasons for ring removal (e.g. for sex or menses). Less adherent women reported fears that partners would oppose the ring or feel it during sex. High adherers expressed altruistic motivations for ring use. Women of all ages attributed young women's non-adherence to their tendency to be less "serious" about the future, HIV prevention and the study; motivated predominantly by benefits; more fearful of fertility-related consequences; and to having less relationship control. When presented with objective adherence data, participants provided reasons for intermittent ring use, while simultaneously portraying themselves as consistent ring users. Further research is needed to understand how women could use the ring in a way that fits into the context of their relationships and their lives while still conferring adequate HIV prophylaxis.

Antioxidant Properties of Pterocarpans through Their Copper(II) Coordination Ability. A DFT Study in Vacuo and in Aqueous Solution

NASA Astrophysics Data System (ADS)

Alagona, Giuliano; Ghio, Caterina

2009-10-01

The antioxidant activity of 3,9-dimethoxy-4-prenylpterocarpan (bitucarpin A) and 3,9-dihydroxy-4,8-diprenylpterocarpan (erybraedin C) is supposed to be related to their copper coordination ability. Therefore several complexes with Cu2+ of low-energy conformers of these two prenylated pterocarpans, whose conformational landscape was the subject of a prior B3LYP/6-31G* study (Alagona, Ghio, Monti Phys. Chem. Chem. Phys. 2004, 6, 2849), have been taken into account at the same computational level, with the metal ion described by effective core potentials in the LanL2DZ valence basis set. Their metal ion affinity (MIA) values have been determined and compared with the results obtained earlier with the same methods for the preferred binding sites of plicatin B, a prenylchalcone that can exist in E and Z configurations as well as in tautomeric forms. The stability order of the metalated species at the various coordination sites strongly depends on their position and nature. The spin density of the cation upon ligand coordination becomes vanishingly small, whereas the ligand spin density approaches 1. Thus the ligand is oxidized to a radical cation (Ligand•+), while Cu(II) is reduced to Cu(I). A very favorable MIA is obtained in vacuo when Cu2+ is chelated between the prenyl and O lone pair moieties for both pterocarpans (MIA = 370 and 380 kcal/mol for bitucarpin A and erybraedin C, respectively). High affinity values are found also when the cation is sequestered within the two end groups (prenyl π density and D ring) in the Ot configuration (MIA = 371 and 373 kcal/mol for bitucarpin A and erybraedin C, respectively). In aqueous solution, the solvent effect dampens the free energy differences and reduces the MIA especially when the ion is remarkably exposed to the solvent. Conversely, when Cu2+ is sequestered, the MIA decrease in solution is limited (MIA = 327 and 360 kcal/mol for bitucarpin A and erybraedin C, respectively). The solvent effect is significantly larger in plicatin B, where the MIA is lowered by 80 to 140 kcal/mol, probably because (a) the screening ability of the substituted phenolic ring is lower and (b) the positive charge on the ligand is less efficiently delocalized than in the four fused ring system of pterocarpans.

Beckmann rearrangement within the ring C of oleanolic acid lactone: Synthesis, structural study and reaction mechanism analysis

NASA Astrophysics Data System (ADS)

Froelich, Anna; Bednarczyk-Cwynar, Barbara; Zaprutko, Lucjusz; Gzella, Andrzej

2017-05-01

Synthesis, spectral and X-ray analysis of three compounds, i.e. 3β-acetoxy-12-hydroxyimino-18β-oleanan-28,13β-olide (substrate) and 3β-acetoxy-12-nitrile-12,13-seco-15(14 → 13)-abeoolean-14(27)-en-28,13β-olide and 3β-acetoxy-12-oxo-12a-aza-C-homoolean-13(18)-en-28-oic acid (Beckmann rearrangement reaction products) are described. Structural analysis revealed that the oxime group in the ring C in substrate molecule had an E-configuration. The nitrile product with retained lactone group was a result of major transformations within rings C and D of oleanane skeleton. In lactam product free carboxyl group and a double bond in ring D instead of lactone system were formed in Beckmann rearrangement reaction.

Minimalist-design, high-functionality, micro-ring resonator-based optical filter with narrow linewidth and low group delay using Looped Back Over- and Under-coupled Resonator (LOBOUR)

NASA Astrophysics Data System (ADS)

Ye, Bo; Dingel, Benjamin B.; Cui, Weili

2013-01-01

We present a minimalist design but high functionality micro-ring resonator based optical filter with narrow linewidth and low group delay using a novel design we called LOBOUR for LOoped-Back Over- and Under- Coupled Resonator (LOBOUR). The characteristics of both narrow linewidth and low group delay (low chromatic dispersion) generally do not come together especially when using a single ring resonator. The Cascaded Over- and Under-Coupled Resonator (COUR) design was able to achieve this goal but introduced many practical fabrication issues. Here, we present an alternative design to COUR which uses only one ring resonator and without fabrication and manufacturing issues. It can achieve 50 dB extinction ratio and tens of ps performance. We also present important parameter selection mapping for LOBOUR.

Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

USGS Publications Warehouse

Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

2010-01-01

We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

N-(Adamantan-1-yl)-1,2,3,4-tetra-hydro-iso-quinoline-2-carbo-thio-amide.

PubMed

El-Emam, Ali A; Al-Abdullah, Ebtehal S; Al-Tuwaijri, Hanaa M; Chidan Kumar, C S; Fun, Hoong-Kun

2013-11-23

In the title compound, C20H26N2S, the N-containing six-membered ring adopts a boat conformation and the dihedral angle between the thio-carbamide group and the benzene ring is 49.67 (9)°. An intra-molecular C-H⋯S hydrogen bond generates an S(6) ring motif. The N-H group is sterically hindered and there are no significant inter-molecular inter-actions beyond van der Waals contacts.

Electronic Properties of Cyclacenes from TAO-DFT

PubMed Central

Wu, Chun-Shian; Lee, Pei-Yin; Chai, Jeng-Da

2016-01-01

Owing to the presence of strong static correlation effects, accurate prediction of the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, symmetrized von Neumann entropy, active orbital occupation numbers, and real-space representation of active orbitals) of cyclacenes with n fused benzene rings (n = 4–100) has posed a great challenge to traditional electronic structure methods. To meet the challenge, we study these properties using our newly developed thermally-assisted-occupation density functional theory (TAO-DFT), a very efficient method for the study of large systems with strong static correlation effects. Besides, to examine the role of cyclic topology, the electronic properties of cyclacenes are also compared with those of acenes. Similar to acenes, the ground states of cyclacenes are singlets for all the cases studied. In contrast to acenes, the electronic properties of cyclacenes, however, exhibit oscillatory behavior (for n ≤ 30) in the approach to the corresponding properties of acenes with increasing number of benzene rings. On the basis of the calculated orbitals and their occupation numbers, the larger cyclacenes are shown to exhibit increasing polyradical character in their ground states, with the active orbitals being mainly localized at the peripheral carbon atoms. PMID:27853249

Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

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

Dooling, J.; Harkay, K.; Ivanyushenkov, Y.

2015-01-01

We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are nearmore » critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.« less

Molecular Packing of Amphiphilic Nanosheets Resolved by X-ray Scattering

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

Harutyunyan, Boris; Dannenhoffer, Adam; Kewalramani, Sumit

2016-12-29

Molecular packing in light harvesting 2D assemblies of photocatalytic materials is a critical factor for solar-to-fuel conversion efficiency. However, structure–function correlations have yet to be fully established. This is partly due to the difficulties in extracting the molecular arrangements from the complex 3D powder averaged diffraction patterns of 2D lattices, obtained via in situ wide-angle X-ray scattering. Here, we develop a scattering theory formalism and couple it with a simple geometrical model for the molecular shape of chromophore 9-methoxy-N-(sodium hexanoate)perylene-3,4-dicarboximide (MeO-PMI) used in our study. This generally applicable method fully reproduces the measured diffraction pattern including the asymmetric line shapesmore » for the Bragg reflections and yields the molecular packing arrangement within a 2D crystal structure with a remarkable degree of detail. We find an approximate edge-centered herringbone structure for the PMI fused aromatic rings and ordering of the carboxypentyl chains above and below the nanosheets. Such a packing arrangement differs from the more symmetric face-to-face orientation of the unsubstituted PMI rings. This structural difference is correlated to our measurement of the reduced catalytic performance of MeO-PMI nanosheets as compared to the mesoscopically similar unsubstituted PMI assemblies.« less

Ferrocene-fused derivatives of acenes, tropones and thiepins

NASA Astrophysics Data System (ADS)

