Feasibility of maintaining in-plane polarization for a storage ring EDM search

Science.gov (United States)

Stephenson, Edward; Storage Ring EDM Collaboration

2014-09-01

A search for an electric dipole moment (EDM) on charged particles using a storage ring requires beam polarization lifetimes approaching 1000 s for in-plane polarization. A feasibility study using beam bunching and sextupole field adjustment is underway with a 0.97-GeV/c vector-polarized deuteron beam at COSY. The polarimeter consists of a thick carbon target positioned at the edge of the beam and the EDDA scintillation detectors. The DAQ system assigns a clock time to each polarimeter event. Once calibrated against the RF-cavity, the clock time is used to select events associated with a maximal sideways polarization (precessing at 120 kHz). With this tool, the in-plane polarization magnitude is tracked versus time. Electron cooling reduces the depolarization from finite emittance and second-order momentum spread acting through synchrotron oscillations. Further lifetime improvement to the level of hundreds of seconds is achieved by adjusting sextupole fields located in the COSY ring arcs at places of large transverse beta functions and dispersion. The dependence of the reciprocal of the lifetime on sextupole field strength is nearly linear, permitting an easy location of the best field values. These typically occur near loci of zero chromaticity. A search for an electric dipole moment (EDM) on charged particles using a storage ring requires beam polarization lifetimes approaching 1000 s for in-plane polarization. A feasibility study using beam bunching and sextupole field adjustment is underway with a 0.97-GeV/c vector-polarized deuteron beam at COSY. The polarimeter consists of a thick carbon target positioned at the edge of the beam and the EDDA scintillation detectors. The DAQ system assigns a clock time to each polarimeter event. Once calibrated against the RF-cavity, the clock time is used to select events associated with a maximal sideways polarization (precessing at 120 kHz). With this tool, the in-plane polarization magnitude is tracked versus time. Electron

Saturn's Rings Edge-on

Science.gov (United States)

1995-01-01

In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian; Mi, Wenbo; Wang, Xiaocha; Wang, Xuhui

2015-01-01

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

KAUST Repository

Zhang, Qian

2015-05-27

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

Bis(2-formylphenyl benzene-1,2-dicarboxylate

Directory of Open Access Journals (Sweden)

Shaaban K. Mohamed

2018-02-01

Full Text Available The asymmetric unit of the title compound, C22H14O6, consists of two independent molecules differing in the orientations of the ester groups. In one molecule, the two terminal benzene rings are inclined to the central benzene ring by 4.99 (13 and 77.46 (13°, while in the other the corresponding angles are 11.03 (13 and 88.09 (12°. In the crystal, molecules are connected into a ribbon structure running along [101] via C—H...O and C—H...π interactions. Adjacent ribbons are further linked by additional C—H...O and C—H...π interactions. The crystal studied was a non-merohedral twin [twin law (0.986 − 0.073 − 0.008, 0.323 1.036 0.148, −0.121 − 0.102 0.942], the ratio of components being 0.937 (4:0.063 (4.

The enhanced spin-polarized transport behaviors through cobalt benzene-porphyrin-benzene molecular junctions: the effect of functional groups

Science.gov (United States)

Cheng, Jue-Fei; Zhou, Liping; Wen, Zhongqian; Yan, Qiang; Han, Qin; Gao, Lei

2017-05-01

The modification effects of the groups amino (NH2) and nitro (NO2) on the spin polarized transport properties of the cobalt benzene-porphyrin-benzene (Co-BPB) molecule coupled to gold (Au) nanowire electrodes are investigated by the nonequilibrium Green’s function method combined with the density functional theory. The calculation results show that functional groups can lead to the significant spin-filter effect, enhanced low-bias negative differential resistance (NDR) behavior and novel reverse rectifying effect in Co-BPB molecular junction. The locations and types of functional groups have distinct influences on spin-polarized transport performances. The configuration with NH2 group substituting H atom in central porphyrin ring has larger spin-down current compared to that with NO2 substitution. And Co-BPB molecule junction with NH2 group substituting H atom in side benzene ring shows reverse rectifying effect. Detailed analyses confirm that NH2 and NO2 group substitution change the spin-polarized transferred charge, which makes the highest occupied molecular orbitals (HOMO) of spin-down channel of Co-BPB closer to the Fermi level. And the shift of HOMO strengthens the spin-polarized coupling between the molecular orbitals and the electrodes, leading to the enhanced spin-polarized behavior. Our findings might be useful in the design of multi-functional molecular devices in the future.

(1-Phenyl-1H-1,2,3-triazol-4-ylmethyl pyridine-3-carboxylate

Directory of Open Access Journals (Sweden)

Zakirjon Karimov

2010-07-01

Full Text Available In the title compound, C15H12N4O2, the dihedral angle between the planes of the nicotinoyloxy fragment and triazole ring is 88.61 (5°. The dihedral angle between the planes of triazole and benzene rings is 16.54 (11°. The crystal structure is stabilized by intermolecular C—H...N, C—H...O and C—H...π(triazole hydrogen bonds and aromatic π–π stacking interactions between the benzene and triazole rings [centroid–centroid distance = 3.895 (1 Å

Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

DEFF Research Database (Denmark)

Emmerling, Uwe; Rasmussen, Peter

1998-01-01

a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC......Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...

1,2-Bis(4-ethynylphenyldisulfane

Directory of Open Access Journals (Sweden)

Hong-Jun Zhu

2010-03-01

Full Text Available In the title compound, C16H10S2, the S atoms are almost coplanar with the benzene rings to which they are bonded [deviations of 0.092 (1 and 0.022 (1 Å from their respective ring planes]. The benzene rings enclose a dihedral angle of 79.17 (3°. An intramolecular C—H...S hydrogen bond results in the formation of a five-membered ring. In the crystal structure, molecules are stacked parallel to the a axis direction. π–π interactions between benzene rings are present, with a face-to-face stacking distance of 3.622 (10 Å.

A Simple, Rapid and Mild One Pot Synthesis of Benzene Ring Acylated and Demethylated Analogues of Harmine under Solvent-free Conditions

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Bina S. Siddiqui

2008-08-01

Full Text Available A simple, rapid, solvent-free, room temperature one pot synthesis of benzene ring acylated and demethylated analogues of harmine using acyl halides/acid anhydrides and AlCl3 has been developed. Eight different acyl halides/acid anhydrides were used in the synthesis. The resulting mixture of products was separated by column chromatography to afford 10- and 12-monoacyl analogues, along with 10,12-diacyl-11-hydroxy products. In five cases the corresponding 10-acyl-11-hydroxy analogues were also obtained. Yields from the eight syntheses (29 products in total were in the 6-34% range and all compounds were fully characterized.

Flexible Enantioselectivity of Tryptophanase Attributable to Benzene Ring in Heterocyclic Moiety of D-Tryptophan

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Akihiko Shimada

2012-05-01

Full Text Available The invariance principle of enzyme enantioselectivity must be absolute because it is absolutely essential to the homochiral biological world. Most enzymes are strictly enantioselective, and tryptophanase is one of the enzymes with extreme absolute enantioselectivity for L-tryptophan. Contrary to conventional knowledge about the principle, tryptophanase becomes flexible to catalyze D-tryptophan in the presence of diammonium hydrogenphosphate. Since D-amino acids are ordinarily inert or function as inhibitors even though they are bound to the active site, the inhibition behavior of D-tryptophan and several inhibitors involved in this process was examined in terms of kinetics to explain the reason for this flexible enantioselectivity in the presence of diammonium hydrogenphosphate. Diammonium hydrogenphosphate gave tryptophanase a small conformational change so that D-tryptophan could work as a substrate. As opposed to other D-amino acids, D-tryptophan is a very bulky amino acid with a benzene ring in its heterocyclic moiety, and so we suggest that this structural feature makes the catalysis of D-tryptophan degradation possible, consequently leading to the flexible enantioselectivity. The present results not only help to understand the mechanism of enzyme enantioselectivity, but also shed light on the origin of homochirality.

N,N′-Bis[3,5-bis(2,6-diisopropylphenylphenyl]butane-2,3-diimine

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Tracy L. Lohr

2011-09-01

Full Text Available The title molecule, C64H80N2, lies on an inversion center wherein the central butanediimine fragment [N=C(Me—C(Me=N] is essentially planar [maximum deviation = 0.002 (2 Å] and its mean plane forms a dihedral of 70.88 (10° with the attached benzene ring. In the symmetry-unique part of the molecule, the dihedral angles between the benzene ring bonded to the N atom and the other two benzene rings are 89.61 (6 and 82.77 (6°.

3′,6′-Bis(diethylamino-3H-spiro[2-benzothiophene-1,9′-xanthene]-3-thione

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Bing-Yuan Su

2008-11-01

Full Text Available The title compound, C28H30N2OS2, was obtained by thionation of 3′,6′-bis(diethylamino-3H-spiro[isobenzofuran-1,9′-xanthene]-3-one with 2,4-bis(p-methoxyphenyl-1,3-dithiadiphosphetane disulfide (Lawesson's reagent. The planes of the two benzene rings of the xanthene system are inclined at a dihedral angle of 17.4 (1°, and the plane of the dithiophthalide group and the planes through the two benzene rings of the xanthene system make dihedral angles of 80.2 (1 and 82.8 (1°, respectively.

Methyl 3′,5′-dimethoxybiphenyl-4-carboxylate

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Sami Nummelin

2013-03-01

Full Text Available In the title compound, C16H16O4, the dihedral angle between the benzene rings is 28.9 (2°. In the crystal, molecules are packed in layers parallel to the b axis in which they are connected via weak intermolecular C—H...O contacts. Face-to-face π–π interactions also exist between the benzene rings of adjacent molecules, with centroid–centroid and plane-to-plane shift distances of 3.8597 (14 and 1.843 (2 Å, respectively.

Crystal structure of 1,3-bis(2,3-dimethylquinoxalin-6-ylbenzene

Directory of Open Access Journals (Sweden)

Charles E. Diesendruck

2015-12-01

Full Text Available The title compound, C26H22N4 (I, was synthesized by C—H iridium-catalyzed borylation followed by Suzuki coupling. The molecular structure of (I consists of a central benzene ring with 3-dimethylquinoxalin-6-yl groups at the 1 and 3 positions. These 2,3-dimethylquinoxalin-6-yl groups twist significantly out of the plane of the benzene ring. There are intermolecular π–π interactions which result in a two-dimensional extended structure. The layers extend parallel to the ab plane and stack along the c axis.

Possibility designing half-wave and full-wave molecular rectifiers by using single benzene molecule

Science.gov (United States)

Abbas, Mohammed A.; Hanoon, Falah H.; Al-Badry, Lafy F.

2018-02-01

This work focused on possibility designing half-wave and full-wave molecular rectifiers by using single and two benzene rings, respectively. The benzene rings were threaded by a magnetic flux that changes over time. The quantum interference effect was considered as the basic idea in the rectification action, the para and meta configurations were investigated. All the calculations are performed by using steady-state theoretical model, which is based on the time-dependent Hamiltonian model. The electrical conductance and the electric current are considered as DC output signals of half-wave and full-wave molecular rectifiers. The finding in this work opens up the exciting potential to use these molecular rectifiers in molecular electronics.

2-(1H-Benzimidazol-2-ylphenol

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S. M. Prakash

2014-02-01

Full Text Available The title molecule, C13H10N2O, is essentially planar, the maximum deviation from the plane of the non-H atoms being 0.016 (2 Å. The imidazole ring makes a dihedral angle of 0.37 (13° with the attached benzene ring. An intramolecular O—H...N hydrogen bond generates an S(6 ring motif. In the crystal, molecules are linked through N—H...O hydrogen bonds, forming chains propagating in [001]. The crystal packing also features four π–π stacking interactions involving the imidazole ring, fused benzene ring and attached benzene ring system [centroid–centroid distances = 3.6106 (17, 3.6108 (17, 3.6666 (17 and 3.6668 (17 Å].

Electronic structure of molecules of substituted benzenes by x-ray spectroscopy. I. Nitrobenzene

International Nuclear Information System (INIS)

Yumatov, V.D.; Murakhtanov, V.V.; Salakhutdinov, N.F.; Okotrub, A.V.; Mazalov, L.N.; Logunova, L.G.; Koptyug, V.A.; Furin, G.G.

1988-01-01

The electronic structure of the nitrobenzene molecule has been studied by x-ray spectroscopy with the aid of quantum-chemical calculations. The structure of the molecular orbitals of nitrobenzene has been compared with the structure of benzene and nitrogen dioxide. It has been shown in the framework of a fragment-by-fragment analysis that the interaction of the highest occupied π orbitals of the benzene ring and the nitro group is weak

Theoretical studies on the effect of benzene and thiophene groups on the charge transport properties of Isoindigo and its derivatives

Science.gov (United States)

Jia, Xu-Bo; Wei, Hui-Ling; Shi, Ya-Ting; Shi, Ya-Rui; Liu, Yu-Fang

2017-12-01

In this work, the charge transport properties of Isoindigo (II) and its derivatives which have the same hexyl chain were theoretically investigated by the Marcus-Hush theory combined with density functional theory (DFT). Here we demonstrate that the changes of benzene and thiophene groups in molecular structure have an important influence on the charge transport properties of organic semiconductor. The benzene rings of II are replaced by thiophenes to form the thienoisoindigo (TII), and the addition of benzene rings to the TII form the benzothienoisoindigo (BTII). The results show that benzene rings and thiophenes change the chemical structure of crystal molecules, which lead to different molecule stacking, thus, the length of hydrogen bond was changed. A shorter intermolecular hydrogen bond lead to tighter molecular stacking, which reduces the center-to-center distance and enhances the ability of charge transfer. At the same time, we theoretically demonstrated that II and BTII are the ambipolar organic semiconductor. BTII has better carrier mobility. The hole mobility far greater than electron mobility in TII, which is p-type organic semiconductor. Among all hopping path, we find that the distance of face-to-face stacking in II is the shortest and the electron-transport electronic coupling Ve is the largest, but II has not a largest anisotropic mobility, because the reorganization energy has a greater influence on the mobility than the electronic coupling. This work is helpful for designing ambipolar organic semiconductor materials with higher charge transport properties by introducing benzene ring and thiophene.

4-[(E-(5-tert-Butyl-2-hydroxyphenyldiazenyl]benzoic acid benzene hemisolvate

Directory of Open Access Journals (Sweden)

Edward R. T. Tiekink

2010-03-01

Full Text Available The title benzene hemisolvate, C17H18N2O3·0.5C6H6, features an essentially planar (the r.m.s. deviation of the non-H atoms, excluding methyl-C, is 0.071 Å diazo molecule with an E conformation about the N=N bond, and a half-molecule of benzene disposed about a centre of inversion. The dihedral angle formed between the benzene rings of the diazo molecule is 7.69 (12°. In the crystal, centrosymmetrically related dimers associate via the eight-membered carboxylic acid dimer synthon, {...HOC(=O}2, and these are connected into a supramolecular chain along the b axis via C—H...O contacts.

Electronic structure of benzene adsorbed on Ni and Cu surfaces

Energy Technology Data Exchange (ETDEWEB)

Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

1997-04-01

Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

Benzene oxidation at diamond electrodes: comparison of microcrystalline and nanocrystalline diamonds.

Science.gov (United States)

Pleskov, Yu V; Krotova, M D; Elkin, V V; Varnin, V P; Teremetskaya, I G; Saveliev, A V; Ralchenko, V G

2012-08-27

A comparative study of benzene oxidation at boron-doped diamond (BDD) and nitrogenated nanocrystalline diamond (NCD) anodes in 0.5 M K(2)SO(4) aqueous solution is conducted by using cyclic voltammetry and electrochemical impedance spectroscopy. It is shown by measurements of differential capacitance and anodic current that during the benzene oxidation at the BDD electrode, adsorption of a reaction intermediate occurs, which partially blocks the electrode surface and lowers the anodic current. At the NCD electrode, benzene is oxidized concurrently with oxygen evolution, a (quinoid) intermediate being adsorbed at the electrode. The adsorption and the electrode surface blocking are reflected in the impedance-frequency and impedance-potential complex-plane plots. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

1-(3,4-Difluorobenzyl-4-(4-methylphenylsulfonylpiperazine

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S. Sreenivasa

2013-07-01

Full Text Available In the title compound, C18H20F2N2O2S, the central piperazine ring adopts a chair conformation. The dihedral angle between the two benzene rings is 40.20°, whereas those between the piperazine ring (considering the best fit plane through all the non-H atoms and the sulfonyl-bound benzene and difluorobenzene rings are 74.96 and 86.16°, respectively. In the crystal, molecules are stacked along the a axis through weak C—H...O and C—H...F interactions.

Electron states in quantum rings with structural distortions under axial or in-plane magnetic fields

International Nuclear Information System (INIS)

Planelles, J; Rajadell, F; Climente, J I

2007-01-01

A comprehensive study of anisotropic quantum rings, QRs, subject to axial and in-plane magnetic field, both aligned and transverse to the anisotropy direction, is carried out. Elliptical QRs for a wide range of eccentricity values and also perfectly circular QRs including one or more barriers disturbing the QR current are considered. These models mimic anisotropic geometry deformations and mass diffusion occurring in the QR fabrication process. Symmetry considerations and simplified analytical models supply physical insight into the obtained numerical results. Our study demonstrates that, except for unusual extremely large eccentricities, QR geometry deformations only appreciably influence a few low-lying states, while the effect of barriers disturbing the QR current is stronger and affects all studied states to a similar extent. We also show that the response of the electron states to in-plane magnetic fields provides accurate information on the structural anisotropy

Formation of a new benzene-ethane co-crystalline structure under cryogenic conditions.

Science.gov (United States)

Vu, Tuan Hoang; Cable, Morgan L; Choukroun, Mathieu; Hodyss, Robert; Beauchamp, Patricia

2014-06-12

We report the first experimental finding of a solid molecular complex between benzene and ethane, two small apolar hydrocarbons, at atmospheric pressure and cryogenic temperatures. Considerable amounts of ethane are found to be incorporated inside the benzene lattice upon the addition of liquid ethane onto solid benzene at 90-150 K, resulting in formation of a distinctive co-crystalline structure that can be detected via micro-Raman spectroscopy. Two new features characteristic of these co-crystals are observed in the Raman spectra at 2873 and 1455 cm(-1), which are red-shifted by 12 cm(-1) from the υ1 (a1g) and υ11 (eg) stretching modes of liquid ethane, respectively. Analysis of benzene and ethane vibrational bands combined with quantum mechanical modeling of isolated molecular dimers reveal an interaction between the aromatic ring of benzene and the hydrogen atoms of ethane in a C-H···π fashion. The most favored configuration for the benzene-ethane dimer is the monodentate-contact structure, with a calculated interaction energy of 9.33 kJ/mol and an equilibrium bonding distance of 2.66 Å. These parameters are comparable to those for a T-shaped co-crystalline complex between benzene and acetylene that has been previously reported in the literature. These results are relevant for understanding the hydrocarbon cycle of Titan, where benzene and similar organics may act as potential hydrocarbon reservoirs due to this incorporation mechanism.

Algebraic Structures on MOD Planes

OpenAIRE

Kandasamy, Vasantha; Ilanthenral, K.; Smarandache, Florentin

2015-01-01

Study of MOD planes happens to a very recent one. In this book, systematically algebraic structures on MOD planes like, MOD semigroups, MOD groups and MOD rings of different types are defined and studied. Such study is innovative for a large four quadrant planes are made into a small MOD planes. Several distinct features enjoyed by these MOD planes are defined, developed and described.

Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs

Science.gov (United States)

Quitián-Lara, Heidy M.; Fantuzzi, Felipe; Nascimento, Marco A. C.; Wolff, Wania; Boechat-Roberty, Heloisa M.

2018-02-01

Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C6H6) rings, emit infrared radiation (3–12 μm) due to the vibrational transitions of the C–H bonds of the aromatic rings. The 3.3 μm aromatic band is generally accompanied by the band at 3.4 μm assigned to the vibration of aliphatic C–H bonds of compounds such as PAHs with an excess of peripheral H atoms (H n –PAHs). Herein we study the stability of fully hydrogenated benzene (or cyclohexane, C6H12) under the impact of stellar radiation in the photodissociation region (PDR) of NGC 7027. Using synchrotron radiation and time-of-flight mass spectrometry, we investigated the ionization and dissociation processes at energy ranges of UV (10–200 eV) and soft X-rays (280–310 eV). Density Functional Theory (DFT) calculations were used to determine the most stable structures and the relevant low-lying isomers of singly charged C6H12 ions. Partial Ion Yield (PIY) analysis gives evidence of the higher tendency toward dissociation of cyclohexane in comparison to benzene. However, because of the high photoabsorption cross-section of benzene at the C1s resonance edge, its photodissociation and photoionization cross-sections are enhanced, leading to a higher efficiency of dissociation of benzene in the PDR of NGC 7027. We suggest that a similar effect is experienced by PAHs in X-ray photon-rich environments, which ultimately acts as an auxiliary protection mechanism of super-hydrogenated polycyclic hydrocarbons. Finally, we propose that the single photoionization of cyclohexane could enhance the abundance of branched molecules in interstellar and circumstellar media.

Quantum Monte Carlo calculations of van der Waals interactions between aromatic benzene rings

Science.gov (United States)

Azadi, Sam; Kühne, T. D.

2018-05-01

The magnitude of finite-size effects and Coulomb interactions in quantum Monte Carlo simulations of van der Waals interactions between weakly bonded benzene molecules are investigated. To that extent, two trial wave functions of the Slater-Jastrow and Backflow-Slater-Jastrow types are employed to calculate the energy-volume equation of state. We assess the impact of the backflow coordinate transformation on the nonlocal correlation energy. We found that the effect of finite-size errors in quantum Monte Carlo calculations on energy differences is particularly large and may even be more important than the employed trial wave function. In addition to the cohesive energy, the singlet excitonic energy gap and the energy gap renormalization of crystalline benzene at different densities are computed.

Crystal structure of [1,1':3',1''-ter-phenyl]-2',3,3''-tri-carb-oxy-lic acid.

Science.gov (United States)

Decato, Daniel A; Berryman, Orion B

2015-09-01

The asymmetric unit of the title compound, C21H14O6, com-prises two symmetrically independent mol-ecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carb-oxy-lic acid groups rotated by 15.8 (1) and 17.5 (1)° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being inter-connected by hydrogen bonds involving the remaining carb-oxy-lic acid groups. The plane of the central carb-oxy-lic acid group forms dihedral angles of 62.5 (1) and 63.0 (1)° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it inter-connects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The 'distal' carb-oxy-lic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1) and 7.1 (1)°. These groups also form intra- and inter-layer hydrogen bonds, but with 'reversed' functionality, as compared with the central carb-oxy-lic acid groups.

Crystal structure of [1,1′:3′,1′′-terphenyl]-2′,3,3′′-tricarboxylic acid

Directory of Open Access Journals (Sweden)

Daniel A. Decato

2015-09-01

Full Text Available The asymmetric unit of the title compound, C21H14O6, comprises two symmetrically independent molecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carboxylic acid groups rotated by 15.8 (1 and 17.5 (1° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being interconnected by hydrogen bonds involving the remaining carboxylic acid groups. The plane of the central carboxylic acid group forms dihedral angles of 62.5 (1 and 63.0 (1° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it interconnects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The `distal' carboxylic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1 and 7.1 (1°. These groups also form intra- and inter-layer hydrogen bonds, but with `reversed' functionality, as compared with the central carboxylic acid groups.

Investigation of benzene and toluene layers on 0001 surface of graphite by means of neutron scattering

International Nuclear Information System (INIS)

Monkenbusch, M.

1981-01-01

The structures of benzene (C 6 H 6 , C 6 D 6 ) and toluene (C 6 H 5 -CH 3 , C 6 D 5 -CD 3 ) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10 -4 cm 2 /s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

3-Benzyl-4-ethyl-1H-1,2,4-triazole-5(4H)-thione.

Science.gov (United States)

Karczmarzyk, Zbigniew; Pitucha, Monika; Wysocki, Waldemar; Pachuta-Stec, Anna; Stańczuk, Andrzej

2013-02-01

The title compound, C(11)H(13)N(3)S, exists in the 5-thioxo tautomeric form. The benzene ring exhibits disorder with a refined ratio of 0.77 (2):0.23 (2) for components A and B with a common bridgehead C atom. The 1,2,4-triazole ring is essentially planar, with a maximum deviation of 0.002 (3) Å for the benzyl-substituted C atom, and forms dihedral angles of 88.94 (18) and 86.56 (49)° with the benzene rings of components A and B, respectively. The angle between the plane of the ethyl chain and the mean plane of 1,2,4-triazole ring is 88.55 (15)° and this conformation is stabilized by an intra-molecular C-H⋯S contact. In the crystal, pairs of N-H⋯S hydrogen bonds link mol-ecules into inversion dimers. π-π inter-actions are observed between the triazole and benzene rings, with centroid-centroid separations of 3.547 (4) and 3.544 (12) Å for components A and B, and slippages of 0.49 (6) and 0.58 (15) Å, respectively.

Characteristics of high-purity Teflon vial for 14C measurement in old tree rings

International Nuclear Information System (INIS)

Sakurai, H.; Saswaki, Y.; Matsumoto, T.; Aoki, T.; Kato, W.; Gandou, T.; Gunji, S.; Tokanai, F.

2003-01-01

14 C concentration in single-year tree rings of an old cedar of ca. 2500 years ago is measured to investigate the 11-yr periodicity of solar activity. Our highly accurate 14 C measuring system is composed of a benzene synthesizer capable of producing a large quantity (10 g) of benzene and a Quantulus 1220 TM liquid scintillation counting system. The accuracy is less than 0.2% for measurements of 14 C concentration. The benzene sample is contained in a high-purity Teflon/copper-counting vial (20 ml) manufactured by Wallac Oy Company. We found a vial with an irregular copper cap for the measurements of 11 tree rings. The behavior of the vial with the irregular cap was investigated. The Teflon sheet inside the cap plays an important role in achieving stable measurement. The rate of volatilization of the benzene was less than 0.35 mg/day for vials with ordinary caps. This results in the volatilization rate of 0.003% for 10.5 g of benzene and hence guarantees measurement at an accuracy of 0.2% for 70 days

1-Benzyl-3′-[(1H-indol-3-ylcarbonyl]-1′-methyl-2-oxo-4′-(pyridin-3-ylspiro[indoline-3,2′-pyrrolidine]-3′-carbonitrile

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P. Seethalakshmi

2016-11-01

Full Text Available In the title compound, C34H27N5O2, the central pyrrolidine ring adopts an envelope conformation, with the N atom as the flap. The mean planes of the two indoline ring systems are inclined to the mean plane of the central pyrrolidine ring by 86.26 (9 and 69.30 (9°, respectively. The dihedral angle between the benzene and pyridine rings is 75.09 (11°. In the crystal, molecules are linked by N—H...N and C—H...N hydrogen bonds, forming sheets parallel to the ab plane.

Benzene-centred tripodal diglycolamides for the sequestration of trivalent actinides : Metal ion extraction and luminescence spectroscopic investigations in a room temperature ionic liquid

NARCIS (Netherlands)

Ansari, Seraj Ahmad; Mohapatra, Prasanta Kumar; Leoncini, Andrea; Huskens, Jurriaan; Verboom, Willem

2017-01-01

Three benzene-centred tripodal diglycolamide (Bz-T-DGA) ligands, where the diglycolamide (DGA) moieties are attached to a central benzene ring through ethylene spacers (LI), amide groups (LII) or ether linkages (LIII), were evaluated for their extraction behaviour towards trivalent actinide and

Crystal structure of the bora-benzene-2,6-lutidine adduct.

Science.gov (United States)

Kivijärvi, Lauri; Haukka, Matti

2015-12-01

In the title compound, C12H14BN, the complete mol-ecule is generated by a crystallographic twofold axis, with two C atoms, the B atom and the N atom lying on the rotation axis. The dihedral angle between the bora-benzene and pyridine rings is 81.20 (6)°. As well as dative electron donation from the N atom to the B atom [B-N = 1.5659 (18) Å], the methyl substituents on the lutidine ring shield the B atom, which further stabilizes the mol-ecule. In the crystal, weak aromatic π-π stacking between the pyridine rings [centroid-centroid separation = 3.6268 (9) Å] is observed, which generates [001] columns of mol-ecules.

1,4-Dihexyloxy-2,5-bis(2-nitrophenylbenzene

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Norma Wrobel

2012-04-01

Full Text Available The title compound, C30H36N2O6, was prepared via twofold Suzuki coupling of a diboronic acid with bromonitrobenzene. The molecule is located on a crystallographic inversion centre. The lateral benzene ring and the central ring make a dihedral angle of 48.75 (14° and the nitro group is twisted by 41.47 (13° out of the plane of the benzene ring. The nitro and hexyloxy groups are in close proximity and the hexyloxy chain adopts an all-anti conformation.

New results from optical polarimetry of Saturn's rings

Energy Technology Data Exchange (ETDEWEB)

Johnson, P E; Kemp, J C; King, R; Parker, T E; Barbour, M S [Oregon Univ., Eugene (USA). Dept. of Physics

1980-01-10

Linear polarimetry of Saturn's rings, obtained through the period of the 1979 opposition, is presented. The polarisation clearly correlates in direction with the plane containing the Sun, planet and Earth, but not the ring plane. The results are consistent with local scattering on the surface of individual ring bodies, covered with frost.

3,3,4,4-Tetrafluoro-1-[2-(3,3,4,4-tetrafluoropyrrolidin-1-ylphenyl]pyrrolidine

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Jin Wang

2011-09-01

Full Text Available The asymmetric unit of the title compound, C14H12F8N2, contains one tetrafluoropyrrolidine system and one half-molecule of benzene; the latter, together with a second heterocyclic unit, are completed by symmetry, with a twofold crystallographic axis crossing through both the middle of the bond between the C atoms bearing the heterocyclic rings and the opposite C—C bonds of the whole benzene molecule. The pyrrolidine ring shows an envelope conformation with the apex at the N atom. The dihedral angle between the least-squares plane of this ring and the benzene ring is 36.9 (5°. There are intramolecular C—H...N interactions generating S(6 ring motifs. In the crystal structure, the molecules are linked by C—H...F interactions, forming chains parallel to [010].

Hubble again views Saturn's Rings Edge-on

Science.gov (United States)

1995-01-01

Saturn's magnificent ring system is seen tilted edge-on -- for the second time this year -- in this NASA Hubble Space Telescope picture taken on August 10, 1995, when the planet was 895 million miles (1,440 million kilometers) away. Hubble snapped the image as Earth sped back across Saturn's ring plane to the sunlit side of the rings. Last May 22, Earth dipped below the ring plane, giving observers a brief look at the backlit side of the rings. Ring-plane crossing events occur approximately every 15 years. Earthbound observers won't have as good a view until the year 2038. Several of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are from left to right, Enceladus, Tethys, Dione and Mimas. 'The Hubble data shows numerous faint satellites close to the bright rings, but it will take a couple of months to precisely identify them,' according to Steve Larson (University of Arizona). During the May ring plane crossing, Hubble detected two, and possibly four, new moons orbiting Saturn. These new observations also provide a better view of the faint E ring, 'to help determine the size of particles and whether they will pose a collision hazard to the Cassini spacecraft,' said Larson. The picture was taken with Hubble's Wide Field Planetary Camera 2 in wide field mode. This image is a composite view, where a long exposure of the faint rings has been combined with a shorter exposure of Saturn's disk to bring out more detail. When viewed edge-on, the rings are so dim they almost disappear because they are very thin -- probably less than a mile thick.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products.

Science.gov (United States)

Liu, Haizhou; Bruton, Thomas A; Li, Wei; Buren, Jean Van; Prasse, Carsten; Doyle, Fiona M; Sedlak, David L

2016-01-19

Sulfate radical (SO4(•-)) is a strong, short-lived oxidant that is produced when persulfate (S2O8(2-)) reacts with transition metal oxides during in situ chemical oxidation (ISCO) of contaminated groundwater. Although engineers are aware of the ability of transition metal oxides to activate persulfate, the operation of ISCO remediation systems is hampered by an inadequate understanding of the factors that control SO4(•-) production and the overall efficiency of the process. To address these shortcomings, we assessed the stoichiometric efficiency and products of transition metal-catalyzed persulfate oxidation of benzene with pure iron- and manganese-containing minerals, clays, and aquifer solids. For most metal-containing solids, the stoichiometric efficiency, as determined by the loss of benzene relative to the loss of persulfate, approached the theoretical maximum. Rates of production of SO4(•-) or hydroxyl radical (HO(•)) generated from radical chain reactions were affected by the concentration of benzene, with rates of S2O8(2-) decomposition increasing as the benzene concentration increased. Under conditions selected to minimize the loss of initial transformation products through reaction with radicals, the production of phenol only accounted for 30%-60% of the benzene lost in the presence of O2. The remaining products included a ring-cleavage product that appeared to contain an α,β-unsaturated aldehyde functional group. In the absence of O2, the concentration of the ring-cleavage product increased relative to phenol. The formation of the ring-cleavage product warrants further studies of its toxicity and persistence in the subsurface.

Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

International Nuclear Information System (INIS)

Bollini, Carlos Guido; Giambiagi, Mario; Giambiagi, Myriam Segre de; Figueiredo, Aloysio Paiva de

2001-02-01

Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I ring values. (author)

Muconaldehyde formation from 14C-benzene in a hydroxyl radical generating system

Energy Technology Data Exchange (ETDEWEB)

Latriano, L.; Zaccaria, A.; Goldstein, B.D.; Witz, G.

1985-01-01

It has recently been proposed that muconaldehyde, a six carbon, alpha, beta-unsaturated dialdehyde, may be a hematotoxic metabolite of benzene. The present studies indicate that trans, trans-muconaldehyde is formed from benzene in vitro in a hydroxyl radical (.OH) generating system containing ascorbate, ferrous sulfate and EDTA in phosphate buffer, pH 6.7. Muconaldehyde formed from benzene in the .OH generating system was identified by trapping it with thiobarbituric acid (TBA), which results in the formation of an adduct with a 495 nm absorption maximum and a 510 nm fluorescence emission maximum. These maxima were identical to those observed after reacting authentic trans, trans-muconaldehyde with TBA. This finding was supported by thin layer chromatography and solid phase extraction studies. In those studies benzene-derived muconaldehyde cochromatographed with the muconaldehyde/TBA standard. Analyses of the products from the .OH generating system using high performance liquid chromatography (HPLC) confirm that trans, trans-muconaldehyde is a product of benzene ring fission. Regardless of whether or not TBA was used for trapping, samples from the .OH system incubated with benzene contained a peak which cochromatographed with the muconaldehyde standard. The radioactivity profile of fractions collected during HPLC analysis demonstrates 14C-benzene to be the source of the trans, trans-muconaldehyde. The role of hydroxyl radicals in the formation of muconaldehyde was investigated by using dimethyl sulfoxide, mannitol, and ethanol as .OH scavengers. These scavengers, at concentrations of 10 and 100 mM, were found to cause a dose-dependent decrease in the formation of muconaldehyde.

3-Benzyl-4-ethyl-1H-1,2,4-triazole-5(4H-thione

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Zbigniew Karczmarzyk

2013-02-01

Full Text Available The title compound, C11H13N3S, exists in the 5-thioxo tautomeric form. The benzene ring exhibits disorder with a refined ratio of 0.77 (2:0.23 (2 for components A and B with a common bridgehead C atom. The 1,2,4-triazole ring is essentially planar, with a maximum deviation of 0.002 (3 Å for the benzyl-substituted C atom, and forms dihedral angles of 88.94 (18 and 86.56 (49° with the benzene rings of components A and B, respectively. The angle between the plane of the ethyl chain and the mean plane of 1,2,4-triazole ring is 88.55 (15° and this conformation is stabilized by an intramolecular C—H...S contact. In the crystal, pairs of N—H...S hydrogen bonds link molecules into inversion dimers. π–π interactions are observed between the triazole and benzene rings, with centroid–centroid separations of 3.547 (4 and 3.544 (12 Å for components A and B, and slippages of 0.49 (6 and 0.58 (15 Å, respectively.

Methyl 4′,5-dichloro-2-hydroxy-4,6-dimethylbiphenyl-3-carboxylate

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Muhammad Adeel

2012-04-01

Full Text Available In the title compound, C16H14Cl2O3, the dihedral angle between the mean planes of the two benzene rings is 55.30 (5°. The methyl ester group lies within the ring plane due to an intramolecular O—H...O hydrogen bond [maximum deviation from the C8O2 mean plane is 0.0383 (13 Å]. In the crystal, molecules are held together by rather weak C—H...O hydrogen bonds.

Lamb shift of energy levels in quantum rings

International Nuclear Information System (INIS)

Kryuchkyan, G Yu; Kyriienko, O; Shelykh, I A

2015-01-01

We study the vacuum radiative corrections to energy levels of a confined electron in quantum rings. The calculations are provided for the Lamb shift of energy levels in a low-momentum region of virtual photons and for both one-dimensional and two-dimensional quantum rings. We show that contrary to the well known case of a hydrogen atom the value of the Lamb shift increases with the magnetic momentum quantum number m. We also investigate the dependence of the Lamb shift on magnetic flux piercing the ring and demonstrate a presence of magnetic-flux-dependent oscillations. For a one-dimensional ring the value of the shift strongly depends on the radius of the ring. It is small for semiconductor rings but can attain measurable quantities in natural organic ring-shape molecules, such as benzene, cycloalcanes and porphyrins. (paper)

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

KAUST Repository

Turias, Francesc; Poater, Jordi; Chauvin, Remi; Poater, Albert

2015-01-01

The present computational study complements experimental efforts to describe and characterize carbo-benzene derivatives as paradigms of aromatic carbo-mers. A long-lasting issue has been the possibility of the π-electron crown of the C18 carbo-benzene ring to fit metals or any chemical agents in its core. A systematic screening of candidate inclusion complexes was carried out by density functional theory calculations. Mayer bond order, aromaticity indices, and energy decomposition analyses complete the understanding of the strength of the host-guest interaction. The change in steric and electronic properties induced by the guest agent is investigated by means of steric maps. Substitution of H atoms at the carbo-benzene periphery by electron-withdrawing or electron-donating groups is shown to have a determining influence on the stability of the inclusion complex ions: while electronegative substituents enhance the recognition of cations, electropositive substituents do the same for anions. The results confirm the experimental failure hitherto to evidence a carbo-benzene complex. Nevertheless, the affinity of carbo-benzene for the potassium cation appears promising for the design of planar hydrocarbon analogues of biologic ion carriers. © 2015 Springer Science+Business Media New York.

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

KAUST Repository

Turias, Francesc

2015-09-25

The present computational study complements experimental efforts to describe and characterize carbo-benzene derivatives as paradigms of aromatic carbo-mers. A long-lasting issue has been the possibility of the π-electron crown of the C18 carbo-benzene ring to fit metals or any chemical agents in its core. A systematic screening of candidate inclusion complexes was carried out by density functional theory calculations. Mayer bond order, aromaticity indices, and energy decomposition analyses complete the understanding of the strength of the host-guest interaction. The change in steric and electronic properties induced by the guest agent is investigated by means of steric maps. Substitution of H atoms at the carbo-benzene periphery by electron-withdrawing or electron-donating groups is shown to have a determining influence on the stability of the inclusion complex ions: while electronegative substituents enhance the recognition of cations, electropositive substituents do the same for anions. The results confirm the experimental failure hitherto to evidence a carbo-benzene complex. Nevertheless, the affinity of carbo-benzene for the potassium cation appears promising for the design of planar hydrocarbon analogues of biologic ion carriers. © 2015 Springer Science+Business Media New York.

Crystal structure of dimethyl 4,4′-dimethoxybiphenyl-3,3′-dicarboxylate

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Fredrik Lundvall

2016-03-01

Full Text Available In the title compound, C18H18O6, the benzene rings are coplanar due to the centrosymmetric nature of the molecule, with an inversion centre located at the midpoint of the C—C bond between the two rings. Consequently, the methyl carboxylate substituents are oriented in a trans fashion with regards to the bond between the benzene rings. The methyl carboxylate and methoxy substituents are rotated slightly out of plane relative to their parent benzene rings, with dihedral and torsion angles of 18.52 (8 and −5.22 (15°, respectively. The shortest O...H contact between neighbouring molecules is about 2.5 Å. Although some structure-directing contributions from C—H...O hydrogen-bonding interactions are possible, the crystal packing seems primarily directed by weak van der Waals forces.

2-Hydroxy-5-nitrobenzaldehyde 2,4-dinitrophenylhydrazone

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Hoong-Kun Fun

2008-04-01

Full Text Available In the title compound, C13H9N5O7, one of the nitro groups is twisted away from the attached benzene ring by 16.21 (8°. The dihedral angle between the two benzene rings is 4.63 (1°. The molecular structure is stabilized by intramolecular N—H...O and O—H...N hydrogen bonds which generate an S(6 ring motif. The molecules pack as layers parallel to the ab plane; molecules of adjacent layers are linked into chains along the [101] direction through N—H...O hydrogen bonds.

2-Phenyl-7-(4-pyridylmethylamino-1,2,4-triazolo[1,5-a][1,3,5]triazin-5(4H-oneFused heterocyclic systems with s-triazine ring. Part 17. For part 16, see Dolzhenko et al. (2011.

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Lip Lin Koh

2011-01-01

Full Text Available In the title compound, C16H13N7O, the 1,2,4-triazolo[1,5-a][1,3,5]triazine heterocyclic system is essentially planar (r.m.s. deviation = 0.0375 Å. The attached benzene ring lies almost in the mean plane of 1,2,4-triazolo[1,5-a][1,3,5]triazine [dihedral angle = 1.36 (23°], while the pyridine ring is turned out of this plane by the aminomethyl bridge [dihedral angle = 69.22 (9°]. The amino group H atom is involved in intramolecular hydrogen bonding with a triazole N atom. In the crystal, molecules are connected via C(=ONH...N hydrogen bonds into C(11 chains parallel to [100]. The amino group H atom acts as a hydrogen-bond donor, forming an NH...O=C hydrogen bond with the carbonyl O atom, which links the molecules into C(6 chains running along [011] and [01overline{1}].

4-(9-Anthryl-1-(2-methoxyphenylspiro[azetidin-3,9′-xanthen]-2-one

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2009-03-01

Full Text Available The stabilized conformation of the title compound, C36H25NO3, 4-(9-anthryl-1-(2-methoxyphenyl-spiro[azetidin-3,9′-xanthen]-2-one, may be compared with that of the isomeric compound 4-(9-anthryl-1-(4-methoxyphenylspiro[azetidin-3,9′-xanthen]-2-one. In the title isomer, the methoxy group is slightly twisted out of the plane of the attached benzene ring, with a C—O—C—C torsion angle of 31.5 (2°. Its β-lactam ring is essentially planar, with a maximum deviation of −0.021 (1 Å. The β-lactam ring makes dihedral angles of 18.815 (9, 83.33 (7 and 53.62 (8° with the mean planes of the benzene, xanthene and anthracene ring systems, respectively. The structure is stabilized by C—H...π, C—H...N and C—H...O interactions.

Vibration of Elastic Functionally Graded Thick Rings

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Guang-Hui Xu

2017-01-01

Full Text Available The free vibration behaviors of functionally graded rings were investigated theoretically. The material graded in the thickness direction according to the power law rule and the rings were assumed to be in plane stress and plane strain states. Based on the first-order shear deformation theory and the kinetic relation of von Kárman type, the frequency equation for free vibration of functionally graded ring was derived. The derived results were verified by those in literatures which reveals that the present theory can be appropriate to predict the free vibration characteristics for quite thick rings with the radius-to-thickness ratio from 60 down to 2.09. Comparison between the plane stress case and the plane strain case indicates a slight difference. Meanwhile, the effects of the structural dimensional parameters and the material inhomogeneous parameter are examined. It is interesting that the value of the logarithmic form of vibration frequency is inversely proportional to the logarithmic form of the radius-to-thickness ratio or the mean radius.

Seco-B-Ring Steroidal Dienynes with Aromatic D Ring: Design, Synthesis and Biological Evaluation

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Marcin Szybinski

2017-10-01

Full Text Available Continuing our structure-activity studies on the vitamin D analogs with the altered intercyclic seco-B-ring fragment, we designed compounds possessing dienyne system conjugated with the benzene D ring. Analysis of the literature data and the docking experiments seemed to indicate that the target compounds could mimic the ligands with a good affinity to the vitamin D receptor (VDR. Multi-step synthesis of the C/D-ring building block of the tetralone structure was achieved and its enol triflate was coupled with the known A-ring fragments, possessing conjugated enyne moiety, using Sonogashira protocol. The structures of the final products were confirmed by NMR, UV and mass spectroscopy. Their binding affinities for the full-length human VDR were determined and it was established that compound substituted at C-2 with exomethylene group showed significant binding to the receptor. This analog was also able to induce monocytic differentiation of HL-60 cells.

Benzene from Traffic

DEFF Research Database (Denmark)

Palmgren, F.; Berkowicz, R.; Skov, H.

The measurements of benzene showed very clear decreasing trends in the air concentrations and the emissions since 1994. At the same time the measurements of CO and NOx also showed a decreasing trend, but not so strong as for benzene. The general decreasing trend is explained by the increasing...... number of petrol vehicles with three way catalysts, 60-70% in 1999. The very steep decreasing trend for benzene at the beginning of the period from 1994 was explained by the combination of more catalyst vehicles and reduced benzene content in Danish petrol. The total amount of aromatics in petrol......, including toluene, increased only weakly. The analyses of air concentrations were confirmed by analyses of petrol sold in Denmark. The concentration of benzene at Jagtvej in Copenhagen is still in 1998 above the expected new EU limit value, 5 µg/m3 as annual average. However, the reduced content of benzene...

3-Methylpyridinium 4-nitrobenzoate–4-nitrobenzoic acid (1/1

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P. Sivakumar

2016-06-01

Full Text Available In the title compound, C6H8N+·C7H4NO4−·C7H5NO4, the cation is protonated at its pyridine N atom and makes a dihedral angle of 74.14 (12° with the benzene ring of the anion. The benzene ring of the neutral molecule and the pyridine ring are inclined at an angle of 79.20 (12°. The two benzene rings form a dihedral angle of 6.00 (12° with each other. In the crystal, N—H...O, O—H...O and C—H...O hydrogen bonds link the cations, anions and neutral molecules to form layers parallel to the ac plane, which enlose R44(18 ring motifs. The layers are linked by further C—H...O hydrogen bonds and C—H...π interactions, forming a three-dimensional supramolecular architecture.

Device for monitoring electron-ion ring parameters

International Nuclear Information System (INIS)

Tyutyunnikov, S.I.; Shalyapin, V.N.

1982-01-01

The invention is classified as the method of collective ion acceleration. The device for electron-ion ring parameters monitoring is described. The invention is aimed at increasing functional possibilities of the device at the expense of the enchance in the number of the ring controlled parameters. The device comprises three similar plane mirrors installed over accelerating tube circumference and a mirror manufactured in the form of prism and located in the tube centre, as well as the system of synchrotron radiation recording and processing. Two plane mirrors are installed at an angle of 45 deg to the vertical axis. The angle of the third plane mirror 3 α and that of prismatic mirror 2 α to the vertical axis depend on geometric parameters of the ring and accelerating tube and they are determined by the expression α=arc sin R K /2(R T -L), where R K - ring radius, R T - accelerating tube radius, L - the height of segment, formed by the mirror and inner surface of the accelerating tube. The device suggested permits to determine longitudinal dimensions of the ring, its velocity and the number of electrons and ions in the ring

Crystal structure of [1,1′:3′,1′′-ter­phenyl]-2′,3,3′′-tri­carb­oxy­lic acid

Science.gov (United States)

Decato, Daniel A.; Berryman, Orion B.

2015-01-01

The asymmetric unit of the title compound, C21H14O6, com­prises two symmetrically independent mol­ecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carb­oxy­lic acid groups rotated by 15.8 (1) and 17.5 (1)° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being inter­connected by hydrogen bonds involving the remaining carb­oxy­lic acid groups. The plane of the central carb­oxy­lic acid group forms dihedral angles of 62.5 (1) and 63.0 (1)° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it inter­connects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The ‘distal’ carb­oxy­lic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1) and 7.1 (1)°. These groups also form intra- and inter-layer hydrogen bonds, but with ‘reversed’ functionality, as compared with the central carb­oxy­lic acid groups. PMID:26396894

Synthesis and Rearrangement of Dewar Benzenes Into Biaryls: Experimental Evidence for Conrotatory Ring Opening

Czech Academy of Sciences Publication Activity Database

Janková, Š.; Dračínský, Martin; Císařová, I.; Kotora, Martin

-, č. 1 (2008), s. 47-51 ISSN 1434-193X R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : Dewar benzene * biaryls * alkynes * Hammett * rearrangement Subject RIV: CC - Organic Chemistry Impact factor: 3.016, year: 2008

Saturn Rings Origin: Quantum Trapping of Superconducting Iced Particles and Meissner Effect Lead to the Stable Rings System

Science.gov (United States)

Viktorovich Tchernyi, Vladimir

2018-06-01

Saturn Rings Origin: Quantum Trapping of Superconducting Iced Particles and Meissner Effect Lead to the Stable Rings System Vladimir V. Tchernyi (Cherny), Andrew Yu. Pospelov Modern Science Institute, SAIBR, Moscow, Russia. E-mail: chernyv@bk.ruAbstractIt is demonstrated how superconducting iced particles of the protoplanetary cloud of Saturn are coming to magnetic equator plane and create the stable enough rings disk. There are two steps. First, after appearance of the Saturn magnetic field due to Meissner phenomenon all particles orbits are moving to the magnetic equator plane. Finally they become distributed as rings and gaps like iron particles around magnet on laboratory table. And they are separated from each other by the magnetic field expelled from them. It takes up to few tens of thousands years with ten meters rings disk thickness. Second, due to their quantum trapping all particles become to be trapped within magnetic well at the magnetic equator plane due to Abrikosov vortex for superconductor. It works even when particles have small fraction of superconductor. During the rings evolution some contribution to the disk also could come from the collision-generated debris of the current moon and from the geysers like it happened due to magnetic coupling of Saturn and Enceladus. The rings are relict of the early days of the magnetic field of Saturn system.

Catalytic transformation of methyl benzenes over zeolite catalysts

KAUST Repository

Al-Khattaf, S.

2011-02-01

Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over ZSM-5, TNU-9, mordenite and SSZ-33 catalysts in a novel riser simulator at different operating conditions. Catalytic experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction conditions on the isomerization to disproportionation product ratio, distribution of trimethylbenzene (TMB) isomers, and p-xylene/o-xylene ratios are reported. The sequence of reactivity of the three alkyl benzenes depends upon the pore structure of zeolites. The zeolite structure controls primarily the diffusion of reactants and products while the acidity of these zeolites is of a secondary importance. In the case of medium pore zeolites, the order of conversion was m-xylene > 1,2,4-TMB > toluene. Over large pore zeolites the order of reactivity was 1,2,4-TMB > m-xylene > toluene for SSZ-33 catalyst, and m-xylene ∼ 1,2,4-TMB > toluene over mordenite. Significant effect of pore size between ZSM-5 and TNU-9 was observed; although TNU-9 is also 3D 10-ring channel system, its slightly larger pores compared with ZSM-5 provide sufficient reaction space to behave like large-pore zeolites in transformation of aromatic hydrocarbons. We have also carried out kinetic studies for these reactions and activation energies for all three reactants over all zeolite catalysts under study have been calculated. © 2011 Elsevier B.V.

Application of [Hydroxy(tosyloxyiodo]benzene in the Wittig-Ring Expansion Sequence for the Synthesis of β-Benzocyclo-alkenones from α-Benzocycloalkenones

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G. Koser

2005-01-01

Full Text Available The conversion of α-benzocycloalkenones to homologous β-benzocyclo-alkenones containing six, seven and eight-membered rings is reported. This wasaccomplished via a Wittig olefination-oxidative rearrangement sequence using[hydroxy(tosyloxyiodo]-benzene (HTIB is the oxidant, that enables the synthesis ofregioisomeric pairs of methyl-substituted β-benzocycloalkenones. The incorporation ofcarbon-13 at C-1 of the β-tetralone nucleus was also demonstrated. The Wittig-HTIBapproach is a useful alternative to analogous sequences in which Tl(NO33·3H2O or thePrevost combination (AgNO3/I2 are employed in the oxidation step.

Triptycene-Based Microporous Cyanate Resins for Adsorption/Separations of Benzene/Cyclohexane and Carbon Dioxide Gas.

Science.gov (United States)

Deng, Gaoyang; Wang, Zhonggang

2017-11-29

Triptycene-based cyanate monomers 2,6,14-tricyanatotriptycene (TPC) and 2,6,14-tris(4-cyanatophenyl)triptycene (TPPC) that contain different numbers of benzene rings per molecule were synthesized, from which two microporous cyanate resins PCN-TPC and PCN-TPPC were prepared. Of interest is the observation that the two polymers have very similar porosity parameters, but PCN-TPPC uptakes considerably higher benzene (77.8 wt %) than PCN-TPC (17.6 wt %) at room temperature since the higher concentration of phenyl groups in PCN-TPPC enhances the π-π interaction with benzene molecules. Besides, the adsorption capacity of benzene in PCN-TPPC is dramatically 7 times as high as that of cyclohexane. Contrary to the adsorption of organic vapors, at 273 K and 1.0 bar, PCN-TPC with more heteroatoms in the network skeleton displays larger uptake of CO 2 and higher CO 2 /N 2 selectivity (16.4 wt %, 60) than those of PCN-TPPC (14.0 wt %, 39). The excellent and unique adsorption properties exhibit potential applications in the purification of small molecular organic hydrocarbons, e.g., separation of benzene from benzene/cyclohexane mixture as well as CO 2 capture from flue gas. Moreover, the results are helpful for deeply understanding the effect of porous and chemical structures on the adsorption properties of organic hydrocarbons and CO 2 gas.

Ethyl 2-(3,4-dimethyl-5,5-dioxo-1H,4H-benzo[e]pyrazolo[4,3-c][1,2]thiazin-1-ylacetate

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Sana Aslam

2012-10-01

Full Text Available In the title molecule, C15H17N3O4S, the heterocyclic thiazine ring adopts a twist-boat conformation, which differs from that in related compounds, with adjacent S and C atoms displaced by 0.981 (4 and 0.413 (5 Å, respectively, on the same side of the mean plane formed by the remaining ring atoms. The mean plane of the benzene ring makes a dihedral angle of 23.43 (14° with the mean plane of the pyrazole ring. In the crystal, molecules are connected by weak C—H...O hydrogen bonds to form a three-dimensional network. The H atoms of the methyl group attached to the pyrazole ring were refined over six sites with equal occupancies.

Ethyl 4-chloro-2′-fluoro-3-hydroxy-5-methylbiphenyl-2-carboxylate

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Muhammad Adeel

2011-09-01

Full Text Available In the title compound, C16H14ClFO3, the dihedral angle between the mean planes of the two benzene rings is 71.50 (5°. Due to an intramolecular O—H...O hydrogen bond between the hydroxy group and the carbonyl O atom of the ethyl ester group, the ethyl ester group lies within the ring plane. The crystal structure is consolidated by intermolecular C—H...O and C—H...F interactions.

Molecular mechanisms in the pyrolysis of unsaturated chlorinated hydrocarbons: formation of benzene rings. 1. Quantum chemical studies.

Science.gov (United States)

McIntosh, Grant J; Russell, Douglas K

2013-05-23

Analogues of important aromatic growth mechanisms in hydrocarbon pyrolysis and combustion systems are extended to chlorinated systems. We consider the addition of C2Cl2 to both C4Cl3 and C4Cl5 radicals at the M06-2X/6-311+G(3df,3p)//B3LYP/6-31G(d) level of theory, and we demonstrate that these reaction systems have much in common with those of nonchlorinated species. In particular, we find that these radicals appear to lead preferentially to fulvenes, and not to the observed aromatic products, as is found in nonchlorinated systems. We have therefore also considered nonradical C4/C2 channels by way of Diels-Alder cyclization of C4Cl4/C2Cl2 and C4H2Cl2/C2HCl pairs to describe aromatic formation. While the latter pair readily leads to the formation of partially chlorinated benzenes, the fully chlorinated congeners are sterically prohibited from ring closing directly; this leads to a series of novel rearrangement processes which predict the formation of hexachloro-1,5-diene-3-yne, in addition to hexachlorobenzene, in good agreement with experiment. This suggests, for the first time, that facile nonradical routes to aromatic formation are operative in partially and fully chlorinated pyrolysis and combustion systems.

Benzene: questions and answers

International Nuclear Information System (INIS)

1999-01-01

This information booklet is intended to inform residents near natural gas dehydration facilities about benzene and its levels in the atmosphere. It was issued following the federal government's decision to place benzene on its Priority Substances List and to require industry to establish means for reducing benzene emissions from natural gas dehydrators and to inform residents about benzene emissions from glycol dehydration facilities. Accordingly, the booklet explains what benzene is (a colourless flammable liquid component of hydrocarbons) how it gets into the air (during gasoline refining, vehicle refueling and the production of steel and petrochemicals), the associated health hazards (a recognized carcinogen, causing an increased incidence of leukemia in concentrations of 100 parts per million), defines a glycol dehydrator (a facility built at or near some natural gas fields for the removal of water from the natural gas to prevent corrosion and freezing of pipelines), and enumerates the steps that are being taken to reduce benzene levels in the air (benzene levels in gasoline have been reduced, along with benzene emissions from petrochemical plants, refineries, steel plants and glycol dehydrators by 54 per cent to date; this will rise to 90 per cent by 2005). In addition to these actions, industry plans call for all existing glycol dehydrators within 750 metres of any permanent residence to be limited to benzene emissions of no more than three tonnes per year before 2001; new glycol dehydrators after that date will be expected to have benzene emissions reduced to the lowest level that can be practically achieved

11-[(E-Benzylidene]-14-hydroxy-8-phenyl-6-thia-3,13-diazaheptacyclo[13.7.1.19,13.02,9.02,14.03,7.019,23]tetracosa-1(22,15(23,16,18,20-pentaen-10-one

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Raju Suresh Kumar

2012-07-01

Full Text Available In the title compound, C34H28N2O2S, the piperidine ring adopts a chair conformation. One of the pyrrolidine rings adopts an envelope conformation with the methylene C atom at the flap whereas the other pyrrolidine ring and the thiazolidine ring adopt half-chair conformations. The mean plane of the dihydroacenaphthylene ring system [maximum deviation = 0.067 (1 Å] makes dihedral angles of 28.31 (5 and 31.32 (6° with the two terminal benzene rings. An intramolecular O—H...N hydrogen bond forms an S(5 ring motif. In the crystal, molecules are linked by C—H...O and C—H...S hydrogen bonds into layers lying parallel to the ac plane.

Deuteration of benzen derivatives and condensed aromatics

International Nuclear Information System (INIS)

Ichikawa, Masaru.

1970-01-01

A process for the deuteration of aromatic compounds (benzene derivatives having one or more cyano, halogeno, nitro or other electron attractive groups, and condensed ring aromatics) is provided. The process comprises reducing said aromatic compound with an alkali metal (preferably K, Rb or Cs) in a solvent (dimethoxyethane, tetrahydrofuran, etc.) to provide an electron-acceptor-donor complex, which is followed by introducing gaseous deuterium into the solution. The deuteration takes place selectively at the position of highest electron density in accordance with nature of the substituent, regardless of steric hindrance. The process is applicable to a wide variety of aromatics to give deuterated compounds in high yields. In one example, 5x10 -3 mole of anthracene (An) was reacted with 2g of metallic potassium in 80cc of dimethoxyethane in a N 2 atmosphere. Into the resulting solution of An=2K + was introduced D 2 gas (30 cmHg) at 25 0 C. After decomposition with air and washing with alcohol, the precipitate was recrystallized from benzene. Yield of recovered AN: more than 90%. Yield of deuteration: 100%. Position of deuteration: 9 and 10 (revealed by NMR and mass spectroscopy). (Kaichi, S.)

12-Benzoyl-2-methylnaphtho[2,3-b]indolizine-6,11-dione

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Yun Liu

2011-06-01

Full Text Available In the title compound, C24H15NO3, the fused naphthaquinone–pyrrole unit is approximately planar, the naphthaquinone ring system making a dihedral angle of 2.91 (10° with the pyrrole ring. The plane of the pyrrole ring makes a dihedral angle 61.64 (14° with that of the benzene ring of the benzoylmethylene group. The crystal structure is stablized by intramolecular C—H...O interactions.

Risk factor benzene

Energy Technology Data Exchange (ETDEWEB)

Stobbe, H.

1981-01-01

Nearly one hundred years ago clinical and epidemiological studies have already assigned benzene as a markedly haematotoxic substance. Nowadays benzene is known as an important professional noxa, which is straight off directed against the haematopoietic system, essentially to a dose-time-effect. By this it can be taken as a model also for other noxious substances. Similar solvents often contain so-called 'hidden benzene', that means not declared benzene, so that the consumer doesn't know what dangerous substance are available for his personal use. Impairments caused by benzene mostly are manifested earliest after months, years or for tens of years, and the point is, that these haematopoietic disorders are irreversible disturbances of the haematopoietic stem cell compartment. The consequence of this fact is a deep involvement of the proliferation of the erythro-, mono-, granulo- and thrombopoietic cell lines, mostly with predominance of one of these myeloproliferative cell systems. In the further progression of the impairments due to benzene three different clinical pictures can be observed: the aplastic bone marrow syndrome (i.e. aplastic anemia), the haematopoietic dysplasia (i.e. preleukemia) and the acute leukemias (with the subtypes erythroleukosis, myeloblastic-promyelocytic or myelomonocytic from respectively). Also the transition from one clinical picture to another is possible.

N-(3-Nitrophenylmaleamic acid

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B. Thimme Gowda

2010-07-01

Full Text Available In the title compound, C10H8N2O5, the molecule is slightly distorted from planarity. The molecular structure is stabilized by two intramolecular hydrogen bonds. The first is a short O—H...O hydrogen bond (H...O distance = 1.57 Å within the maleamic acid unit and the second is a C—H...O hydrogen bond (H...O distance = 2.24 Å which connects the amide group with the benzene ring. The nitro group is twisted by 6.2 (2° out of the plane of the benzene ring. The crystal structure manifests a variety of hydrogen bonding. The packing is dominated by a strong intermolecular N—H...O interaction which links the molecules into chains running along the b axis. The chains within a plane are further assembled by three additional types of intermolecular C—H...O hydrogen bonds to form a sheet parallel to the (overline{1}01 plane.

Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei

International Nuclear Information System (INIS)

Sabourin, P.J.; Sun, J.D.; MacGregor, J.T.; Wehr, C.M.; Birnbaum, L.S.; Lucier, G.; Henderson, R.F.

1990-01-01

Metabolism of benzene is thought to be necessary to produce the toxic effects, including carcinogenicity, associated with benzene exposure. To extrapolate from the results of rodent studies to potential health risks in man, one must know how benzene metabolism is affected by species, dose, dose rate, and repeated versus single exposures. The purpose of our studies was to determine the effect of repeated inhalation exposures on the metabolism of [14C]benzene by rodents. Benzene metabolism was assessed by characterizing and quantitating urinary metabolites, and by quantitating 14C bound to hemoglobin and micronuclei induction. F344/N rats and B6C3F1 mice were exposed, nose-only, to 600 ppm benzene or to air (control) for 6 hr/day, 5 days/week for 3 weeks. On the last day, both benzene-pretreated and control animals were exposed to 600 ppm, 14C-labeled benzene for 6 hr. Individual benzene metabolites in urine collected for 24 hr after the exposure were analyzed. There was a significant decrease in the respiratory rate of mice (but not rats) pretreated with benzene which resulted in lower levels of urinary [14C]benzene metabolites. The analyses indicated that the only effects of benzene pretreatment on the metabolite profile in rat or mouse urine were a slight shift from glucuronidation to sulfation in mice and a shift from sulfation to glucuronidation in rats. Benzene pretreatment also had no effect, in either species, on formation of [14C]benzene-derived hemoglobin adducts. Mice and rats had similar levels of hemoglobin adduct binding, despite the higher metabolism of benzene by mice. This indicates that hemoglobin adduct formation occurs with higher efficiency in rats. After 1 week of exposure to 600 ppm benzene, the frequency of micronucleated, polychromatic erythrocytes (PCEs) in mice was significantly increased

Novel manifestations of the Aharonov-Bohm effect in quantum rings and Moebius rings

International Nuclear Information System (INIS)

Fomin, Vladimir M.

2013-01-01

- An overview is given on the recent experimental and theoretical advancements in studies of novel manifestations of the Aharonov-Bohm quantum-interference effect for excitons confined to self assembled quantum rings and other semiconductor nanostructures with ring-like states of charge carriers as well as for electrons in Moebius rings at the micro- and nanoscale. The exciton Aharonov-Bohm effect can be effectively controlled by an out-of-plane magnetic field, a vertical electric field, a spin disorder. A 'delocalization-to-localization' transition for the electron ground state occurs in a Moebius ring as it is made more inhomogeneous. (authors)

Synthesis, structure and two-photon absorption properties of a new multi-branched compound, 1,2,4,5-tetrakis(4-pyridylvinyl)benzene

International Nuclear Information System (INIS)

Wang Lei; Tao Xutang; Yang Jiaxiang; Yu Wentao; Ren Yan; Xin Qian; Liu Zhi; Jiang Minhua

2004-01-01

A conjugated and symmetric multi-branched compound, 1,2,4,5-tetrakis(4-pyridylvinyl)benzene (TKPVB), has been synthesized and the crystal structures of TKPVB and its intermediate, 1,2,4,5-tetrakis(dimethoxyphosphorylmethyl)benzene, were determined by diffraction method. TKPVB with four units of 4-vinylpyridine moieties attached to the central benzene core presents an A-π-A general framework, where A is a π-deficient pyridine ring. The single-photon and two-photon absorption and fluorescence properties in different solvents of varying polarity have been investigated. It is also found that the one- and two-photon-induced fluorescence spectra are quite similar, which indicate that the one- and two-photon allowed-excited states are the same

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

Science.gov (United States)

Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

2013-01-01

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

1-Methyl-1H-2,1-benzothiazin-4(3H-one 2,2-dioxide

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Muhammad Nadeem Arshad

2008-03-01

Full Text Available In the crystal structure of the title compound, C9H9NO3S, there is distorted tetrahedral geometry around the S atom. The sulfonyl group is almost normal to the benzene ring, while the carbonyl O atom and methyl C atom are on opposite sides of this ring. The heterocyclic ring adopts a half-boat conformation with the S atom out of the plane. The molecules are dimerized by hydrogen bonding involving the benzene ring and the sulfonyl group. These dimers are linked to each other in the same way. There is an intramolecular hydrogen bond between a methyl C—H group and a sulfonyl O atom, and a π–π interaction between the aromatic rings of two dimers at a centroid-to-centroid distance of 3.6373 (13 Å.

4-(4-Chlorophenyl-6-(methylsulfanylpyrimidin-2-amine

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Qi-Hua Zhao

2009-08-01

Full Text Available In the title compound, C11H10ClN3S, the dihedral angle between the benzene and pyrimidine rings is 3.99 (4°. In the crystal, intermolecular N—H...N hydrogen bonds link the molecules into ribbons of R22(8 rings parallel to [100]. Weak C—H...S contacts connect adjacent ribbons into a two-dimensional undulating layer-like structure extending parallel to (110. The benzene and pyrimidine rings of adjacent molecules have the offset face-to-face π–π stacking interactions in a zigzag fashion along the c axis, with perpendicular ring distances of 3.463 and 3.639 Å, and a dihedral angle between the planes of 3.99< (2°. The distance between the ring centroids is 4.420 (2 Å.

Organosulfur chemistry on W(211) surfaces. 2. A comparison of benzene, thiophene, and tetrahydrothiophene

International Nuclear Information System (INIS)

Preston, R.E.; Benziger, J.B.

1985-01-01

The interactions of benzene, thiophene, and tetrahydrothiophene with clean, oxidized, and sulfided W(211) surfaces were studied with LEED, AES, and temperature programmed reaction. Benzene and thiophene appear to absorb as bases making π-bonds to the surface. Benzene decomposed to yield adsorbed carbon and hydrogen. Thiophene appeared to undergo electrophilic attack at the 2-position forming a carbon bound surface intermediate. This surface intermediate was desulfurized and the resulting hydrocarbon surface intermediate underwent C-C bond scission forming C 3 hydrocarbons as the dominate desorption product. The electrophilic attack at the 2-position was shown by methyl group elimination from 2,5-dimethylthiophene. Adsorbed oxygen and sulfur enhanced the adsorption of benzene and thiophene by making the surface more acidic. Tetrahydrothiophene (THT) appear to adsorb as a base, forming a bond between the S(3p) electrons and the surface. Desulfurization of adsorbed THT led to C 4 hydrocarbons as the dominate desorption product. Adsorbed oxygen and sulfur inhibited reaction of THT. These results suggest that the surface reactivity and subsequent desulfurization of thiophene is controlled by electrophilic attack on the aromatic ring, and the ensuing reduction of resonance stabilization facilitates sulfur removal. 41 references, 8 figures, 4 tables

On Finite Hjelmslev Planes of Parameters (pk−1, p)

OpenAIRE

Atilla Akpinar

2010-01-01

In this paper, we study on finite projective Hjelmslev planes M(Zq) coordinatized by Hjelmslev ring Zq (where prime power q = pk). We obtain finite hyperbolic Klingenberg planes from these planes under certain conditions. Also, we give a combinatorical result on M(Zq), related by deleting a line from lines in same neighbour.

Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

CERN Document Server

Bollini, C G; Giambiagi, M

2001-01-01

Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I sub r sub i sub n sub g values.

4-[(3-Phenyl-4,5-dihydroisoxazol-5-ylmethyl]-2H-benzo[b][1,4]thiazin-3(4H-one

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Nada Kheira Sebbar

2016-06-01

Full Text Available In the title compound, C18H16N2O2S, the 5-dihydroisoxazol-5-yl ring and its phenyl substituent are nearly coplanar, with the largest deviation from the mean plane being 0.0184 (16 Å. The thiomorpholin-3-one ring adopts a screw-boat conformation and the attached benzene ring makes a dihedral angle of 42.26 (7° with the mean plane through the 3-phenyl-4,5-dihydroisoxazol-5-yl ring system. In the crystal, molecules are linked by pairs of C—H...N hydrogen bonds, forming inversion dimers. These dimers are linked via C—H...O hydrogen bonds, generating a three-dimensional network.

Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

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Zhengjun Zhang

2011-12-01

Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

(E-1-(2-Bromophenyl-3-(2,5-dimethoxyphenylprop-2-en-1-one

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Jerry P. Jasinski

2010-08-01

Full Text Available The title compound, C17H15BrO3, is a chalcone with the 2-bromophenyl and 2,5-dimethoxyphenyl rings bonded at opposite ends of a propene group. The dihedral angle between the mean planes of the ortho-bromo and ortho,meta-dimethoxy-substituted benzene rings is 77.3 (1°. The dihedral angles between the mean plane of the prop-2-ene-1-one group and the mean planes of the 2-bromophenyl and 2,5-dimethoxyphenyl rings are 58.6 (1 and 30.7 (4°, respectively. Weak C—H...O, C—H...Br and π–π stacking intermolecular interactions [centroid–centroid distance = 3.650 (2 Å] are present in the structure.

Aromaticity of benzene in condensed phases. A case of a benzene-water system

Science.gov (United States)

Zborowski, Krzysztof K.

2014-05-01

A theoretical Density Functional Theory study was performed for a benzene molecule in water cages. Two DFT functionals (B3LYP and BLYP) were employed. The optimized geometries of the studied clusters were used to calculate the aromaticity of benzene in a condensed phase using the aromaticity indices: HOMA, NICS, PDI, and H. The results were compared with aromaticity of a single benzene molecule in the gas phase and in the solvent environment provided by the PCM continuum model. It is argued that high aromaticity of benzene in the gas phase is retained in the water environment.

Development of Catalysts for the Hydrogenation of the Aromatic Ring in Gasolines

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L. R. Sassykova

2018-01-01

Full Text Available Liquid-phase hydrogenation of benzene ring in gasoline fractions of Atyrau Oil Refinery LLP (Kazakhstan was studied. Mono- and bimetallic catalysts on the basis of platinum metals on various carriers were synthesized. It was succeeded to reduce aromatic compounds content (totally for “hydrogenate” fraction to 0.6–4.64 % (in initial gasoline – 11.2 %, and also to completely exclude the content of benzene from final sample or to reduce its quantity to 0.06 % (in the initial sample – 2.54 %. For the fraction “stable catalysate” benzene content was reduced to 0.15 wt. % (in the initial sample –5.17 % wt., benzene conversion – 97 %. For the fraction “hydrogenate” aromatic compounds content was decreased from 13.70 to 2.26 wt.%. For the “stable catalysate” an amount of aromatic compounds was reduced from 51.5 to 22.96 wt.%. At catalytic hydrodearomatization of the gasoline fractions octane number was not reduced.