Maharjan, Bidhya Laxmi

This research project is concentrated on tuning the properties of small organic molecules, namely polyacenes, tropones and thiepins, by incorporating redox-active transition metal centers pi-bonded to terminal cyclopentadienyl ligands. Organometallicfused acenequinones, tropones, thiepins and cyclopentadiene-capped polyacenes were synthesized and characterized. This work was divided into three parts: first, the synthesis of ferrocene-fused acenequinones, cyclopentadiene-capped acenequinones and their subsequent aromatization to polyacenes; second, the synthesis of ferrocene-fused tropones, thiotropones and tropone oxime; and third, the synthesis of ferrocene-fused thiepins. Ferrocene-fused quinones are the precursors to our target complexes. Our synthetic route to ferrocenequinones involved two-fold aldol condensation between 1,2- diformylferrocene and naphthalene-1,4-diol or anthracene-1,4-diol, and four-fold condensation between 1,2-diformylferrocene and 1,4-cyclohexanedione. Reduction of ferrocene-fused quinones with borane in THF resulted in ferrocene-fused dihydroacenes. Attempts to reduce ferrocene-fused acenequinones with sodium dithionite led to metalfree cyclopentadiene- (Cp-) capped acenequinones. Cp-capped acenequinones were aromatized to bis(triisopropylsilyl)ethynyl polyacenes by using lithium (triisopropylsilyl)acetylide (TIPSC≡CLi) with subsequent dehydroxylation by stannous chloride. The compounds were characterized by using spectroscopic methods and X-ray crystallography. Further, the electronic properties of these compounds were studied by using cyclic voltammetry and UV-visible spectroscopy. Cyclic voltammetry showed oxidation potentials of Cp-capped TIPS-tetracene and bis-Cp-capped TIPS-anthracene as 0.49 V and 0.61 V, respectively (vs. ferrocene/ferrocenium). The electrochemical band gaps were 2.15 eV and 2.58 eV, respectively. Organic thin-film transistor device performance of Cp-capped polyacenes was studied using solution deposition bottomcontact, bottom-gate (BCBG) device architecture and the resulting performance parameters are described herein. Similarly, we are also interested in potential applications of metallocene-fused tropones and derivatives as organic electronic materials. Condensation of 1,2- diformylferrocene with acetone or 1,3-diphenylacetone in the presence of KOH resulted in the ferrocene-fused tropone (eta5-2,4-cyclopentadien-1-yl)[(1,2,3,3a,8a-eta)-1,6-dihydro- 6-oxo-1-azulenyl]iron (1, R = H, E = O) and its 5,7-diphenyl derivative (1, R = Ph, E = O) as previously reported by Tirouflet. The use of piperidine as base resulted in Michael addition of piperidine to one of the carbon-carbon double bonds of the tropones. Lawesson's reagent converted the ferrocene-fused tropones to either a thiotropone (1, R = H, E = S) or a detached 5,7-diphenylazulenethiol (2). Reaction of the ferrocene-fused thiotropone with hydroxylamine gave the corresponding oxime (1, R = H, E = NOH). Products were characterized by using spectroscopic methods and X-ray crystallography. Their electronic properties were studied by using cyclic voltammetry and UV-visible spectroscopy. The third project involved the two-fold aldol condensation of 1,2- diformylferrocene with dimethylthioglycolate S-oxide in the presence of freshly distilled triethylamine, which gave mono- and di-dehydrated products. Deoxygenation of the ferrocene-fused thiepin S-oxide with 2-chloro-1,3,2-benzodioxaphosphole in the presence of pyridine resulted in the corresponding thiepin. The ester groups of the thiepin and thiepin S-oxide were hydrolyzed under basic conditions to give carboxylic acids, which were converted into acid chlorides using oxalyl chloride. Attempts to decarboxylate the thiepin and thiepin S-oxide diacids resulted in decomposition.

Group-multicast capable optical virtual private ring with contention avoidance

NASA Astrophysics Data System (ADS)

Peng, Yunfeng; Du, Shu; Long, Keping

2008-11-01

A ring based optical virtual private network (OVPN) employing contention sensing and avoidance is proposed to deliver multiple-to-multiple group-multicast traffic. The network architecture is presented and its operation principles as well as performance are investigated. The main contribution of this article is the presentation of an innovative group-multicast capable OVPN architecture with technologies available today.

Metal complexes of substituted Gable porphyrins as oxidation catalysts

DOEpatents

Lyons, James E.; Ellis, Jr., Paul E.; Wagner, Richard W.

1996-01-01

Transition metal complexes of Gable porphyrins having two porphyrin rings connected through a linking group, and having on the porphyrin rings electron-withdrawing groups, such as halogen, nitro or cyano. These complexes are useful as catalysts for the oxidation of organic compounds, e.g. alkanes.

Successful removal of strangulating metal penile ring using a dental handpiece.

PubMed

Etetafia, Mabel Okiemute; Nwajei, Charles Onochie

2014-07-11

Under emergency conditions, the dental handpiece can be a useful tool for removing a strangulating penile ring. To report the successful use of a dental handpiece (dental drill) to remove a strangulating penile ring in an emergency. A case report of a strangulating metal penile ring in a psychiatric patient who presented at the accident and emergency unit of Delta State University Teaching Hospital. The metal ring was removed using a diamond bur in a dental handpiece. In case of emergency, the dental handpiece is a useful tool for removing a strangulating penile ring. 2014 BMJ Publishing Group Ltd.

Synthesis of amide isosteres of schweinfurthin-based stilbenes.

PubMed

Stockdale, David P; Beutler, John A; Wiemer, David F

2017-10-15

The schweinfurthins are plant-derived stilbenes with an intriguing profile of anti-cancer activity. To obtain analogues of the schweinfurthins that might preserve the biological activity but have greater water solubility, a formal replacement of the central olefin with an amide has been explored. Two pairs of amides have been prepared, each containing the same hexahydroxanthene "left half" joined through an amide linkage to two different "right halves." In each series, the amide has been inserted in both possible orientations, placing the carbonyl group on the tricyclic ABC ring system and the amine on the D-ring, or placing the amine on the hexahydroxanthene and the carbonyl group on the D-ring. The four new schweinfurthin analogues have been tested in the NCI 60 cell line screen, and in both cases the more active isomer carried the carbonyl group on the C-ring. Copyright © 2017 Elsevier Ltd. All rights reserved.

(E)-1-(Pyridin-2-yl)-3-(3,4,5-trimeth­oxy­phen­yl)prop-2-en-1-one

PubMed Central

Fun, Hoong-Kun; Suwunwong, Thitipone; Chantrapromma, Suchada

2011-01-01

In the title heteroaryl chalcone derivative, C17H17NO4, the dihedral angle between the pyridine and benzene rings is 10.82 (5)°. The two meth­oxy groups at the meta positions are essentially coplanar with the attached benzene rings [C—O—C—C torsion angles = −0.97 (14) and 179.47 (9)°], whereas the meth­oxy group at the para position is twisted from the attached ring with a C—O—C—C torsion angle of −104.48 (11)°. A C—H⋯O close contact involving two of the meth­oxy groups generates an S(6) ring motif. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions into columns along the b axis. PMID:22058997

Periodic mesoporous organosilicas containing interconnected [Si(CH2)]3 rings.

PubMed

Landskron, Kai; Hatton, Benjamin D; Perovic, Doug D; Ozin, Geoffrey A

2003-10-10

A periodic mesoporous organosilica composed of interconnected three-ring [Si(CH2)]3 units built of three SiO2(CH2)2 tetrahedral subunits is reported. It represents the archetype of a previously unknown class of nanocomposite materials in which two bridging organic groups are bound to each silicon atom. It can be obtained with powder and oriented film morphologies. The nanocomposite is self-assembled from the cyclic three-ring silsesquioxane [(EtO)2Si(CH2)]3 precursor and a surfactant mesophase to give a well-ordered mesoporous framework. Low dielectric constants and good mechanical stability of the films were measured, making this material interesting for microelectronic applications. Methylene group reactivity of the three-ring precursor provides entry to a family of nanocomposites, exemplified by the synthesis and self-assembly of [(EtO)2Si(CHR)][(EtO)2Si(CH2)]2 (where R indicates iodine, bromine, or an ethyl group).