Transient negative ions in benzene. Some N-heterocyclic and mono-substituted derivatives

International Nuclear Information System (INIS)

Nenner, Irene

1975-01-01

Electron transmission spectroscopy is used to study transient negative ions or shape resonances in various benzene derivatives. Because of the long lifetime of these ions (τ > 10 -14 S) the vibrational structure of their first two electronic states is observed superposed on the total electron cross section curves in the energy range 0-6 eV and the corresponding adiabatic electron affinities are determined. The comparison of the first electron affinity with the first ionization potential and the energy on the first excited state of each of the derivatives is used to characterize the 'donor' substituents on the benzene ring. As a complementary study, these derivatives are studied in the liquid phase using polarography (cyclic voltametry). The linear correlation established between polarographic potentials measured in dimethyl formamide and the electron affinities was used to deduce electron affinities for several molecules which are difficult to measure in the gas phase. (author) [fr

Problem Definition Studies on Potential Environmental Pollutants. 4. Physical, Chemical, Toxicological, and Biological Properties of Benzene; Toluene; Xylenes; and para-Chlorophenyl Methyl Sulfide, Sulfoxide, and Sulfone

Science.gov (United States)

1976-06-01

microorganisms. The presence of nitro, amino or sulfonic acid groups or halogens on the ring will almost always render benzene and related compounds...benzoquinone --- muconic acid Their later experiments with tea and grape leaf homogenates support this * conclusion. 12 2 Tkhelidze 1 2 3 showed that grape ...of such chemicals as phenol, aniline, cumene, adipic acid , diphenyl, and ethyl- * benzene, each of which is a starting material for other products

Fulltext PDF

Indian Academy of Sciences (India)

Administrator

... respectively, in poly-2-cynoaniline. The peak at 1455 cm–1 is attributed to C–N stretching of nitrile group attached to the benzene ring. The bands at. 1120 and 762 cm–1 can be attributed to the in-plane and out-of-plane C–H bending vibration modes, respectively. The 1331 cm–1 band may be assigned to C–C stretching.

Crystal structure of 3,5-dimethoxy-2-[5-(naphthalen-1-yl-4,5-dihydro-1H-pyrazol-3-yl]phenol

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Dongsoo Koh

2015-10-01

Full Text Available In the title compound, C21H20N2O3, the planes of the benzene ring and the naphthalene ring system are inclined to one another by 70.95°, and by 4.99 (6 and 75.93 (5°, respectively, to the mean plane of the pyrazoline ring. The latter has an envelope conformation with the methine (CH C atom as the flap. There is an intramolecular O—H...N hydrogen bond that forms an S(6 ring motif. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming chains along [100]. The chains are linked via C—H...N hydrogen bonds, forming sheets parallel to the ab plane. The sheets are linked by a series of N—H...π and C—H...π interactions forming a three-dimensional structure.

First results of cavity ring down signals from exhaled air

Science.gov (United States)

Revalde, G.; Grundšteins, K.; Alnis, J.; Skudra, A.

2017-12-01

In this paper we report first results from the developed cavity ring-down spectrometer for application in human breath analysis for the diagnostics of diabetes and later for early detection of lung cancer. Our cavity ring-down spectrometer works in UV region with pulsed Nd:YAG laser at 266 nm wavelength. First experiments allow us to determine acetone and benzene at the level bellow ppm. In our experiment, first results from breath samples from volunteers after doing different activities were collected and examined. Influence of the smoking on the breath signals also was examined.

3,6-Dibromo-9-(4-tert-butylbenzyl-9H-carbazole

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Duan-Lin Cao

2008-08-01

Full Text Available In the title compound, C23H21Br2N, which was synthesized by the N-alkylation of 1-tert-butyl-4-(chloromethylbenzene with 3,6-dibromo-9H-carbazole, the asymmetric unit contains two unique molecules. Each carbazole ring system is essentially planar, with mean deviations of 0.0077 and 0.0089 Å for the two molecules. The carbazole planes make dihedral angles of 78.9 (2 and 81.8 (2° with the planes of the respective benzene rings.

Design and synthesis of chalcone-based macrocyclic polyethers

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Subrata Jana

2015-12-01

Full Text Available A series of chalcone-based macrocyclic ethers have been synthesized. These macrocyclic ethers contain polyether as well as extended conjugation to the benzene ring to function as fluorescent sensor for cations. The modeling studies show that the chalcone part of the receptors remains partially out of plane from the polyether part and the keto moiety of the receptors always directed outwardly in the receptor itself. This may be changed during the recognition of metal ions. The tendency of the fluorophore, to be out of plane, increases with increasing the ring size.

4-Methylbenzenecarbothioamide

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Saqib Ali

2010-06-01

Full Text Available In the title molecule, C8H9NS, the mean plane of the carbothioamide group is twisted slightly with respect to the mean plane of the benzene ring, making a dihedral angle of 17.03 (10°. The crystal structure is stabilized by intermolecular N—H...S hydrogen bonds, resulting in the formation of eight-membered rings lying about inversion centers and representing R22(8 and R42(8 motifs. Futhermore, these hydrogen bonds build up chains parallel to the b axis.

4-Nitro-N-[(E-thiophen-2-ylmethylidene]aniline

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Abdullah M. Asiri

2012-07-01

Full Text Available In the title compound, C11H8N2O2S, there is a twist in the molecule, with the dihedral angle between the five- and six-membered rings being 31.77 (9°. The nitro group is slightly twisted out of the plane of the benzene ring to which it is attached [O—N—C—C torsion angle = 9.0 (3°]. The S and N atoms are syn. In the crystal, supramolecular layers parallel to (-204 are formed by C—H...O and C—H...N interactions. These layers are connected into a three-dimensional architecture by π–π interactions occurring between centrosymmetrically related benzene rings [centroid–centroid distance = 3.6020 (11 Å].

A STUDY ON THE DEGRADATION MECHANISM OF PHOTOCROSSLINKING PRODUCTS FORMED BY CYCLIZED POLYISOPRENE-DIAZIDE SYSTEM UNDER THE INFLUENCE OF ALKYL BENZENE SULFONIC ACIDS

Institute of Scientific and Technical Information of China (English)

HUANG Junlian; SUN Meng

1989-01-01

The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects ofalkyl chain length and the concentration of alkyl benzene sulfonic acids on the rate of degradation reaction were discussed. It was found that in the initial stage of degradation, the cyclicity ratio and the average fused ring number did not change considerably, but the percentage of uncyclized parts content varied significantly. The suitable mechanism was supposed.

Benzene Monitor System report

International Nuclear Information System (INIS)

Livingston, R.R.

1992-01-01

Two systems for monitoring benzene in aqueous streams have been designed and assembled by the Savannah River Technology Center, Analytical Development Section (ADS). These systems were used at TNX to support sampling studies of the full-scale open-quotes SRAT/SME/PRclose quotes and to provide real-time measurements of benzene in Precipitate Hydrolysis Aqueous (PHA) simulant. This report describes the two ADS Benzene Monitor System (BMS) configurations, provides data on system operation, and reviews the results of scoping tests conducted at TNX. These scoping tests will allow comparison with other benzene measurement options being considered for use in the Defense Waste Processing Facility (DWPF) laboratory. A report detailing the preferred BMS configuration statistical performance during recent tests has been issued under separate title: Statistical Analyses of the At-line Benzene Monitor Study, SCS-ASG-92-066. The current BMS design, called the At-line Benzene Monitor (ALBM), allows remote measurement of benzene in PHA solutions. The authors have demonstrated the ability to calibrate and operate this system using peanut vials from a standard Hydragard trademark sampler. The equipment and materials used to construct the ALBM are similar to those already used in other applications by the DWPF lab. The precision of this system (±0.5% Relative Standard Deviation (RSD) at 1 sigma) is better than the purge ampersand trap-gas chromatograpy reference method currently in use. Both BMSs provide a direct measurement of the benzene that can be purged from a solution with no sample pretreatment. Each analysis requires about five minutes per sample, and the system operation requires no special skills or training. The analyzer's computer software can be tailored to provide desired outputs. Use of this system produces no waste stream other than the samples themselves (i.e. no organic extractants)

Crystal structures of 4-methoxy-N-(4-methylphenylbenzenesulfonamide and N-(4-fluorophenyl-4-methoxybenzenesulfonamide

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Vinola Z. Rodrigues

2015-11-01

Full Text Available Crystal structures of two N-(arylarylsulfonamides, namely, 4-methoxy-N-(4-methylphenylbenzenesulfonamide, C14H15NO3S, (I, and N-(4-fluorophenyl-4-methoxybenzenesulfonamide, C13H12FNO3S, (II, were determined and analyzed. In (I, the benzenesulfonamide ring is disordered over two orientations, in a 0.516 (7:0.484 (7 ratio, which are inclined to each other at 28.0 (1°. In (I, the major component of the sulfonyl benzene ring and the aniline ring form a dihedral angle of 63.36 (19°, while in (II, the planes of the two benzene rings form a dihedral angle of 44.26 (13°. In the crystal structure of (I, N—H...O hydrogen bonds form infinite C(4 chains extended in [010], and intermolecular C—H...πaryl interactions link these chains into layers parallel to the ab plane. The crystal structure of (II features N—H...O hydrogen bonds forming infinite one dimensional C(4 chains along [001]. Further, a pair of C—H...O intermolecular interactions consolidate the crystal packing of (II into a three-dimensional supramolecular architecture.

Crystal structure of 1-{4-hydroxy-3-[(pyrrolidin-1-ylmethyl]phenyl}-3-phenylprop-2-en-1-one

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Abdullah Aydın

2016-05-01

Full Text Available In the title compound, C20H21NO2, the pyrrolidine ring adopts an envelope conformation with the N atom at the flap position. The central benzene ring makes dihedral angles of 21.39 (10 and 80.10 (15° with the phenyl ring and the mean plane of the pyrrolidine ring, respectively. The molecular conformation is stabilized by an intramolecular O—H...N hydrogen bond, which closes an S(6 ring. A weak C—H...π interaction is observed in the crystal.

4-[(5-Hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-ylphenylmethyl]-5-methyl-2-phenyl-1H-pyrazol-3(2H-one ethanol hemisolvate

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Hoong-Kun Fun

2009-01-01

Full Text Available The asymmetric unit of the title compound, C27H24N4O2·0.5C2H6O, comprises two crystallographically independent molecules (A and B with slightly different conformations, and one ethanol molecule of crystallization. Intramolecular C—H...O and O—H...O hydrogen bonds generate six- and eight-membered rings, producing S(6 and S(8 ring motifs, respectively. In molecule A, one of the benzene rings is disordered over two positions, with site-occupancy factors of 0.542 (11 and 0.458 (11. The dihedral angles between the central benzene ring and the two outer benzene rings are 73.88 (9 and 82.6 (2/88.9 (2° in molecule A, and 80.81 (8 and 79.38 (8° in molecule B. In the crystal structure, molecules form infinite one-dimensional chains in the (101 plane. The crystal structure is stabilized by intermolecular O—H...N, N—H...N, N—H...O and C—H...O hydrogen bonds, weak C—H...π and π–π [centroid–centroid = 3.5496 (1 Å] interactions.

Vibronic interactions proceeding from combined analytical and numerical considerations: Covalent functionalization of graphene by benzene, distortions, electronic transitions

Energy Technology Data Exchange (ETDEWEB)

Krasnenko, V.; Boltrushko, V.; Hizhnyakov, V. [Institute of Physics, University of Tartu, W. Ostwaldi Str 1, 50411 Tartu (Estonia)

2016-04-07

Chemically bound states of benzene molecules with graphene are studied both analytically and numerically. The states are formed by switching off intrabonds of π-electrons in C{sub 6} rings to interbonds. A number of different undistorted and distorted structures are established both with aligned and with transversal mutual orientation of benzene and graphene. The vibronic interactions causing distortions of bound states are found, by using a combination of analytical and numerical considerations. This allows one to determine all electronic transitions of π-electrons without explicit numerical calculations of excited states, to find the conical intersections of potentials, and to show that the mechanism of distortions is the pseudo-Jahn-Teller effect. It is found that the aligned distorted benzene molecule placed between two graphene sheets makes a chemical bond with both of them, which may be used for fastening of graphene sheets together.

Trimethyl 3,3′,3′′-(benzene-1,3,5-triyltripropynoate

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Felix Katzsch

2016-04-01

Full Text Available In the title compound, C18H12O6, the alkyne bonds are distorted, featuring bond angles around the C—C[triple-bond]C—C group of 173.6 (1/179.0 (1, 178.1 (1/178.4 (1 and 174.9 (1/175.9 (1°, and the ester groups make angles of 3.5 (1, 13.8 (1 and 14.5 (1° with the central benzene ring. In the crystal, molecules are connected in layers parallel to (131 by weak C—H...O hydrogen bonds, giving rise to a system of hydrogen-bonded ring motifs with graph sets R22(14 and R44(22. The layers are linked by C—H...O and C—H...π contacts.

Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

2010-10-01

Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

(2E-1-(3-Chlorophenyl-3-(4-chlorophenylprop-2-en-1-one

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Jerry P. Jasinski

2009-11-01

Full Text Available The title compound, C15H10Cl2O, is a chalcone with 3-chlorophenyl and 4-chlorophenyl substituents bonded at the opposite ends of a propenone group, the biologically active region. The dihedral angle between mean planes of these two chloro-substituted benzene rings is 46.7 (7° compared to 46.0 (1 and 32.4 (1° in similar published sructures. The angles between the mean plane of the prop-2-en-1-one group and the mean planes of the 3-chlorophenyl and 4-chlorophenyl rings are 24.1 (2 and 29.63°, respectively. While no classical hydrogen bonds are present, weak intermolecular C—H...π-ring interactions are observed, which contribute to the stability of crystal packing.

PROCESS SIMULATION OF BENZENE SEPARATION COLUMN OF LINEAR ALKYL BENZENE (LABPLANT

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Zaid A. AbdelRahman

2013-05-01

Full Text Available       CHEMCAD process simulator was used for the analysis of existing benzene separation column in LAB plant(Arab Detergent Company/Beiji-Iraq.         Simulated column performance curves were constructed. The variables considered in this study are the thermodynamic model option, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates compositions, were constructed. Four different thermodynamic models options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.            For Benzene Column (32 real stages, feed stage 14, the simulated results show that bottom temperature above 200 oC the weight fractions of top components, except benzene, increases sharply, where as benzene top weight fraction decreasing sharply. Also, feed temperature above 180 oC  shows same trends. The column profiles remain fairly constant from tray 3 (immediately below condenser to tray 10 (immediately above feed and from tray 15 (immediately below feed to tray 25 (immediately above reboiler. Simulation of the benzene separation column in LAB production plant using CHEMCAD simulator, confirms the real plant operation data. The study gives evidence about a successful simulation with CHEMCAD.

NMR study of conjugation effects. 15. /sup 13/C-/sup 13/C spin-spin coupling constants in phenylalkyl ether

Energy Technology Data Exchange (ETDEWEB)

Kalabin, G.A. (Siberian Branch of the Academy of Sciences of the USSR); Krivdin, L.B.; Trofimov, B.A.

1982-07-20

In order to elucidate the /sup 13/C-/sup 13/-C SSCC (spin-spin coupling constants) segment with the electronic excitations induced by the R group, a series of phenyl alkyl ethers, PhOAlk, where Alk = Me(I), Et(II), i-Pr(III), and t-Bu(IV), were studied. This series was chosen because in studying the /sup 13/C CS in monosubstituted benzenes it was observed that the intensity of the ..pi..-electron interaction of the unshared electron pairs of oxygen with the ..pi.. system of the benzene ring was practically the same in some compounds, but increased by 30% in others. This is related to the fact that the latter is characterized by an average noncoplanar conformation, with a dihedral angle between the benzene-ring plane and the C-O-C bond of approx. 45/sup 0/, whereas some compounds have an angle < 20/sup 0/. The reason for the difference is significant steric interaction of the alkyl hydrogens with the o-position of the ring. Thus, consideration of the /sup 13/C-/sup 13/C SSCC of a series of quite similar compounds, especially when compared to the whole set of such SSCC for other monosubstituted benzenes, shows that their relationship to the structure of the substituent R is extremely complex.

Dynamics of polynomials in finite and infinite Benz planes

OpenAIRE

Rafael Artzy

1992-01-01

The classical Benz planes, that is, Möbius, Minkowski, and Laguerre planes, can be coordinatized [cf. 1], respectively, by the field C of complex numbers, the ring of “double numbers” z=x+jy (x,y ∊ R) where an element j  not in R, with j2=1 is adjoined, and the ring of “dual numbers” z=x+ye where an element e not in R with e2=0 is adjoined to R. When the field R is replaced by another field, in our case finite prime fields Fp (p a prime), one also obtains co...

N,N′-Diphenyl-9,10-dioxo-9,10-dihydroanthracene-2,7-disulfonamide

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Wei-Guan Yuan

2013-07-01

Full Text Available The title molecule, C26H18N2O6S2, has an overall Z-shaped conformation, in which the benzene rings are inclined to the anthraquinone mean plane by 60.60 (9 and 50.66 (13°. In the crystal, N—H...O and C—H...O hydrogen bonds link the molecules into layers parallel to the bc plane.

Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

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Alberto Reyna

2014-01-01

Full Text Available This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction.

Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

Science.gov (United States)

Reyna, Alberto; Panduro, Marco A.; Del Rio Bocio, Carlos

2014-01-01

This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. PMID:24701150

Twin "Fano-Snowflakes" Over the Smallest Ring of Ternions

Czech Academy of Sciences Publication Activity Database

Saniga, M.; Havlicek, H.; Planat, M.; Pracna, Petr

2008-01-01

Roč. 4, - (2008), 050-1-7 ISSN 1815-0659 Institutional research plan: CEZ:AV0Z40400503 Keywords : geometry over rings * non-communicative ring of order eight * Fano plane Subject RIV: CF - Physical ; Theoretical Chemistry

From stationary annular rings to rotating Bessel beams

CSIR Research Space (South Africa)

Dudley, Angela L

2012-04-01

Full Text Available contributions from the two ring-slits completely overlap (evident in Fig. 1), the angular rotation is non-zero and the entire field at P3 experiences the rotation. 3. EXPERIMENTAL METHODOLOGY The experimental setup used to generate superpositions of higher...) as a ?petal?-field. The field at the ring-slit hologram (i.e., the field at plane P1), we will term the ?singularity?-field and that formed at plane P2 (a distance of 2f from lens L4) will be termed as the ?spiral?-field. 4. RESULTS AND DISCUSSION...

Steric/π-electronic insulation of the carbo-benzene ring: dramatic effects of tert-butyl vs phenyl crowns on geometric, chromophoric, redox and magnetic properties.

Science.gov (United States)

Listunov, Dymytrii; Duhayon, Carine; Poater, Albert; Mazères, Serge; Saquet, Alix; Maraval, Valérie; Chauvin, Remi

2018-04-13

Hexa-tert-butyl-carbo-benzene C18tBu6 and three phenylated counterparts C18tBumPh6-m (m = 4, 2) have been synthesized. The peralkylated version (m = 6) provides experimental access to intrinsic features of the insulated C18 core independently from the influence of π-conjugated substituent. Over the series, structural, spectroscopical and electrochemical properties are compared with those of the hexaphenylated reference (m = 0). Anchoring tBu substituents at the C18 macrocycle is shown to enhance stability and solubility, and to dramatically modify UV-vis absorption and redox properties. Whereas all the carbo-benzenes reported hitherto were obtained as dark-reddish/greenish solids, crystals and solutions of C18tBu6 happen to be yellow (max = 379 nm vs 472 nm for C18Ph6). By comparison to C18Ph6, reduction of C18tBu6 remains reversible but occurs at a twice higher absolute potential (E1/2 = -1.36 V vs -0.72 V). Systematic X-ray diffraction analyses and DFT calculations show that the C18 ring symmetry is the nearest to D6h for m = 6, indicating a maximum geometrical aromaticity. According to calculated nucleus independent chemical shifts, the macrocyclic magnetic aromaticity is also found to be maximum for C18tBu6: NICS(0)=-17.2 ppm, vs -18.0±0.1 ppm for the theoretical references C18H6 and C18F6, and -13.5 ppm for C18Ph6. Accurate correlations of NICS(0) with experimental or calculated maximum UV-vis absorption wavelength max and chemical hardness =ELUMO-EHOMO are evidenced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

tert-Butyl 2-methyl-2-(4-nitrobenzoylpropanoate

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Chelsey M. Crosse

2010-02-01

Full Text Available The title compound, C15H19NO5, is bent with a dihedral angle of 61.8 (2° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C. The dihedral angle of 0.8 (2° between the mean planes of the nitro group and the benzene ring indicates near coplanarity. In the crystal, each molecule is linked to four adjacent molecules by weak C—H...O hydrogen-bonding interactions. Both benzene H atoms ortho to the ketone O atom form C—H...O hydrogen bonds with the keto O atoms of two neighboring molecules (of the keto and ester groups, respectively, and the two other interactions involve the H atoms from a methyl group of the dimethyl residue, displaying C—H...O interactions with the O atoms of the nitro groups. These four interactions for each molecule lead to the formation of two-dimensional sheets with a hydrophilic interior, held together by weak hydrogen-bonded interactions, and a hydrophobic exterior composed of protruding methyl groups which interstack with the methyl groups in adjacent sheets.

Crystal structures of (RS-N-[(1R,2S-2-benzyloxy-1-(2,6-dimethylphenylpropyl]-2-methylpropane-2-sulfinamide and (RS-N-[(1S,2R-2-benzyloxy-1-(2,4,6-trimethylphenylpropyl]-2-methylpropane-2-sulfinamide: two related protected 1,2-amino alcohols

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Matthew R. Carbone

2014-11-01

Full Text Available The title compounds, C22H31NO2S, (1, and C23H33NO2S, (2, are related protected 1,2-amino alcohols. They differ in the substituents on the benzene ring, viz. 2,6-dimethylphenyl in (1 and 2,4,6-trimethylphenyl in (2. The plane of the phenyl ring is inclined to that of the benzene ring by 28.52 (7° in (1 and by 44.65 (19° in (2. In the crystal of (1, N—H...O=S and C—H...O=S hydrogen bonds link molecules, forming chains along [100], while in (2, similar hydrogen bonds link molecules into chains along [010]. The absolute structures of both compounds were determined by resonance scattering.

3-Hydroxy-2-[(4-hydroxy-3,5-dimethoxyphenyl(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-ylmethyl]-5,5-dimethylcyclohex-2-en-1-one

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Xiao-Hui Yang

2011-02-01

Full Text Available In the title compound, C25H32O7, the 3-hydroxy-5,5-dimethylcyclohex-2-enone rings adopt slightly distorted envelope conformations with the two planes at the base of the envelope forming dihedral angles of 57.6 (4 and 53.9 (9° with the benzene ring. There is an intramolecular hydroxy–ketone O—H...O interaction between the two substituted cyclohexane rings as well as a short intramolecular phenol–methoxy O—H...O interaction.

4-Hydroxy-5-(4-methoxyphenylpyrrolidin-2-one

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Suchada Chantrapromma

2008-03-01

Full Text Available In the title compound, C11H13NO3, the pyrrolidin-2-one ring is in an envelope conformation with the hydroxyl and 4-methoxyphenyl substituents mutually cis. The methoxy group is slighty twisted away from the mean plane of the attached benzene ring. The molecules are arranged into screw chains along the c axis. These chains are interconnected via intermolecular O—H...O and N—H...O hydrogen bonds into sheets parallel to the ac plane. The crystal structure is further stabilized by weak intermolecular C—H...O and C—H...π interactions.

N-(4-Fluorophenyl-2,6-dimethyl-1,3-dioxan-4-amine

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Gottimukkala Rambabu

2013-11-01

Full Text Available In the title compound, C12H16FNO2, the dioxane ring adopts a chair conformation with the methyl substituents and the C—N bond in equatorial orientations. Its mean plane subtends a dihedral angle of 40.17 (6° with the benzene ring. In the crystal, weak N—H...F hydrogen bonds link the molecules into C(7 chains propagating in [100].

Crystal structure and computational study of 2,4-dichloro-N-[(E-(5-nitrothiophen-2-ylmethylidene]aniline

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Yavuz Köysal

2016-08-01

Full Text Available The title compound, C11H6Cl2N2O2S, is a Schiff base that incorporates an N-bound 2,4-dichlorophenyl and a C-bound 5-nitrothiophene ring. The molecule is approximately planar, the maximum deviation from the mean plane being 0.233 (4 Å for the C=N N atom. The dihedral angle between the benzene and thiophene rings is 9.7 (2°. The C=N double bond has an E configuration. The crystal structure features C—H...O hydrogen bonds,forming sheets parallel to (10-1, and π–π stacking interactions between symmetry-related thiophene and benzene rings, in which the distance between adjacent ring centroids is 3.707 (4 Å, forming a three-dimensional supramolecular structure. Geometric parameters from quantum-chemical calculations are in good agreement with experimental X-ray diffraction results.

Benzene formation in electronic cigarettes.

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James F Pankow

Full Text Available The heating of the fluids used in electronic cigarettes ("e-cigarettes" used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen from e-cigarette fluids containing propylene glycol (PG, glycerol (GL, benzoic acid, the flavor chemical benzaldehyde, and nicotine.Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice, and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG and glycerol (GL, and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

2-Methoxy-4-(prop-2-en-1-ylphenyl 4-methoxybenzoate

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Mallikarjuna Rao Pichika

2013-06-01

Full Text Available In the title compound, C18H18O4, the planes of the benzene rings are twisted by 81.60 (5°. In the crystal, weak C—H...O hydrogen bonds link the molecules into supramolecular chains extending along the a axis.

Benzene-1,2-dicarboxylic acid–pyridinium-2-olate (1/1

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Chua-Hua Yu

2012-07-01

Full Text Available The asymmetric unit of the title compound, C5H5NO·C8H6O4, contains one o-phthalate acid molecule and one pyridin-2-ol molecule, which exists in a zwitterionic form. In the o-phthalate acid molecule, the carboxylate groups are twisted from the benzene ring by dihedral angles of 13.6 (1° and 73.1 (1°; the hydroxy H atom in the latter group is disordered over two positons in a 1:1 ratio. In the crystal, O—H...O and N—H...O hydrogen bonds link the molecules into zigzag chains in [-101].

Synthesis of disodium [benzene-U-{sup 14}C]-(4-chlorophenylthio)methylenediphosphonate, [benzene-U-{sup 14}C]-tiludronate

Energy Technology Data Exchange (ETDEWEB)

Burgos, Alain; Ellames, G.J. [Alnwick Research Centre (United Kingdom). Dept. of Metabolism and Pharmacokinetics

1995-12-31

Disodium [benzene-U-{sup 14}C]-(4-chlorophenylithio)methylenediphosphonate, [benzene-{sup 14}C]-Tiludronate, 2, has been prepared in six steps from [benzene-U-{sup 14}C]-acetanilide in an overall radiochemical yield of 41%. A key step in this transformation was the efficient conversion of [U-{sup 14}C]-4-chloroaniline to [benzene-U-{sup 14}C]-4-chlorophenylthiocyanate, 5, in 83% yield by treatment of the corresponding diazonium salt, 9 with iron(111) thiocyanate. It should be noted that formation of the isomeric [benzene-U-{sup 14}C]-4-chlorophenylisothiocyanate, 11, as a byproduct, was observed in only {approx} 1% yield. (author).

N-(1,3-Dioxo-2,3-dihydro-1H-isoindol-2-yl-4,4′′-difluoro-5′-hydroxy-1,1′:3′,1′′-terphenyl-4′-carboxamide

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Hoong-Kun Fun

2012-09-01

Full Text Available The asymmetric unit of the title compound, C27H16F2N2O4, consists of two crystallographically independent molecules (A and B. In molecule B, the isoindoline-1,3-dione ring system is disordered over two set of sites with a site-occupancy ratio of 0.658 (12:0.342 (12. In molecule A, the fluoro-substituted benzene rings make dihedral angles of 18.36 (8 and 46.37 (8° with the central benzene ring, whereas the corresponding angles are 40.90 (8 and 52.89 (9° in molecule B. The isoindoline ring system in molecule A and the major and minor components of the disordered isoindoline ring system in molecule B make dihedral angles of 58.50 (4, 54.13 (16 and 70.01 (28 °, respectively, with their attached benzene rings, linked through the amide group. An intramolecular O—H...O hydrogen bond generates an S(6 ring in each molecule. In the crystal, molecules are linked by N—H...O, C—H...F and C—H...O hydrogen bonds into sheets lying parallel to the bc plane. The crystal studied was a non-merohedral twin with a refined twin component ratio of 0.9316 (8:0.0684 (8.

(2,7-Dimethoxynaphthalen-1-yl(phenylmethanone

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Noriyuki Yonezawa

2010-10-01

Full Text Available The asymmetric unit of the title compound, C19H16O3, contains three independent conformers. Each of the three conformers has essentially the same feature of non-coplanar aromatic rings whereby the aroyl group at the 1-position of the naphthalene ring is twisted in a perpendicular manner to the naphthalene ring. The dihedral angles between the benzene ring planes and the naphthalene ring systems are 75.34 (7, 86.47 (7 and 76.55 (6° in the three conformers. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds.

Deriving the effective focal plane for the CBM-RICH detector

Energy Technology Data Exchange (ETDEWEB)

Kres, Ievgenii [Wuppertal University (Germany); Collaboration: CBM-Collaboration

2016-07-01

The Compressed Baryonic Matter (CBM) experiment at the future FAIR complex will investigate the phase diagram of strongly interacting matter at high baryon density and moderate temperatures in A+A collisions from 2-11 AGeV (SIS100). A central component of the proposed detector setup is a ring imaging Cherenkov detector (RICH) using CO2 as radiator gas, and a focussing optic with a large spherical mirror. In the present design, the optimal focal plane is approximated using four individual, flat detection surfaces. However, the exact shape and position of the ideal focal plane is subject to further optimization due to effects from tilting the focussing mirror and from momentum dependant deflection of the electron tracks in the magnetic stray field. In this talk, we present a new approach to derive the effective 3-dimensional shape of the focal plane based on a set of Monte Carlo simulations, comparing the ring sharpness at each point of a preliminary focal plane as function of z-position.

2-Chloroethyl 2-(5-bromo-3-methylsulfinyl-1-benzofuran-2-ylacetate

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Uk Lee

2009-05-01

Full Text Available In the title compound, C13H12BrClO4S, the O atom and the methyl group of the methylsulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment. There is a mean deviation of 0.016 (4 Å from the least-squares plane defined by the nine constituent benzofuran atoms. The crystal structure is stabilized by aromatic π–π interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.689 (7 Å]and by a weak C—H...π interaction between an H atom of the methylene group bonded to the carboxylate O atom and the benzene ring of an adjacent molecule. In addition, the crystal structure exhibits weak non-classical intermolecular C—H...O hydrogen bonds. The chloroethyl group is disordered over two positions, with refined site-occupancy factors of 0.767 (6 and 0.233 (6.

Coupling and power transfer efficiency enhancement of modular and array of planar coils using in-plane ring-shaped inner ferrites for inductive heating applications

Science.gov (United States)

Kilic, V. T.; Unal, E.; Demir, H. V.

2017-07-01

We propose and demonstrate a highly effective method of enhancing coupling and power transfer efficiency in inductive heating systems composed of planar coils. The proposed method is based on locating ring-shaped ferrites in the inner side of the coils in the same plane. Measurement results of simple inductive heating systems constructed with either a single or a pair of conventional circular coils show that, with the in-plane inner ferrites, the total dissipated power of the system is increased by over 65%. Also, with three-dimensional full electromagnetic solutions, it is found that power transfer efficiency of the system is increased up to 92% with the inner ferrite placement. The proposed method is promising to be used for efficiency enhancement in inductive heating applications, especially in all-surface induction hobs.

3-Fluoro-N-(p-tolylbenzamide

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Aamer Saeed

2008-11-01

Full Text Available In the crystal structure of the title compound, C14H12FNO, the amide –NHCO– mean plane makes dihedral angles of 28.6 (2 and 37.5 (2° with the mean planes through the fluorobenzene and methylbenzene units, respectively. The dihedral angle between the two benzene ring mean planes is 65.69 (10°. In the crystal structure, molecules are linked through N—H...O hydrogen bonds and stack along the b axis.

The formation of quasi-alicyclic rings in alkyl-aromatic compounds

Science.gov (United States)

Straka, Pavel; Buryan, Petr; Bičáková, Olga

2018-02-01

The alkyl side chains of n-alkyl phenols, n-alkyl benzenes and n-alkyl naphthalenes are cyclised, as demonstrated by GC measurements, FTIR spectroscopy and molecular mechanics calculations. Cyclisation occurs due to the intramolecular interaction between an aromatic ring (-δ) and a hydrogen of the terminal methyl group (+δ) of an alkyl chain. In fact, conventional molecules are not aliphatic-aromatic, but quasi-alicyclic-aromatic. With the aromatic molecules formed with a quasi-alicyclic ring, the effect of van der Waals attractive forces increases not only intramolecularly but also intermolecularly. This effect is strong in molecules with propyl and higher alkyl substituents. The increase of intermolecular van der Waals attractive forces results in bi-linearity in the GC retention time of the compounds in question, observed in the dependence of the logarithm of the relative retention time on the number of carbons in a molecule in both polar and nonpolar stationary phases with both capillary and packed columns. The role of van der Waals forces has been demonstrated using the potential energies of covalent and noncovalent interactions for 2-n-alkyl phenols, n-alkyl benzenes and 1-n-alkyl- and 2-n-alkyl naphthalenes.

4-(Prop-2-yn-1-yloxybenzene-1,2-dicarbonitrile

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Yee Jan Chin

2012-07-01

Full Text Available In the title compound, C11H6N2O, the complete molecule is generated by the application of crystallographic twofold symmetry (the molecule is disordered about this axis. The prop-2-yn-1-yl residue is slightly twisted out of the plane of the benzene ring [C—O—C—C torsion angle = 173.1 (3°] and is orientated away from the nitrile substituents. In the crystal, supramolecular chains along the a axis, arising from C—H...N interactions, are connected into stacks along the c axis by π–π interactions between the benzene rings [centroid–centroid distance = 3.6978 (6 Å = length of the c axis].

Crystal structure of 3,4-dichloroanilinium hydrogen phthalate

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Muhammad Shahid

2015-07-01

Full Text Available In the title salt, C6H6Cl2N+·C8H5O4−, the carboxylic acid and carboxylate groups of the anion form dihedral angles of 20.79 (19 and 74.76 (14°, respectively, with the plane of the benzene ring. In the crystal, molecules are assembled into a two-dimensional polymeric network parallel to (100 via N—H...O and O—H...O hydrogen bonds. In addition, within the layer, there are π–π stacking interactions between the benzene rings of the cation and the anion [centroid–centroid distance = 3.6794 (17 Å]. A weak C—H...O interaction is also observed.

Benzene and lymphohematopoietic malignancies in humans.

Science.gov (United States)

Hayes, R B; Songnian, Y; Dosemeci, M; Linet, M

2001-08-01

Quantitative evaluations of benzene-associated risk for cancer have relied primarily on findings from a cohort study of highly exposed U.S. rubber workers. An epidemiologic investigation in China (NCI/CAPM study) extended quantitative evaluations of cancer risk to a broader range of benzene exposures, particularly at lower levels. We review the evidence implicating benzene in the etiology of hematopoietic disorders, clarify methodologic aspects of the NCI/CAPM study, and examine the study in the context of the broader literature on health effects associated with occupational benzene exposure. Quantitative relationships for cancer risk from China and the U.S. show a relatively smooth increase in risk for acute myeloid leukemia and related conditions over a broad dose range of benzene exposure (below 200 ppm-years mostly from the China study and above 200 ppm-years mostly from the U.S. study). Risks of acute myeloid leukemia and other malignant and nonmalignant hematopoietic disorders associated with benzene exposure in China are consistent with other information about benzene exposure, hematotoxicity, and cancer risk, extending evidence for hematopoietic cancer risks to levels substantially lower than had previously been established. Published 2001 Wiley-Liss, Inc.

Crystal structure of (2E,3E-N2,N3-bis(3-ethyl-[1,1′-biphenyl]-4-ylbutane-2,3-diimine

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Yan Zhao

2015-04-01

Full Text Available In the title compound, C32H32N2, synthesized by the condensation reaction of 2-ethyl-4-phenylaniline and 2,3-butanedione, the conformation about the C=N bonds is E and the substituted biphenyl units are trans to one another. In the two biphenyl ring systems, the planes of the two rings are inclined to one another by 25.25 (19 and 28.01 (19°. The planes of the ethyl-substituted benzene rings are inclined to one another by 20.23 (19° and to the mean plane of the butane-2,3-diimine unit [maximum deviation = 0.014 (4 Å] by 83.19 (19 and 63.38 (19°. In the crystal, molecules are linked by C—H...π interactions, forming sheets lying parallel to (101.

1-Benzyl-3-[3-(naphthalen-2-yloxypropyl]imidazolium hexafluorophosphate

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Kun Huang

2011-08-01

Full Text Available In the title salt, C23H23N2O+·PF6−, the PF6− anion is highly disordered (occupancy ratios of 0.35:0.35:0.3, 0.7:0.15:0.15, 0.7:0.3 and 0.35:0.35:0.15:0.15 with the four F atoms in the equatorial plane rotating about the axial F—P—F bond. The mean plane of the imidazole ring makes dihedral angles of 82.44 (17 and 14.39 (16°, respectively, with the mean planes of the benzene ring and the naphthalene ring system. The crystal structure is stabilized by C—H...F hydrogen bonds. In addition, π–π [centroid–centroid distances = 3.7271 (19–3.8895 (17 Å] and C—H...π interactions are observed.

Economical benzene emission reduction

International Nuclear Information System (INIS)

Schuetz, R.

1999-01-01

Benzene has been classified as a toxic compound under the Canadian Environmental Protection Act. This has prompted the Alberta Energy and Utilities Board (AEUB) to introduce specific reporting and monitoring guidelines for the oil and gas industry regarding excessive benzene emissions. Glycol dehydration units have been determined to be the major single source of benzene emissions causing air and soil pollution. DualTank Corp. has designed a condensation and storage tank unit to enhance emission reduction, odour elimination and liquid recovery from dehydration units. Their newly designed combined tank unit consists of a large, uninsulated surface area for cooling, and an excessive internal volume for increased retention time. The first prototype was installed in December 1998 at an Enerplus Resources Site. The system provides excellent benzene emission reduction and the elimination of odours and visual plumes. Effective January 1, 1999, the petroleum and natural gas industry must either clean up excessive emissions voluntarily or face government imposed regulations, facility shutdowns and/or fines. 1 fig

Microstructure of the regions on a plane copper electrode surface affected by a spark discharge in air in the point-plane gap

Science.gov (United States)

Tren'kin, A. A.; Karelin, V. I.; Shibitov, Yu. M.; Blinova, O. M.; Yasnikov, I. S.

2017-09-01

The microstructure of the regions affected by spark discharge on the surface of a plane copper electrode in atmospheric air in the point-plane gap has been studied using a scanning electron microscope for both the positive and negative polarity of the point electrode. It has been found that the affected regions have the shape of round spots or groups of spots with diameters of individual spots varying in the range of 20-200 μm. It has been revealed that the spots have an internal spatial structure in the form of an aggregate of concentric rings. These rings are aggregates of a large number of microscopic craters with diameters of 0.1-1.0 μm.

Benzene exposures in urban areas

International Nuclear Information System (INIS)

Valerio, F.; Pala, M.; Cipolla, M.; Stella, A.

2001-01-01

Benzene exposures in urban areas were reviewed. Available data confirm that both in USA and Europe, benzene concentrations measured by fixed outdoor monitoring stations underestimate personal exposures of urban residents. Indoor sources, passive smoke and the high exposures during commuting time may explain this difference. Measures in European towns confirm that very frequently mean daily personal exposures to benzene exceed 10 μg/m 3 , current European air quality guideline for this carcinogenic compound [it

Benzene in Canadian gasoline : report on the effect of the benzene in gasoline regulations 2002

Energy Technology Data Exchange (ETDEWEB)

Guthrie, J. [Environment Canada, Ottawa, ON (Canada); Sabourin, R. [Carleton Univ., Ottawa, ON (Canada); Brunet, E. [Waterloo Univ., ON (Canada)

2003-11-01

The response of primary suppliers to Benzene in Gasoline Regulations was reviewed, and a summary of the effects of those regulations on the composition of gasoline in Canada in 2002 was offered. These regulations, effective July 1, 1999, were designed to provide a new approach to control fuel composition. It allowed suppliers, as a basis for compliance, the option to elect to use a yearly pool average. The benzene emission number (BEN) of gasoline was regulated, and a limit imposed on a per-litre limit for benzene at point of sale. The results indicated that reported benzene levels were significantly reduced, while aromatic levels remained practically unchanged from 1994. Since 1998, rural ambient benzene concentrations decreased by more than 32 per cent, while in urban areas, they decreased by 47 per cent over the same period. The regulated requirements for benzene concentration were met by primary suppliers in Canada in 2002 (with one exception), as were BEN levels. A number of instances of non-compliance with laboratory procedures were discovered during independent audits required for those suppliers who elected to be on on a yearly pool average. Corrective action designed to address these issues was implemented. 41 tabs., 24 figs.

Occupational exposure to benzene in South Korea.

Science.gov (United States)

Kang, Seong-Kyu; Lee, Mi-Young; Kim, Tae-Kyun; Lee, Jeong-Oh; Ahn, Yeon Soon

2005-05-30

Benzene has been used in various industries as glues or solvents in Korea. Since 1981, a preparation containing more than 1% benzene is not allowed to be manufactured, used or dealt with in the workplace, except in laboratories and in those situations benzene must be used in a completely sealed process as specified in Industrial Safety and Health Act (ISHA). Claims for compensation of hematopoietic diseases related to benzene have been rising even though the work environment has been improved. This study was conducted to assess the status of benzene exposure in different industries in Korea. We reviewed the claimed cases investigated by the Korea Occupational Safety and Health Agency (KOSHA) between 1992 and 2000. The Survey of National Work Environment Status in 1998 was analyzed to assume the number of workers and factories exposed to benzene. In 2000, six factories were investigated to evaluate benzene exposure. Personal air monitoring was performed in 61 workers and urine samples were collected from 57 workers to measure trans,trans-muconic acid (t,t-MA). Hematologic examination has performed. Thirty-four cases of hematopoietic diseases were investigated by KOSHA including eight cases of myelodysplastic syndrome and eight cases of acute myelocytic leukemia. Eight cases were accepted as related to benzene exposure. The number of workers possibly exposed to benzene can be estimated to be 196,182 workers from 6219 factories based on the database. The geometric mean of benzene in air was 0.094 (0.005-5.311) ppm. Seven samples were higher than 1 ppm but they did not go over the 10 ppm occupational exposure limit (OEL) value in Korea. The geometric mean of trans,trans-muconic acid in urine was 0.966 (0.24-2.74) mg/g creatinine. The benzene exposure level was low except in a factory where benzene was used to polymerize other chemicals. The ambient benzene from 0.1 to 1 ppm was significantly correlated with urine t,t-MA concentration (r=0.733, p<0.01). Hematologic

4-Acetamido-N-(λ5-triphenyl­phospho­ranyl­idene)benzene­sulfonamide

Science.gov (United States)

Prugovečki, Biserka; Marinković, Marina; Vinković, Mladen; Dumić, Miljenko

2010-01-01

There are two independent mol­ecules per asymmetric unit of the title compound, C26H23N2O3PS. Their superposition shows that they differ in the conformation of the CH3CO– group and the benzene rings from the triphenyl­phospho­rane group. In the crystal structure, independent mol­ecules are inter­conected by strong N—H⋯O hydrogen bonds, forming infinite chains along the a axis. PMID:21579151

4′-Methyl-1H-14′,19′-dioxa-4′-azaspiro[indole-3,5′-tetracyclo[18.4.0.02,6.08,13]tetracosane]-1′(24′,8′,10′,12′,20′,22′-hexaene-2,7′(3H-dione

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Sibi Narayanan

2012-12-01

Full Text Available In the title compound, C29H28N2O4, the indoline ring system is essentially planar, with a maximum deviation of 0.027 (2 Å; the carbonyl O atom lies 0.102 (1 Å out of the least-squares plane of the indole ring. The pyrrolidine ring adopts a C-envelope conformation, with a C atom displaced by 0.643 (2 Å from the mean plane formed by the remaining ring atoms. The pyrrolidine ring makes a dihedral angle of 86.1 (8° with the indoline ring system. In the crystal, N—H...O hydrogen bonds result in the formation of cyclic centrosymmetric dimers [R22(8]. C—H...π interactions also occur, leading to a chain along the b-axis direction. There is a rather weak π–π electron interaction between the pyrrazole and benzene rings, with a centroid–centroid distance of 3.765 (1 Å.

Proton and hydrogen formation by cyclohexyl benzene during overcharge of Li-ion batteries

Science.gov (United States)

Lee, Hochun; Kim, Soojin; Jeon, Jongho; Cho, Jeong-Ju

This study provides experimental evidence for proton and hydrogen formation caused by the anodic electropolymerization of cyclohexyl benzene (CHB), which is a popular electrolyte additive for overcharge protection of lithium-ion batteries (LIBs). It is found that considerable H 2 evolution is observed in overcharged LiCoO 2/graphite cells, especially when CHB is included as an electrolyte additive. In order to confirm the proton generation during the CHB oxidation, Pt/Pt-rotating ring disc electrode (RRDE) measurements are performed in 1 M Li(C 2F 5SO 2) 2N ethylene carbonate/ethyl methyl carbonate (1/2, v/v) solutions with and without CHB. The cathodic ring current is intimately correlated to the anodic disc current, and the cathodic reaction at the ring is determined to be the reduction of the proton. The proton generation efficiency during the CHB oxidation is as high as 90%. Proton liberation is also observed during the anodic decomposition of the electrolyte solvents, although it occurs in a much less stoichiometric way compared with that during the CHB oxidation.

Mechanistic considerations in benzene physiological model development.

Science.gov (United States)

Medinsky, M A; Kenyon, E M; Seaton, M J; Schlosser, P M

1996-12-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Because benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol, and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus the potential exists for competition among various enzymes for phenol. Zonal localization of phase I and phase II enzymes in various regions of the liver acinus also impacts this competition. Biologically based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans.

Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

2010-12-01

Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Gap solitons in a chain of split-ring resonator dimers

Energy Technology Data Exchange (ETDEWEB)

Cui, Wei-na, E-mail: cuiweinaa@163.com [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Hong-xia, E-mail: hxli@njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Sun, Min [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Bu, Ling-bing [Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2017-06-21

Dynamics of a chain of split-ring resonator dimers with Kerr nonlinear interaction are investigated. A dimer is built as a pair of coupled split-ring resonators with different size. It is shown that the gap solitons with frequency lying in the gap exist due to the interaction of the discreteness and nonlinearity. Such localized structures are studied in the phase plane and analytical and numerical expressions are also obtained. - Highlights: • The coupling of the two modes is studied in the chain of split-ring resonator dimers with Kerr nonlinear interaction. • The evolution of the localized structures is studied in the phase plane. • This system supports gap solitons with the frequencies lying in the gap.

Benzene and its Isomers

Indian Academy of Sciences (India)

instantly brings benzene to mind. Benzene is one of the most basic structural units of thousands of the so-called aromatic compounds, which include dyes, drugs, polymers and many more types of compounds that are very useful for our existence and progress. The whole gamut of the chemistry of aromatic compounds, ...

1,2-Diiodo-4,5-dimethyl­benzene

Science.gov (United States)

Hathaway, Bruce A.; Kilgore, Uriah J.; Bond, Marcus R.

2009-01-01

The structure of the title compound, C8H8I2, conforms closely to the mm2 symmetry expected for the free mol­ecule and is the first reported structure of a diiodo­dimethyl­benzene. Repulsion by neighboring I atoms and the neighboring methyl groups opposite to them results in a slight elongation of the mol­ecule along the approximate twofold rotation axis that bis­ects the ring between the two I atoms. In the extended structure, the mol­ecules form inversion-related pairs which are organized in approximately hexa­gonal close-packed layers and the layers then stacked so that mol­ecules in neighboring layers abut head-to-tail in a manner that optimizes dipole–dipole inter­actions. PMID:21583089

Elevated Atmospheric Levels of Benzene and Benzene-Related Compounds from Unconventional Shale Extraction and Processing: Human Health Concern for Residential Communities.

Science.gov (United States)

Rich, Alisa L; Orimoloye, Helen T

2016-01-01

The advancement of natural gas (NG) extraction across the United States (U.S.) raises concern for potential exposure to hazardous air pollutants (HAPs). Benzene, a HAP and a primary chemical of concern due to its classification as a known human carcinogen, is present in petroleum-rich geologic formations and is formed during the combustion of bypass NG. It is a component in solvents, paraffin breakers, and fuels used in NG extraction and processing (E&P). The objectives of this study are to confirm the presence of benzene and benzene-related compounds (benzene[s]) in residential areas, where unconventional shale E&P is occurring, and to determine if benzene[s] exists in elevated atmospheric concentrations when compared to national background levels. Ambient air sampling was conducted in six counties in the Dallas/Fort Worth Metroplex with passive samples collected in evacuated 6-L Summa canisters. Samples were analyzed by gas chromatography/mass spectrometry, with sampling performed at variable distances from the facility fence line. Elevated concentrations of benzene[s] in the atmosphere were identified when compared to U.S. Environmental Protection Agency's Urban Air Toxics Monitoring Program. The 24-hour benzene concentrations ranged from 0.6 parts per billion by volume (ppbv) to 592 ppbv, with 1-hour concentrations from 2.94 ppbv to 2,900.20 ppbv. Benzene is a known human carcinogen capable of multisystem health effects. Exposure to benzene is correlated with bone marrow and blood-forming organ damage and immune system depression. Sensitive populations (children, pregnant women, elderly, immunocompromised) and occupational workers are at increased risk for adverse health effects from elevated atmospheric levels of benzene[s] in residential areas with unconventional shale E&P.

2-Dichloromethyl-N-ethyl-5-(1-phenylsilolan-1-ylcyclopent-3-enecarboxamide

Directory of Open Access Journals (Sweden)

Han Xiao

2013-10-01

Full Text Available In the title compound, C19H25Cl2NOSi, the NH group and the carbonyl O atom of the amide fragment are involved in an intermolecular N—H...O hydrogen bond forming chains of molecules. The plane of the benzene ring forms a dihedral angle of 50.5 (2° with respect to the silolane ring and an angle of 49.74 (2° with the cyclopentyl moiety.

4-Chloro-N-o-tolylbenzamide

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Hiroyuki Ishida

2008-10-01

Full Text Available In the molecule of the title compound, C14H12ClNO, the two benzene rings are close to coplanar [dihedral angle = 7.85 (4°]. The amide N—C=O plane makes dihedral angles of 34.04 (4 and 39.90 (3°, respectively, with the 4-chloro- and 2-methylphenyl rings. In the crystal structure, intermolecular N—H...O hydrogen bonds link the molecules into chains.

2-{[(2-Methoxynaphthalen-1-ylmethyl]amino}phenol

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Sara Mahdjoub

2016-07-01

Full Text Available The asymmetric unit of the title compound, C18H17NO2, contains two independent molecules (A and B. The dihedral angle between the naphthalene ring system and the benzene ring is 74.67 (10° in molecule A and 78.81 (9° in molecule B. In the crystal, molecules are linked by a series of C—H...π interactions, forming sheets parallel to the ab plane.

Experimental and theoretical investigation of the production of cations containing C-N bonds in the reaction of benzene with atomic nitrogen ions

International Nuclear Information System (INIS)

Di Stefano, Marco; Rosi, Marzio; Sgamellotti, Antonio; Ascenzi, Daniela; Bassi, Davide; Franceschi, Pietro; Tosi, Paolo

2003-01-01

In the last few years, astronomical spectra have revealed the presence of aromatic and polyaromatic molecules in extraterrestrial environments, near carbon stars, in molecular clouds and meteorites. Moreover, the recent observation of benzene in interstellar space has noticeably increased the interest in the entire class of molecules and in their chemical behavior. In this work, we have investigated the reaction between the benzene molecule and the atomic nitrogen cation and, in particular, the mechanisms by which the reactants are converted into cationic products containing at least one C-N bond, according to the general scheme C 6 H 6 +N + →H m C n N + +C x H y . We have measured the energy dependence of the cross section in a guided ion beam tandem mass spectrometer. Relevant stationary points of the potential energy surface have been studied by using the density functional theory hybrid functional B3LYP with the 6-31G* basis set. Thermochemical calculations, and the comparison with experimental results, allow us to distinguish between exoergic and endoergic processes and to obtain a detailed description of the reaction mechanisms. We show that aromatic hydrocarbons may be converted into organic-nitrogen compounds via the insertion of N + into the benzene ring and the formation of C-N bonds from C-C ring reactants

Ring-shaped functions and Wigner 6j-symbols

International Nuclear Information System (INIS)

Mardoyan, L.G.; Erevanskij Gosudarstvennyj Univ., Erevan

2006-01-01

The explicit expression for the ring-shaped matrix connecting the ring-shaped functions relating to different values of the axial parameter is obtained. The connection of this matrix with Wigner 6j-symbols is found out. The motion of quantum particle in the ring-shaped model with the zero priming potential is investigated. The bases of this model, which are factored in spherical cylindrical coordinates, are obtained. The formula generalizing the Rayleigh expansion of a plane wave with respect to spherical waves in the ring-shaped model is deduced [ru

Poly[[(μ4-benzene-1,3,5-tricarboxylato-κ4O1:O1′:O2:O3bis(2,2-bipyridine-κ2N,N′(μ2-hydroxidodicopper(II] trihydrate

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Mohamed N. El-kaheli

2014-07-01

Full Text Available In the title two-dimensional coordination polymer, {[Cu2(C9H3O6(OH(C10H8N22]·3H2O}n, each of the two independent CuII atoms is coordinated by a bridging OH group, two O atoms from two benzene-1,3,5-tricarboxylate (L ligands and two N atoms from a 2,2- bipyridine (bipy ligand in a distorted square-pyramidal geometry. Each L ligand coordinates four CuII atoms, thus forming a polymeric layer parallel to the bc plane with bipy molecules protruding up and down. The lattice water molecules involved in O—H...· O hydrogen bonding are situated in the inner part of each layer. The crystal packing is consolidated by π–π interactions between the aromatic rings of bipy ligands from neigbouring layers [intercentroid distance = 3.762 (3 Å].

On harmonicity in some Moufang-Klingenberg planes

OpenAIRE

ÇELİK, Basri; AKPINAR, Atilla; ÇİFTÇİ, Süleyman

2010-01-01

In this paper we study Moufang-Klingenberg planes M (A) defined over a local alternative ring A of dual numbers. We show that some collineations of M (A) preserve cross-ratio and thus establish a relation between harmonicity and harmonic position.

Atmospheric benzene and toluene

International Nuclear Information System (INIS)

Rasmussen, R.A.; Khalil, M.A.K.

1983-01-01

Atmospheric concentrations of benzene (C 6 H 6 ) and toluene (C 7 H 8 )have been observed at nine remote locations of the world ranging in latitude from inside the arctic circle to the south pole. The observations span all seasons at each location. In the northern hemisphere it is observed that C 6 H 6 and C 7 H 8 are most abundant during winter and least abundant during summer. Based on the limited data available, such cycles are not observed in the tropics. These findings are consistent with the expected latitudinal and seasonal variations of OH radicals which cause benzene and toluene to be removed from the atmosphere. The latitude distribution shows high concentrations at mid latitude and low levels in the southern hemisphere. This finding is consistent with the present understanding that the sources of benzene and toluene are primarily anthropogenic. The observed concentration distribution and varibility are consistent with the short expected atmospheric lifetime of the order of months for benzene and days for toluene

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

Science.gov (United States)

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.

A novel in-plane mode rotary ultrasonic motor

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Lu Xiaolong

2014-04-01

Full Text Available Ultrasonic motors have the merits of high ratio of torque to volume, high positioning precision, intrinsic holding torque, etc., compared to the conventional electromagnetic motors. There have been several potential applications for this type of motor in aerospace exploration, but bearings and bonding mechanism of the piezoelectric ring in the motors limit the performance of them in the space operation conditions. It is known that the Langevin type transducer has excellent energy efficiency and reliability. Hence using the Langevin type transducer in ultrasonic motors may improve the reliability of piezoelectric motors for space applications. In this study, a novel in-plane mode rotary ultrasonic motor is designed, fabricated, and characterized. The proposed motor operates in in-plane vibration mode which is excited by four Langevin-type bending vibrators separately placed around a ring-shaped stator. Two tapered rotors are assembled to the inner ring of the stator and clamped together by a screw nut. In order to make the motor more stable and convenient to fix, a thin cylindrical support is placed under the stator ring. Due to its no-bearing structure and Langevin transducer excitation, the prototype ultrasonic motor may operate well in aeronautic and astronautic environments.

Physically elastic analysis of a cylindrical ring as a unit cell of a complete composite under applied stress in the complex plane using cubic polynomials

Science.gov (United States)

Monfared, Vahid

2018-03-01

Elastic analysis is analytically presented to predict the behaviors of the stress and displacement components in the cylindrical ring as a unit cell of a complete composite under applied stress in the complex plane using cubic polynomials. This analysis is based on the complex computation of the stress functions in the complex plane and polar coordinates. Also, suitable boundary conditions are considered and assumed to analyze along with the equilibrium equations and bi-harmonic equation. This method has some important applications in many fields of engineering such as mechanical, civil and material engineering generally. One of the applications of this research work is in composite design and designing the cylindrical devices under various loadings. Finally, it is founded that the convergence and accuracy of the results are suitable and acceptable through comparing the results.

The influence of different light quality and benzene on gene expression and benzene degradation of Chlorophytum comosum.

Science.gov (United States)

Setsungnern, Arnon; Treesubsuntorn, Chairat; Thiravetyan, Paitip

2017-11-01

Benzene, a carcinogenic compound, has been reported as a major indoor air pollutant. Chlorophytum comosum (C. comosum) was reported to be the highest efficient benzene removal plant among other screened plants. Our previous studies found that plants under light conditions could remove gaseous benzene higher than under dark conditions. Therefore, C. comosum exposure to airborne benzene was studied under different light quality at the same light intensity. C. comosum could remove 500 ppm gaseous benzene with the highest efficiency of 68.77% under Blue:Red = 1:1 LED treatments and the lowest one appeared 57.41% under white fluorescent treatment within 8 days. After benzene was uptaken by C. comosum, benzene was oxidized to be phenol in the plant cells by cytochrome P450 monooxygenase system. Then, phenol was catalyzed to be catechol that was confirmed by the up-regulation of phenol 2-monooxygenase (PMO) gene expression. After that, catechol was changed to cic, cis-muconic acid. Interestingly, cis,cis-muconic acid production was found in the plant tissues higher than phenol and catechol. The result confirmed that NADPH-cytochrome P450 reductase (CPR), cytochrome b5 (cyt b5), phenol 2-monooxygenase (PMO) and cytochrome P450 90B1 (CYP90B1) in plant cells were involved in benzene degradation or detoxification. In addition, phenol, catechol, and cis,cis-muconic acid production were found under the Blue-Red LED light conditions higher than under white fluorescent light conditions due to under LED light conditions gave higher NADPH contents. Hence, C. comosum under the Blue-Red LED light conditions had a high potential to remove benzene in a contaminated site. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Electron transmission through coupled quantum dots in an Aharonov-Bohm ring

International Nuclear Information System (INIS)

Joe, Y. S.; Kim, Y. D.

2006-01-01

Stimulated by recent intriguing experiments with a quantum dot in an Aharonov-Bohm (AB) ring, we investigate novel resonant phenomena by studying the total transmission probability of nanoscale AB ring with embedded double quantum dots in one arm and a magnetic flux passing through the rings' center. In this system, we show an overlapping and merging of Fano resonances as the interaction parameter between the dots changes. In the strong overlapping region of Fano resonances, the transmission zeros leave the real-energy axis and move away in opposite directions in the complex-energy plane. The behavior of the Fano zero-pole resonances in the complex-energy plane as a function of the external magnetic flux is also investigated for various coupling integrals between the quantum dots in the ring.

Crystal structure of (E-4,4,4-trifluoro-3-phenylbut-2-enoic acid

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Alexey Barkov

2015-12-01

Full Text Available In the title compound, C10H7F3O2, the dihedral angle between the benzene ring and the ethylene plane is 76.34 (11°. In the crystal, O—H...O hydrogen bonds link the molecules into C(4 chains propagating in [010].

3-(4-Chlorobenzoyl-4-(4-chlorophenyl-1-phenethylpiperidin-4-ol

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Abdullah Aydın

2011-06-01

Full Text Available In the title compound, C26H25Cl2NO2, the piperidine ring adopts a chair conformation with a cis configuration of the carbonyl and hydroxy substituents. The dihedral angle between the aromatic rings of the chlorobenzene groups is 24.3 (2°. The phenyl ring forms dihedral angles of 59.4 (3 and 44.1 (3° with the benzene rings. In the crystal, molecules are linked by intermolecular O—H...N and C—H...O hydrogen bonds and C—H...π interactions into layers parallel to the bc plane.

2-(4-Chlorobenzoyl-3,6-dimethoxynaphthalene

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Noriyuki Yonezawa

2008-03-01

Full Text Available In the title compound, C19H15ClO3, the interplanar angle between the naphthalene and benzene ring systems is 62.67 (6°. The carbonyl group is twisted from both ring planes, with torsion angles of −44.9 (2° with respect to the naphthalene ring and −26.7 (2° with respect to the phenylene ring. There is an intermolecular hydrogen bond between an H atom of one methoxy group and the O atom of the second methoxy group, forming chains along the ac diagonal.

1-Acetyl-3-ferrocenyl-5-(2-nitrophenyl-2-pyrazoline

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Orhan Büyükgüngör

2008-04-01

Full Text Available In the title compound, [Fe(C5H5(C16H14N3O3], the pyrazoline ring and the substituted cyclopentadienyl ring are nearly coplanar, with a dihedral angle of 8.17 (2°, while the nitro-substituted benzene ring is twisted out of the pyrazoline ring plane by 70.76 (1°. The molecules in the crystal structure are held together by three intermolecular C—H...O hydrogen bonds. There is also an intramolecular C—H...N hydrogen bond. The H atoms of the methyl group are disordered equally over two positions.

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

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S. Ranjith

2011-07-01

Full Text Available 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].

2-(Diphenylmethylidene-2,3-dihydro-1H-inden-1-one

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Helen Sheridan

2013-08-01

Full Text Available In the title molecule, C22H16O, the indanone ring system is approximately planar with a dihedral angle between the fused rings of 5.13 (14°. Two benzene rings are linked together at one side of a double bond, sitting on either side of the indanone ring system and making dihedral angles of 70.30 (12 and 44.74 (13° with it. In the crystal, hydrogen bonding is not present, but weak C—H...π or π–π interactions occur and molecules form a sheet-like structure in the bc plane.

2-Oxo-2H-chromen-3-yl 4-tert-butylbenzoate

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Konan René Kambo

2016-10-01

Full Text Available In the title coumarin derivative, C20H18O4, the benzene ring of the benzoate group is oriented at a dihedral angle of 57.55 (9° with respect to the planar chromene ring system [maximum deviation from plane is 0.027 (2 Å]. In the crystal, inversion-related molecules are linked into dimers via C—H...O hydrogen bonds, generating R22(12 loops. The dimers are linked by further C—H...O hydrogen bonds forming layers, parallel to the bc plane, which are linked via C—H...π interactions, forming a three-dimensional framework

(E-4-Chloro-N-[(E-2-methyl-3-phenylallylidene]aniline

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Jim Simpson

2009-02-01

Full Text Available The title Schiff base compound, C16H14ClN, adopts E configurations with respect to both the C=C and C=N bonds. The dihedral angle between the two aromatic rings is 53.27 (4°, while the plane through the C=C—C=N system is inclined at 9.06 (8° to the benzene ring and 44.92 (5° to the chlorobenzene ring. In the crystal structure, weak C—H...Cl and C—H...N hydrogen bonds stack the molecules down the a axis.

A molecular dynamics study for the isomerization of Ar solvated (benzene){sub 2}-K{sup +} heteroclusters

Energy Technology Data Exchange (ETDEWEB)

Alberti, M. [CERQT, Departament de Quimica Fisica Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Pacifici, L. [Department of Mathematics and Computer Science, University of Perugia, via Vanvitelli, 1 06123 Perugia (Italy); Lagana, A. [Department of Chemistry, University of Perugia, via Elce di Sotto, 8 06123 Perugia (Italy)], E-mail: lag@dyn.unipg.it; Aguilar, A. [CERQT, Departament de Quimica Fisica Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain)

2006-08-21

A dynamical study of the (benzene){sub 2}-K{sup +} heteroclusters solvated by Ar atoms has been performed using an analytical force field of the atom (ion)-bond type. An analysis of the relevant calculated structural and energetic properties of these systems is made to understand involved molecular processes. The key effect found in the calculations is the tieing up of the two rings to sandwich K{sup +} and the weaking of this effect by solvation.

8-{1-[(4′-Fluoro-[1,1′-biphenyl]-4-ylmethyl]piperidin-4-yl}-3,4-dihydroquinolin-2(1H-one chloroform 0.25-solvate

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Nisar Ullah

2014-02-01

Full Text Available In the asymmetric unit of the title compound, C27H27FN2O·0.25CHCl3, there are two independent molecules (A and B together with a partially disordered chloroform molecule situated about an inversion center. The conformation of the two molecules is very similar. The bridging piperidine rings each have a chair conformation while the piperidin-2-one rings of the quinoline moiety have screw-boat conformations. The benzene rings of the biphenyl moiety are inclined to one another by 26.37 (4 and 23.75 (15° in molecules A and B, respectively. The mean plane of the central piperidine ring [r.m.s. deviation = 0.241 (2 Å in both molecules A and B] is inclined to the benzene ring of the quinoline moiety by 80.06 (4 in A and 83.75 (15° in B, while it is inclined to the adjacent benzene ring of the biphenyl group by 73.623 (15 in A and 75.65 (14° in B. In the crystal, individual molecules are linked by pairs of N—H...O hydrogen bonds, forming A–A and B–B inversion dimers with R22(8 ring motifs. The dimers are stabilized by C—H...O hydrogen bonds and linked via C—H...F and C—H...N hydrogen bonds into a three-dimensional network. Several C—H...π interactions are also present.

An Archetype Semi-Ring Fabry-Perot (SRFP) Resonator

Science.gov (United States)

Taghavi-Larigani, Shervin; VanZyl, Jakob

2009-01-01

We introduce and demonstrate the generation of a novel resonator, termed Semi-Ring Fabry-Perot (SRFP), that exhibits unique features, such as, its use of one plane mirror, allowing the SRFP to be easily fabricated as a symmetrical device. In addition to its unique features, it exhibits advantages of ring and Fabry-Perot resonators: 1) compared to a ring resonator that only allows a transmitted intensity, the Semi-Ring Fabry-Perot (SRFP) supports standing waves, allowing both a reflected and transmitted intensity; 2) the reflected light spectrum of the SRFP resonator is much narrower than similar Fabry-Perot, implying higher finesse.

A new and general method for the preparation of novel II-heterocyclic derivatives of ruthenium [C5Me5Ru (η6-arene)]X (arene = benzene, thiophene, 3-methylthiophene, benzothiophene, pyridine, 2.6 and 3.5-lutidine, quinoline, acridine). X-ray crystal structure of [(C5Me5)2Ru2Cl2(pyridine)2] PF6

International Nuclear Information System (INIS)

Chaudret, B.; Jalon, F.; Perez-Manrique, M.; Lahoz, F.; Plou, F.J.

1990-01-01

Zinc reduction of (Cp*RuCl 2 ) n (Cp* = C 5 Me 5 ) in acetone or THF followed by addition of 1 equivalent of an arene or aromatic heterocycle leads to compounds of general formulation [Cp* Ru(arene)]X (X = Cl, BF 4 ). Coordination of benzene is rapid and competes successfully with any other arene. Thiophene and 3-methylthiophene give stable π adducts whereas benzothiophene is coordinated through the benzene not through the heterocyclic ring. 2.6 and 3.5-lutidine coordinate through the ring, thus demonstrating an electronic rather than steric stabilization. Again, quinoline and acridine coordinate through the benzene ring. Pyridine gives an unstable π adduct in THF. A paramagnetic mixed-valence species, byproduct of the reaction in THF, has been characterized by an X-ray crystal structure determination. Crystals are triclinic, space group P-1

(E-N-[2-(9-Fluorenylidene-3a,5,7-trimethyl-3,3a-dihydro-2H-indol-3-ylidene]-2,4,6-trimethylaniline

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Norihiro Tokitoh

2008-02-01

Full Text Available The title compound, C33H30N2, has an E configuration at the imine double bond. The angle between the least-squares planes of the imine C=N—C group and the benzene ring of the 2,4,6-trimethylphenyl substituent is 85.38 (11°. The crystal structure is sustained mainly by intermolecular π–π interactions (3.510 Å between the two fluorene rings and some C—H...π interactions.

4-Fluoro-N-[(E-3,4,5-trimethoxybenzylidene]aniline

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Jiban Podder

2013-08-01

Full Text Available The title compound, C16H16FNO3, exists in a trans configuration with respect to the C=N bond [1.258 (2 Å]. The central methoxy O atom deviates from the plane of the attached benzene ring by 0.0911 (14 Å. The dihedral angle between the aromatic rings is 47.58 (11°. The crystal structure features C—H...N and C—H...O interactions.

Assimilation and transformation of benzene by higher plants

Energy Technology Data Exchange (ETDEWEB)

Durmishidze, S V; Ugrekhelidze, D Sh; Dzhikiya, A N

1974-01-01

Higher plants are capable of assimilating benzene, the molecules of which are subjected to deep chemical transformations; the products of its metabolism move along the plant. Taking part in total metabolism, carbon atoms of benzene molecules incorporate into composition of low-molecular compounds of the plant cell. The bulk of benzene carbon incorporates into composition of organic acids and a comparatively small part - into composition of amino acids. In the metabolism process benzene carbon localizes mainly in the chloroplasts. Phenol, muconic acid and CO/sub 2/ are isolated and identified from the products of benzene enzymatic oxidation. A range of benzene assimilation by higher plants is extremely wide. 9 references, 5 tables.

Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

Science.gov (United States)

Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

2007-01-01

The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

6-Chloro-7-fluoro-4-oxo-4H-chromene-3-carbaldehyde

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Yoshinobu Ishikawa

2014-07-01

Full Text Available In the title compound, C10H4ClFO3, a chlorinated and fluorinated 3-formylchromone derivative, all atoms are essentially coplanar (r.m.s. = 0.0336 Å for the non-H atoms, with the largest deviation from the least-squares plane [0.062 (2 Å] being for a benzene-ring C atom. In the crystal, molecules are linked through stacking interactions [centroid–centroid distance between the benzene and pyran rings = 3.958 (3 Å and interplanar distance = 3.259 (3 Å], C—H...O hydrogen bonds, and short C...O contacts [2.879 (3 Å]. Unsymmetrical halogen–halogen interactions between the Cl and F atoms [Cl...F = 3.049 (3 Å, C—Cl...F = 148.10 (9° and C—F...Cl = 162.06 (13°] are also formed, giving a meandering two-dimensional network along the a axis.

Benzene poisoning

Science.gov (United States)

... may be admitted to the hospital if the poisoning is severe. ... benzene they swallowed and how quickly they receive treatment. The ... Poisoning can cause rapid death. However, deaths have occurred ...

4,4′-[Thiophene-2,5-diylbis(ethyne-2,1-diyl]dibenzonitrile

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Kari Rissanen

2008-04-01

Full Text Available In the solid state, the title compound, C22H10N2S, forms centrosymmetric dimers by pairs of non-classical C—H...S hydrogen bonds linking approximately coplanar molecules. The benzene ring involved in this interaction makes a dihedral angle of only 7.21 (16° with the thiophene ring, while the other benzene ring is twisted somewhat out of the plane, with a dihedral angle of 39.58 (9°. The hydrogen-bonded dimers stack on top of each other with an interplanar spacing of 3.44 Å. C—H...N hydrogen bonds link together stacks that run in approximately perpendicular directions. Each molecule thus interacts with 12 adjacent molecules, five of them approaching closer than the sum of the van der Waals radii for the relevant atoms. Optimization of the inter-stack contacts contributes to the non-planarity of the molecule.

2-Aminobenzoic acid–4-[2-(pyridin-4-ylethyl]pyridine (2/1

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Hadi D. Arman

2013-11-01

Full Text Available The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-ylethyl]pyridine molecule and a 2-aminobenzoic acid molecule in a general position. The acid has a small twist between the carboxylic acid residue and the ring [dihedral angle = 7.13 (6°] despite the presence of an intramolecular N—H...O(carbonyl hydrogen bond. Three-molecule aggregates are formed via O—H...N(pyridyl hydrogen bonds, and these are connected into supramolecular layers in the bc plane by N—H...O(carbonyl hydrogen bonds and π–π interactions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9 Å]. Layers are connected along the a axis by weak π–π interactions between benzene rings [3.9577 (10 Å].

Crystal structure of cafenstrole

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Gihaeng Kang

2015-08-01

Full Text Available The title compound (systematic name: N,N-diethyl-3-mesitylsulfonyl-1H-1,2,4-triazole-1-carboxamide, C16H22N4O3S, is a triazole herbicide. The dihedral angle between the planes of the triazole and benzene ring planes is 88.14 (10°. In the crystal, C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming one-dimensional chains along the a axis.

Ring faults and ring dikes around the Orientale basin on the Moon.