Chemical Characteristics, Synthetic Methods, and Biological Potential of Quinazoline and Quinazolinone Derivatives

PubMed Central

2014-01-01

The heterocyclic fused rings quinazoline and quinazolinone have drawn a huge consideration owing to their expanded applications in the field of pharmaceutical chemistry. Quinazoline and quinazolinone are reported for their diversified biological activities and compounds with different substitutions bring together to knowledge of a target with understanding of the molecule types that might interact with the target receptors. Quinazolines and quinazolinones are considered as an important chemical for the synthesis of various physiological significance and pharmacological utilized molecules. Quinazolines and quinazolinone are a large class of biologically active compounds that exhibited broad spectrum of biological activities such as anti-HIV, anticancer, antifungal, antibacterial, antimutagenic, anticoccidial, anticonvulsant, anti-inflammatory, antidepressant, antimalarial, antioxidant, antileukemic, and antileishmanial activities and other activities. Being considered as advantaged scaffold, the alteration is made with different substituent. PMID:25692041

Apert Syndrome: Molecularly Confirmed C.758C>G (P.Pro253Arg) in FGFR2

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

Cha Gon, Lee, E-mail: leechagon@eulji.ac.kr

A 5-day-old girl was referred to our clinic for evaluation of congenital malformations. She was identified with a pathogenic mutation c.758C>G (p.Pro253Arg) in FGFR2 gene using targeted exome sequencing. The de novo mutation was confirmed with Sanger sequencing in the patient and her parents. She showed occipital plagiocephaly with frontal bossing (Figure A and B). Skull frontal and lateral radiography revealed fusion of most of the sutures except coronal suture, with convolutional markings (Figure D and E). She had complete cleft palate (Figure C). Her fused bilateral hands showed type II syndactyly with complete syndactyly between the ring and themore » little fingers (Figure F1-F3). Both toes were simple syndactyly with side-to-side fusion of skin (Figure G1-)« less

Rhodomollacetals A-C, PTP1B Inhibitory Diterpenoids with a 2,3:5,6-Di-seco-grayanane Skeleton from the Leaves of Rhododendron molle.

PubMed

Zhou, Junfei; Sun, Na; Zhang, Hanqi; Zheng, Guijuan; Liu, Junjun; Yao, Guangmin

2017-10-06

Three novel diterpenoids with an unprecedented 2,3:5,6-di-seco-grayanane carbon skeleton, rhodomollacetals A-C (1-3), are isolated from the leaves of Rhododendron molle. Their structures are elucidated by comprehensive spectroscopic techniques and single-crystal X-ray diffraction. Rhodomollacetal A (1) possesses a novel cis/cis/cis/cis-fused 6/6/6/6/5 pentacyclic ring system, featuring an unprecedented 11,13,18-trioxa-pentacyclo [8.7.1.1 5,8 .0 2,8 .0 12,17 ]nonadecane scaffold. Compounds 2 and 3 have a rare 4-oxatricyclo[7.2.1.0 1,6 ]dodecane moiety and a 2,3-dihydro-4H-pyran-4-one unit. Compounds 1-3 showed moderate PTP1B inhibitory activities, and their molecular dockings were investigated.

Synthesis and conformational study of 3,4-carbocyclic bridged indole melatonin and serotonin analogues.

PubMed

Bedini, Annalida; Di Giacomo, Barbara; Gatti, Giuseppe; Spadoni, Gilberto

2005-08-01

Tetrahydrobenz[cd]indole, has been usually assumed to be a rigid scaffold of arylethylamines of pharmaceutical interest, such as melatonin and serotonin. A series of molecules containing this scaffold has been synthesized and their conformation in solution has been determined by 1H NMR. The values of the coupling constants show that the carbocycle fused with the indole ring is a mixture of the two conformers with substituent in equatorial or axial orientation. The molar fraction of the conformers appears to be sensibly affected by the bulkiness of the C-2 indole substituent. A pseudo-axial orientation of the C-3 alkylamido side chain is important for melatonin ligands to access the binding site and exhibit potent in vitro affinity, as illustrated for melatonin ligand 1 (pK(i)=9.32).

Ynamides in Ring Forming Transformations

PubMed Central

WANG, XIAO-NA; YEOM, HYUN-SUK; FANG, LI-CHAO; HE, SHUZHONG; MA, ZHI-XIONG; KEDROWSKI, BRANT L.; HSUNG, RICHARD P.

2013-01-01

Conspectus The ynamide functional group activates carbon-carbon triple bonds through an attached nitrogen atom that bears an electron-withdrawing group. As a result, the alkyne has both electrophilic and nucleophilic properties. Through the selection of the electron-withdrawing group attached to nitrogen chemists can modulate the electronic properties and reactivity of ynamides, making these groups versatile synthetic building blocks. The reactions of ynamides also lead directly to nitrogen-containing products, which provides access to important structural motifs found in natural products and molecules of medicinal interest. Therefore, researchers have invested increasing time and research in the chemistry of ynamides in recent years. This Account surveys and assesses new organic transformations involving ynamides developed in our laboratory and in others around the world. We showcase the synthetic power of ynamides for rapid assembly of complex molecular structures. Among the recent reports of ynamide transformations, ring-forming reactions provide a powerful tool for generating molecular complexity quickly. In addition to their synthetic utility, such reactions are mechanistically interesting. Therefore, we focus primarily on the cyclization chemistry of ynamides. This Account highlights ynamide reactions that are useful in the rapid synthesis of cyclic and polycyclic structural manifolds. We discuss the mechanisms active in the ring formations and describe representative examples that demonstrate the scope of these reactions and provide mechanistic insights. In this discussion we feature examples of ynamide reactions involving radical cyclizations, ring-closing metathesis, transition metal and non-transition metal mediated cyclizations, cycloaddition reactions, and rearrangements. The transformations presented rapidly introduce structural complexity and include nitrogen within, or in close proximity to, a newly formed ring (or rings). Thus, ynamides have emerged as powerful synthons for nitrogen-containing heterocycles and nitrogen-substituted rings, and we hope this Account will promote continued interest in the chemistry of ynamides. PMID:24164363

[The influence of different opaque thickness on the bond strength of porcelain-fused-to metal restoration].

PubMed

Xu, Kan; He, Fan; Geng, Yi

2009-12-01

To study the influence of different opaque thickness on the bond strength of porcelain-fused-to metal (PFM) restorations. The testing sheets were made as the samples of ISO9693. With different sintering temperature and different opaque thickness on the bond strength of PFM restorations, the primary pressure of porcelain crack was measured by using three-points-bending test. Statistical analysis was carried out using a SPSS 10.0 software package. A post hoc multiple comparison test (Student-Newman-Keuls) was performed to evaluate the differences between the individual groups. In low sintering temperature group, the thin layer of opaque significantly improved the bond strength compared with thick layer of opaque (P<0.05). In high sintering temperature group, the thickness of opaque has no significant influence on the PFM bonding strength. Using the opaque, the bonding strength was better than those without opaque. The thickness of opaque has a little influence on the PFM bonding strength.

Antioxidative and antiradical properties of plant phenolics.

PubMed

Sroka, Zbigniew

2005-01-01

The plant phenolic compounds such as flavonoids, tannins and phenolic acids appeared to be strong antiradical and antioxidant compounds. The number of hydroxy groups and the presence of a 2,3-double bond and orthodiphenolic structure enhance antiradical and antioxidative activity of flavonoids. The glycosylation, blocking the 3-OH group in C-ring, lack of a hydroxy group or the presence of only a methoxy group in B-ring have a decreasing effect on antiradical or antioxidative activity of these compounds. Tannins show strong antioxidative properties. Some tannins in red wine or gallate esters were proved to have antioxidative effect in vivo. The number of hydroxy groups connected with the aromatic ring, in ortho or para position relative to each other, enhance antioxidative and antiradical activity of phenolic acids. The substitution of a methoxy group in ortho position to the OH in monophenols seems to favour the antioxidative activity of the former.

Discovery of Novel, Highly Potent, and Selective Matrix Metalloproteinase (MMP)-13 Inhibitors with a 1,2,4-Triazol-3-yl Moiety as a Zinc Binding Group Using a Structure-Based Design Approach.

PubMed

Nara, Hiroshi; Kaieda, Akira; Sato, Kenjiro; Naito, Takako; Mototani, Hideyuki; Oki, Hideyuki; Yamamoto, Yoshio; Kuno, Haruhiko; Santou, Takashi; Kanzaki, Naoyuki; Terauchi, Jun; Uchikawa, Osamu; Kori, Masakuni

2017-01-26

On the basis of a superposition study of X-ray crystal structures of complexes of quinazoline derivative 1 and triazole derivative 2 with matrix metalloproteinase (MMP)-13 catalytic domain, a novel series of fused pyrimidine compounds which possess a 1,2,4-triazol-3-yl group as a zinc binding group (ZBG) was designed. Among the herein described and evaluated compounds, 31f exhibited excellent potency for MMP-13 (IC 50 = 0.036 nM) and selectivities (greater than 1,500-fold) over other MMPs (MMP-1, -2, -3, -7, -8, -9, -10, and -14) and tumor necrosis factor-α converting enzyme (TACE). Furthermore, the inhibitor was shown to protect bovine nasal cartilage explants against degradation induced by interleukin-1 and oncostatin M. In this article, we report the discovery of extremely potent, highly selective, and orally bioavailable fused pyrimidine derivatives that possess a 1,2,4-triazol-3-yl group as a novel ZBG for selective MMP-13 inhibition.

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

Buchstaber, V M; Ustinov, A V

We describe the coefficient rings of universal formal group laws which arise in algebraic geometry, algebraic topology and their application to mathematical physics. We also describe the homomorphisms of these coefficient rings coming from reductions of one formal group law to another. The proofs are based on the number-theoretic properties of binomial coefficients. Bibliography: 37 titles.

Metal complexes of substituted Gable porphyrins as oxidation catalysts

DOEpatents

Lyons, J.E.; Ellis, P.E. Jr.; Wagner, R.W.

1996-01-02

Transition metal complexes of Gable porphyrins are disclosed having two porphyrin rings connected through a linking group, and having on the porphyrin rings electron-withdrawing groups, such as halogen, nitro or cyano. These complexes are useful as catalysts for the oxidation of organic compounds, e.g. alkanes.

Mass-marking of otoliths of lake trout sac fry by temperature manipulation

USGS Publications Warehouse

Bergstedt, Roger A.; Eshenroder, Randy L.; Bowen, Charles; Seelye, James G.; Locke, Jeffrey C.

1990-01-01

The otoliths of 676,000 sac fry of lake trout Salvelinus namaycush in 1986, and of 1,100,000 in 1987, were marked by daily manipulation of water temperature. The fish were stocked into Lake Huron in the spring. Otolith marks consisted of groups of daily growth rings accentuated into recognizable patterns by steadily raising and lowering the temperature about 10 degrees C (from a base of 1-4 degrees C) over 14 h. In 1987, groups of marked and control fish were held for 6 months. The otoliths were removed from samples of the fish, embedded in epoxy, thin sectioned by grinding in the sagittal plane, etched, and viewed by using a combination of a compound microscope (400-1000x) and a video enhancement system. One or more readable otolith sections were obtained from 39 of a sample of 40 fish. Three independent readers examined 41 otoliths for marks and correctly classified the otoliths, with accuracies of 85, 98, and 100%, as being from marked or unmarked fish. The exact number of rings in a recognizable pattern sometimes differed from the number of temperature cycles to which the fish were exposed. Counts of daily rings within groups of six rings varied less than counts within groups of rings.

Mass-marking of otoliths of lake trout sac fry by temperature manipulation

USGS Publications Warehouse

Bergstedt, R.A.; Eshenroder, R.L.; Bowen, C. II; Seelye, J.G.; Locke, J.C.; Parker, N.C.; Giorgi, A.E.; Heidenger, R.C.; Jester, D. B.; Prince, E.D.; Winans, G.A.

1990-01-01

The otoliths of 676,000 sac fry of lake trout Salvelinus namaycush in 1986, and of 1,100,000 in 1987, were marked by daily manipulation of water temperature. The fish were stocked into Lake Huron in the spring. Otolith marks consisted of groups of daily growth rings accentuated into recognizable patterns by steadily raising and lowering the temperature about IOA?C (from a base of 1-4A?C) over 14h. In 1987, groups of marked and control fish were held for 6 months. The otoliths were removed from samples of the fish, embedded in epoxy, thin-sectioned by grinding in the sagittal plane, etched, and viewed by using a combination of a compound microscope (400-1000x) and a video enhancement system. One or more readable otolith sections were obtained from 39 of a sample of 40 fish. Three independent readers examined 41 otoliths for marks and correctly classified the otoliths, with accuracies of 85, 98,and 100%, as being from marked or unmarked fish. The exact number of rings in a recognizable pattern sometimes differed from the number of temperature cycles to which the fish were exposed. Counts of daily rings within groups of six rings varied less than counts within groups of three rings.

29 CFR 1910.399 - Definitions applicable to this subpart.

Code of Federal Regulations, 2010 CFR

2010-07-01

... assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade... in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil...

29 CFR 1910.399 - Definitions applicable to this subpart.

Code of Federal Regulations, 2013 CFR

2013-07-01

... assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade... in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil...

29 CFR 1910.399 - Definitions applicable to this subpart.

Code of Federal Regulations, 2014 CFR

2014-07-01

... assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade... in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil...

29 CFR 1910.399 - Definitions applicable to this subpart.

Code of Federal Regulations, 2011 CFR

2011-07-01

... assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade... in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil...

29 CFR 1910.399 - Definitions applicable to this subpart.

Code of Federal Regulations, 2012 CFR

2012-07-01

... assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade... in which all or part of the fuse support and its fuse link or disconnecting blade are mounted in oil...

Methyl 2-methyl-4-(oxiran-2-ylmeth­oxy)-2H-1,2-benzothia­zine-3-carboxyl­ate 1,1-dioxide

PubMed Central

Ahmad, Matloob; Siddiqui, Hamid Latif; Zia-ur-Rehman, Muhammad; Elsegood, Mark R. J.; Weaver, George W.

2010-01-01

In the title compound, C14H15NO6S, the thia­zine ring adopts a distorted half-chair conformation. The structure displays several cooperative weak inter­molecular C—H⋯O hydrogen-bonding inter­actions, giving rise to a two-dimensional sheet packing motif. The CH2 group in the meth­oxy linker to the oxirane ring, and the CH group in that ring, exhibit twofold positional disorder. The three-membered oxirane ring is twisted approximately perpendicular with respect to thia­zine ring (dihedral angle = 60/86° for the major/minor disorder components). 1,2-Benzothia­zines of this kind have a wide range of biological activities and are mainly used as medicines in the treatment of inflammation and rheumatoid arthritis. PMID:21579762

Functional electrolyte for lithium-ion batteries

DOEpatents

Zhang, Lu; Zhang, Zhengcheng; Amine, Khalil

2015-04-14

Functional electrolyte solvents include compounds having at least one aromatic ring with 2, 3, 4 or 5 substituents, at least one of which is a substituted or unsubstituted methoxy group, at least one of which is a tert-butyl group and at least one of which is a substituted or unsubstituted polyether or poly(ethylene oxide) (PEO) group bonded through oxygen to the aromatic ring, are provided.

Electrically conducting porphyrin and porphyrin-fullerene electropolymers

DOEpatents

Gust, Jr., John Devens; Liddell, Paul Anthony; Gervaldo, Miguel Andres; Bridgewater, James Ward; Brennan, Bradley James; Moore, Thomas Andrew; Moore, Ana Lorenzelli

2014-03-11

Compounds with aryl ring(s) at porphyrin meso position(s) bearing an amino group in position 4 relative to the porphyrin macrocycle, and at least one unsubstituted 5 (hydrogen-bearing) meso position with the 10-, 15-, and/or 20-relationship to the aryl ring bearing the amino group, and metal complexes thereof, feature broad spectral absorption throughout the visible region. These compounds are electropolymerized to form electrically conducting porphyrin and porphyrin-fullerene polymers that are useful in photovoltaic applications. The structure of one such electrically conducting porphyrin polymer is shown below. ##STR00001##

Ab initio study of naphtho-homologated DNA bases.

PubMed

Vazquez-Mayagoita, Alvaro; Huertas, Oscar; Fuentes-Cabrera, Miguel; Sumpter, Bobby G; Orozco, Modesto; Luque, F Javier

2008-02-21

Naphtho-homologated DNA bases have been recently used to build a new type of size-expanded DNA known as yyDNA. We have used theoretical techniques to investigate the structure, tautomeric preferences, base-pairing ability, stacking interactions, and HOMO-LUMO gaps of the naphtho-bases. The structure of these bases is found to be similar to that of the benzo-fused predecessors (y-bases) with respect to the planarity of the aromatic rings and amino groups. Tautomeric studies reveal that the canonical-like forms of naphtho-thymine (yyT) and naphtho-adenine (yyA) are the most stable tautomers, leading to hydrogen-bonded dimers with the corresponding natural nucleobases that mimic the Watson-Crick pairing. However, the canonical-like species of naphtho-guanine (yyG) and naphtho-cytosine (yyC) are not the most stable tautomers, and the most favorable hydrogen-bonded dimers involve wobble-like pairings. The expanded size of the naphtho-bases leads to stacking interactions notably larger than those found for the natural bases, and they should presumably play a dominant contribution in modulating the structure of yyDNA duplexes. Finally, the HOMO-LUMO gap of the naphtho-bases is smaller than that of their benzo-base counterparts, indicating that size-expansion of DNA bases is an efficient way of reducing their HOMO-LUMO gap. These results are examined in light of the available experimental evidence reported for yyT and yyC.

Divergent synthesis and chemical reactivity of bicyclic lactone fragments of complex rearranged spongian diterpenes.

PubMed

Schnermann, Martin J; Beaudry, Christopher M; Genung, Nathan E; Canham, Stephen M; Untiedt, Nicholas L; Karanikolas, Breanne D W; Sütterlin, Christine; Overman, Larry E

2011-11-02

The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described. In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed. Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group, in either the bridged or fused series, is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.