Science.gov (United States)

Andrews-Hanna, Jeffrey C; Head, James W; Johnson, Brandon; Keane, James T; Kiefer, Walter S; McGovern, Patrick J; Neumann, Gregory A; Wieczorek, Mark A; Zuber, Maria T

2018-08-01

The Orientale basin is the youngest and best-preserved multiring impact basin on the Moon, having experienced only modest modification by subsequent impacts and volcanism. Orientale is often treated as the type example of a multiring basin, with three prominent rings outside of the inner depression: the Inner Rook Montes, the Outer Rook Montes, and the Cordillera. Here we use gravity data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission to reveal the subsurface structure of Orientale and its ring system. Gradients of the gravity data reveal a continuous ring dike intruded into the Outer Rook along the plane of the fault associated with the ring scarp. The volume of this ring dike is ~18 times greater than the volume of all extrusive mare deposits associated with the basin. The gravity gradient signature of the Cordillera ring indicates an offset along the fault across a shallow density interface, interpreted to be the base of the low-density ejecta blanket. Both gravity gradients and crustal thickness models indicate that the edge of the central cavity is shifted inward relative to the equivalent Inner Rook ring at the surface. Models of the deep basin structure show inflections along the crust-mantle interface at both the Outer Rook and Cordillera rings, indicating that the basin ring faults extend from the surface to at least the base of the crust. Fault dips range from 13-22° for the Cordillera fault in the northeastern quadrant, to 90° for the Outer Rook in the northwestern quadrant. The fault dips for both outer rings are lowest in the northeast, possibly due to the effects of either the direction of projectile motion or regional gradients in pre-impact crustal thickness. Similar ring dikes and ring faults are observed around the majority of lunar basins.

Crystal structure of 2-oxo-2H-chromen-7-yl 4-fluorobenzoate

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Akoun Abou

2018-05-01

Full Text Available In the title compound, C16H9FO4, (I, the benzene ring is oriented at an acute angle of 59.03 (15° relative to the coumarin plane (r.m.s deviation = 0.009 Å. This conformation of (I is stabilized by an intramolecular C—H...O hydrogen bond, which closes a five-membering ring. In the crystal, molecules of (I form infinite zigzag chains along the b-axis direction, linked by C—H...O hydrogen bonds. Furthermore, the crystal structure is supported by π–π stacking interactions between neighbouring pyrone and benzene or coumarin rings [centroid–centroid distances in the range 3.5758 (18–3.6115 (16 Å], as well as C=O...π interactions [O...centroid distances in the range 3.266 (3–3.567 (3 Å]. The theoretical data for (I obtained from quantum chemical calculations are in good agreement with the observed structure, although the calculated C—O—C—C torsion angle between the coumarin fragment and the benzene ring (73.7° is somewhat larger than the experimental value [63.4 (4°]. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.

Benzene adsorption and oxidation on Ir(111)

NARCIS (Netherlands)

Weststrate, C.J.; Bakker, J.W.; Gluhoi, A.C.; Ludwig, W.; Nieuwenhuys, B.E.

2007-01-01

Adsorption, decompn. and oxidn. of benzene on Ir(1 1 1) was studied by high resoln. (synchrotron) XPS, temp. programmed desorption and LEED. Mol. adsorption of benzene on Ir(1 1 1) is obsd. between 170 K and 350 K. Above this temp. both desorption and decompn. of benzene take place. An ordered

Survey of benzene and aromatics in Canadian Gasoline - 1994

International Nuclear Information System (INIS)

Tushingham, M.

1996-01-01

A comprehensive database of the benzene and aromatics levels of gasoline produced in or imported into Canada during 1994, was presented. Environment Canada conducted a survey that requested refineries and importers to report quarterly on benzene and aromatics levels in gasoline. Benzene, which has been declared toxic by the Canadian Environmental Protection Act, is found in gasoline and is formed during the combustion of the aromatic components of gasoline. It was shown that benzene and aromatics levels differ regionally and seasonally. There are also variations in benzene levels between batches of gasoline produced at any one refinery. This report listed the responses to the benzene/aromatics survey. It also described the analytical procedures used to measure benzene and aromatics levels in gasoline, and provided guidelines for reporting gasoline benzene and total aromatics data. 7 tabs., 21 figs

Muonium radicals in benzene-styrene mixtures

International Nuclear Information System (INIS)

Ng, B.W.; Stadlbauer, J.W.; Walker, D.C.

1984-01-01

Muonium radicals were observed through their μ + SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10 -9 -10 -5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

Hydrogen bonding in (substituted benzene)·(water)n clusters with n≤4

International Nuclear Information System (INIS)

Barth, H.-D.; Buchhold, K.; Djafari, S.; Reimann, B.; Lommatzsch, U.; Brutschy, B.

1998-01-01

Infrared ion-depletion spectroscopy, a double resonance method combining vibrational predissociation with resonant two-photon ionization (R2PI) spectroscopy, has been applied to study mixed clusters of the type (substituted benzene)·(H 2 O) n with n≤4. The UV chromophores were p-difluorobenzene, fluorobenzene, benzene, toluene, p-xylene and anisole. From the IR depletion spectra in the region of the OH stretching vibrations it could be shown that the water molecules are attached as subclusters to the chromophores. Size and configuration of the subclusters could be deduced from the IR depletion spectra. In the anisole·(H 2 O) 1 a nd 2 complexes the water clusters form an ordinary hydrogen bond to the oxygen atom of the methoxy group. In all other mixed complexes a π-hydrogen bond is formed between one of the free OH groups of a water subcluster and the π-system of the chromophore. According to the strength of this interaction the frequency of the respective absorption band exhibits a characteristic red-shift which could be related to the total atomic charges in the aromatic ring. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Bosonic and fermionic dipoles on a ring

DEFF Research Database (Denmark)

Zöllner, Sascha; Pethick, C. J.; Bruun, Georg Morten

2011-01-01

We show that dipolar bosons and fermions confined in a quasi-one-dimensional ring trap exhibit a rich variety of states because their interaction is inhomogeneous. For purely repulsive interactions, with increasing strength of the dipolar coupling there is a crossover from a gaslike state...... to an inhomogeneous crystal-like one. For small enough angles between the dipoles and the plane of the ring, there are regions with attractive interactions, and clustered states can form....

Tris{2-[(2-aminobenzylideneamino]ethyl}amine

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Perla Elizondo Martínez

2010-12-01

Full Text Available The title Schiff base, C27H33N7, is a tripodal amine displaying C3 symmetry, with the central tertiary N atom lying on the threefold crystallographic axis. The N—CH2—CH2—N conformation of the pendant arms is gauche [torsion angle = 76.1 (3°], which results in a claw-like molecule, with the terminal aniline groups wrapped around the symmetry axis. The lone pair of the apical N atom is clearly oriented inwards towards the cavity, and should thus be chemically inactive. The amine NH2 substituents lie in the plane of the benzene ring to which they are bonded. With such an arrangement, one amine H atom forms an S(6 motif through a weak N—H...N hydrogen bond with the imine N atom, while the other is engaged in an intermolecular N—H...π contact involving the benzene ring of a neighbouring molecule related by inversion. The benzene rings also participate in an intramolecular C—H...π contact of similar strength. In the crystal structure, molecules are separated by empty voids (ca 5% of the crystal volume, although the crystal seems to be unsolvated.

4,4′-([4,4′-Bipyridine]-1,1′-diium-1,1′-diyldibenzoate dihydrate

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Mark A. Rodriguez

2016-06-01

Full Text Available We report here the synthesis of a neutral viologen derivative, C24H16N2O4·2H2O. The non-solvent portion of the structure (Z-Lig is a zwitterion, consisting of two positively charged pyridinium cations and two negatively charged carboxylate anions. The carboxylate group is almost coplanar [dihedral angle = 2.04 (11°] with the benzene ring, whereas the dihedral angle between pyridine and benzene rings is 46.28 (5°. The Z-Lig molecule is positioned on a center of inversion (Fig. 1. The presence of the twofold axis perpendicular to the c-glide plane in space group C2/c generates a screw-axis parallel to the b axis that is shifted from the origin by 1/4 in the a and c directions. This screw-axis replicates the molecule (and solvent water molecules through space. The Z-Lig molecule links to adjacent molecules via O—H...O hydrogen bonds involving solvent water molecules as well as intermolecular C—H...O interactions. There are also π–π interactions between benzene rings on adjacent molecules.

Crystal structure of 2-(adamantan-1-yl-5-(4-bromophenyl-1,3,4-oxadiazole

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Nourah Z. Alzoman

2014-12-01

Full Text Available In the title molecule, C18H19BrN2O, the benzene ring is inclined to the oxadiazole ring by 10.44 (8°. In the crystal, C—H...π interactions link the molecules in a head-to-tail fashion, forming chains extending along the c-axis direction. The chains are further connected by π–π stacking interactions, with centroid–centroid distances of 3.6385 (7 Å, forming layers parallel to the bc plane.

4-Nitro-N-(8-quinolylbenzamide

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Li Zhou

2008-12-01

Full Text Available In the title compound, C16H11N3O3, the amide group is twisted away from the plane of the quinoline benzene ring by 3.93 (5°, but is twisted away from the nitrobenzene ring by 22.68 (4°. A weak intramolecular C—H...O hydrogen bond is observed. In the crystal structure, molecules are linked into a chain along the a axis by intermolecular C—H...O hydrogen bonds.

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

Science.gov (United States)

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

10-(Prop-2-ynyl-10H-phenothiazine

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Younas Aouine

2010-11-01

Full Text Available In the molecule of the title compound, C15H11NS, the butterfly angle between the two planes defined by the two wings of the phenothiazine unit is 33.5 (8°. The dihedral angles between the two benzene rings and the propynyl group are 85 (4 and 63 (4°.

3-Chloro-N-(4-sulfamoylphenylpropanamide

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Mehmet Akkurt

2010-07-01

Full Text Available In the title compound, C9H11ClN2O3S, the dihedral angle between the benzene ring and the amido –NHCO– plane is 15.0 (2°. An intramolecular C—H...O hydrogen bond generates an S(6 ring motif. In the crystal structure, the amino NH2 group is involved in intermolecular N—H...O hydrogen bonds, which connect the molecules into a double layer structure expanding parallel to the bc plane. The layers are further linked by an amido N—H...O hydrogen bond. Between the layers, a weak π–π interaction with a centroid–centroid distance of 3.7447 (12 Å is also observed.

10-[1,1-Dichloro-4-(trimethylsilylbut-1-en-3-yn-2-yl]-10H-phenothiazine

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Satoru Umezono

2018-02-01

Full Text Available The title compound, C19H17Cl2NSSi, is an enamine derivative, in which the N atom adopts a shallow trigonal–pyramidal geometry [displacement from the plane of its attached C atoms = 0.1383 (18 Å]. The dihedral angle between the plane through the three amino carbon atoms and the vinyl group is 89.47 (7°. The phenothiazine unit has a butterfly structure and the central six-membered ring adopts a boat conformation. The fold angle between the benzene rings is 28.52 (7°. The crystal structure features weak Csp3—H...Cl hydrogen bonds, H...S contacts and π–π stacking interactions between phenothiazine units.

1-Bromo-2,4,6-tricyclohexylbenzene

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Joel T. Mague

2008-01-01

Full Text Available The title compound, C24H25Br, packs efficiently in the crystal structure with no solvent-accessible voids and several intermolecular H...H contacts approximating the sum of the van der Waals radii. The molecule is quite crowded, with intramolecular Br...H and C...H contacts ca 0.38 and 0.30 Å, respectively, less than the sum of the corresponding van der Waals radii. All cyclohexyl rings adopt chair conformations with the `seat' of the chair inclined at approximately 57–81° to the mean plane of the benzene ring, while those ortho to bromine have their centroids displaced in opposite directions from this plane.

3-{2-[(3-{(E-2-[4-(Dimethylaminophenyl]ethenyl}quinoxalin-2-yloxy]ethyl}-1,3-oxazolidin-2-one monohydrate

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Youssef Ramli

2012-01-01

Full Text Available In the title compound, C23H24N4O3·H2O, the 1,3-oxazoline ring is nearly planar [maximum deviation = 0.059 (2 Å] and its mean plane is twisted by 30.12 (8° with respect to the quinoxaline fused-ring system; the benzene ring is nearly coplanar with the quinoxaline fused-ring system [dihedral angle = 2.52 (2°]. The water molecule of crystallization is hydrogen-bond donor to an N atom of the quinoxaline ring system as well as an O atom of the oxazolinone unit, the two hydrogen bonds generating a chain running along the c axis.

4-Methyl-2-oxo-2H-chromen-7-yl 4-methoxybenzenesulfonate

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Suman Sinha

2011-12-01

Full Text Available In the title compound, C17H14O6S, the 2H-chromene ring is essentially planar, with a maximum deviation of 0.016 (1 Å. The dihedral angle between the 2H-chromene and the benzene rings is 54.61 (5°. The C atom of the methoxy group is close to coplanar with its attached ring [deviation = 0.082 (2 Å]. In the crystal, molecules are connected via C—H...O hydrogen bonds, forming sheets lying parallel to the bc plane. Weak C—H...π interactions are also observed.

Twin ''Fano-Snowflakes'' over the Smallest Ring of Ternions

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Metod Saniga

2008-06-01

Full Text Available Given a finite associative ring with unity, R, any free (left cyclic submodule (FCS generated by a unimodular (n + 1-tuple of elements of R represents a point of the n-dimensional projective space over R. Suppose that R also features FCSs generated by (n + 1-tuples that are not unimodular: what kind of geometry can be ascribed to such FCSs? Here, we (partially answer this question for n = 2 when R is the (unique non-commutative ring of order eight. The corresponding geometry is dubbed a ''Fano-Snowflake'' due to its diagrammatic appearance and the fact that it contains the Fano plane in its center. There exist, in fact, two such configurations – each being tied to either of the two maximal ideals of the ring – which have the Fano plane in common and can, therefore, be viewed as twins. Potential relevance of these noteworthy configurations to quantum information theory and stringy black holes is also outlined.

Indicators of benzene emissions and exposure in Bangkok street

International Nuclear Information System (INIS)

Leong, S.T.; Laortanakul, Preecha

2003-01-01

Ambient benzene measurements were conducted for the first time at four air monitoring sites in the Bangkok metropolitan region (BMR), from January to December 2001. Analytical results show that the mean benzene concentrations range from 42.4 μg/m 3 at the Din Daeng urban site to 15.1 μg/m 3 at the Chaeng Wattana suburban site. The monitoring results show that at a larger distance from the roadside or a higher level from the street surface, the level of benzene decreases. Analysis of the ambient benzene concentrations was carried out with reference to meteorological influences and traffic density. In traffic analysis, the combined effects of street topography and traffic flows established high impact on the overall benzene concentration in Bangkok. Statistical analysis shows good correlations of blood benzene levels and trans, trans-muconic acid with ambient benzene and demonstrated substantial exposure from traffic

Benzene exposure is associated with cardiovascular disease risk.

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Wesley Abplanalp

Full Text Available Benzene is a ubiquitous, volatile pollutant present at high concentrations in toxins (e.g. tobacco smoke known to increase cardiovascular disease (CVD risk. Despite its prevalence, the cardiovascular effects of benzene have rarely been studied. Hence, we examined whether exposure to benzene is associated with increased CVD risk. The effects of benzene exposure in mice were assessed by direct inhalation, while the effects of benzene exposure in humans was assessed in 210 individuals with mild to high CVD risk by measuring urinary levels of the benzene metabolite trans,trans-muconic acid (t,t-MA. Generalized linear models were used to assess the association between benzene exposure and CVD risk. Mice inhaling volatile benzene had significantly reduced levels of circulating angiogenic cells (Flk-1+/Sca-1+ as well as an increased levels of plasma low-density lipoprotein (LDL compared with control mice breathing filtered air. In the human cohort, urinary levels of t,t-MA were inversely associated several populations of circulating angiogenic cells (CD31+/34+/45+, CD31+/34+/45+/AC133-, CD34+/45+/AC133+. Although t,t-MA was not associated with plasma markers of inflammation or thrombosis, t,t-MA levels were higher in smokers and in individuals with dyslipidemia. In smokers, t,t-MA levels were positively associated with urinary metabolites of nicotine (cotinine and acrolein (3-hydroxymercapturic acid. Levels of t,t-MA were also associated with CVD risk as assessed using the Framingham Risk Score and this association was independent of smoking. Thus, benzene exposure is associated with increased CVD risk and deficits in circulating angiogenic cells in both smokers and non-smokers.

The contribution of benzene to smoking-induced leukemia.

Science.gov (United States)

Korte, J E; Hertz-Picciotto, I; Schulz, M R; Ball, L M; Duell, E J

2000-04-01

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts to estimate the leukemogenic potency of benzene. Using multiple-decrement life tables, we calculated lifetime risks of total leukemia and AML deaths for never, light, and heavy smokers. We repeated these calculations, removing the effect of benzene in cigarettes based on the estimated potencies. From these life tables we determined smoking-attributable risks and benzene-attributable risks. The ratio of the latter to the former constitutes the proportion of smoking-induced cases attributable to benzene. Based on linear potency models, the benzene in cigarette smoke contributed from 8 to 48% of smoking-induced total leukemia deaths [95% upper confidence limit (UCL), 20-66%], and from 12 to 58% of smoking-induced AML deaths (95% UCL, 19-121%). The inclusion of a quadratic term yielded results that were comparable; however, potency models with only quadratic terms resulted in much lower attributable fractions--all models substantially overestimate low-dose risk, linear extrapolations from empirical data over a dose range of 10- to 100-fold resulted in plausible predictions.

Benzene monitoring at CPPI service stations

International Nuclear Information System (INIS)

Davis, C.S.

1996-01-01

A study was conducted in which ambient airborne concentration levels of benzene were measured at a representative set of gasoline service stations in Toronto and Vancouver. Benzene is considered to be toxic under the Canadian Environmental Protection Act (CEPA). It is a component in gasoline (0.1 to 4.7 per cent by volume) and is present in vehicle evaporative and exhaust emissions. Measurements were made every 18 days at each station for one year. The objective of the study was to assess the ambient and employee exposure levels of benzene at service stations and to determine whether the levels were typical of those published in the literature. In a 1986 PACE (Petroleum Association for Conservation of the Canadian Environment) survey of exposure to gasoline hydrocarbon vapours at Canadian service stations, airborne benzene concentration data was inconsistent with similar ambient and personal exposure data in the international literature. It was concluded that both the mean ambient benzene concentration and the personal exposure level measurements in this study were generally lower than similar measurements made in other countries. The same observation was made with respect to ambient and personal exposure levels measured in this study vis-a-vis those measured during the PACE study conducted in 1985/86. . 31 refs., 24 tabs., 5 figs

Mechanistic considerations in benzene physiological model development.

OpenAIRE

Medinsky, M A; Kenyon, E M; Seaton, M J; Schlosser, P M

1996-01-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergis...

4-Methyl-N-(1-methyl-1H-indazol-5-ylbenzenesulfonamide

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Hakima Chicha

2013-09-01

Full Text Available 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.

Vinclozolin: 3-(3,5-di-chloro-phen-yl)-5-ethenyl-5-methyl-1,3-oxazolidine-2,4-dione.

Science.gov (United States)

Cho, Seonghwa; Kim, Jineun; Lee, Sangjin; Kim, Tae Ho

2014-07-01

In the title compound, C12H9Cl2NO3, which is the fungicide vinclozolin, the dihedral angle between the oxazolidine ring mean plane [r.m.s. deviation = 0.029 Å] and the benzene ring is 77.55 (8)°. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming chains along [010]. The chains are linked by short Cl⋯Cl contacts [3.4439 (3) and 3.5798 (3) Å], resulting in a three-dimensional architecture.

Magnetically pinned ring dots for spin valve or magnetic tunnel junction memory cells

International Nuclear Information System (INIS)

Nakatani, Ryoichi; Yoshida, Tetsuo; Endo, Yasushi; Kawamura, Yoshio; Yamamoto, Masahiko; Takenaga, Takashi; Aya, Sunao; Kuroiwa, Takeharu; Beysen, Sadeh; Kobayashi, Hiroshi

2005-01-01

Ni-Fe/Mn-Ir asymmetric ring dots with partially planed outer sides are investigated in order to confirm a method for obtaining pinned layers in magnetic memories with asymmetric ring shapes. Magnetic force microscopy revealed that the direction of vortical magnetization is pinned in Ni-Fe/Mn-Ir asymmetric ring dots despite the direction of the magnetic fields. This investigation shows that the Ni-Fe/Mn-Ir asymmetric ring dots can be applied to pinned layers in magnetic memories with asymmetric ring shapes

Radiocarbon dating methods using benzene liquid scintillation

International Nuclear Information System (INIS)

Togashi, Shigeko; Matsumoto, Eiji

1983-01-01

The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

Fabrication of CDs/CdS-TiO2 ternary nano-composites for photocatalytic degradation of benzene and toluene under visible light irradiation

Science.gov (United States)

Wang, Meng; Hua, Jianhao; Yang, Yaling

2018-06-01

An efficient cadmium sulfide quantum-dots (CdS QDs) and carbon dots (CDs) modified TiO2 photocatalyst (CdS/CDs-TiO2) was successfully fabricated. The as-prepared ternary nano-composites simultaneously improved the photo-corrosion of CdS and amplified its photocatalytic activity. The introduction of CdS QDs and CDs could enhance more absorbance of light, prevent the undesirable electron/hole recombination, and promote charge separation, which was important for the continuous formation of rad OH and rad O2- radicals. When the optimal mass ratio of CdS QDs to CDs was 3:1, above 90% degradation efficiencies were achieved for benzene within 1 h and toluene in 2 h, while that of pure TiO2 (P25), CdS QDs-TiO2, CDs-TiO2 nano-composites was around 15%. Owing to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was more difficult than benzene to carry on. The new fabricated nano-composites showed good prospective application of cleaning up refractory pollutants and the resource utilization.

Measurement Verification of Plane Wave Synthesis Technique Based on Multi-probe MIMO-OTA Setup

DEFF Research Database (Denmark)

Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum

2012-01-01

Standardization work for MIMO OTA testing methods is currently ongoing, where a multi-probe anechoic chamber based solution is an important candidate. In this paper, the probes located on an OTA ring are used to synthesize a plane wave field in the center of the OTA ring. This paper investigates...

Externally controlled local magnetic field in a conducting mesoscopic ring coupled to a quantum wire

International Nuclear Information System (INIS)

Maiti, Santanu K.

2015-01-01

In the present work, the possibility of regulating local magnetic field in a quantum ring is investigated theoretically. The ring is coupled to a quantum wire and subjected to an in-plane electric field. Under a finite bias voltage across the wire a net circulating current is established in the ring which produces a strong magnetic field at its centre. This magnetic field can be tuned externally in a wide range by regulating the in-plane electric field, and thus, our present system can be utilized to control magnetic field at a specific region. The feasibility of this quantum system in designing spin-based quantum devices is also analyzed

An Alternative Derivation of the Energy Levels of the "Particle on a Ring" System

Science.gov (United States)

Vincent, Alan

1996-10-01

All acceptable wave functions must be continuous mathematical functions. This criterion limits the acceptable functions for a particle in a linear 1-dimensional box to sine functions. If, however, the linear box is bent round into a ring, acceptable wave functions are those which are continuous at the 'join'. On this model some acceptable linear functions become unacceptable for the ring and some unacceptable cosine functions become acceptable. This approach can be used to produce a straightforward derivation of the energy levels and wave functions of the particle on a ring. These simple wave mechanical systems can be used as models of linear and cyclic delocalised systems such as conjugated hydrocarbons or the benzene ring. The promotion energy of an electron can then be used to calculate the wavelength of absorption of uv light. The simple model gives results of the correct order of magnitude and shows that, as the chain length increases, the uv maximum moves to longer wavelengths, as found experimentally.

Benzene: a case study in parent chemical and metabolite interactions.

Science.gov (United States)

Medinsky, M A; Kenyon, E M; Schlosser, P M

1995-12-28

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia and pancytopenia, and acute myelogenous leukemia. A combination of metabolites (hydroquinone and phenol for example) is apparently necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Since benzene and its hydroxylated metabolites (phenol, hydroquinone and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus, the potential exists for competition among various enzymes for phenol. However, zonal localization of Phase I and Phase II enzymes in various regions of the liver acinus regulates this competition. Biologically-based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans.

2-Aminobenzoic acid–4,4′-bipyridine (2/1

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Hadi D. Arman

2013-09-01

Full Text Available The asymmetric unit of title co-crystal, C10H8N2·2C7H7NO2, comprises a centrosymmetric 4,4′-bipyridine molecule, and a 2-aminobenzoic acid molecule in a general position. The latter is effectively planar [C—C—C—O torsion angle = 5.0 (3°] owing to an intramolecular N—H...O(carbonyl hydrogen bond. Three-molecule aggregates are formed via O—H...N(pyridyl hydrogen bonds and these are connected into supramolecular layers in the bc plane by N—H...O(carbonyl hydrogen bonds and π–π interactions between pyridyl and benzene rings [inter-centroid distance = 3.634 (2 Å]. Layers are connected along the a axis by weak π–π interactions between benzene rings [3.964 (2 Å].

Storage ring to investigate cold unidimensional atomic collisions

International Nuclear Information System (INIS)

Marcassa, L. G.; Caires, A. R. L.; Nascimento, V. A.; Dulieu, O.; Weiner, J.; Bagnato, V. S.

2005-01-01

In this paper we employ a circulating ring of trapped atoms, that we have named the atomotron, to study cold collisions. The atomotron is obtained from a conventional magneto-optical trap when the two pairs of normally retroreflecting Gaussian laser beams in the x-y plane are slightly offset. Circulating stable atomic orbits then form a racetrack geometry in this plane. The circulating atom flux behaves similarly to an atomic beam with an average tangential velocity much greater than the transverse components, and is therefore suitable for one-dimensional atomic collision studies. Using the atomotron, we have investigated the polarization dependence of ultracold photoassociation collisions between Rb atoms circulating in the racetrack. The ability to investigate collisions in ultracold circulating atomic rings reveals alignment and orientation properties that are averaged away in ordinary three-dimensional magneto-optical trap collision processes

3-(4-Fluorophenylsulfinyl-5-iodo-2-methyl-1-benzofuran

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Hong Dae Choi

2010-07-01

Full Text Available In the title compound, C15H10FIO2S, the O atom and the 4-fluorophenyl group of the 4-fluorophenylsulfinyl substituent are located on opposite sides of the plane through the benzofuran fragment; the 4-fluorophenyl ring is nearly perpendicular to this plane, making a dihedral angle of 83.37 (7°. The crystal structure is stabilized by weak intermolecular C—H...O hydrogen bonds and an I...O interaction [I...O = 3.255 (2 Å]. The crystal structure also exhibits intermolecular C—F...π interactions [3.068 (2 Å], and aromatic π–π interactions between the furan and benzene rings of neighbouring benzofuran fragments [centroid–centroid distance = 3.636 (2 Å].

Anaerobic degradation of benzene by marine sulfate-reducing bacteria

Science.gov (United States)

Musat, Florin; Wilkes, Heinz; Musat, Niculina; Kuypers, Marcel; Widdel, Friedrich

2010-05-01

Benzene, the archetypal aromatic hydrocarbon is a common constituent of crude oil and oil-refined products. As such, it can enter the biosphere through natural oil seeps or as a consequence of exploitation of fossil fuel reservoirs. Benzene is chemically very stable, due to the stabilizing aromatic electron system and to the lack of functional groups. Although the anaerobic degradation of benzene has been reported under denitrifying, sulfate-reducing and methanogenic conditions, the microorganisms involved and the initial biochemical steps of degradation remain insufficiently understood. Using marine sediment from a Mediterranean lagoon a sulfate-reducing enrichment culture with benzene as the sole organic substrate was obtained. Application of 16S rRNA gene-based methods showed that the enrichment was dominated (more than 85% of total cells) by a distinct phylotype affiliated with a clade of Deltaproteobacteria that include degraders of other aromatic hydrocarbons, such as naphthalene, ethylbenzene and m-xylene. Using benzoate as a soluble substrate in agar dilution series, several pure cultures closely related to Desulfotignum spp. and Desulfosarcina spp. were isolated. None of these strains was able to utilize benzene as a substrate and hybridizations with specific oligonucleotide probes showed that they accounted for as much as 6% of the total cells. Incubations with 13C-labeled benzene followed by Halogen in situ Hybridization - Secondary Ion Mass Spectroscopy (HISH-SIMS) analysis showed that cells of the dominant phylotype were highly enriched in 13C, while the accompanying bacteria had little or no 13C incorporation. These results demonstrate that the dominant phylotype was indeed the apparent benzene degrader. Dense-cell suspensions of the enrichment culture did not show metabolic activity toward added phenol or toluene, suggesting that benzene degradation did not proceed through anaerobic hydroxylation or methylation. Instead, benzoate was identified in

In situ synthesis of silver benzene-dithiolate hybrid films

Energy Technology Data Exchange (ETDEWEB)

Brenier, Roger, E-mail: roger.brenier@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Piednoir, Agnès, E-mail: agnes.piednoir@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Bertorelle, Franck, E-mail: franck.bertorelle@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Penuelas, José, E-mail: jose.penuelas@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France); Grenet, Geneviève, E-mail: genevieve.grenet@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France)

2016-02-01

In this article, a method for in situ synthesis of silver benzene-dithiolate hybrid films is presented. Silver nanoparticles, generated on ZrO{sub 2} films, are transformed into silver benzene 1,4-dithiolate or, partially, into silver benzene 1,2-dithiolate after sample immersion in the corresponding thiol solutions. These transformations occur at room temperature owing to the catalytic action of ZrO{sub 2}. It is also shown that TiO{sub 2} in place of ZrO{sub 2} is very efficient, both for the catalytic generation of silver nanoparticles and for their further transformation in benzene 1,4-dithiolate compound. This latter semiconductor has an optical bandgap of about 3 eV and the film is made of touching nanoparticles in an amorphous state. Our work has potential applications in the electronic and photovoltaic fields. - Highlights: • A method for in situ synthesis of silver benzene-dithiolate hybrid semiconductor films is presented. • Silver nanoparticles are, first, generated on ZrO{sub 2} or on TiO{sub 2} coated silica substrates. • The samples are immersed in benzene dithiol solution for two days at room temperature. • During the immersion, the silver nanoparticles are transformed into silver benzene dithiolate. • The silver benzene dithiolate film is made of amorphous nanoparticles with a banbgap of 3 eV.

3-Ethylsulfinyl-2-(4-iodophenyl-5-methyl-1-benzofuran

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Hong Dae Choi

2010-08-01

Full Text Available In the title compound, C17H15IO2S, the 4-iodophenyl ring makes a dihedral angle of 35.39 (8° with the plane of the benzofuran fragment. In the crystal, molecules are linked by intermolecular C—H...O and C—H...π interactions, and an I...O contact [3.378 (2 Å]. The crystal structure also exhibits aromatic π–π interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.495 (3 Å].

Vinclozolin: 3-(3,5-dichlorophenyl-5-ethenyl-5-methyl-1,3-oxazolidine-2,4-dione

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Seonghwa Cho

2014-07-01

Full Text Available In the title compound, C12H9Cl2NO3, which is the fungicide vinclozolin, the dihedral angle between the oxazolidine ring mean plane [r.m.s. deviation = 0.029 Å] and the benzene ring is 77.55 (8°. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming chains along [010]. The chains are linked by short Cl...Cl contacts [3.4439 (3 and 3.5798 (3 Å], resulting in a three-dimensional architecture.

8-Chloro-4-oxo-4H-chromene-3-carbaldehyde

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Yoshinobu Ishikawa

2014-07-01

Full Text Available In the title compound, C10H5ClO3, a chlorinated 3-formylchromone derivative, all atoms are essentially coplanar (r.m.s. deviation = 0.032 Å for the non-H atoms, with the largest deviation from the least-squares plane [0.0598 (14 Å] being for a pyran-ring C atom. In the crystal, molecules are linked through stacking interactions along the b axis [shortest centroid–centroid distance between the pyran and benzene rings = 3.566 (2 Å].

(E-1-(1,3-Benzodioxol-5-yl-3-[4-(dimethylaminophenyl]prop-2-en-1-one

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Karthik Kumara

2017-01-01

Full Text Available In the title compound, C18H17NO3, the olefinic double bond adopts an E conformation. The molecule is nearly planar as indicated by the dihedral angle of 3.11 (6° between the benzodioxole and benzene rings. The carbonyl group lies in the plane of the olefinic double bond and the benzodioxole ring. The trans conformation of the C=C double bond in the central enone group is confirmed by the C=C—C—C torsion angle of −177.82 (14°.

Benzene exposure and risk of non-Hodgkin lymphoma.

Science.gov (United States)

Smith, Martyn T; Jones, Rachael M; Smith, Allan H

2007-03-01

Exposure to benzene, an important industrial chemical and component of gasoline, is a widely recognized cause of leukemia, but its association with non-Hodgkin lymphoma (NHL) is less clear. To clarify this issue, we undertook a systematic review of all case-control and cohort studies that identified probable occupational exposures to benzene and NHL morbidity or mortality. We identified 43 case-control studies of NHL outcomes that recognized persons with probable occupational exposure to benzene. Forty of these 43 (93%) studies show some elevation of NHL risk, with 23 of 43 (53%) studies finding statistically significant associations between NHL risk and probable benzene exposure. We also identified 26 studies of petroleum refinery workers reporting morbidity or mortality for lymphomas and all neoplasms and found that in 23 (88%), the rate of lymphoma morbidity or mortality was higher than that for all neoplasms. A substantial healthy-worker effect was evident in many of the studies and a comprehensive reevaluation of these studies with appropriate adjustments should be undertaken. Numerous studies have also reported associations between benzene exposure and the induction of lymphomas in mice. Further, because benzene is similar to alkylating drugs and radiation in producing leukemia, it is plausible that it might also produce lymphoma as they do and by similar mechanisms. Potential mechanisms include immunotoxicity and the induction of double-strand breaks with subsequent chromosome damage resulting in translocations and deletions. We conclude that, overall, the evidence supports an association between occupational benzene exposure and NHL.

Vacuum ultraviolet photoabsorption spectroscopy of crystalline and amorphous benzene

DEFF Research Database (Denmark)

Dawes, Anita; Pascual, Natalia; Hoffmann, Soren V.

2017-01-01

We present the first high resolution vacuum ultraviolet photoabsorption study of amorphous benzene with com parisons to annealed crystalline benzene and the gas phase. Vapour deposited benzene layers w ere grow n at 25 K and annealed to 90 K under conditions pertinent to interstellaricy dust grains...

Benzene and cyclohexane separation using 1-butyl-3-methylimidazolium thiocyanate

Science.gov (United States)

Gonfa, Girma; Ismail, Marhaina; Bustam, Mohamad Azmi

2017-09-01

Cyclohexane is mainly produced by catalytic hydrogenation of benzene. Removal of unreacted benzene from the product stream is very important in this process. However, due to their close boiling points and azeotrope formation, it is very difficult to separate cyclohexane and benzene by conventional distillation. Currently, special separation processes such as processes extractive distillation is commercially used for this separation. However, this extractive distillation suffers from process complexity and higher energy consumption due to their low extractive selectivity of molecular entrainers used. The aim of the present work is to investigate the applicability of ionic liquids as entrainer in extractive distillation of benzene and cyclohexane mixture. In this study, we investigated 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) ionic liquid for separation of benzene and cyclohexane by measuring the Vapor Liquid Equilibrium data of the two components in the presence of the ionic liquid. As green and potential environmentally friendly solvents, ionic liquids have attracted increasing attention as alternative conventional entrainers in extractive distillation. Isothermal Vapor Liquid Equilibrium for the benzene + cyclohexane + [BMIM][SCN] ternary system was obtained at 353.15 K using a Head Space Gas Chromatography. The addition of [BMIM][SCN] breaks the benzene-cyclohexane azeotrope and increased the relative volatility cyclohexane to benzene in the mixture. The effect of [BMIM][SCN] on the relative volatility cyclohexane to benzene was studied at various benzene and cyclohexane compositions and solvent to feed ratios. The performance of [BMIM][SCN] was compared with typical conventional solvents, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The results show that the relative volatility of cyclohexane to benzene in the presence of [BMIM][SCN] is higher compared that of DMSO and DMF.

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

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Hakima Chicha

2014-06-01

Full Text Available The indazole ring system of the title compound, C17H18ClN3O4S, is almost planar (r.m.s. deviation = 0.0113 Å and forms dihedral angles of 32.22 (8 and 57.5 (3° with the benzene ring and the mean plane through the 4-ethoxy group, respectively. In the crystal, molecules are connected by pairs of N—H...O hydrogen bonds into inversion dimers, which are further linked by π–π interactions between the diazole rings [intercentroid distance = 3.4946 (11 Å], forming chains parallel to [101].

N-(2,4-Dichlorophenyl-1,3-thiazol-2-amine

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Ayesha Babar

2012-09-01

Full Text Available In the title molecule, C9H6Cl2N2S, the mean planes of the benzene and thiazole rings make a dihedral angle of 54.18 (8°. In the crystal, molecules are joined into dimers with an R22(8 ring motif by pairs of N—H...N hydrogen bonds. These dimers are linked by C—H...Cl interactions into layers parallel to (011. The thiazole rings form columns along the c-axis direction, with a centroid–centroid separation of 3.8581 (9 Å, indicating π–π interactions. An intramolecular C—H...S contact also occurs.