3D H-bonding networks self-assembly from pyridinium derivatives and bis(maleonitriledithiolato)zincate(II)

NASA Astrophysics Data System (ADS)

Ren, Xiaoming; Xie, Jingli; Chen, Youcun; Kremer, Reinhard Karl

2003-11-01

The two ion-pair complexes, [pyH] 2[Zn(mnt) 2] ( 1) and [4,4'-bipyH 2]-[Zn(mnt) 2] ( 2), were synthesized, where mnt 2- denotes maleonitriledithiolate, and [pyH] +, [4,4'-bipyH 2] 2+ represent pyridinium and diprotonated 4,4'-bipyridinium, respectively. Their single crystal structures show that there are strong bifurcated H-bonding interactions between the cations of the pyridinium derivative and the [Zn(mnt) 2] 2- anions in both 1 and 2. The bifurcated H-bonding interactions between the N-H of the pyridiniums and the CN groups of the mnt 2- ligands give rise to a 2D layered H-bonding network, the adjacent layers come together in such way as mutual embrace to give a tight pack, thus 2D hydrogen-bonding sheets further develop into 3D H-bonding networks through weak C-H⋯S and π⋯π stacking interactions in 1. As for 2, the cations and anions connect into several types of H-bonding macrorings ([2+2], [3+3] and [4+4]), these H-bonding macrorings fuse to extend into 2D layered structure, the interpenetration between [3+3] and [4+4] type H-bonding macrorings in the adjacent layers give further rise to novel 3D extended H-bonding networks, in which there are clearly parallel stacks of cations and the chelate rings of anions.

The Crystal Structure of the Ring-Hydroxylating Dioxygenase from Sphingomonas CHY-1

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

Jakoncic,J.; Jouanneau, Y.; Meyer, C.

The ring-hydroxylating dioxygenase (RHD) from Sphingomonas CHY-1 is remarkable due to its ability to initiate the oxidation of a wide range of polycyclic aromatic hydrocarbons (PAHs), including PAHs containing four- and five-fused rings, known pollutants for their toxic nature. Although the terminal oxygenase from CHY-1 exhibits limited sequence similarity with well characterized RHDs from the naphthalene dioxygenase family, the crystal structure determined to 1.85 {angstrom} by molecular replacement revealed the enzyme to share the same global {alpha}{sub 3}{beta}{sub 3} structural pattern. The catalytic domain distinguishes itself from other bacterial non-heme Rieske iron oxygenases by a substantially larger hydrophobic substrate bindingmore » pocket, the largest ever reported for this type of enzyme. While residues in the proximal region close to the mononuclear iron atom are conserved, the central region of the catalytic pocket is shaped mainly by the side chains of three amino acids, Phe350, Phe404 and Leu356, which contribute to the rather uniform trapezoidal shape of the pocket. Two flexible loops, LI and LII, exposed to the solvent seem to control the substrate access to the catalytic pocket and control the pocket length. Compared with other naphthalene dioxygenases residues Leu223 and Leu226, on loop LI, are moved towards the solvent, thus elongating the catalytic pocket by at least 2 {angstrom}. An 11 {angstrom} long water channel extends from the interface between the {alpha} and {beta} subunits to the catalytic site. The comparison of these structures with other known oxygenases suggests that the broad substrate specificity presented by the CHY-1 oxygenase is primarily due to the large size and particular topology of its catalytic pocket and provided the basis for the study of its reaction mechanism.« less

Structure-function correlation of chloroquine and analogues as transgene expression enhancers in nonviral gene delivery.

PubMed

Cheng, Jianjun; Zeidan, Ryan; Mishra, Swaroop; Liu, Aijie; Pun, Suzie H; Kulkarni, Rajan P; Jensen, Gregory S; Bellocq, Nathalie C; Davis, Mark E

2006-11-02

To understand how chloroquine (CQ) enhances transgene expression in polycation-based, nonviral gene delivery systems, a number of CQ analogues with variations in the aliphatic amino side chain or in the aromatic ring are synthesized and investigated. Our studies indicate that the aliphatic amino moiety of CQ is essential to provide increased gene expression. Further, the enhancements are more dramatically affected by changes to the aromatic ring and are positively correlated to the strength of intercalation between DNA and the CQ analogues. Quinacrine (QC), a CQ analogue with a fused acridinyl structure that can strongly intercalate DNA, enhances transfection similarly to CQ at a concentration 10 times lower, while N(4)-(4-pyridinyl)-N(1),N(1)-diethyl-1,4-pentanediamine (CP), a CQ analogue that has a weakly intercalating pyridinyl ring, shows no effect on gene expression. Subtle change on the 7-substituent of the chloroquine aromatic structure can also greatly affect the ability of the CQ analogues to enhance transgene expression. Transfection in the presence of N(4)-(7-trifluoromethyl-4-quinolinyl)-N(1),N(1)-diethyl-1,4-pentanediamin e (CQ7a) shows expression efficiency 10 times higher than in the presence of CQ at same concentration, while transfection in the presence of N(4)-(4-quinolinyl)-N(1),N(1)-diethyl-1,4-pentanediamine (CQ7b) does not reveal any enhancing effects on expression. Through a number of comparative studies with CQ and its analogues, we conclude that there are at least three mechanistic features of CQ that lead to the enhancement in gene expression: (i) pH buffering in endocytic vesicles, (ii) displacement of polycations from the nucleic acids in polyplexes, and (iii) alteration of the biophysical properties of the released nucleic acid.

Group invariant solutions of the Ernst equation of general relativity theory

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

Pryse, P.V.

The local symmetry group of the Ernst Equation for stationary, axisymmetric, vacuum space-time manifolds is computed by application of the method of Olver. Several implicit solutions of the equation are found by use of this group. Each of these solutions is given in terms of a function defined as a solution of an ordinary differential equation. One of these equations is integrated by quadratures by use of its own local symmetry group, the result being three explicit solutions of the Ernst Equation. For one of these solutions the metric of the space-time manifold is constructed and studied. The solutions hasmore » a ring curvature singularity and it is asymptotically flat in the sense that the curvature invariants approach zero at spatial infinity. The timelike and null geodesics on the symmetry axis and in the plane of the ring singularity are described. The test particles following these geodesics are seen to be repelled by the ring, which suggests the interpretation of this solution as representing the exterior gravitational field of a rotating ring of matter with negative gravitational mass.« less

A longitudinal study of the comparative efficacy of Women for Sobriety, LifeRing, SMART Recovery, and 12-step groups for those with AUD.

PubMed

Zemore, Sarah E; Lui, Camillia; Mericle, Amy; Hemberg, Jordana; Kaskutas, Lee Ann

2018-05-01

Despite the effectiveness of 12-step groups, most people reporting a prior alcohol use disorder (AUD) do not sustain involvement in such groups at beneficial levels. This highlights the need for research on other mutual help groups that address alcohol problems and may attract those who avoid 12-step groups. The current study addresses this need, offering outcome data from the first longitudinal, comparative study of 12-step groups and their alternatives: The Peer ALlternatives for Addiction (PAL) Study. Adults with a lifetime AUD were surveyed at baseline (N=647), 6months (81% response rate) and 12months (83% response rate). Members of the largest known secular mutual help alternatives, namely Women for Sobriety (WFS), LifeRing, and SMART, were recruited in collaboration with group directors; current 12-step attendees were recruited from an online meeting hub. Online surveys assessed demographic and clinical variables; mutual help involvement; and alcohol and drug use and severity. Analyses involved multivariate logistic GEEs separately modelling alcohol abstinence, alcohol problems, and total abstinence across 6 and 12months. Key predictors were baseline primary group affiliation (PGA); primary group involvement (PGI) at both baseline and 6months; and the interaction between baseline PGA and 6-month PGI. The critical effects of interest were the interactions, expressing whether associations between changes in PGI from baseline to 6months and substance use outcomes differed by primary group. None of the interactions between baseline PGA and 6-month PGI were significant, suggesting no differences in the efficacy of WFS, LifeRing, or SMART, vs. 12-step groups. Nevertheless, some PGA main effects emerged. Compared to 12-step members, those identifying SMART as their primary group at baseline fared worse across outcomes, and those affiliating with LifeRing showed lower odds of total abstinence. Still, these effects became nonsignificant when controlling for baseline alcohol recovery goal, suggesting that any group differences may be explained by selection of those with weaker abstinence motivation into LifeRing and (especially) SMART. This study makes a valuable contribution in view of the extremely limited evidence on mutual help alternatives. Results tentatively suggest that WFS, LifeRing, and SMART are as effective as 12-step groups for those with AUDs, and that this population has the best odds of success when committing to lifetime total abstinence. An optimal care plan may thus involve facilitating involvement in a broad array of mutual help groups and supporting abstinence motivation. Copyright © 2018 Elsevier Inc. All rights reserved.

Vibration-rotation interactions and ring-puckering in 3,3-dimethyl oxetane by microwave spectroscopy

NASA Astrophysics Data System (ADS)

López, Juan C.; Lesarri, Alberto G.; Villamañán, Rosa M.; Alonso, Josél.

1990-06-01

Ring puckering in 3,3-dimethyl oxetane has been investigated using microwave spectroscopy. Microwave spectra of the ground state, the first six ring-puckering excited states, and nine excited states of the methyl groups' deformation vibrations have been observed. The μa electric dipole moment component has been determined as 2.03(3) D from Stark-effect measurements. The vibrational dependence of the rotational constants is consistent with the ring-puckering potential function derived by Duckett et al. ( J. Mol. Spectrosc.69, 159-165 (1978)). Coriolis coupling interactions have been observed and are satisfactorily accounted for with a quartic centrifugal distortion Hamiltonian. The vibrational dependence of the centrifugal distortion constants has been analyzed using the theory developed by Creswell and Mills. In order to reproduce the experimental value of the vibration-rotation interaction parameter, {δμ ab}/{δQ}, a dynamical model allowing the rocking of the CH 3CCH 3 group should be used. The equilibrium ring puckering angle calculated with this model and the ring-puckering potential function is 17.5°.

Additive manufacturing of tools for lapping glass

NASA Astrophysics Data System (ADS)

Williams, Wesley B.

2013-09-01

Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

Cycloruthenated complexes from imine-based heterocycles: synthesis, characterization, and reactivity toward alkynes.

PubMed

Cuesta, Luciano; Soler, Tatiana; Urriolabeitia, Esteban P

2012-11-19

Novel cycloruthenated complexes 2 a-c, 4 a-c, and 6 a, b based on heteroaromatic cores have been synthesized by reaction of a series of heterocycle-based imines with [{RuCl(η(6)-p-cymene)}(2)(μ-Cl)(2)] and Cu(OAc)(2). This approach has proved efficient for the cyclometalation of thiophene, benzothiophene, furan, benzofuran, pyrrole, and indole derivatives. In addition, even a double cyclometalation process over the same heterocyclic ring is possible, yielding unprecedented bimetallic complexes. These ruthenacycles react with 3-hexyne through an unexpected pathway, which involves the coupling of the original imino heterocycle and acetylene followed by dearomatization to afford fused hetero-hydropyridyl ligands bonded to the {Ru(p-cymene)} organometallic moiety (i.e., 7 a-c and 8 a-c). These complexes represent, as far as we know, the first examples of this type of compound within the context of cyclometalation, and an exhaustive analysis of their structure was carried out in solution and solid state. Furthermore, these unique species react with CuCl(2), which promotes the rearomatization and the release of highly valuable aromatic fused bis-heterocycles (i.e., 9 a-c, 10 a-c, 11 a, and 12 a/12 a'), providing a novel and appealing synthetic route to this extraordinary family of molecules. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

PubMed Central

Kolb, Christof; Nölker, Georg; Lennerz, Carsten; Jetter, Hansmartin; Semmler, Verena; Pürner, Klaus; Gutleben, Klaus-Jürgen; Reents, Tilko; Lang, Klaus; Lotze, Ulrich

2012-01-01

Objective The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming. Methods Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation. Results A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62). Conclusion The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization. Trial Registration ClinicalTrials.gov NCT00512915 PMID:22745661

Use of an atrial lead with very short tip-to-ring spacing avoids oversensing of far-field R-wave.

PubMed

Kolb, Christof; Nölker, Georg; Lennerz, Carsten; Jetter, Hansmartin; Semmler, Verena; Pürner, Klaus; Gutleben, Klaus-Jürgen; Reents, Tilko; Lang, Klaus; Lotze, Ulrich

2012-01-01

The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming. Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation. A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62). The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization. ClinicalTrials.gov NCT00512915.

Self-healing fuse development

NASA Technical Reports Server (NTRS)

Jones, N. D.; Kinsinger, R. E.; Harris, L. P.

1973-01-01

The mercury-filled self-healing fuses developed for this program afford very good protection from circuit faults with rapid reclosure. Fuse performance and design parameters have been characterized. Life tests indicate a capability of 500 fuse operations. Fuse ratings are 150 v at 5, 15, 25 and 50 circuit A. A series of sample fuses using alumina and beryllia insulation have been furnished to NASA for circuit evaluation.

Efficacy and safety of the contraceptive vaginal ring (NuvaRing) compared with a combined oral contraceptive in Chinese women: a 1-year randomised trial.

PubMed

Fan, Guang Sheng; Ren, Mulan; Di, Wen; Su, Ping; Chang, Qin; Wu, Shuying; Qin, Yun; Korver, Tjeerd; Marintcheva-Petrova, Maya; Yacik, Carol; McCrary Sisk, Christine; Wang, Guoqin

2016-08-01

The aim of the study was to assess the efficacy and tolerability of the monthly vaginal ring (NuvaRing; 15 μg ethinylestradiol [EE] and 120 μg etonogestrel per day) compared with a monophasic (21/7) combined oral contraceptive (COC) containing 30 μg EE and 3 mg drospirenone in healthy Chinese women aged 18-40 years. This was a phase III, open-label, randomised multicentre trial conducted in China. Participants received NuvaRing or COC for 13 cycles (3 weeks of ring/pill treatment followed by a 1-week ring-free/pill-free period). Contraceptive efficacy was assessed by in-treatment pregnancies and expressed by the Pearl Index (PI; number of pregnancies/100 woman-years of use). Cycle control was assessed by unscheduled (breakthrough) and absence of scheduled (withdrawal) bleeding events. Safety and tolerability were assessed throughout the study. Participants were randomised either to the NuvaRing (n = 732) or to the COC (n = 214); 588 (82.4%) and 182 (78.4%) participants, respectively, completed the study. There were 10 in-treatment pregnancies in the NuvaRing group (PI 1.92; 95% confidence interval [CI] 0.92, 3.53) and five in the COC group (PI 3.12; 95% CI 1.01, 7.29). Breakthrough bleeding/spotting ranged from 18.6% (Cycle 1) to 4.2% (Cycle 11) for NuvaRing and from 21.6% (Cycle 1) to 7.9% (Cycle 11) for COC. Absence of withdrawal bleeding ranged from 8.6% (Cycle 1) to 3.0% (Cycle 11) for NuvaRing and from 14.6% (Cycle 1) to 6.4% (Cycle 5) for COC. For NuvaRing and COC, respectively, 26.6% and 25.0% of participants had treatment-related adverse events, and 7.0% and 9.1% discontinued the study as a result. Once-monthly NuvaRing is efficacious and safe for use in Chinese women.

Ring-laser gyroscope system using dispersive element(s)

NASA Technical Reports Server (NTRS)

Smith, David D. (Inventor)

2010-01-01

A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

Conformational dynamics in fluorophenylcarbamoyl-alpha-chymotrypsins.

PubMed

Kairi, M; Gerig, J T

1990-06-19

A series of fluorine-substituted diphenylcarbamoyl chlorides have been synthesized and used to prepare corresponding diphenylcarbamoylated derivatives of alpha-chymotrypsin. The enzyme is rapidly inactivated by these compounds, as has been previously observed for the unsubstituted chloride, and the derivatives are stable enough to permit extensive studies by fluorine NMR spectroscopy. In combination with previously reported results, these NMR experiments suggest that the aromatic rings of a diphenylcarbamoyl group attached to chymotrypsin may be found in two magnetically and dynamically distinguishable sites, with exchange between these sites taking place by a process that involves rotation about the carbamoyl N-CO bond and localized unfolding of the enzyme. The extent to which a given fluoroaromatic ring is found in one of these sites is dependent on the position of the fluorine substituent and the nature of the partner aromatic ring. It is found that a 2-fluorophenyl ring, when present, dominantly determines site occupation, while a 3-fluorophenyl ring has no effects that are detectably different from those of an unsubstituted phenyl ring. There is evidence for slow aromatic ring rotation within at least one of the phenyl ring interaction sites. Saturation transfer and lineshape methods provide information about the rates of interconversion of the N-phenyl groups between these sites. Line-width, spin-lattice relaxation times and fluorine-proton nuclear Overhauser effects determined at 282 and 470 MHz are reported for each system examined.

Proton nuclear magnetic resonance characterization of the aromatic residues in the variant-3 neurotoxin from Centruroides sculpturatus Ewing

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

Krishna, N.R.; Nettesheim, D.G.; Klevit, R.E.

1989-02-21

The amino acid sequence for the variant-3 (CsE-v3) toxin from the venom of the scorpion Centruroides sculpturatus Ewing contains eight aromatic residues. By use of 2D NMR spectroscopic methods, the resonances from the individual protons (NH, C{sup alpha}H, C{sup beta}H{prime}, H{double prime}, and the ring) for each of the individual aromatic residues have been completely assigned. The spatial arrangement of the aromatic ring systems with respect to each other has been qualitatively analyzed by 2D-NOESY techniques. The results show that Trp-47, Tyr-4, and Tyr-42 are in close spatial proximity to each other. The NOESY contacts and the ring current inducedmore » shifts in the resonances of the individual protons of Tyr-4 and Trp-47 suggest that the aromatic ring planes of these residues are in an orthogonal arrangement. A comparison with the published crystal structure suggests that there is a minor rearrangement of the aromatic rings in the solution phase. No 2D-NOESY contacts involving Phe-44 and Tyr-14 to any other aromatic ring protons have been observed. The pH dependence of the aromatic ring proton chemical shifts has also been studied. These results suggest that the Tyr-58 phenolic group is experiencing a hydrogen-bonding interaction with a positively charged group, while Tyr-4, -14, -38, and -40 are experiencing through-space interactions with proximal negatively charged groups. These studies define the microenvironment of the aromatic residues in the variant-3 neurotoxin in aqueous solution.« less

The Abundances of the Iron Group Elements in Early B Stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Peters, C.