A physically interpretable quantum-theoretic QSAR for some carbonic anhydrase inhibitors with diverse aromatic rings, obtained by a new QSAR procedure.

Science.gov (United States)

Clare, Brian W; Supuran, Claudiu T

2005-03-15

A QSAR based almost entirely on quantum theoretically calculated descriptors has been developed for a large and heterogeneous group of aromatic and heteroaromatic carbonic anhydrase inhibitors, using orbital energies, nodal angles, atomic charges, and some other intuitively appealing descriptors. Most calculations have been done at the B3LYP/6-31G* level of theory. For the first time we have treated five-membered rings by the same means that we have used for benzene rings in the past. Our flip regression technique has been expanded to encompass automatic variable selection. The statistical quality of the results, while not equal to those we have had with benzene derivatives, is very good considering the noncongeneric nature of the compounds. The most significant correlation was with charge on the atoms of the sulfonamide group, followed by the nodal orientation and the solvation energy calculated by COSMO and the charge polarization of the molecule calculated as the mean absolute Mulliken charge over all atoms.

The solubilities of benzene polycarboxylic acids in water

International Nuclear Information System (INIS)

Apelblat, Alexander; Manzurola, Emanuel; Abo Balal, Nazmia

2006-01-01

The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities

A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

International Nuclear Information System (INIS)

Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

2006-01-01

Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to 'hop' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power (≥330 We at beginning of life) during the 10-year cruise and 1-year science mission (∼11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030

Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae was identified as dominant benzene degrader by Stable Isotope Probing (SIP)

NARCIS (Netherlands)

Zaan, van der B.M.; Talarico Saia, F.; Plugge, C.M.; Vos, de W.M.; Smidt, H.; Stams, A.J.M.; Langenhoff, A.A.M.; Gerritse, J.

2012-01-01

An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a

Mapping the Thermal Inertia of Saturn’s Rings with Cassini CIRS

Science.gov (United States)

Brooks, Shawn M.; Spilker, L. J.; PIlorz, S. H.; Showalter, M. R.

2013-10-01

We use data from Cassini's Composite Infrared Spectrometer to map out the thermal response of Saturn's ring particles passing through Saturn's shadow and to determine variations in ring thermal inertia. CIRS records far infrared radiation in three separate detectors, each of which covers a distinct wavelength range. In this work, we analyze rings spectra recorded at focal plane 1 (FP1), as its wavelength response (16.7-1000 microns) is well suited to detecting direct thermal emission from Saturn's rings. The thermal budget of the rings is typically dominated by solar radiation. When ring particles enter Saturn’s shadow this source of energy is abruptly cut off with a consequential drop in ring temperature. Likewise, temperatures rebound when particles exit the shadow. To characterize these heating and cooling events, FP1 was repeatedly scanned across the main rings. Each scan was offset from either the ingress or egress shadow boundary by an amount corresponding to a fraction of a Keplerian orbit. By resampling these scans onto a common radial grid, we can map out the rings’ response to the abrupt changes in insolation at shadow ingress and egress. Periods near equinox represent a unique situation. During this time the Sun's disk crosses the ring plane and its rays strike the rings at zero incidence. Solar heating is virtually absent, and thermal radiation from Saturn and sunlight reflected by Saturn dominate the thermal environment. While ring temperature variations at equinox are much more subtle, they represent temperature contrasts that vary at the unique timescale corresponding to variations in Saturn contributions to the rings’ thermal budget. By analyzing CIRS data at a variety of locations and epochs, we will map out thermal inertia across the rings and attempt to tease out structural information about the particles which comprise Saturn’s rings. This presentation will report upon our progress towards these ends. This research was carried out at the

Comparison of personal air benzene and urine t,t-muconic acid as a benzene exposure surrogate during turnaround maintenance in petrochemical plants.

Science.gov (United States)

Koh, Dong-Hee; Lee, Mi-Young; Chung, Eun-Kyo; Jang, Jae-Kil; Park, Dong-Uk

2018-04-12

Previous studies have shown that biomarkers of chemicals with long half-lives may be better surrogates of exposure for epidemiological analyses, leading to less attenuation of the exposure-disease association, than personal air samples. However, chemicals with short half-lives have shown inconsistent results. In the present study, we compared pairs of personal air benzene and its short-half-life urinary metabolite trans,trans-muconic acid (t,t-MA), and predicted attenuation bias of theoretical exposure-disease association. Total 669 pairs of personal air benzene and urine t,t-MA samples were taken from 474 male workers during turnaround maintenance operations held in seven petrochemical plants. Maintenance jobs were classified into 13 groups. Variance components were calculated for personal air benzene and urine t, t-MA separately to estimate the attenuation of the theoretical exposure-disease association. Personal air benzene and urine t, t-MA showed similar attenuation of the theoretical exposure-disease association. Analyses for repeated measurements showed similar results, while in analyses for values above the limits of detection (LODs), urine t, t-MA showed less attenuation of the theoretical exposure-disease association than personal air benzene. Our findings suggest that there may be no significant difference in attenuation bias when personal air benzene or urine t,t-MA is used as a surrogate for benzene exposure.

The contribution of benzene to smoking-induced leukemia.

OpenAIRE

Korte, J E; Hertz-Picciotto, I; Schulz, M R; Ball, L M; Duell, E J

2000-01-01

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts t...

INMS measures an influx of molecules from Saturn's rings

Science.gov (United States)

Perry, M. E.

2017-12-01

In 1984, Connerney and Waite proposed water influx from Saturn's rings to explain the low electron densities measured during Pioneer and Voyager radio occultation experiments. Charge exchange with this minor species depleted the H+ ions and provided a faster path to electron recombination. With ice the primary constituent of the rings, water was the most likely in-falling molecule. During the Grand Finale orbits, Cassini's Ion and Neutral Mass Spectrometer (INMS) detected and quantified an influx from the rings. Unexpectedly, the primary influx molecules are CH4 and a heavier carbon-bearing species. Water was detected, but quantities were factors of ten lower than these other species. Distribution in both altitude and latitude are consistent with a ring influx. The concentration of the minor species in Saturn's atmosphere shows that they enter Saturn's atmosphere from the top. Both molecules have their highest concentrations at the highest altitudes, with concentrations >0.4% at 3,500 km altitude and only 0.02% at 2,700 km. Molecules from the rings deorbit to Saturn's atmosphere at altitudes near 4,000 km, consistent with the INMS measurements. The latitudinal dependence of the minor species indicates that their source is near the equatorial plane. At high altitudes, the minor species were observed primarily at zero latitude, where the 28u species was six times more concentrated than at 5° latitude. At lower altitudes, the peaking ratio was 1, indicating that the species had diffused and was fully mixed into Saturn's H2 atmosphere. The lighter molecule, CH4, diffuses more rapidly than the 28u species. INMS also detected both of these species during the earlier F-ring passes, finding that the neutrals were centered at the ring plane and extended 3,000 km (half width, half max) north and south.

2-(4-Methylanilinoacetohydrazide

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Hoong-Kun Fun

2009-09-01

Full Text Available In the title molecule, C9H13N3O, the non-hydrogen atoms of the hydrazide group are essentially planar [maximum deviation = 0.028 (1 Å for one of the N atoms]. The mean plane of this group forms a dihedral angle of 83.34 (5° with the plane of the benzene ring. In the crystal structure, molecules are linked by intermolecular N—H...O, N—H...N and weak C—H...N hydrogen bonds into a two-dimensional network parallel to the ab plane. Additional stabilization is provided by a weak C—H...π interaction.

Benzene degradation in a denitrifying biofilm reactor

NARCIS (Netherlands)

Waals, van der Marcelle J.; Atashgahi, Siavash; Rocha, da Ulisses Nunes; Zaan, van der Bas M.; Smidt, Hauke; Gerritse, Jan

2017-01-01

Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more

2-(4-Bromophenyl-2-oxoethyl 2-methylbenzoate

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Hoong-Kun Fun

2011-11-01

Full Text Available In the title compound, C16H13BrO3, the dihedral angle formed between the bromo- and methyl-substituted benzene rings is 66.66 (8°. In the crystal, molecules are linked by intermolecular C—H...O hydrogen bonds, forming a two-dimensional network parallel to the ac plane. The crystal packing is further consolidated by C—H...π interactions.

Environmental and biological monitoring of benzene during self-service automobile refueling.

OpenAIRE

Egeghy, P P; Tornero-Velez, R; Rappaport, S M

2000-01-01

Although automobile refueling represents the major source of benzene exposure among the nonsmoking public, few data are available regarding such exposures and the associated uptake of benzene. We repeatedly measured benzene exposure and uptake (via benzene in exhaled breath) among 39 self-service customers using self-administered monitoring, a technique rarely used to obtain measurements from the general public (130 sets of measurements were obtained). Benzene exposures averaged 2.9 mg/m(3) (...

Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

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Anne B. Stephansen

2017-07-01

Full Text Available The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3 is found to undergo internal conversion in the triplet manifold within ≈100–150 fs (toluene or ≈180–200 fs (p-xylene as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.

Influence of benzene emission from motorcycle on Bangkok air quality

Science.gov (United States)

Leong, Shing Tet; Muttamara, S.; Laortanakul, Preecha

This study investigated the influence of benzene concentration from motorcycle exhaust emissions on ambient air quality in Bangkok Metropolitan Region (BMR). Measurement of benzene concentration in exhaust emissions is performed on a standard test driving cycle through which each motorcycle to be tested is driven. The test result revealed that average benzene concentrations in exhaust emission for the test motorcycles ranged from 3.02 to 109.68 mg/m 3. The finding also indicated that two-stroke motorcycles emitted five times more benzene than that of four-stroke motorcycles. Four air monitoring sites were strategically established to determine the relationship between average benzene concentrations with different traffic configurations in each traffic zone of BMR during peak/non-peak hours, day/night times and weekday/weekend. The shape of the curve for benzene level usually shows two peaks corresponding to the morning and evening traffic rush or commuter rush hours. The finding shows that the mean concentrations for benzene in all monitoring stations in the ambient air for peak hours (07:00-09:00 and 16:00-18:00 h) ranged from 15.1 to 42.4 μg/m 3. For non-peak hour (11:30-15:00 h), benzene levels were found in the range 16.3-30.9 μg/m 3. It is observed that higher levels of benzene are found among roadside stations with slow moving traffic while lower levels are found among roadside stations with fast traffic movement. Additional factors such as temperature, wind speed, rainfall, etc. are also considered in this study to determine the relationship between traffic conditions and ambient benzene levels.

A 30 Mbps in-plane full-duplex light communication using a monolithic GaN photonic circuit

Science.gov (United States)

Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Li, Yuanhang; Yuan, Wei; Zhu, Guixia; Zhu, Hongbo; Feng, Meixin; Sun, Qian; Liu, Yuhuai; Wang, Yongjin

2017-07-01

We propose, fabricate and characterize photonic integration of a InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED), waveguide, ring resonator and InGaN/GaN MQW-photodiode on a single chip, in which the photonic circuit is suspended by the support beams. Both experimental observations and simulation results illustrate the manipulation of in-plane light coupling and propagation by the waveguide and the ring resonator. The monolithic photonic circuit forms an in-plane data communication system using visible light. When the two suspended InGaN/GaN MQW-diodes simultaneously serve as the transmitter and the receiver, an in-plane full-duplex light communication is experimentally demonstrated with a transmission rate of 30 Mbps, and the superimposed signals are extracted using the self-interference cancellation method. The suspended photonic circuit creates new possibilities for exploring the in-plane full-duplex light communication and manufacturing complex GaN-based monolithic photonic integrations.

Investigation of the possibility of functionalization of C20 fullerene by benzene via Diels-Alder reaction

Science.gov (United States)

Siadati, Seyyed Amir; Nami, Navabeh

2016-10-01

C20 fullerene, this novel species with all its pentagonal faces has displayed some unique operations in making fast pericyclic reactions. As an example, the high dienophile character of the C20 fullerene and the ability of this species in making an ultra-fast Diels-Alder reaction with 1,3-butadiene, has been recently reported. Moreover, new experimental reports claim that the C60 fullerene, one of the fullerene family, could make a Diels-Alder reaction with the central ring of anthracene and make the ring non-aromatic. These reports may encourage researchers to do more studies on the properties of this small carbon cage. To address this question, the present research has discussed all the reaction channels of the Diels-Alder cycloaddition of benzene molecule as a 1,3-diene with the C20 fullerene in order to answer this question: ;Is C20fullerene able to make a Diels-Alder reaction with this molecule?;.

Damping rates of the SRRC storage ring

International Nuclear Information System (INIS)

Hsu, K.T.; Kuo, C.C.; Lau, W.K.; Weng, W.T.

1995-01-01

The SRRC storage ring is a low emittance synchrotron radiation machine with nominal operation energy 1.3 GeV. The design damping time due to synchrotron radiation is 10.7, 14.4, 8.7 ms for the horizontal, vertical and longitudinal plane, respectively. The authors measured the real machine damping time as a function of bunch current, chromaticity, etc. To damp the transverse beam instability, especially in the vertical plane, they need to increase chromaticity to large positive value. The damping rates are much larger than the design values. Landau damping contribution in the longitudinal plane is quite large, especially in the multibunch mode. The estimated synchrotron tune spread from the Landau damping is in agreement with the measured coherent longitudinal coupled bunch oscillation amplitude

Crystal structure of 4-(4-chlorophenyl-6-(morpholin-4-ylpyridazin-3(2H-one

Directory of Open Access Journals (Sweden)

Abdullah Aydın

2015-08-01

Full Text Available In the title compound, C14H14ClN3O2, the morpholine ring adopts a chair conformation, with the exocyclic N—C bond in an equatorial orientation. The 1,6-dihydropyridazine ring is essentially planar, with a maximum deviation of 0.014 (1 Å, and forms a dihedral angle of 40.16 (7° with the plane of the benzene ring. In the crystal, pairs of centrosymmetrically related molecules are linked into dimers via N—H...O hydrogen bonds, forming R22(8 ring motifs. The dimers are connected via C—H...O and C—H...Cl hydrogen bonds, forming a three-dimensional network. Aromatic π–π stacking interactions [centroid–centroid distance = 3.6665 (9 Å] are also observed. Semi-empirical molecular orbital calculations were carried out using the AM1 method. The calculated dihedral angles between the pyridizine and benzene rings and between the pyridizine and morpholine (all atoms rings are 34.49 and 76.96°, respectively·The corresponding values obtained from the X-ray structure determination are 40.16 (7 and 12.97 (9°, respectively. The morpholine ring of the title compound in the calculated gas-phase seems to have a quite different orientation compared to that indicated by the X-ray structure determination.

Ringed Accretion Disks: Evolution of Double Toroidal Configurations

Energy Technology Data Exchange (ETDEWEB)

Pugliese, D.; Stuchlík, Z., E-mail: daniela.pugliese@fpf.slu.cz, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

2017-04-01

We investigate ringed accretion disks composed of two tori (rings) orbiting on the equatorial plane of a central supermassive Kerr black hole. We discuss the emergence of the instability phases of each ring of the macro-configuration (ringed disk) according to the Paczynski violation of mechanical equilibrium. In the full general relativistic treatment, we consider the effects of the geometry of the Kerr spacetimes relevant to the characterization of the evolution of these configurations. The discussion of ring stability in different spacetimes enables us to identify particular classes of central Kerr attractors depending on their dimensionless spin. As a result of this analysis, we set constraints on the evolutionary schemes of the ringed disks relative to the torus morphology and on their rotation relative to the central black hole and to each other. The dynamics of the unstable phases of this system is significant for the high-energy phenomena related to accretion onto supermassive black holes in active galactic nuclei and the extremely energetic phenomena in quasars, which could be observed in their X-ray emission.

Diaquabis(4-bromobenzoato-κObis(nicotinamide-κN1copper(II

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Hacali Necefoğlu

2011-07-01

Full Text Available The asymmetric unit of the title mononuclear CuII complex, [Cu(C7H4BrO22(C6H6N2O2(H2O2], contains one half-molecule, the CuII atom being located on an inversion center. The unit cell contains two nicotinamide (NA, two 4-bromobenzoate (PBB ligands and two coordinated water molecules. The four O atoms in the equatorial plane around the CuII ion form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxylate group and the adjacent benzene ring is 22.17 (16°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 82.80 (6°. In the crystal, N—H...O, O—H...O and C—H...O hydrogen bonds link the molecules into a three-dimensional network. A weak C—H...π interaction is also observed.

Velocity-dependent emission factors of benzene, toluene and C 2-benzenes of a passenger car equipped with and without a regulated 3-way catalyst

Science.gov (United States)

Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian; Mattrel, Peter

Time-resolved chemical ionization mass spectrometry (CI-MS) has been used to investigate the velocity-dependent emission factors for benzene, toluene, the C 2-benzenes (xylenes and ethyl benzene) and nitrogen monoxide of a gasoline-driven passenger car (1.4 l, model year 1995) driven with or without catalytic exhaust gas treatment. A set of seven different driving cycles - including the European Driving Cycle (EDC), the US Urban (FTP 75) and the Highway driving cycles - with a total driving time of 12,000 s have been studied. From the obtained emission data, two sets of 15,300 and 17,200 data points which represent transient driving in the velocity range of 0-150 km h -1 and in an acceleration window of -2-3 m s -2 were explored to gain velocity-dependent emission factors. The passenger car, equipped with a regulated rhodium-platinum based three-way catalyst, showed optimal conversion efficiency (>95%) for benzene in the velocity range of 60-120 km h -1. The conversion of benzene was reduced (speed and engine load (>130 km h -1). Whereas the conversion efficiency for the class of C 2-benzenes was reduced to 10%, no net conversion could be found for toluene and benzene when driven above 130 km h -1. In contrast, the benzene and toluene emissions exceeded those of the untreated exhaust gas in the velocity range of 130-150 km h -1 by 50-92% and by 10-34%, respectively. Thus, benzene and toluene were formed across the examined three-way catalyst if the engine is operated for an extended time in a fuel-rich mode (lambda<1).

Benzene biodegradation using an anaerobic column coupled to Mn(IV) reduction

Energy Technology Data Exchange (ETDEWEB)

Villatoro-Monzon, W.R.; Velasquez-Mejia, E.K.; Morales-Ibarria, M.G.; Razo-Flores, E. [Instituto Mexicano del Petroleo (Mexico). Programo de Biotenologia del Petroleo

2004-07-01

Benzene, toluene, and o, m, p-xylene compounds make up a large proportion of gasoline. Due to spills and leaks from underground tanks, these compounds frequently contaminate groundwater and sediment. In particular the high solubility of benzene makes it very mobile and an extra danger to groundwater. Moreover, there are strong links between benzene and cancer and thus benzene is considered a serious pollutant. Contaminated sites usually become anaerobic due to microbe action. In this study, benzene biodegradation was done in a glass column inoculated with anaerobic Rhine River sediment and using Mn(IV) as the final electron acceptor. Under steady state operation, benzene biodegradation efficiency was as high as 95 per cent. Carbon dioxide and Mn(II) recovery rates were 81 and 77 per cent respectively. Reactor sediment was withdrawn on day 104 and subject to DGGE profiling. This sediment showed different band patterns than the original sediment that was not exposed to benzene. The authors conclude that the species associated with the degradation of benzene are of the genus Propionibacterium and Actinomyces. 17 refs., 2 figs.

Variability of benzene exposure among filling station attendants

International Nuclear Information System (INIS)

Carere, A.; Iacovella, N.; Turrio Baldassarri, L.; Fuselli, S.; Iavarone, I.; Lagorio, S.; Proietto, A.R.

1996-12-01

A monitoring survey of filling station attendants aimed at identifying sources of variability of exposure to benzene and other aromatics was carried out. Concurrent samples of the worker's breathing zone air, atmospheric air in the service station proximity, and gasoline were collected, along with information about daily workloads and other exposure-related factors. Benzene personal exposure was characterised by a small between-worker variability and a predominant within-worker variance component. Such elevated day-to-day variability yields to imprecise estimates of mean personal exposure. Almost 70% of the overall personal exposure variance was explained by a model including daily benzene from dispensed fuel, presence of a shelter over the refueling area, amount of fuel supplied to the station if a delivery occurred, and background atmospheric benzene concentration

Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge.

Science.gov (United States)

Wang, Shizong; Yang, Qi; Bai, Zhiyong; Wang, Shidong; Wang, Yeyao; Nowak, Karolina M

2015-01-01

The acclimation of aerobic-activated sludge for degradation of benzene derivatives was investigated in batch experiments. Phenol, benzoic acid, toluene, aniline and chlorobenzene were concurrently added to five different bioreactors which contained the aerobic-activated sludge. After the acclimation process ended, the acclimated phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic-activated sludge were used to explore the co-metabolic degradation activities of trichloroethylene (TCE). Monod equation was employed to simulate the kinetics of co-metabolic degradation of TCE by benzene derivative-grown sludge. At the end of experiments, the mixed microbial communities grown under different conditions were identified. The results showed that the acclimation periods of microorganisms for different benzene derivatives varied. The maximum degradation rates of TCE for phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic sludge were 0.020, 0.017, 0.016, 0.0089 and 0.0047 mg g SS(-1) h(-1), respectively. The kinetic of TCE degradation in the absence of benzene derivative followed Monod equation well. Also, eight phyla were observed in the acclimated benzene derivative-grown aerobic sludge. Each of benzene derivative-grown aerobic sludge had different microbial community composition. This study can hopefully add new knowledge to the area of TCE co-metabolic by mixed microbial communities, and further the understanding on the function and applicability of aerobic-activated sludge.

5,6-Dimethyl-1,2,9,10-tetrahydropyrano[3,2-f]chromene-3,8-dione

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Shailesh K. Goswami

2012-07-01

Full Text Available The title molecule, C14H14O4, lies on a twofold rotation axis that bisects the central benzene ring, with only one half-molecule in the asymmetric unit. The pyranone systems adopt distorted twist- boat conformations, with the two methylene C atoms displaced by 0.537 (1 and 0.163 (2 Å from the best-fit plane through the remaining five C and O atoms (r.m.s. deviation = 0.073 Å. In the crystal, bifurcated C—H...(O,O hydrogen bonds link pairs of adjacent molecules in an obverse fashion, stacking molecules along c. These contacts are further stabilized by very weak π–π interactions between adjacent benzene rings with centroid–centroid distances of 4.1951 (4 Å. Additional C—H...O contacts link these stacks, giving a three-dimensional network.

N-[3-(2,6-Dimethylanilino-1-methylbut-2-enylidene]-2,6-dimethylanilinium chlorideThis paper is dedicated to Professor Dr Dr mult. h.c. Herbert W. Roesky.

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Víctor M. Jiménez-Pérez

2009-07-01

Full Text Available The title salt, C21H27N2+·Cl− resulted from the condensation between 2,6-dimethylaniline and acetylacetone in acidified ethanol. The bulky cation is stabilized in a β-iminoenamine tautomeric form, and presents a W-shaped conformation. The benzene rings are arranged almost parallel, with a dihedral angle of 6.58 (4° between the mean planes. Both N—H groups in the cation form strong hydrogen bonds with two symmetry-related chloride anions. The resulting supramolecular structure is a one dimensional polymer running along [001], alternating cations and anions. The π–π interaction observed in the molecule, characterized by a centroid–centroid separation of 4.298 (4 Å, is thus extended to the chains, with separations of 5.222 (4 Å between benzene rings of neighbouring cations in the crystal.

1-Methyl-2-[(E-2,4,5-trimethoxystyryl]pyridinium iodideThis paper is dedicated to the late His Majesty King Chulalongkorn (King Rama V of Thailand for his numerous reforms to modernize the country on the occasion of Chulalongkorn Day (Piyamaharaj Day which fell on the 23rd October.

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Hoong-Kun Fun

2010-12-01

Full Text Available In the title compound, C17H20NO3+·I−, the cation exists in the E configuration. The pyridinium and benzene rings are close to coplanar, with a dihedral angle of 7.43 (12° between them. The three methoxy groups of 2,4,5-trimethoxyphenyl are essentially coplanar with the benzene plane, with C—O—C—C torsion angles of 1.0 (3, −1.9 (3 and 3.6 (3°. A weak intramolecular C—H...O interaction generates an S(6 ring motif. In the crystal, the cations are stacked in columns in an antiparallel manner along the a axis through π–π interactions, with a centroid–centroid distance of 3.7714 (16 Å. The iodide anion is situated between the columns and linked to the cation by a weak C—H...I interaction.

Ionic liquid-based single-drop microextraction/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene and xylene isomers in waters.

Science.gov (United States)

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2008-08-01

The direct coupling between ionic liquid-based single-drop microextraction and gas chromatography/mass spectrometry is proposed for the rapid and simple determination of benzene, toluene, ethylbenzene and xylenes isomers (BTEX) in water samples. The extraction procedure exploits not only the high affinity of the selected ionic liquid (1-methyl-3-octyl-imidazolium hexaflourophosphate) to these aromatic compounds but also its special properties like viscosity, low vapour pressure and immiscibility with water. All the variables involved in the extraction process have been studied in depth. The developed method allows the determination of these single-ring compounds in water under the reference concentration level fixed by the international legislation. In this case, limits of detection were in the range 20 ng L(-1) (obtained for benzene) and 91 ng L(-1) (for o-xylene). The repeatability of the proposed method, expressed as RSD (n=5), varied between 3.0% (o-xylene) and 5.2% (toluene).

The in-plane deformation of a tire carcass: analysis and measurement

OpenAIRE

Xiong, Yi; Tuononen, Ari

2015-01-01

The deformation of parts of a tire is the direct result of tire–road interactions, and therefore is of great interest in tire sensor development. This case study focuses on the analysis of the deformation of the tire carcass and investigates its potential for the estimation of the in-plane tire force. The deformation of the tire carcass due to applied steady-state in-plane forces is first analyzed with the flexible ring model and then validated through optical tire sensor measurements. Couple...

Expected first-order effects of a notional equatorial ring on Earth's night sky: a geometric consideration

Science.gov (United States)

Hancock, L. O.

2013-12-01

G. Jones (1856) was first to suggest that the Earth might have its own ring, noting that an Earth ring in the ecliptic plane would account for the latitude dependence of the zodiacal light. Jones's proposal was not accepted: it is difficult to see why the ecliptic would accumulate mass within the Earth-Moon system. Very recently, however, this objection has been mitigated by the discovery of Saturn's Phoebe ring: evidently, the plane of a planetary moon's orbit has now been observed as the site of mass accumulation. An adjustment of just a few degrees from ecliptic to the plane of the lunar orbit gives Jones's proposal the boost of an existing Solar System analogue, mysterious though the analogue is. J. O'Keefe (1980) was first to suggest that an Earth ring system could drive climate: a ring in the equatorial plane, waxing and waning in optical depth, could drive the alternation of Ice Age and interglacial climates. This driver would account for the observation that the Ice Age climate was mainly a difference in winter only. Could Earth have a ring system with one or both elements? Even if light and unstable, it would be important to assess, as it could drive climate change. Dust assessments have not discovered a ring system, but they do not cover low orbits well, nor rule out very small particles stringently. Yet tiny particles can be optically important. There are many difficulties with this hypothesis: Why have ground-based observers never identified an equatorial ring, which after all should be the brightest element of a ring system? Why should a ring system be made of very small particles only? The material must be constantly falling to Earth - where is it? Finally, can we believe in the level of lunar geological activity needed to sustain an Earth ring system? This presentation addresses only one issue: Could ground-based observers have seen but misidentified an equatorial ring? To support consideration of that question, herewith a simple geometric exercise

Physiological and phylogenetic characterization of a stable benzene-degrading, chlorate-reducing microbial community

NARCIS (Netherlands)

Weelink, S.A.B.; Tan, N.C.G.; Broeke, H. ten; Doesburg, W. van; Langenhoff, A.A.M.; Gerritse, J.; Stams, A.J.M.

2007-01-01

A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene

An Extended Octagonal Ring Dynamometer for Measurement of ...

African Journals Online (AJOL)

The analysis, design, construction, evaluation and use of an extended octagonal ring dynamometer for measurement of draught, vertical force and moment on a simple tillage tool are presented. The dynamometer was used to measure tool forces as functions of depth, rake angle and speed, for a wide plane blade.

Benzene in blood as a biomarker of low level occupational exposure

Energy Technology Data Exchange (ETDEWEB)

Brugnone, F.; Perbellini, L.; Romeo, L.; Cerpelloni, M.; Bianchin, M.; Tonello, A. [Institute of Occupational Medicine, University of Verona, Policlinico Borgo Roma, 37134 Verona (Italy)

1999-09-01

The occupational airborne exposure to benzene of 150 workers employed in petrol stations and a refinery plant was assessed using personal sampling pumps. All workers provided blood samples after the end of work and on the following morning before resuming work. Benzene concentrations in the blood of 243 non-occupationally-exposed subjects were also measured. The median occupational benzene exposure for all 150 workers studied was 80 {mu}g/m{sup 3}. Overall median blood benzene of all workers was 251 ng/l at the end of the shift, and 174 ng/l the following morning. The benzene concentrations measured in blood collected the following morning proved to be significantly lower than those measured at the end of the shift. Median blood benzene for the 243 'normal' subjects was 128 ng/l, which was significantly lower than that measured in the workers before a new work shift. The median blood benzene concentration was significantly higher in smokers than in non-smokers, both in the general population (210 ng/l vs. 110 ng/l) and in the exposed workers at the end of the shift (476 ng/l vs. 132 ng/l) and the following morning (360 ng/l vs. 99 ng/l). End-of-shift blood benzene correlated significantly with environmental exposure; this correlation was better in the 83 non-smokers than in the 67 smokers. In non-smokers with the median benzene occupational exposure of 50 {mu}g/m{sup 3}, no difference was found in blood benzene concentration in exposed and non-exposed subjects.

40 CFR 80.1275 - How are early benzene credits generated?

Science.gov (United States)

2010-07-01

...), per § 80.1280(a). Bavg,y = Average benzene concentration of gasoline produced at the refinery during averaging period y (volume percent benzene), per § 80.1238. Ve,y = Total volume of gasoline produced at the... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading...

Evidence that humans metabolize benzene via two pathways.

NARCIS (Netherlands)

Rappaport, S.M.; Kim, S.; Lan, Q.; Vermeulen, R.C.H.; Waidyanatha, S.; Zhang, L.; Li, G.; Yin, S.; Hayes, R.B.; Rothman, N.; Smith, M.T.

2009-01-01

BACKGROUND: Recent evidence has shown that humans metabolize benzene more efficiently at environmental air concentrations than at concentrations > 1 ppm. This led us to speculate that an unidentified metabolic pathway was mainly responsible for benzene metabolism at ambient levels. OBJECTIVE: We

(2R,3aR,4S,7R,7aS,9R,10aR,11S,14R,14aS-rel-3a,4,7,7a,10a,11,14,14a-Octahydro-4,14:7,11-diepoxy-2,9-propanonaphtho[1,2-f:5,6-f′]diisoindole-1,3,8,10-tetrone (9CI: a cyclophane derived from naphtho[1,2-c:5,6-c]difuran

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Peter W. Dibble

2008-09-01

Full Text Available The title compound, C25H18N2O6, is a naphthalenophane styled in the manner of Warrener's alicyclic cyclophanes or molecular racks wherein a trimethylene tether is perfectly staggered between the two N atoms such that the central methylene H atoms point toward the naphthalene π-system. The dihedral angle between the mean planes of the two benzene rings is 7.61 (7°.

2-[(2-Chlorobenzylideneamino]-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile

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Abdullah M. Asiri

2011-09-01

Full Text Available In the title compound, C16H13ClN2S, the mean planes fitted through all non-H atoms of the heterocyclic five-membered and the benzene rings are oriented at a dihedral angle of 5.19 (7°. In the crystal, a weak C—H...π interaction occurs, along with weak π–π interactions [cenroid–centroid distance = 3.7698 (11 Å].

Structural and vibrational study of a neurotransmitter molecule: Dopamine [4-(2-aminoethyl) benzene-1,2-diol].

Science.gov (United States)

Jha, Omkant; Yadav, T K; Yadav, R A

2018-01-15

Structural and vibrational studies for the most stable conformer of dopamine {4-(2-Aminoethyl) benzene-1, 2-diol} have been carried out at the DFT/B3LYP/6-311++G** level using the Gaussian 09 software. The IR and Raman spectra have been recorded and analyzed in light of the computed vibrational parameters using the DFT and the PEDs computed with the help of the GAR2PED software. Some of the fundamentals have considerably changed frequencies in going from benzene to dopamine. Except the rocking and wagging modes of the NH 2 group the other four modes are pure group modes. The rocking and wagging modes of the NH 2 group show mixing with the other modes. The two OH stretching vibrations are highly localized modes. The Kekule phenyl ring stretching mode is found to remain almost unchanged. The HOMO-LUMO study suggests the existence of charge transfer within the molecule and the energy gap supports the pharmacological active property of the dopamine molecule. The NBO analysis has been carried out to understand the proper and improper hydrogen bonding. Copyright © 2017. Published by Elsevier B.V.

(Pyridin-2-ylmethyl 6-bromo-2-oxo-1-[(pyridin-2-ylmethyl]-1,2-dihydroquinoline-4-carboxylate

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Yassir Filali Baba

2018-02-01

Full Text Available In the central dihydroquinoline unit of the title compound, C22H16BrN3O3, the dihydropyridinone and benzene rings are inclined to one another by 2.0 (1°, while the outer pyridine rings are almost perpendicular to the plane of the dihydroquinoline ring system. The conformation of the molecule is partially determined by an intramolecular C—H...O hydrogen bond. In the crystal, molecules stack along the b-axis direction through a combination of C—H...N and C—H...O hydrogen bonds and π–π stacking interactions involving the dihydroquinoline units, with a centroid-to-centroid distance of 3.7648 (15 Å.

Radar imaging of Saturn's rings

Science.gov (United States)

Nicholson, Philip D.; French, Richard G.; Campbell, Donald B.; Margot, Jean-Luc; Nolan, Michael C.; Black, Gregory J.; Salo, Heikki J.

2005-09-01

We present delay-Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°⩽|B|⩽26.7°. The average radar cross-section of the A ring is ˜77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the cross-section of the C ring and 9% on that of the Cassini Division. These results are consistent with those obtained by Ostro et al. [1982, Icarus 49, 367-381] from radar observations at |B|=21.4°, but provide higher resolution maps of the rings' reflectivity profile. The average cross-section of the A and B rings, normalized by their projected unblocked area, is found to have decreased from 1.25±0.31 to 0.74±0.19 as the rings have opened up, while the circular polarization ratio has increased from 0.64±0.06 to 0.77±0.06. The steep decrease in cross-section is at variance with previous radar measurements [Ostro et al., 1980, Icarus 41, 381-388], and neither this nor the polarization variations are easily understood within the framework of either classical, many-particle-thick or monolayer ring models. One possible explanation involves vertical size segregation in the rings, whereby observations at larger elevation angles which see deeper into the rings preferentially see the larger particles concentrated near the rings' mid-plane. These larger particles may be less reflective and/or rougher and thus more depolarizing than the smaller ones. Images from all four years show a strong m=2 azimuthal asymmetry in the reflectivity of the A ring, with an amplitude of ±20% and minima at longitudes of 67±4° and 247±4° from the sub-Earth point. We attribute the asymmetry to the presence of gravitational wakes in the A ring as invoked by Colombo et al. [1976, Nature 264, 344-345] to explain the similar asymmetry long seen at optical wavelengths. A simple radiative transfer model suggests that the enhancement of the azimuthal

3-(4-Hexyloxyphenyl-1,2,4-triazolo[3,4-b]benzothiazole

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Dieter Schollmeyer

2014-03-01

Full Text Available The title compound, C20H21N3OS, was prepared by Huisgen reaction of 5-(4-hexyloxyphenyltetrazole and chlorobenzothiazole. The essentially planar benzothiazolotriazole framework [maximum deviation from the mean plane of 0.077 (1 Å for the bridgehead N atom] and the phenyl ring form a dihedral angle of 53.34 (5°. The hexyloxy chain adopts a gauche–all-anti conformation. The intracentroid separation of 3.7258 (8 Å between the triazole and benzene rings is the closest contact between individual molecules in the crystal.

4-{3-[Hydroxy(phenylmethyl]-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-4-yl}benzenesulfonamide

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Mehmet Akkurt

2010-04-01

Full Text Available In the title compound, C15H14N4O3S2, the hydroxy group is disordered over two positions with occupancies of 0.619 (5 and 0.381 (5. The benzene ring attached to the heterocycle makes a dihedral angle of 86.92 (9° with respect to the best plane through the five-membered ring. The crystal packing is stabilized by intermolecular O—H...O, N—H...S, N—H...N, C—H...O and C—H...N hydrogen bonds, and N—H...π and C—H...π interactions.