FUSE observations of four sharp-lined early B main-sequence band stars in the Magellanic Clouds will be carried through to determine the abundances of the heavy elements, especially those of the Fe group. The FUSE spectral region contains numerous Fe III lines, including the resonance multiplet (UV1) near 1130 A that is excellent for abundance determinations and two strong multiplets of V III, an ion that does not produce measurable lines longward of 1200 A in metal-deficient stars. In addition there are several measurable lines from Cr III and Mn III. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, ground-based studies do not yield this information because measurable lines from these species, except for a few Fe III lines, are found only in the UV spectral region. The abundances of heavy elements provide information on the production of such elements in previous generations of stars. From FUSE data obtained in Cycle 3 we are determining the abundances of the Fe group elements in two sharp-lined early B stars in the SMC (AV 304, a field star, and NGC346-637, a star in a mini-starburst cluster). This project will allow one to compare the abundances in AV 304 and NGC346-637 with those in the LMC and other regions in the SMC and look for asymmetry in heavy element production in the Magellanic Clouds.

Materials Testing and Cost Modeling for Composite Parts Through Additive Manufacturing

DTIC Science & Technology

2016-04-30

FDM include plastic jet printing (PJP), fused filament modeling ( FFM ), and fused filament fabrication (FFF). FFF was coined by the RepRap project to...additive manufacturing processes? • Fused deposition modeling (FDM) trademarked by Stratasys • Fused filament modeling ( FFM ) and fused filament

New group-V elemental bilayers: A tunable structure model with four-, six-, and eight-atom rings

NASA Astrophysics Data System (ADS)

Kong, Xiangru; Li, Linyang; Leenaerts, Ortwin; Liu, Xiong-Jun; Peeters, François M.

2017-07-01

Two-dimensional group-V elemental materials have attracted widespread attention due to their nonzero band gap while displaying high electron mobility. Using first-principles calculations, we propose a series of new elemental bilayers with group-V elements (Bi, Sb, As). Our study reveals the dynamical stability of four-, six-, and eight-atom ring structures, demonstrating their possible coexistence in such bilayer systems. The proposed structures for Sb and As are large-gap semiconductors that are potentially interesting for applications in future nanodevices. The Bi structures have nontrivial topological properties with a direct nontrivial band gap. The nontrivial gap is shown to arise from a band inversion at the Brillouin zone center due to the strong intrinsic spin-orbit coupling in Bi atoms. Moreover, we demonstrate the possibility of tuning the properties of these materials by enhancing the ratio of six-atom rings to four- and eight-atom rings, which results in wider nontrivial band gaps and lower formation energies.

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

PubMed

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M; Yusoff, Siti Fairus M

2014-09-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro-benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro-benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl-thio-amide group and its attached ring is 12.98 (10)°. The major twists in the mol-ecule occur about the C-N-N-C bonds [torsion angle = -138.7 (2)°] and the Car-Car-C-N (ar = aromatic) bonds [-132.0 (2)°]. An intra-molecular N-H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯S hydrogen bonds, generating (001) sheets. Weak C-H⋯O and C-H⋯F inter-actions are also observed.

The Pedagogical Examples of Groups and Rings That Algebraists Think Are Most Important in an Introductory Course

ERIC Educational Resources Information Center

Cook, John Paul; Fukawa-Connelly, Tim

2015-01-01

This article reports on an exploratory study designed to investigate the reasoning behind algebraists' selection of examples. Variation theory provided a lens to analyze their collections of examples. Our findings include the classes of examples of groups and rings that algebraists believe to be most pedagogically useful. Chief among their…

(E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-phenyl-prop-2-en-1-one.

PubMed

Niu, Chao; Liu, Y Q; He, Y W; Aisa, H A

2013-05-01

The title compound, C19H20O6, consists of a tetra-substituted benzene ring with one substituent being an α,β-unsaturated cinnamoyl group, which forms an extended conjugated system in the mol-ecule. In addition, two meth-oxy-meth-oxy and one hy-droxy group are bonded to the central benzene ring. The dihedral angle between eh rings is 10.22 (10)°. An intra-molecular hydrogen bond is observed between the hy-droxy group and the carbonyl O atom. One of the meth-oxy-meth-oxy substituents is conformationally disordered over two sets of sites with site-occupation factors of 0.831 (3) and 0.169 (3).

Copper-Catalyzed Cyclopropanol Ring Opening Csp(3)-Csp(3) Cross-Couplings with (Fluoro)Alkyl Halides.

PubMed

Ye, Zhishi; Gettys, Kristen E; Shen, Xingyu; Dai, Mingji

2015-12-18

Novel and general copper-catalyzed cyclopropanol ring opening cross-coupling reactions with difluoroalkyl bromides, perfluoroalkyl iodides, monofluoroalkyl bromides, and 2-bromo-2-alkylesters to synthesize various β-(fluoro)alkylated ketones are reported. The reactions feature mild conditions and excellent functional group compatibility and can be scaled up to gram scale. Preliminary mechanistic studies suggest the involvement of radical intermediates. The difluoroalkyl-alkyl cross-coupling products can also be readily converted to more valuable and diverse gem-difluoro-containing compounds by taking advantage of the carbonyl group resulting from cyclopropanol ring opening.

Femtosecond Laser in situ Keratomileusis Flap Creation in Narrow Palpebral Fissure Eyes without Suction.

PubMed

Chang, John S M; Law, Antony K P; Ng, Jack C M; Cheng, May S Y

2017-01-01

To evaluate a surgical technique used in eyes with narrow palpebral fissure undergoing femtosecond laser flap creation without suction during laser in situ keratomileusis (LASIK). All data of 2 patient groups were collected through chart review. Group 1 consisted of 6 eyes with narrow palpebral fissure in which the suction ring was manually fixated and femtosecond laser was applied accordingly. Thirty comparison cases were randomly drawn from among eyes that underwent a standard LASIK procedure matched for age and preoperative refraction (group 2). Only 1 eye of each patient was selected to compare the refractive and visual outcomes between groups. In all group 1 eyes, the flaps were created successfully with manual fixation of the suction ring without suction. No eyes lost 2 or more lines of vision. No significant difference was found in the safety and refractive outcomes between groups. Manual fixation of the suction ring in eyes with narrow palpebral fissure without suction was feasible for flap creation during LASIK.

Femtosecond Laser in situ Keratomileusis Flap Creation in Narrow Palpebral Fissure Eyes without Suction

PubMed Central

Chang, John S.M.; Law, Antony K.P.; Ng, Jack C.M.; Cheng, May S.Y.

2017-01-01

Purpose To evaluate a surgical technique used in eyes with narrow palpebral fissure undergoing femtosecond laser flap creation without suction during laser in situ keratomileusis (LASIK). Methods All data of 2 patient groups were collected through chart review. Group 1 consisted of 6 eyes with narrow palpebral fissure in which the suction ring was manually fixated and femtosecond laser was applied accordingly. Thirty comparison cases were randomly drawn from among eyes that underwent a standard LASIK procedure matched for age and preoperative refraction (group 2). Only 1 eye of each patient was selected to compare the refractive and visual outcomes between groups. Results In all group 1 eyes, the flaps were created successfully with manual fixation of the suction ring without suction. No eyes lost 2 or more lines of vision. No significant difference was found in the safety and refractive outcomes between groups. Conclusion Manual fixation of the suction ring in eyes with narrow palpebral fissure without suction was feasible for flap creation during LASIK. PMID:28690535

Usefulness of 2D fusion of postmortem CT and antemortem chest radiography studies for human identification.

PubMed

Shinkawa, Norihiro; Hirai, Toshinori; Nishii, Ryuichi; Yukawa, Nobuhiro

2017-06-01

To determine the feasibility of human identification through the two-dimensional (2D) fusion of postmortem computed tomography (PMCT) and antemortem chest radiography. The study population consisted of 15 subjects who had undergone chest radiography studies more than 12 months before death. Fused images in which a chest radiograph was fused with a PMCT image were obtained for those subjects using a workstation, and the minimum distance gaps between corresponding anatomical landmarks (located at soft tissue and bone sites) in the images obtained with the two modalities were calculated. For each fused image, the mean of all these minimum distance gaps was recorded as the mean distance gap (MDG). For each subject, the MDG obtained for the same-subject fused image (i.e., where both of the images that were fused derived from that subject) was compared with the MDGs for different-subject fused images (i.e., where only one of the images that were fused derived from that subject; the other image derived from a different subject) in order to determine whether same-subject fused images can be reliably distinguished from different-subject fused images. The MDGs of the same-subject fused images were found to be significantly smaller than the MDGs of the different-subject fused images (p < 0.01). When bone landmarks were used, the same-subject fused image was found to be the fused image with the lowest MDG for 33.3% of the subjects, the fused image with the lowest or second-lowest MDG for 73.3% of the subjects, and the fused image with the lowest, second-lowest, or third-lowest MDG for 86.7% of the subjects. The application of bone landmarks rather than soft-tissue landmarks made it significantly more likely that, for each subject, the same-subject fused image would have the lowest MDG (or one of the lowest MDGs) of all the fused images compared (p < 0.05). The 2D fusion of antemortem chest radiography and postmortem CT images may assist in human identification.

Characterization and diagenesis of strong-acid carboxyl groups in humic substances

USGS Publications Warehouse

Leenheer, J.A.; Wershaw, R. L.; Brown, G.K.; Reddy, M.M.

2003-01-01

A small fraction of carboxylic acid functional groups in humic substances are exceptionally acidic with pKa values as low as 0.5. A review of acid-group theory eliminated most models and explanations for these exceptionally acidic carboxyl groups. These acidic carboxyl groups in Suwannee River fulvic acid were enriched by a 2-stage fractionation process and the fractions were characterized by elemental, molecular-weight, and titrimetric analyses, and by infrared and 13C- and 1H-nuclear magnetic resonance spectrometry. An average structural model of the most acidic fraction derived from the characterization data indicated a high density of carboxyl groups clustered on oxygen-heterocycle alicyclic rings. Intramolecular H-bonding between adjacent carboxyl groups in these ring structures enhanced stabilization of the carboxylate anion which results in low pKa1 values. The standard, tetrahydrofuran tetracarboxylic acid, was shown to have similar acidity characteristics to the highly acidic fulvic acid fraction. The end products of 3 known diagenetic pathways for the formation of humic substances were shown to result in carboxyl groups clustered on oxygen-heterocycle alicyclic rings.

[Effect of sintering gold paste coating on the bonding strength of pure titanium and three low-fusing porcelains].

PubMed

Zhang, Ya-li; Luo, Xiao-ping; Zhou, Li

2012-05-01

To study the effect of sintering gold paste coating of pure titanium on the adhesion of three porcelains following the protocol ISO 9693, and to investigate the titanium-porcelains interfaces. Sixty machined pure titanium samples were prepared in a rectangular shape according to ISO 9693 and divided equally into six groups. Half of the strips were coated with gold paste (Deckgold) and sintered. Three ultra-low-fusing dental porcelains (I: Initial Ti, S: Super porcelain Ti-22, T: TitanKeramik) were fused onto the titanium surfaces. A thin layer of bonding agent was only applied on the surfaces of uncoated gold specimens. The interface of the porcelain and titanium was observed with a field emission scanning electron microscope (FE-SEM) after metallographic preparation and sputtered with a very thin carbon layer of the embedded titanium-porcelain interface. After three-point bending test was performed, optical stereomicroscope was used to characterize the titanium-porcelains adhesion and determine the mode of failure. FE-SEM illustrated intermetallic compounds of Au-Ti formed with some visible microcracks in the gold layer and the interface of gold layer and ceramic. All the uncoated gold titanium-porcelain system showed predominately adhesive fracture at the titanium oxidation, whereas the failure modes in all gold coated systems were cohesive and adhesive, mainly cohesive. The three-point-bending test showed that the bonding strength of GS and GI groups [(37.08 ± 4.32) and (36.20 ± 2.40) MPa] were higher than those in uncoated groups [(31.56 ± 3.74) and (30.88 ± 2.60) MPa, P < 0.05], while no significant difference was found between T group and GT group (P > 0.05). The gold paste intermediate coatings can improve bond strengths of Super porcelain Ti-22 system and Initial Ti system, which have potential applications in clinical fields.

A Novel Group-Fused Sparse Partial Correlation Method for Simultaneous Estimation of Functional Networks in Group Comparison Studies.

PubMed

Liang, Xiaoyun; Vaughan, David N; Connelly, Alan; Calamante, Fernando

2018-05-01

The conventional way to estimate functional networks is primarily based on Pearson correlation along with classic Fisher Z test. In general, networks are usually calculated at the individual-level and subsequently aggregated to obtain group-level networks. However, such estimated networks are inevitably affected by the inherent large inter-subject variability. A joint graphical model with Stability Selection (JGMSS) method was recently shown to effectively reduce inter-subject variability, mainly caused by confounding variations, by simultaneously estimating individual-level networks from a group. However, its benefits might be compromised when two groups are being compared, given that JGMSS is blinded to other groups when it is applied to estimate networks from a given group. We propose a novel method for robustly estimating networks from two groups by using group-fused multiple graphical-lasso combined with stability selection, named GMGLASS. Specifically, by simultaneously estimating similar within-group networks and between-group difference, it is possible to address inter-subject variability of estimated individual networks inherently related with existing methods such as Fisher Z test, and issues related to JGMSS ignoring between-group information in group comparisons. To evaluate the performance of GMGLASS in terms of a few key network metrics, as well as to compare with JGMSS and Fisher Z test, they are applied to both simulated and in vivo data. As a method aiming for group comparison studies, our study involves two groups for each case, i.e., normal control and patient groups; for in vivo data, we focus on a group of patients with right mesial temporal lobe epilepsy.

(Z)-3-Methyl-4-[1-(4-methyl­anilino)propyl­idene]-1-phenyl-1H-pyrazol-5(4H)-one

PubMed Central

Sharma, Naresh; Vyas, Komal M.; Jadeja, R. N.; Kant, Rajni; Gupta, Vivek K.

2013-01-01

In the title mol­ecule, C20H21N3O, the central pyrazole ring forms dihedral angles of 4.75 (9) and 49.11 (9)°, respectively, with the phenyl and methyl-substituted benzene rings. The dihedral angle between the phenyl and benzene rings is 51.76 (8)°. The amino group and carbonyl O atom are involved in an intra­molecular N—H⋯O hydrogen bond. In the crystal, π–π inter­actions are observed between benzene rings [centroid–centroid seperation = 3.892 (2) Å] and pyrazole rings [centroid–centroid seperation = 3.626 (2) Å], forming chains along [111]. The H atoms of the methyl group on the p-tolyl substituent were refined as disordered over two sets of sites in a 0.60 (4):0.40 (4) ratio. PMID:24109353

Fungi as a source of natural coumarins production.

PubMed

Costa, Tania Maria; Tavares, Lorena Benathar Ballod; de Oliveira, Débora

2016-08-01

Natural coumarins and derivatives are compounds that occur naturally in several organisms (plant, bacteria, and fungi) consisting of fused benzene and α-pyrone rings. These compounds show high technological potential applications in agrochemical, food, pharmaceuticals, and cosmetics industries. Therefore, the need for bulk production of coumarins and the advancement of the chemical and pharmaceutical industries led to the development of synthetic coumarin. However, biotransformation process, synthetic bioengineering, metabolic engineering, and bioinformatics have proven effective in the production of natural products. Today, these biological systems are recognized as green chemistry innovation and business strategy. This review article aims to report the potential of fungi for synthesis of coumarin. These microorganisms are described as a source of natural products capable of synthesizing many bioactive metabolites. The features, classification, properties, and industrial applications of natural coumarins as well as new molecules obtained by basidiomycetes and ascomycetes fungi are reported in order to explore a topic not yet discussed in the scientific literature.

Isolation of pyrrolocins A-C: cis- and trans-decalin tetramic acid antibiotics from an endophytic fungal-derived pathway.

PubMed

Jadulco, Raquel C; Koch, Michael; Kakule, Thomas B; Schmidt, Eric W; Orendt, Anita; He, Haiyin; Janso, Jeffrey E; Carter, Guy T; Larson, Erica C; Pond, Christopher; Matainaho, Teatulohi K; Barrows, Louis R

2014-11-26

Three new decalin-type tetramic acid analogues, pyrrolocins A (1), B (2), and C (3), were defined as products of a metabolic pathway from a fern endophyte, NRRL 50135, from Papua New Guinea. NRRL 50135 initially produced 1 but ceased its production before chemical or biological evaluation could be completed. Upon transfer of the biosynthetic pathway to a model host, 1-3 were produced. All three compounds are structurally related to equisetin-type compounds, with 1 and 3 having a trans-decalin ring system, while 2 has a cis-fused decalin. All were active against Mycobacterium tuberculosis, with the trans-decalin analogues 1 and 3 exhibiting lower MICs than the cis-decalin analogue 2. Here we report the isolation, structure elucidation, and antimycobacterial activities of 1-3 from the recombinant expression as well as the isolation of 1 from the wild-type fungus NRRL 50135.