2-[4-(2-Chloroacetylphenyl]-2-methyl-1-(pyrrolidin-1-ylpropan-1-one

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Dong-mei Ren

2013-08-01

Full Text Available The asymmetric unit of the title compound, C16H20ClNO2, contains two molecules in which the dihedral angles between the benzene ring and the plane of the amide unit are 77.4 (1 and 81.1 (1°. In both molecules, the five-membered ring adopts an envelope conformation with one of the β-C atoms as the flap. In the crystal, molecules are connected via C—H...O hydrogen bonds, forming chains along the b-axis direction. These chains are further linked by C—H...π interactions, forming a three-dimensional network.

1-Ferrocenyl-3-(2-methylanilinopropan-1-one

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Zorica Leka

2012-07-01

Full Text Available In the ferrocene-containing Mannich base, [Fe(C5H5(C15H16NO], the dihedral angle between the mean planes of the benzene ring and the substituted cyclopentadienyl ring is 84.63 (7°. The conformation of the title compound significantly differs from those found in corresponding m-tolylamino and p-tolylamino derivatives. In the crystal, C—H...O interactions connect the molecules into chains, which further interact by means of C—H...π interactions. It is noteworthy that the amino H atom is shielded and is not involved in hydrogen bonding.

N-(4-Chlorophenyl-2-(hydroxyiminoacetamide

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Jie Sun

2009-09-01

Full Text Available The title compound, C8H7ClN2O2, is an intermediate in the synthesis of 5-chloroisatin, which can be further transformed to 5-chloro-2-indolinone via a Wolff–Kishne reduction. The C2N acetamide plane forms a dihedral angle of 6.3 (3° with the benzene ring. An intramolecular C—H...O interaction results in the formation of a six-membered ring. In the crystal, intermolecular N—H...O, N—H...N and O—H...O hydrogen bonds link the molecules into multimers, forming sheets.

2,3-Bis[(3-methylbiphenyl-4-ylimino]butane

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Jingjing Chen

2014-04-01

Full Text Available The title compound, C30H28N2, is a product of the condensation reaction of 2-methyl-4-phenylaniline and butane-2,3-dione. The molecule lies on a crystallographic inversion centre. The C=N bond has an E conformation. The dihedral angle between the two benzene rings of the 4-phenyl-2-methylphenyl group is 29.19 (76°. The 1,4-diazabutadiene plane makes an angle of 70.1 (10° with the N-bonded methylphenyl ring and an angle of 81.08 (97° with the terminal phenyl group.

Crystal structure of 5-[(4-carboxybenzyloxy]isophthalic acid

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Md. Serajul Haque Faizi

2016-08-01

Full Text Available The molecular shape of the title compound, C16H12O7, is bent around the central CH2—O bond. The two benzene rings are almost perpendicular to one another, making a dihedral angle of 87.78 (7°. In the crystal, each molecule is linked to three others by three pairs of O—H...O hydrogen bonds, forming undulating sheets parallel to the bc plane and enclosing R22(8 ring motifs. The sheets are linked by C—H...O hydrogen bonds and C—H...π interactions, forming a three-dimensional network.

Metagenomic and proteomic analyses to elucidate the mechanism of anaerobic benzene degradation

Energy Technology Data Exchange (ETDEWEB)

Abu Laban, Nidal [Helmholtz (Germany)

2011-07-01

This paper presents the mechanism of anaerobic benzene degradation using metagenomic and proteomic analyses. The objective of the study is to find out the microbes and biochemistry involved in benzene degradation. Hypotheses are proposed for the initial activation mechanism of benzene under anaerobic conditions. Two methods for degradation, molecular characterization and identification of benzene-degrading enzymes, are described. The physiological and molecular characteristics of iron-reducing enrichment culture are given and the process is detailed. Metagenome analysis of iron-reducing culture is presented using a pie chart. From the metagenome analysis of benzene-degrading culture, putative mobile element genes were identified in the aromatic-degrading configurations. Metaproteomic analysis of iron-reducing cultures and the anaerobic benzene degradation pathway are also elucidated. From the study, it can be concluded that gram-positive bacteria are involved in benzene degradation under iron-reducing conditions and that the catalysis mechanism of putative anaerobic benzene carboxylase needs further investigation.

Difference between ²JC2H3 and ²JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis.

Science.gov (United States)

Contreras, Rubén H; dos Santos, Francisco P; Ducati, Lucas C; Tormena, Cláudio F

2010-12-01

Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the σ-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the ring' effects. The latter, associated with σ-ring currents, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in σ-ring currents for the five-membered rings (furan, thiophene, selenophene and pyrrol) and also for the six-membered rings (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study. Copyright © 2010 John Wiley & Sons, Ltd.

Progress of epidemiological and molecular epidemiological studies on benzene in China.

Science.gov (United States)

Li, Guilan; Yin, Songnian

2006-09-01

Benzene is an organic solvent that has been used in industry for about 100 years throughout the world. Since 1973, a series of toxicological and molecular epidemiological studies on benzene were conducted by researchers at the Chinese Academy of Preventive Medicine (CAPM) (1973-1986) and subsequently by a collaboration between the CAPM and the National Cancer Institute (NCI) in the United States that began in 1986, which was joined by investigators from the University of California at Berkeley, the University of North Carolina at Chapel Hill, and New York University. The findings demonstrated that the risk of leukemia and lymphoma among benzene-exposed workers was significantly increased, with elevated risks for leukemia present not only at higher exposure but also among workers exposed to under 10 ppm. Therefore, the benzene permissible level was decreased to 1.8 ppm (6 mg/m(3)) and benzene-induced leukemia is treated as an occupational cancer in China. The benzene permissible level is 1.0 in the United States and in several other developed countries and it has been suggested to be decreased to 0.5 ppm (ACGIH). A number of potential biomarkers are related to benzene exposure and poisoning. Some of these are benzene oxide-protein adducts, chromosome aberration of lymphocytes, and GPA mutations in erythrocytes, a decrease in B cell and CD4(-)T cell counts in peripheral blood, and altered expression of CXCL16, ZNF331, JUN, and PF4 in lymphocytes. Variation in multiple benzene metabolizing genes may be associated with risk of benzene hematotoxicity, including CYP2E1, MPO, NQO1, and GSTT1.

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor

Energy Technology Data Exchange (ETDEWEB)

Singh, Dipty [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India); Fulekar, M.H., E-mail: mhfulekar@yahoo.com [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)

2010-03-15

Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

Dehydrogenation of benzene on Pt(111) surface

Science.gov (United States)

Gao, W.; Zheng, W. T.; Jiang, Q.

2008-10-01

The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

Biodegradation of benzene by halophilic and halotolerant bacteria under aerobic conditions.

Science.gov (United States)

Nicholson, Carla A; Fathepure, Babu Z

2004-02-01

A highly enriched halophilic culture was established with benzene as the sole carbon source by using a brine soil obtained from an oil production facility in Oklahoma. The enrichment completely degraded benzene, toluene, ethylbenzene, and xylenes within 1 to 2 weeks. Also, [14C]benzene was converted to 14CO2, suggesting the culture's ability to mineralize benzene. Community structure analysis revealed that Marinobacter spp. were the dominant members of the enrichment.

4-Fluoro-N-methyl-N-(1,2,3,4-tetra-hydro-carbazol-3-yl)benzene-sulfonamide

DEFF Research Database (Denmark)

Rasmussen, Kaspar Gothardt; Ulven, Trond; Bond, Andrew D

2009-01-01

into layers containing the carbazole units and fluoro-phenyl rings in alternate (200) planes. The carbazole units form centrosymmetric face-to-face inter-actions [inter-planar separation = 4.06 (1) Å] and edge-to-face inter-actions in which the N-H group is directed towards an adjacent carbazole face......, with a shortest H⋯C contact of 2.53 Å. The fluoro-phenyl rings form face-to-face contacts with an approximate inter-planar separation of 3.75 Å and a centroid-centroid distance of 4.73 (1) Å....

Study of benzene release from Savannah River in-tank precipitation process slurry simulant

International Nuclear Information System (INIS)

Rappe, K.G.; Gauglitz, P.A.

1998-08-01

At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry simulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every minute

CIRS High-Resolution Thermal Scans and the Structure of Saturn's B Ring

Science.gov (United States)

Brooks, S. M.; Spilker, L. J.; Showalter, M.; Pilorz, S.; Edgington, S. G.

2017-12-01

The flyby of Titan on November 29, 2016, sent the Cassini spacecraft on a trajectory that would take it within 10,000 kilometers of Saturn's F ring multiple times before a subsequent Titan encounter on April 22, 2017, would send it on ballistic trajectory carrying it between Saturn's cloud tops and the planet's D ring for several flybys. This geometry has proven beneficial for high-resolution studies of the rings, not just because of Cassini's proximity to the rings, but also because of the spacecraft's high elevation angle above the rings, which reduces the foreshortening that tends to degrade resolution in the ring plane. We will report on several observations of Saturn's main rings at the high spatial resolutions enabled by the end-of-mission geometry, particulary the B ring, with the Composite Infrared Spectrometer onboard Cassini during the F-ring and proximal orbits. CIRS' three infrared detectors cover a combined spectral range of 10 to 1400 cm-1 (1 mm down to 7 microns). We focus on data from Focal Plane 1, which covers the 10 to 600 cm-1 range (1 mm to 16 microns). The apodized spectral resolution of the instrument can be varied from 15 cm-1 to 0.5 cm-1 (Flasar et al. 2004). FP1's wavelength range makes it well-suited to sensing thermal emission from objects at temperatures typical of Saturn's rings. Correlating ring optical depth with temperatures retrieved from scans of the face of the rings exposed to direct solar illumination (the lit face) and the opposite (unlit) face suggests differences in ring structure or particle transport between the lit and unlit sides of the rings in different regions of the B ring. Lit side temperatures in the core of the B ring range between 82 and 87 K; temperatures on the unlit side of the core vary from 66 K up to 74 K. Ferrari and Reffet (2013) and Pilorz et al. (2015) published thorough analyses of the thermal throughput across this optically thick ring. We will discuss these recent CIRS rings observations and their

Catalytic conversion of alcohols to hydrocarbons with low benzene content

Energy Technology Data Exchange (ETDEWEB)

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2016-03-08

A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

Catalytic conversion of alcohols to hydrocarbons with low benzene content

Energy Technology Data Exchange (ETDEWEB)

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2016-09-06

A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

3-{(E-[4-(4-Hydroxy-3-methoxyphenylbutan-2-ylidene]amino}-1-phenylurea: crystal structure and Hirshfeld surface analysis

Directory of Open Access Journals (Sweden)

Ming Yueh Tan

2018-01-01

Full Text Available Two independent molecules (A and B comprise the asymmetric unit of the title compound, C18H21N3O3. The urea moiety is disubstituted with one amine being linked to a phenyl ring, which is twisted out of the plane of the CN2O urea core [dihedral angles = 25.57 (11 (A and 29.13 (10° (B]. The second amine is connected to an imine (E conformation, which is linked in turn to an ethane bridge that links a disubstituted benzene ring. Intramolecular amine-N—H...N(imine and hydroxyl-O—H...O(methoxy hydrogen bonds close S(5 loops in each case. The molecules have twisted conformations with the dihedral angles between the outer rings being 38.64 (81 (A and 48.55 (7° (B. In the crystal, amide-N—H...O(amide hydrogen bonds link the molecules A and B via an eight-membered {...HNCO}2 synthon. Further associations between molecules, leading to supramolecular layers in the ac plane, are hydrogen bonds of the type hydroxyl-O—H...N(imine and phenylamine-N—H...O(methoxy. Connections between layers, leading to a three-dimensional architecture, comprise benzene-C—H...O(hydroxy interactions. A detailed analysis of the calculated Hirshfeld surfaces shows molecules A and B participate in very similar intermolecular interactions and that any variations relate to conformational differences between the molecules.

Mechanism of microsomal metabolism of benzene to phenol

Energy Technology Data Exchange (ETDEWEB)

Hinson, J.A.; Freeman, J.P.; Potter, D.W.; Mitchum, R.K.; Evans, F.E.

1985-05-01

The mechanism of microsomal hydroxylation of benzene to phenol has been studied by examining the microsomal metabolism of the specifically deuterated derivative 1,3,5-(/sub 2/H/sup 3/)benzene. Evidence for the formation of the following four products was obtained: 2,3,5-(/sub 2/H/sup 3/)phenol, 3,5-(/sub 2/H/sup 2/)phenol, 2,4,6-(/sub 2/H/sup 3/)phenol, and 2,4-(/sub 2/H/sup 2/)phenol. The presence of 2,3,5-(2H3)phenol and 2,4-(/sub 2/H/sup 2/)phenol shows that, in the microsomal metabolism of benzene to phenol, a NIH shift had occurred. A deuterium isotope effect (kH/kD) of approximately 4 was detected in both the meta- and para-deuterated phenols. This finding indicates that cyclohexadienone, formed either by isomerization of the epoxide or directly from the enzyme-substrate complex, is a major intermediate in the metabolism of benzene to phenol.

(Liquid + liquid) equilibria for benzene + cyclohexane + N,N-dimethylformamide + sodium thiocyanate

International Nuclear Information System (INIS)

Dong, Hongxing; Yang, Xiaoguang; Yue, Guojun; Zhang, Wei; Zhang, Jin

2013-01-01

Graphical abstract: On the left, the figure was phase diagram about the LLE date. On the right, the figure was about the effects of mass fraction of benzene in the raffinate phase to the selectivity(S) coefficient under different salt concentration. ■, the NaSCN and DMF in ratio of 5/95; • , the NaSCN and DMF in ratio of 10/90; ▴, the NaSCN and DMF in ratio of 15/85; ★, the NaSCN and DMF in ratio of 20/80; ▾, the NaSCN and DMF in ratio of 23/77. ♦, only DMF was used extractant (the selectivity coefficient was calculated by literature 17). w 22 , refer to the mass fraction of benzene in the raffinate phase (cyclohexane-rich phase). Highlights: • (Liquid + liquid) equilibrium for quaternary system was measured. • The components include benzene, cyclohexane, N,N-dimethylformamide, sodium thiocyanate. • The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. • Separation of benzene and cyclohexane by NaSCN + DMF was discussed. -- Abstract: (Liquid + liquid) equilibrium (LLE) data for benzene + cyclohexane + N,N-dimethylformamide (DMF) + sodium thiocyanate (NaSCN) were measured experimentally at atmospheric pressure and 303.15 K. The selectivity coefficients from these LLE data were calculated and compared to those previously reported in the literature for the systems (benzene + cyclohexane + DMF) and (benzene + cyclohexane + DMF + KSCN). The NRTL equation was used to correlate the experimental data. The agreement between the predicted and experimental results was good. It was found that the selectivity coefficients of DMF + NaSCN for benzene ranged from 2.45 to 11.99. Considering the relatively high extraction capacity and selectivity for benzene, DMF + NaSCN may be used as a potential extracting solvent for the separation of benzene from cyclohexane

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

Science.gov (United States)

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

(E-2-[2-(4-Carboxyphenylethenyl]-8-hydroxyquinolin-1-ium chloride ethanol monosolvate

Directory of Open Access Journals (Sweden)

Edwin Weber

2013-12-01

Full Text Available In the title compound, C18H14NO3+·Cl−·CH3CH2OH, the dihedral angle formed by the mean planes of the quinolinium and benzene rings is 3.4 (1°, while the carboxy substituent is tilted at an angle of 4.8 (1° with respect to the benzene ring. There is a short N—H...O contact in the cation. In the crystal, due to the planar molecular geometry, two-dimensional aggregates are formed parallel to (221 via C—H...O, C—H...Cl, O—H...Cl and N—H...Cl hydrogen bonds. Interlayer association is accomplished by O—Hethanol...Cl and O—H...Oethanol hydrogen bonds and π–π stacking interactions [centroid–centroid distances vary from 3.6477 (12 to 3.8381 (11 Å]. A supramolecular three-dimensional architecture results from a stacked arrangement of layers comprising the ionic and hydrogen-bonded components.

The Storage Ring Proton EDM Experiment

Science.gov (United States)

Semertzidis, Yannis; Storage Ring Proton EDM Collaboration

2014-09-01

The storage ring pEDM experiment utilizes an all-electric storage ring to store ~1011 longitudinally polarized protons simultaneously in clock-wise and counter-clock-wise directions for 103 seconds. The radial E-field acts on the proton EDM for the duration of the storage time to precess its spin in the vertical plane. The ring lattice is optimized to reduce intra-beam scattering, increase the statistical sensitivity and reduce the systematic errors of the method. The main systematic error is a net radial B-field integrated around the ring causing an EDM-like vertical spin precession. The counter-rotating beams sense this integrated field and are vertically shifted by an amount, which depends on the strength of the vertical focusing in the ring, thus creating a radial B-field. Modulating the vertical focusing at 10 kHz makes possible the detection of this radial B-field by a SQUID-magnetometer (SQUID-based BPM). For a total number of n SQUID-based BPMs distributed around the ring the effectiveness of the method is limited to the N = n /2 harmonic of the background radial B-field due to the Nyquist sampling theorem limit. This limitation establishes the requirement to reduce the maximum radial B-field to 0.1-1 nT everywhere around the ring by layers of mu-metal and aluminum vacuum tube. The metho's sensitivity is 10-29 e .cm , more than three orders of magnitude better than the present neutron EDM experimental limit, making it sensitive to SUSY-like new physics mass scale up to 300 TeV.

Persistent organic pollutants in ringed seals from the Russian Arctic.

Science.gov (United States)

Savinov, Vladimir; Muir, Derek C G; Svetochev, Vladislav; Svetocheva, Olga; Belikov, Stanislav; Boltunov, Andrey; Alekseeva, Ludmila; Reiersen, Lars-Otto; Savinova, Tatiana

2011-06-15

Organochlorine compounds total DDT (ΣDDT), total HCH isomers (ΣHCH), toxaphenes (sum of Parlar 26, 50, 62), mirex, endrin, methoxychlor, total chlorinated benzenes (ΣCBz), total chlordane compounds (ΣCHL), polychlorinated biphenyls (total of 56 congeners; ΣPCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (sum of 7 tri- to hepta congeners; ΣPBDEs) were analysed in the blubber of adult ringed seals from the four areas of the Russian Arctic (White Sea, Barents Sea, Kara Sea and Chukchi Sea) collected in 2001-2005. Ringed seals from the south-western part of the Kara Sea (Dikson Island - Yenisei estuary) were the most contaminated with ΣDDTs, ΣPCBs, ΣCHL, and mirex as compared with those found in the other three areas of Russian Arctic, while the highest mean concentrations of ΣHCHs and PCDD/Fs were found in the blubber of ringed seals from the Chukchi Sea and the White Sea, respectively. Among all organochlorine compounds measured in ringed seals from the European part of the Russian Arctic, concentrations of ΣDDT and ΣPCBs only were higher as compared with the other Arctic regions. Levels of all other organochlorine compounds were similar or lower than in seals from Svalbard, Alaska, the Canadian Arctic and Greenland. ΣPBDEs were found in all ringed seal samples analysed. There were no significant differences between ΣPBDE concentrations found in the blubber of ringed seals from the three studied areas of the European part of the Russian Arctic, while PBDE contamination level in ringed seals from the Chukchi Sea was 30-50 times lower. ΣPBDE levels in the blubber of seals from the European part of the Russian Arctic are slightly higher than in ringed seals from the Canadian Arctic, Alaska, and western Greenland but lower compared to ringed seals from Svalbard and eastern Greenland. Copyright © 2011 Elsevier B.V. All rights reserved.

An analysis of violations of Osha's (1987) occupational exposure to benzene standard.

Science.gov (United States)

Williams, Pamela R D

2014-01-01

The Occupational Safety and Health Administration (OSHA), which was formed by the Occupational Safety and Health Act of 1970 (OSH Act), establishes enforceable health and safety standards in the workplace and issues violations and penalties for non-compliance with these standards. The purpose of the current study was to evaluate the number and type of violations of the OSHA (1987) Occupational Exposure to Benzene Standard. Violations of the OSHA Hazard Communication Standard (HCS), particularly those that may pertain to specific provisions of the benzene standard, were also assessed. All analyses were based on OSHA inspection data that have been collected since the early 1970s and that are publicly available from the U.S. Department of Labor enforcement website. Analysis of these data shows that fewer than a thousand OSHA violations of the benzene standard have been issued over the last 25+ years. The results for benzene are in contrast to those for some other toxic and hazardous substances that are regulated by OSHA, such as blood-borne pathogens, lead, and asbestos, for which there have been issued tens of thousands of OSHA violations. The number of benzene standard violations also varies by time period, standard provision, industry sector, and other factors. In particular, the greatest number of benzene standard violations occurred during the late 1980s to early/mid 1990s, soon after the 1987 final benzene rule was promulgated. The majority of benzene standard violations also pertain to noncompliance with specific provisions and subprovisions of the standard dealing with initial exposure monitoring requirements, the communication of hazards to employees, and medical surveillance programs. Only a small fraction of HCS violations are attributed, at least in part, to potential benzene hazards in the workplace. In addition, most benzene standard violations are associated with specific industries within the manufacturing sector where benzene or benzene

4-(3-Bromopropyloxy-1-hydroxy-9,10-anthraquinone

Directory of Open Access Journals (Sweden)

Natsumi Ohira

2016-05-01

Full Text Available In the molecule of the title compound, C17H13BrO4, the anthraquinone ring system is slightly bent, with a dihedral angle of 169.99 (7° between the planes of the two benzene rings. The side chain (O—C—C—C—Br has a gauche–gauche conformation, as indicated by the O—C—C—C and C—C—C—Br torsion angles of −66.9 (2 and −65.8 (2°, respectively. In addition, there is an intramolecular O—H...O hydrogen bond enclosing an S(6 ring motif. The hydrogen-bond donor is bifurcated; in the crystal, a pair of O—H...O hydrogen bonds connects two molecules, forming an inversion dimer with an R22(12 ring motif.

Treatment of co-mingled benzene, toluene and TCE in groundwater.

Science.gov (United States)

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 μg/L and 500 μg/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. Copyright © 2014 Elsevier B.V. All rights reserved.

Benzene adsorption and hydrogenation on Pd-Ru alloy by pulse chromatography

International Nuclear Information System (INIS)

Dobrokhotov, V.G.; Pavlova, L.F.; Gryaznov, V.M.

1983-01-01

Pulse chromatography has been applied to investigate benzene adsorption and hydrogenation on the Walls of a capillary of the Pd-6% Ru alloy at different hydrogen contents in the alloy and various methods of hydrogen supply: as a mixture with benzene vapors or by diffusion through the walls of the capillary. It is stated that reversible adsorption of benzene vapors on the Pd-6% Ru alloy at 303 K under the conditions of the β-phase existence in the alloy-hydrogen system does not change whereas in the region of the α-phase existence it slightly increases with a growth of hydrogen pressure. Strongly adsorbed benzene occupies approximately 7% of the surface. Only strongly adsorbed benzene is hydrogenated on the α-phase of the alloy-hydrogen system. Hydrogen supply to the hydrogenation zone by diffusion throUgh the alloy results in supersaturation of the surface active in the reaction of benzene hydrogenation with a chemisorbed hydrogen form

Peer Review Comments on the IRIS Assessment of Benzene

Science.gov (United States)

Attachment to IRIS file for benzene, January 19, 2000, RESPONSE TO THE PEER REVIEW COMMENTS, II. Extrapolation of the Benzene Inhalation Unit Risk Estimate to the Oral Route of Exposure (EPA/NCEA-W-0517, July 1999)

Electric dipole moment of magnetoexciton in concentric quantum rings

Science.gov (United States)

García, L. F.; Mikhailov, I. D.; Revinova, S. Yu

2017-12-01

We study properties of exciton in a weakly coupled concentric quantum rings, penetrated by an axially directed magnetic flux and subjected to an electric field in the ring’s plane. To this end, we adopt a simple model of quasi-one-dimensional rotator, for which the wave functions and the corresponding energies we found by using the double Fourier series expansion method. Revealed multiple intersections of the energy levels provide conditions for abrupt changes of the radial and the angular quantum numbers, making possible the tunnelling of carriers between rings and allowing the formation of a permanent large dipole moment. We show that the electric and magnetic polarizability of concentric quantum rings with a trapped exciton are very sensible to external electric and magnetic fields.

Destruction of benzene (VOC) using electron beam radiation in flue gas treatment

International Nuclear Information System (INIS)

Mohd Nahar Othman; Mohd Noor Muhd Yunus

2004-01-01

In this study, Benzene, one of the volatile organic compounds (VOCs) is used to destruct by electron beam. As we know Benzene is one of the most stable compound and very difficult to break. By using the powerful energy produced by electron beam, the benzene compound can be broken up to form new compounds. The technique used in this experiment is by using static process in a control condition where other gases are not allowed to enter the Tedlar bag or glass jar. The Tedlar Bag and Glass jar are used as media for benzene gas to be irradiated. From the experiment it was found that the Tedlag Bag is more suitable than the glass jar the electron beam can easily penetrate and destroy benzene gas. Nitrogen and Helium gas is used as a cleaning gas. The concentrations of benzene gas used for this study are 100 ppm. (part per million), 1 ppmv, and 1 ppmv each for 32 types of VOC. From the result it can be concluded that the electron beam technique used for destruction of benzene (VOQ is very suitable for the low concentration of benzene, the dose needed for the destruction to reach 85-95% is only between 8-12 kGy. It was also observed that many new compound can be produced when benzene is destruct by electron beam. (Author)

4-Bromo-N-phenylbenzamidoxime

Directory of Open Access Journals (Sweden)

Mihaela Cibian

2009-11-01

Full Text Available The title compound, C13H11BrN2O, a hydroxyamidine derivative (an amidoxime, was obtained by addition of the corresponding imidoyl chloride to hydroxylamine. The benzene and phenyl rings are twisted from the mean plane of the hydroxyamidine group by 34.4 (1 and 59.2 (1°, respectively. In the crystal structure, intermolecular O—H...N hydrogen bonds link pairs of molecules, forming centrosymmetric dimers.

(2E-3-[4-(Dimethylaminophenyl]-1-(4-fluorophenylprop-2-en-1-one

Directory of Open Access Journals (Sweden)

Jerry P. Jasinski

2011-02-01

Full Text Available The mean planes of the two benzene rings in the title compound, C17H16FNO, are twisted slightly, making a dihedral angle of 7.8 (1°. The prop-2-en-1-one group is also twisted slightly with a C—C—C—O torsion angle of −11.6 (3°. In the crystal, weak intermolecular C—H...O interactions link pairs of molecules, forming centrosymmetric dimers.

Di-tert-butyl N-[2,6-bis(methoxymethoxyphenyl]iminodiacetate

Directory of Open Access Journals (Sweden)

Ben Capuano

2009-04-01

Full Text Available The title molecule, C20H31NO8, has pseudo-C2 symmetry about the C—N bond, with the bis(tert-butoxycarbonylamino group twisted from the benzene ring plane by ca 60° and the bulky tert-butoxycarbonyl (Boc groups are orientated away from the substituted aniline group. As part of an antibacterial drug discovery programme furnishing analogues of platensimycin, we unexpectedly synthesized the bis-Boc-protected aniline.

STABILITY OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE AND 1,4-BENZOQUINONE AFTER ADMINISTRATION OF BENZENE TO F344 RATS

Science.gov (United States)

The stability of cysteinyl adducts of benzene oxide (BO) and mono-S-substituted cysteinyl adducts of 1,4-benzoquinone (1,4-BQ) was investigated in both hemoglobin (Hb) and albumin (Alb) following administration of a single oral dose of 400 mg [U-14C/13C6]benzene/kg body weight ...

Establishment of a Methanogenic Benzene-Degrading Culture and its Implication in Bioremediation

Science.gov (United States)

Qiao, W.; Luo, F.; Bawa, N.; Guo, S.; Ye, S.; Edwards, E.

2017-12-01

Benzene is a known human carcinogen and it is a common pollutant in groundwater, mainly resulting from petrochemical industry. Anaerobic degradation of benzene has significant advantages over aerobic processes for in situ bioremediation. In this study, new methanogenic and sulfate-reducing benzene degrading cultures have been enriched. Microbial community composition was characterized with two other previously established benzene-degrading cultures, and their potential use in bioaugmentation is investigated. In this study, a lab microcosm study was conducted anaerobically with contaminated soil and groundwater from a former chemical plant. Benzene degradation was observed in the presence of co-contaminants and electron donor. Through repetitive amendment of benzene, two enrichment cultures have been developed under sulfate and methanogenic conditions. Results from DNA amplicon sequencing and qPCR analysis revealed that an organism similar to previously described benzene-degrading Deltaproteobacterium has been enriched. The microbial community of this culture was compared with other two methanogenic benzene-degrading enrichment cultures that were derived from an oil refinery and a decommissioned gasoline station, and have been maintained for decades. Deltaproteobacterium ORM2-like microbes were dominate in all enrichment cultures, which brought to light benzene-degrading microbes, ORM2 were enriched under different geological conditions distributed around the world. The relative abundance of methanogens was much lower compared to previously established cultures, although substantial amount of methane was produced. The peripheral organisms also vary. To investigate effectiveness of using ORM2-dominant enrichment cultures in bioremediation, microcosm studies were set up using contaminated materials, and a ORM2-dominating methanogenic benzene-degrading culture was used for bioaugmentation. Results revealed that benzene degradation was speeded up under methanogenic or

Excess molar volumes and refractive indices of (methoxybenzene+benzene, or toluene, or o-xylene, or m-xylene, or p-xylene, or mesitylene) binary mixtures between T=(288.15 to 303.15)K

International Nuclear Information System (INIS)

Al-Kandary, Jasem A.; Al-Jimaz, Adel S.; Abdul-Latif, Abdul-Haq M.

2006-01-01

Densities ρ and refractive indices n D for (anisole+benzene, or toluene, or o-xylene, or m-xylene or p-xylene or mesitylene) binary mixtures over the entire range of mole fraction, at temperatures (288.15, 293.15, 298.15, and 303.15)K and atmospheric pressure, have been measured. The excess molar volume V E and molar refraction deviation ΔR m , have been calculated and fitted to the Redlich-Kister polynomial relation to estimate the binary coefficients and standard errors. The excess molar volumes are positive for (anisole+mesitylene) binary mixtures and negative for (anisole+benzene, or toluene, or xylene isomers) binary mixtures at various temperatures. Partial molar volumes V-bar i and partial excess molar volumes V-bar i E have been also derived from the experimental data. The calculated values have been used to explain the dependency of intermolecular interaction between the mixing components on the alkyl substitution on benzene ring

Cultivating microbial dark matter in benzene-degrading methanogenic consortia.

Science.gov (United States)

Luo, Fei; Devine, Cheryl E; Edwards, Elizabeth A

2016-09-01

The microbes responsible for anaerobic benzene biodegradation remain poorly characterized. In this study, we identified and quantified microbial populations in a series of 16 distinct methanogenic, benzene-degrading enrichment cultures using a combination of traditional 16S rRNA clone libraries (four cultures), pyrotag 16S rRNA amplicon sequencing (11 cultures), metagenome sequencing (1 culture) and quantitative polymerase chain reaction (qPCR; 12 cultures). An operational taxonomic unit (OTU) from the Deltaproteobacteria designated ORM2 that is only 84% to 86% similar to Syntrophus or Desulfobacterium spp. was consistently identified in all enrichment cultures, and typically comprised more than half of the bacterial sequences. In addition to ORM2, a sequence belonging to Parcubacteria (candidate division OD1) identified from the metagenome data was the only other OTU common to all the cultures surveyed. Culture transfers (1% and 0.1%) were made in the presence and absence of benzene, and the abundance of ORM2, OD1 and other OTUs was tracked over 415 days using qPCR. ORM2 sequence abundance increased only when benzene was present, while the abundance of OD1 and other OTUs increased even in the absence of benzene. Deltaproteobacterium ORM2 is unequivocally the benzene-metabolizing population. This study also hints at laboratory cultivation conditions for a member of the widely distributed yet uncultivated Parcubacteria (OD1). © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Crack initiation under generalized plane strain conditions

International Nuclear Information System (INIS)

Shum, D.K.M.; Merkle, J.G.

1991-01-01

A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations

International Nuclear Information System (INIS)

Del Gratta, F.; Durif, M.; Fagault, Y.; Zdanevitch, I.

2004-12-01

This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

Ab initio dynamics and photoionization mass spectrometry reveal ion-molecule pathways from ionized acetylene clusters to benzene cation.

Science.gov (United States)

Stein, Tamar; Bandyopadhyay, Biswajit; Troy, Tyler P; Fang, Yigang; Kostko, Oleg; Ahmed, Musahid; Head-Gordon, Martin

2017-05-23

The growth mechanism of hydrocarbons in ionizing environments, such as the interstellar medium (ISM), and some combustion conditions remains incompletely understood. Ab initio molecular dynamics (AIMD) simulations and molecular beam vacuum-UV (VUV) photoionization mass spectrometry experiments were performed to understand the ion-molecule growth mechanism of small acetylene clusters (up to hexamers). A dramatic dependence of product distribution on the ionization conditions is demonstrated experimentally and understood from simulations. The products change from reactive fragmentation products in a higher temperature, higher density gas regime toward a very cold collision-free cluster regime that is dominated by products whose empirical formula is (C 2 H 2 ) n + , just like ionized acetylene clusters. The fragmentation products result from reactive ion-molecule collisions in a comparatively higher pressure and temperature regime followed by unimolecular decomposition. The isolated ionized clusters display rich dynamics that contain bonded C 4 H 4 + and C 6 H 6 + structures solvated with one or more neutral acetylene molecules. Such species contain large amounts (>2 eV) of excess internal energy. The role of the solvent acetylene molecules is to affect the barrier crossing dynamics in the potential energy surface (PES) between (C 2 H 2 ) n + isomers and provide evaporative cooling to dissipate the excess internal energy and stabilize products including the aromatic ring of the benzene cation. Formation of the benzene cation is demonstrated in AIMD simulations of acetylene clusters with n > 3, as well as other metastable C 6 H 6 + isomers. These results suggest a path for aromatic ring formation in cold acetylene-rich environments such as parts of the ISM.

Ab initio dynamics and photoionization mass spectrometry reveal ion–molecule pathways from ionized acetylene clusters to benzene cation

Science.gov (United States)

Stein, Tamar; Bandyopadhyay, Biswajit; Troy, Tyler P.; Fang, Yigang; Kostko, Oleg

2017-01-01

The growth mechanism of hydrocarbons in ionizing environments, such as the interstellar medium (ISM), and some combustion conditions remains incompletely understood. Ab initio molecular dynamics (AIMD) simulations and molecular beam vacuum-UV (VUV) photoionization mass spectrometry experiments were performed to understand the ion–molecule growth mechanism of small acetylene clusters (up to hexamers). A dramatic dependence of product distribution on the ionization conditions is demonstrated experimentally and understood from simulations. The products change from reactive fragmentation products in a higher temperature, higher density gas regime toward a very cold collision-free cluster regime that is dominated by products whose empirical formula is (C2H2)n+, just like ionized acetylene clusters. The fragmentation products result from reactive ion–molecule collisions in a comparatively higher pressure and temperature regime followed by unimolecular decomposition. The isolated ionized clusters display rich dynamics that contain bonded C4H4+ and C6H6+ structures solvated with one or more neutral acetylene molecules. Such species contain large amounts (>2 eV) of excess internal energy. The role of the solvent acetylene molecules is to affect the barrier crossing dynamics in the potential energy surface (PES) between (C2H2)n+ isomers and provide evaporative cooling to dissipate the excess internal energy and stabilize products including the aromatic ring of the benzene cation. Formation of the benzene cation is demonstrated in AIMD simulations of acetylene clusters with n > 3, as well as other metastable C6H6+ isomers. These results suggest a path for aromatic ring formation in cold acetylene-rich environments such as parts of the ISM. PMID:28484019

[Myelofibrosis in a benzene-exposed cleaning worker].

Science.gov (United States)

Bausà, Roser; Navarro, Lydia; Cortès-Franch, Imma

Long-term exposure to benzene has been associated with several blood malignancies, including aplastic anemia, myeloproliferative neoplasms, and different leukemias. We present a case of primary myelofibrosis in a 59-year-old woman who worked as a cleaner at a car dealership and automobile mechanic shop. For 25 years, she used gasoline as a degreaser and solvent to clean engine parts, floors and work desks on a daily basis. She was referred by her primary care provider to the Occupational Health Unit of Barcelona to assess whether her illness was work-related. Review of her job history and working conditions revealed chronic exposure to benzene in the absence of adequate preventive measures. An association between benzene exposure and myeloproliferative disease was established, suspicious for an occupational disease. Copyright belongs to the Societat Catalana de Salut Laboral.

Duality and noncommutative planes

DEFF Research Database (Denmark)

Jøndrup, Søren

2015-01-01

We study extensions of simple modules over an associative ring A   and we prove that for twosided ideals mm and nn with artinian factors the condition ExtA1(A/m,A/n)≠0 holds for the left A  -modules A/mA/m and A/nA/n if and only if it holds for the right modules A/nA/n and A/mA/m. The methods pro...... proving this are applied to show that noncommutative models of the plane, i.e. algebras of the form k〈x,y〉/(f)k〈x,y〉/(f), where f∈([x,y])f∈([x,y]) are noetherian only in case (f)=([x,y])...

On Radiative Factors in Planetary Rings: New Insight Derived from Cassini CIRS Observations at Saturn Equinox

Science.gov (United States)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Deau, E.; Morishima, R.

2012-12-01

Since arriving at Saturn in 2004, Cassini's Composite Infrared Spectrometer has recorded tens of millions of spectra of Saturn's rings (personal communication, M. Segura). CIRS records far infrared radiation (16.7-1000 microns) at focal plane 1 (FP1). Thermal emission from Saturn's rings peaks at FP1 wavelengths. CIRS spectra are well characterized as blackbody emission at an effective temperature Te, multiplied by a scalar factor related to ring emissivity (Spilker et al. [2005, 2006]). CIRS can therefore characterize the rings' temperature and study the thermal environment to which the ring particles are subject. We focus on CIRS data from the 2009 Saturnian equinox. As the Sun's disk crossed the ring plane, CIRS obtained several radial scans of the rings at a variety of phase angles, local hour angles and distances. With the Sun's rays striking the rings at an incidence angle of zero, solar heating is virtually absent, and thermal radiation from Saturn and sunlight reflected by Saturn dominate the thermal environment. These observations appear to present a paradox. Equinox data show that the flux of thermal energy radiated by the rings can even exceed the energy incident upon them as prescribed by thermal models, particularly in the C ring and Cassini Division (Ferrari and Leyrat [2006], Morishima et al. [2009, 2010]). Conservation principles suggest that such models underestimate heating of the rings in these cases, as it is clearly unphysical for the rings to radiate significantly more energy than is incident upon them. In this presentation, we will describe our efforts to resolve this paradox and determine what doing so can teach us about Saturn's rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2012 California Institute of Technology. Government sponsorship acknowledged.

The classes of the quasihomogeneous Hilbert schemes of points on the plane

NARCIS (Netherlands)

Buryak, A.

2012-01-01

Abstract: In this paper we give a formula for the classes (in the Grothendieck ring of complex quasi-projective varieties) of irreducible components of -quasi-homogeneous Hilbert schemes of points on the plane. We find a new simple geometric interpretation of the -Catalan numbers. Finally, we

(3′R-3′-Benzyl-2′,3′-dihydro-1H-spiro[indole-3,1′-naphtho[2,3-c]pyrrole]-2,4′,9′-trione

Directory of Open Access Journals (Sweden)

Garima Sharma

2012-09-01

Full Text Available In the title compound, C26H18N2O3, the maximum deviations from planarity for the tetrahydro-1H-naphtho[2,3-c]pyrrole and indoline rings systems are 0.091 (1 and 0.012 (2 Å, respectively. These ring systems make a dihedral angle of 89.95 (6° with each other and they make dihedral angles of 73.42 (8 and 71.28 (9°, respectively, with the benzene ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generate R22(8 loops and C—H...O interactions connect the dimers into corrugated sheets lying parallel to the bc plane.

Dimethyl 4,4′-dihydroxy-3,3′-{[(3aRS,7aRS-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl]bis(methylene}dibenzoate

Directory of Open Access Journals (Sweden)

Augusto Rivera

2011-11-01

Full Text Available The title compound, C25H30N2O6, has the imidazolidine ring in an envelope conformation. There are two intramolecular O—H...N hydrogen-bond interactions with graph-set motif S(6. The cyclohexane ring adopts a slightly distorted chair conformation. One methyl carboxylate substituent forms a dihedral angle of 12.00 (5° with the plane of the benzene ring, while the other methyl carboxylate group is almost coplanar, making a dihedral angle of 2.26 (9°. In the crystal, pairs of intermolecular C—H...O hydrogen bonds form racemic dimers, corresponding to an R22(18 graph-set motif. Further weak C—H...O interactions generate a chain running along the c axis.

Crystal structure of 2-((1E-{2-[bis(2-methylbenzylsulfanylmethylidene]hydrazin-1-ylidene}methyl-6-methoxyphenol

Directory of Open Access Journals (Sweden)

Enis Nadia Md Yusof

2015-04-01

Full Text Available In the title compound, C25H26N2O2S2, the central CN2S2 atoms are almost coplanar (r.m.s. deviation = 0.0058 Å. One phenyl ring clearly lies to one side of the central plane, while the other is oriented in the plane but splayed. Despite the different relative orientations, the phenyl rings form similar dihedral angles of 64.90 (3 and 70.06 (3° with the central plane, and 63.28 (4° with each other. The benzene ring is twisted with respect to the central plane, forming a dihedral angle of 13.17 (7°. The S2C=N, N—N and N—N=C bond lengths of 1.2919 (19, 1.4037 (17 and 1.2892 (19 Å, respectively, suggest limited conjugation over these atoms; the configuration about the N—N=C bond is E. An intramolecular O—H...N hydrogen bond is noted. In the crystal, phenyl–methoxy C—H...O and phenyl–phenyl C—H...π interactions lead to supramolecular double chains parallel to the b axis. These are connected into a layer via methyl–phenyl C—H...π interactions, and layers stack along the a axis, being connected by weak π–π interactions between phenyl rings [inter-centroid distance = 3.9915 (9 Å] so that a three-dimensional architecture ensues.

Thermodynamic Features of Benzene-1,2-Diphosphonic Acid Complexes with Several Metal Ions

Energy Technology Data Exchange (ETDEWEB)

Syouhei Nishihama; Ryan P. Witty; Leigh R Martin; Kenneth L. Nash

2013-08-01

Among his many contributions to the advancement of f-element chemistry and separation science, Professor Gregory R. Choppin’s research group completed numerous investigations featuring the application of distribution techniques to the determination of metal complexation equilibrium quotients. Most of these studies focused on the chemistry of lanthanide and actinide complexes. In keeping with that tradition, this report discusses the complex formation equilibrium constants for complexes of trivalent europium (Eu3+) with benzene-1,2-diphosphonic acid (H4BzDP) determined using solvent extraction distribution experiments in 0.2 M (Na,H)ClO4 media in the temperature range of 5 – 45 degrees C. Protonation constants for HnBzDP4-n and stoichiometry and stability of BzDP4- complexes with Zn2+, Ni2+, and Cu2+ have also been determined using potentiometric titration (at I = 0.1 M) and 31P NMR spectroscopy. Heats of protonation of HnBzDPn-4 species have been determined by titration calorimetry. From the temperature dependence of the complex Eu3+-HnBzDPn-4 equilibrium constant, a composite enthalpy (?H = -15.1 (+/-1.0) kJ mol-1) of complexation has been computed. Comparing these thermodynamic parameters with literature reports on other diphosphonic acids and structurally similar carboxylic acids indicates that exothermic heats of complexation are unique to the Eu-BzDP system. Comparisons with thermodynamic data from the literature indicate that the fixed geometry imposed by the benzene ring enhances complex stability.

Electrical impedance tomography in 3D using two electrode planes: characterization and evaluation.

Science.gov (United States)

Wagenaar, Justin; Adler, Andy

2016-06-01

Electrical impedance tomography (EIT) uses body surface electrical stimulation and measurements to create conductivity images; it shows promise as a non-invasive technology to monitor the distribution of lung ventilation. Most applications of EIT have placed electrodes in a 2D ring around the thorax, and thus produced 2D cross-sectional images. These images are unable to distinguish out-of-plane contributions, or to image volumetric effects. Volumetric EIT can be calculated using multiple electrode planes and a 3D reconstruction algorithm. However, while 3D reconstruction algorithms are available, little has been done to understand the performance of 3D EIT in terms of the measurement configurations available. The goal of this paper is to characterize the phantom and in vivo performance of 3D EIT with two electrode planes. First, phantom measurements are used to measure the reconstruction characteristics of seven stimulation and measurement configurations. Measurements were then performed on eight healthy volunteers as a function of body posture, postures, and with various electrode configurations. Phantom results indicate that 3D EIT using two rings of electrodes provides reasonable resolution in the electrode plane but low vertical resolution. For volunteers, functional EIT images are created from inhalation curve features to analyze the effect of posture (standing, sitting, supine and decline) on regional lung behaviour. An ability to detect vertical changes in lung volume distribution was shown for two electrode configurations. Based on tank and volunteer results, we recommend the use of the 'square' stimulation and measurement pattern for two electrode plane EIT.

Crystal structure of trans-diaquabis(4-cyanobenzoato-κObis(nicotinamide-κN1cobalt(II

Directory of Open Access Journals (Sweden)

Gülçin Şefiye Aşkın

2015-05-01

Full Text Available In the title complex, [Co(C8H4NO22(C6H6N2O2(H2O2], the CoII atom is located on an inversion centre and is coordinated by two 4-cyanobenzoate (CNB anions, two nicotinamide (NA ligands and two water molecules. The four O atoms in the equatorial plane form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination sphere is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxylate group and the adjacent benzene ring is 22.11 (15°, while the pyridine and benzene rings are oriented at a dihedral angle of 89.98 (5°. In the crystal, intermolecular N—H...O and O—H...O hydrogen bonds link the molecules, enclosing R22(8 and R44(8 ring motifs, forming layers parallel to (100. The layers are linked via C—H...O and C—H...N hydrogen bonds, resulting in a three-dimensional network. A weak C—H...π interaction is also observed.

Polyfunctional catalyst for processiing benzene fractions

Energy Technology Data Exchange (ETDEWEB)

G. Byakov; B.D. Zubitskii; B.G. Tryasunov; I.Ya. Petrov [Kuznetsk Basin State Technical University, Kemerovo (Russian Federation)

2009-05-15

A by-product of the coke industry is a raw benzene fraction benzene- 1 which may serve as for catalytic processes. The paper reports a study on the influence of the composition and temperatures on the activity and selectivity of NiO-V{sub 2}O{sub 6}-MoO{sub 3}/{gamma}-Al{sub 2}O{sub 3} catalysts and the corresponding binary and tertiary subsystems are studied by a pulse method in model reactions; the hydrodealkylating of toluene and the hydrodesulfurizing of thioprhene. The optimal catalyst composition is established. The new catalyst is compared with industrial catalysts.

10-Ethyl-3-(5-methyl-1,3,4-oxadiazol-2-yl-10H-phenothiazine

Directory of Open Access Journals (Sweden)

Li-Cheng Sun

2012-03-01

Full Text Available In the title compound, C17H15N3OS, the phenothiazine ring system is slightly bent, with a dihedral angle of 13.68 (7° between the benzene rings. The dihedral angle between the oxadiazole ring and the adjacent benzene ring is 7.72 (7°. In the crystal, a π–π interaction with a centroid–centroid distance of 3.752 (2 Å is observed between the benzene rings of neighbouring molecules.

Control of the spin geometric phase in semiconductor quantum rings.

Science.gov (United States)

Nagasawa, Fumiya; Frustaglia, Diego; Saarikoski, Henri; Richter, Klaus; Nitta, Junsaku

2013-01-01

Since the formulation of the geometric phase by Berry, its relevance has been demonstrated in a large variety of physical systems. However, a geometric phase of the most fundamental spin-1/2 system, the electron spin, has not been observed directly and controlled independently from dynamical phases. Here we report experimental evidence on the manipulation of an electron spin through a purely geometric effect in an InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying an in-plane magnetic field, a phase shift of the Aharonov-Casher interference pattern towards the small spin-orbit-coupling regions is observed. A perturbation theory for a one-dimensional Rashba ring under small in-plane fields reveals that the phase shift originates exclusively from the modulation of a pure geometric-phase component of the electron spin beyond the adiabatic limit, independently from dynamical phases. The phase shift is well reproduced by implementing two independent approaches, that is, perturbation theory and non-perturbative transport simulations.

Development of an Acoustic Levitation Linear Transportation System Based on a Ring-Type Structure.

Science.gov (United States)

Thomas, Gilles P L; Andrade, Marco A B; Adamowski, Julio Cezar; Silva, Emilio Carlos Nelli

2017-05-01

A linear acoustic levitation transportation system based on a ring-type vibrator is presented. The system is composed by two 21-kHz Langevin transducers connected to a ring-shaped structure formed by two semicircular sections and two flat plates. In this system, a flexural standing wave is generated along the ring structure, producing an acoustic standing wave between the vibrating ring and a plane reflector located at a distance of approximately a half wavelength from the ring. The acoustic standing wave in air has a series of pressure nodes, where small particles can be levitated and transported. The ring-type transportation system was designed and analyzed by using the finite element method. Additionally, a prototype was built and the acoustic levitation and transport of a small polystyrene particle was demonstrated.

Interim report: Study of benzene release from Savannah River in-tank precipitation process slurry simulant

International Nuclear Information System (INIS)

Rappe, K.G.; Gauglitz, P.A.

1997-09-01

At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form a 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses both flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry stimulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every 3 minutes. The following 75-mL samples were measured for release rates: KTPB slurry with 15,000 ppm freshly added benzene that was gently mixed with the slurry, KTPB slurry homogenized (energetically mixed) with 15,000 ppm and 5,000 ppm benzene, clear and filtered KTPB salt solution saturated with benzene (with and without a pure benzene layer on top of the solution), and a slurry sample from a large demonstration experiment (DEMO slurry) containing-benzene generated in situ

2-Propoxybenzamide

Directory of Open Access Journals (Sweden)

Yosef Al Jasem

2012-09-01

Full Text Available In the title molecule, C10H13NO2, the amide –NH2 group is oriented toward the propoxy substituent and an intramolecular N—H...O hydrogen bond is formed between the N—H group and the propoxy O atom. The benzene ring forms dihedral angles of 12.41 (2 and 3.26 (2° with the amide and propoxy group mean planes, respectively. In the crystal, N—H...O hydrogen bonds order pairs of molecules with their molecular planes parallel, but at an offset of 0.73 (2 Å to each other. These pairs are ordered into two types of symmetry-related columns extended along the a axis with the mean plane of a pair in one column approximately parallel to (-122 and in the other to (-1-22. The two planes form dihedral angle of 84.40 (1°. Overall, in a three-dimensional network, the hydrogen-bonded pairs of molecules are either located in (-1-22 or (-122 layers. In one layer, each pair is involved in four C—H...O contacts, twice as a donor and twice as an acceptor. Additionally, there is a short C—H...C contact between a benzene C—H group and the amide π-system.

Supplementary measurements for air monitoring under NOVANA - Benzene and PAH; Supplerende maalinger til luftovervaagning under NOVANA - benzen og PAH

Energy Technology Data Exchange (ETDEWEB)

Ellermann, T.; Klenoe Noejgaard, J.; Bossi, R.

2011-10-15

The report presents results from a project carried out for the Danish Environmental Protection Agency. The aim of the project was to carry out several measuring campaigns in order to be able to better assess the monitoring needs for PAH and benzene in relation to EU's air quality directives. The results show that the mean concentrations of benzene are almost at the same level in Denmark's four largest cities, and that the concentrations are both below the threshold value (5mug/m3) as well as below the lower assessment threshold (2mug/m3). The report presents a method for objectively estimation the benzene concentration based on measurements of CO. The method can be applied to fulfil the monitoring need for benzene in those zones where no measurements of benzene are made. Measurements of PAH, especially benzo(a)pyrene, have been made during 12 months in the period 2010-2011 in an area with many wood burning furnaces are used (the town Jyllinge). The concentrations of benzo(a)pyrene in Jyllinge is almost three times higher than in the street H.C. Andersens Boulevard in Copenhagen. The concentrations of benzo(a)pyrene in Jylllinge are 0,6 ng/m3, which corresponds to the upper assessment threshold (0,6 ng/m3) and is 40% below the measuring value (1 ng/m3). On this basis, there is a need for re-evaluating the monitoring of PAH in the sub-programme for air under NOVANA. Measurements of PM{sub 10} showed that the levels in the towns Jyllinge, Lille Valby/Risoe and at the H.C. Oersted Institute in Copenhagen are all at about 20-22 mug/m3. (LN)

Radiolysis of triphenylarsine in a mixture of benzene and cyclohexane. [. gamma. radiation

Energy Technology Data Exchange (ETDEWEB)

Nazir, S B; Rai, R S [Birla Inst. of Tech. and Science, Pilani (India). Dept. of Chemistry

1975-06-01

A number of degassed samples of triphenylarsine were irradiated by gamma radiation in a mixture of benzene and cyclohexane. The condensable products formed were pentane, hexane, benzene and cyclohexane in cyclohexane solution containing triphenylarsine and cyclohexane in benzene in presence of triphenylarsine. When the composition of the solvent was varried by stepwise addition of benzene from 5 to 50%, the main condensable radiolytic products observed by vapour phase chromatography were hexane, : hexane and cyclohexene. No pentane was observed when benzene was present in the mixture upto 15%. However, it was detected in the presence of 20-30% benzene mixture. When the amount of benzene was 35-50% in the mixture, two isomers of hexane and hexene were also detected. A mechanism has been worked out for the formation of these compounds and protection and sensitization mechanisms have been invoked to explain the yields per 100 ev. From the kinetic analysis, it has been found out that the rate of formation of cyclohexene is much faster than rates of different products formed during gamma radiolysis and from the analysis of experimental data, sponge type protection has been postulated in this radiolytic system.

Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

Energy Technology Data Exchange (ETDEWEB)

Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

2011-11-15

Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

International Nuclear Information System (INIS)

Cervantes, Francisco J.; Mancilla, Ana Rosa; Toro, E. Emilia Rios-del; Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia

2011-01-01

Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L -1 , linked to the reduction of 619 ± 81 μEq L -1 of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

Canada-wide standard for benzene phase 1 : Progress report 2001

International Nuclear Information System (INIS)

2001-01-01

In June 2000, the Canadian Council of Ministers of the Environment (CCME) ratified the Canada-Wide Standard (CWS) for Benzene Phase 1. Benzene is classified as a carcinogen to humans and any level of exposure is generally considered to carry some probability of harmful effects. The Ministers committed to reducing national benzene emissions by 30 per cent between 1995 and 2000. This report presents the progress thus far and describes how the Alberta Government has focused on effecting emission reductions in the natural gas sector, dehydrators, petroleum refineries and in chemical manufacturing plants. Their initiatives led to a 66 per cent decrease in benzene emissions by 1999. In addition, overall emissions in the province were reduced by 50 per cent from industry and mobile sources. The measures initiated during Phase 1 will continue beyond the time frame, and Phase 2, not yet ratified, will call for a follow-through on those measures. Phase 2 recognizes best management practices and jurisdictional regulations that will minimize emissions. Specifically, Phase 2 calls for an additional reduction of 6 kilotonnes in benzene emissions for existing facilities by the end of 2010. The minimization of benzene emissions through the application of best available pollution prevention and control techniques is contained for new and expanding facilities. The implementation of the CWS comprises the follow-up of existing initiatives resulting from the application of Phase 1 and the promotion and application of best management practices for new and expanding facilities, the determination and tracking of ancillary emission reductions of benzene realized as a result of other CWS initiatives, and the monitoring and reporting of progress. 13 refs., 4 tabs., 3 figs

Effective ligand functionalization of zirconium-based metal-organic frameworks for the adsorption and separation of benzene and toluene: a multiscale computational study.

Science.gov (United States)

Wu, Ying; Chen, Huiyong; Liu, Defei; Xiao, Jing; Qian, Yu; Xi, Hongxia

2015-03-18

The adsorption and separation properties of benzene and toluene on the zirconium-based frameworks UiO-66, -67, -68, and their functional analogues UiO-Phe and UiO-Me2 were studied using grand canonical Monte Carlo simulations, density functional theory, and ideal adsorbed solution theory. Remarkable higher adsorption uptakes of benzene and toluene at low pressures on UiO-Phe and -Me2 were found compared to their parent framework UiO-67. It can be ascribed to the presence of functional groups (aromatic rings and methyl groups) that significantly intensified the adsorption, majorly by reducing the effective pore size and increasing the interaction strength with the adsorbates. At high pressures, the pore volumes and accessible surfaces of the frameworks turned out to be the dominant factors governing the adsorption. In the case of toluene/benzene separation, toluene selectivities of UiOs showed a two-stage separation behavior at the measured pressure range, resulting from the greater interaction affinities of toluene at low pressures and steric hindrance effects at high pressures. Additionally, the counterbalancing factors of enhanced π delocalization and suitable pore size of UiO-Phe gave rise to the highest toluene selectivity, suggesting the ligand functionalization strategy could reach both high adsorption capacity and separation selectivity from aromatic mixtures at low concentrations.

Dynamics of Rb{sup +}-benzene and Rb{sup +}-benzene-Ar {sub n} (n {<=} 3) clusters

Energy Technology Data Exchange (ETDEWEB)

Alberti, M. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain)], E-mail: m.alberti@ub.edu; Aguilar, A. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Lucas, J.M. [Centre de Recerca en Quimica Teorica, Departament de Quimica Fisica, Parc Cientific, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Cappelletti, D. [Dipartimento di Ingegneria Civile ed Ambientale, Universita di Perugia, 06123 Perugia (Italy); Lagana, A. [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy); Pirani, F. [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy)

2006-09-29

The potential energy function of the Rb{sup +}-benzene cluster and of some of its Ar solvated variants is here modeled using a combination (pairwise sum) of ion(atom)-molecular bond and ion-molecular charges interaction contributions which provide, respectively, the non electrostatic and the electrostatic terms of the total non covalent intermolecular potential energy. In particular, such interaction contributions have been represented using, in addition to the ion(atom) polarizability, the bond polarizability tensor components and the charge distribution which account, respectively, for the polarizability and the quadrupolar moment of the benzene molecule. On the resulting potential energy surface, dynamical calculations have been carried out for the microcanonical ensemble by focusing on isomerization processes and on the effect of the mass of the cation.

Examining the Combined Saturn and Ring Exosphere/Ionosphere using Cassini's Proximal orbits

Science.gov (United States)

Tucker, O. J.; Tseng, W. L.; Johnson, R. E.; Perry, M. E.

2017-12-01

Neutral molecules that are emitted from Saturn's exobase (i.e., H2) and the main rings (i.e., H2, O2, H) are a source of material for both the Saturn and ring ionospheres as well as Saturn's magnetosphere (Tseng et al., 2013 [PSS 85 164 - 167]). However, the density gradient of H2 produced from the main rings is very different than that produced by Saturn's exospheric flux due to its emission from the ring plane and distance from Saturn. Cassini measurements obtained during the proximal orbits can likely be used to identify contributions from Saturn and the rings. Here we present results obtained from Monte Carlo models of the Saturn and ring exosphere used to analyze INMS data of neutrals and ions measured along the trajectories of the Proximal orbits. Understanding the sources of neutrals and the concomitant ions can help provide insight about the dynamics occurring in the Saturn system.

Butane-1,4-diaminium bis[3,4,5,6-tetrachloro-2-(methoxycarbonylbenzoate

Directory of Open Access Journals (Sweden)

Zu Pei Liang

2011-06-01

Full Text Available In the title salt, C4H14N2+·2C9H3Cl4O4−, the cation lies on an inversion center. In the anion, the mean planes of methoxycarbonyl and carboxylate groups form dihedral angles of 64.9 (3 and 58.5 (3°, respectively, with the benzene ring. In the crystal, intermolecular N—H...O hydrogen bonds connect the components into sheets parallel to (100.

2-Bromo-2-methyl-N-p-tolylpropanamide

Directory of Open Access Journals (Sweden)

Rodolfo Moreno-Fuquen

2011-06-01

Full Text Available In the title molecule, C11H14BrNO, there is twist between the mean plane of the amide group and the benzene ring [C(=O—N—C...;C torsion angle = −31.2 (5°]. In the crystal, intermolecular N—H...O and weak C—H...O hydrogen bonds link molecules into chains along [100]. The methyl group H atoms are disordered over two sets of sites with equal occupancy.

Matrix isolation study of the interaction between water and the aromatic π-electron system

International Nuclear Information System (INIS)

Engdahl, A.; Nelander, B.

1987-01-01

The interaction of water (H 2 O, D 2 O, HDO) with toluene, the xylenes, pseudocumene, mesitylene, pentamethylbenzene, and hexamethylbenzene in argon matrices has been studied with infrared spectroscopy. Interaction energy estimates are given. The shapes of the observed absorption bands suggest that water executes a complicated motion relative to the ring plane of the aromatic hydrocarbon. The infrared spectrum of the benzene-water complex has been recorded as a function of temperature in argon, krypton, and nitrogen matrices

4-Hydroxy-N′-(4-hydroxy-3-nitrobenzylidenebenzohydrazide

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Zhen Zhang

2011-02-01

Full Text Available The molecule of the title compound, C14H11N3O5, assumes an E configuration with respect to the methylidene unit. An intramolecular O—H...O hydrogen bond is present in the molecule. The dihedral angle between the mean planes of the two benzene rings is 5.46 (15°. The crystal structure is stabilized by intermolecular O—H...O, O—H...N, and N—H...O hydrogen bonds.

Pressure Dependence of Molar Volume near the Melting Point in Benzene

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The pressure dependence of the molar volume was at constant temperatures close to the melting point in benzene. The molar volume of benzene was calculated using experimental data for the thermal expansivity for constant temperatures of 25℃, 28.5℃, 40℃, and 51℃ at various pressures for both the solid and liquid phases. The predictions are in good agreement with the observed volumes in both the solid and liquid phases of benzene. The predicted values of the molar volume for a constant temperature of 28.5℃ in the liquid phase of benzene agree well with experimental data in the literature.

5-(4-Bromophenyl-2-(3,4-methylenedioxyphenyl-3-methylsulfanyl-1-benzofuran

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Hong Dae Choi

2009-10-01

Full Text Available The title compound, C22H15BrO3S, crystallizes with four molecules in the asymmetric unit. The 4-bromophenyl rings are rotated out of the benzofuran planes, with dihedral angles for the four molecules of 20.8 (2, 17.8 (2, 23.5 (4 and 23.9 (4°. The dihedral angles between the 3,4-methylenedioxyphenyl ring and the benzofuran plane are 13.5 (2, 7.1 (2, 18.6 (3 and 14.2 (3° in the four molecules. The crystal structure is stabilized by weak nonclassical intermolecular C—H...O hydrogen bonds. The crystal structure also exhibits intermolecular aromatic π–π interactions between the benzene and furan rings and between the 4-bromophenyl and 3,4-methylenedioxyphenyl rings from molecules of the same type; the centroid–centroid distances are 3.92 (1 and 3.79 (1, 3.91 (1, 3.77 (1 and 3.77 (1, and 3.79 (1 and 3.75 (1Å in the four molecules.

Amplitude and polarization asymmetries in a ring laser

Science.gov (United States)

Campbell, L. L.; Buholz, N. E.

1971-01-01

Asymmetric amplitude effects between the oppositely directed traveling waves in a He-Ne ring laser are analyzed both theoretically and experimentally. These effects make it possible to detect angular orientations of an inner-cavity bar with respect to the plane of the ring cavity. The amplitude asymmetries occur when a birefringent bar is placed in the three-mirror ring cavity, and an axial magnetic field is applied to the active medium. A simplified theoretical analysis is performed by using a first order perturbation theory to derive an expression for the polarization of the active medium, and a set of self-consistent equations are derived to predict threshold conditions. Polarization asymmetries between the oppositely directed waves are also predicted. Amplitude asymmetries similar in nature to those predicted at threshold occur when the laser is operating in 12-15 free-running modes, and polarization asymmetry occurs simultaneously.

Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

International Nuclear Information System (INIS)

Dougal, R.A.

1993-08-01

High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a 60 Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of 60 Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 μg/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. 60 Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants

Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens

DEFF Research Database (Denmark)

Zhang, Tian; Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar

2014-01-01

Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter...... metallireducens can anaerobically oxidize benzene to carbon dioxide with Fe(III) as the sole electron acceptor and that phenol is an intermediate in benzene oxidation. In an attempt to identify enzymes that might be involved in the conversion of benzene to phenol, whole-genome gene transcript abundance...... was compared in cells metabolizing benzene and cells metabolizing phenol. Eleven genes had significantly higher transcript abundance in benzene-metabolizing cells. Five of these genes had annotations suggesting that they did not encode proteins that could be involved in benzene metabolism and were not further...

Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

International Nuclear Information System (INIS)

Nobusada, Katsuyuki; Yabana, Kazuhiro

2007-01-01

We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

Ethyl 3-[7-eth­oxy-6-(4-meth­oxy­benzene­sulfonamido)-2H-indazol-2-yl]propano­ate

Science.gov (United States)

Abbassi, Najat; Oulemda, Bassou; Rakib, El Mostapha; Geffken, Detlef; Zouihri, Hafid

2012-01-01

In the title compound, C21H25N3O6S, the dihedral angle between the meth­oxy­benzene and indazole rings is 74.96 (5)°. The crystal packing is stabilized by an N—H⋯O hydrogen bond into a two-dimensional network. In addition, C—H⋯π inter­actions and a π–π contact, with a centroid–centroid distance of 3.5333 (6) Å, are observed. The crystal packing is stabilized by N—H⋯O and C—H⋯O hydrogen bonds. PMID:22589994

Photocatalytic Hydrogen-Evolution Cross-Couplings: Benzene C-H Amination and Hydroxylation.

Science.gov (United States)

Zheng, Yi-Wen; Chen, Bin; Ye, Pan; Feng, Ke; Wang, Wenguang; Meng, Qing-Yuan; Wu, Li-Zhu; Tung, Chen-Ho

2016-08-17

We present a blueprint for aromatic C-H functionalization via a combination of photocatalysis and cobalt catalysis and describe the utility of this strategy for benzene amination and hydroxylation. Without any sacrificial oxidant, we could use the dual catalyst system to produce aniline directly from benzene and ammonia, and phenol from benzene and water, both with evolution of hydrogen gas under unusually mild conditions in excellent yields and selectivities.

Disturbance response indicators of Impatiens walleriana exposed to benzene and chromium.

Science.gov (United States)

Campos, V; Lessa, S S; Ramos, R L; Shinzato, M C; Medeiros, T A M

2017-08-03

The purpose of this study was to evaluate the remediation potential and disturbance response indicators of Impatiens walleriana exposed to benzene and chromium. Numerous studies over the years have found abundant evidence of the carcinogenicity of benzene and chromium (VI) in humans. Benzene and chromium are two toxic industrial chemicals commonly found together at contaminated sites, and one of the most common management strategies employed in the recovery of sites contaminated by petroleum products and trace metals is in situ remediation. Given that increasing interest has focused on the use of plants as depollution agents, direct injection tests and benzene misting were performed on I. walleriana to evaluate the remediation potential of this species. I. walleriana accumulated hexavalent chromium, mainly in the root system (164.23 mg kg -1 ), to the detriment of the aerial part (39.72 mg kg -1 ), and presented visible damage only at the highest concentration (30 mg L -1 ). Unlike chromium (VI), chromium (III) was retained almost entirely by the soil, leaving it available for removal by phytotechnology. However, after the contamination stopped, I. walleriana responded positively to the detoxification process, recovering its stem stiffness and leaf color. I. walleriana showed visible changes such as leaf chlorosis during the ten days of benzene contamination. When benzene is absorbed by the roots, it is translocated to and accumulated in the plant's aerial part. This mechanism the plant uses ensures its tolerance to the organic compound, enabling the species to survive and reproduce after treatment with benzene. Although I. walleriana accumulates minor amounts of hexavalent chromium in the aerial part, this amount suffices to induce greater oxidative stress and to increase the amount of hydrogen peroxide when compared to that of benzene. It was therefore concluded that I. walleriana is a species that possesses desirable characteristics for phytotechnology.

Human risk assessment of benzene after a gasoline station fuel leak

Directory of Open Access Journals (Sweden)

Miriam dos Anjos Santos

2013-06-01

Full Text Available OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals, probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L.The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals. The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk. Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

Raman spectra of iodine-derivatives of tyrosine and thyronine

International Nuclear Information System (INIS)

Loh, E.

1974-01-01

The Raman spectra of the iodine derivatives of tyrosine and thyronine in the form of compressed crystalline powders have been excited by 4880 A Argon laser on rotating samples at room temperature. The strong peaks in the low-frequency, -1 , region may be described by analogous vibrations of benzene as: I. the C-I out-of-plane bendings of E 1 sub(g) mode from 100 cm -1 to 180 cm -1 ; II. the C-I in-plane bendings of E 2 sub(g) and A 2 sub(g) mode from 190 cm -1 to 330 cm -1 and III. the C-I stretchings of E 2 sub(g) mode from 330 cm -1 to 400 cm -1 . In 3,3',5-triiodo-derivatives, the number of both the C-I in-plane bendings and C-I stretchings on the inner phenyl ring approximately doubles from thet of diiodo-derivatives. This doubling in number of peaks is presumably due to the modulation caused by the libration, which is associated with the C-I out-of-plane bending at position 3', of the outer phenyl ring

Impact of a new gasoline benzene regulation on ambient air pollutants in Anchorage, Alaska

Science.gov (United States)

Yano, Yuriko; Morris, Stephen S.; Salerno, Christopher; Schlapia, Anne M.; Stichick, Mathew

2016-05-01

The purpose of this study was to quantify the impact of a new U.S. Environmental Protection Agency (EPA) standard that limits the amount of benzene allowed in gasoline on ambient benzene concentrations. This new standard, together with two companion regulations that limit cold-temperature automotive emissions and the permeability of portable fuel containers, was expected to lower the levels of ambient benzene and other volatile organic compounds (VOCs) nationwide. In this study the impact of the gasoline benzene standard was evaluated in Anchorage, Alaska in a two-phase ambient air monitoring study conducted before and after the new gasoline standard was implemented. Gasoline sold by Anchorage retailers was also evaluated in each phase to determine the content of benzene and other gasoline components. The average benzene content in Anchorage gasoline was reduced by 70%, from 5.05% (w/w) to 1.53% (w/w) following the implementation of the standard. The annual mean ambient benzene concentration fell by 51%, from 0.99 ppbv in Phase 1 to 0.49 ppbv in Phase 2. Analysis suggests the change in gasoline benzene content alone reduced benzene emissions by 46%. The changes in toluene, ethylbenzene, and xylene content in gasoline between Phase 1 and 2 were relatively small and the differences in the mean ambient concentrations of these compounds between phases were modest. Our results suggest that cold winter communities in high latitude and mountainous regions may benefit more from the gasoline benzene standard because of high benzene emissions resulting from vehicle cold start and a tendency to develop atmospheric stagnation conditions in the winter.

Quantum rings in magnetic fields and spin current generation.

Science.gov (United States)

Cini, Michele; Bellucci, Stefano

2014-04-09

We propose three different mechanisms for pumping spin-polarized currents in a ballistic circuit using a time-dependent magnetic field acting on an asymmetrically connected quantum ring at half filling. The first mechanism works thanks to a rotating magnetic field and produces an alternating current with a partial spin polarization. The second mechanism works by rotating the ring in a constant field; like the former case, it produces an alternating charge current, but the spin current is dc. Both methods do not require a spin-orbit interaction to achieve the polarized current, but the rotating ring could be used to measure the spin-orbit interaction in the ring using characteristic oscillations. On the other hand, the last mechanism that we propose depends on the spin-orbit interaction in an essential way, and requires a time-dependent magnetic field in the plane of the ring. This arrangement can be designed to pump a purely spin current. The absence of a charge current is demonstrated analytically. Moreover, a simple formula for the current is derived and compared with the numerical results.

Benzene and its Isomers

Indian Academy of Sciences (India)

organic chemistry in particular is the period between 1825 when benzene was isolated and 1865 when its correct structure was proposed. Significant initial strides were made during these years in finding new organic reactions and searching for meth- ods to draw molecular structures. For an average chemist the molecular ...

Radiation Resistance and Gain of Homogeneous Ring Quasi-Array

DEFF Research Database (Denmark)

Knudsen, H. L.

1954-01-01

In a previous paper homogeneous ring quasi-arrays of tangential or radial dipoles were introduced, i.e. systems of dipoles arranged equidistantly along a circle, the dipoles being oriented in tangential or radial directions and carrying currents with the same amplitude, but with a phase that incr......In a previous paper homogeneous ring quasi-arrays of tangential or radial dipoles were introduced, i.e. systems of dipoles arranged equidistantly along a circle, the dipoles being oriented in tangential or radial directions and carrying currents with the same amplitude, but with a phase...... that increases uniformly along the circle. Such quasi-arrays are azimuthally omnidirectional, and the radiated field will be mainly horizontally polarized and concentrated around the plane of the circle. In this paper expressions are obtained for the radiation resistance and the gain of homogeneous ring quasi...

Asymmetric transmission in planar chiral split-ring metamaterials: Microscopic Lorentz-theory approach

DEFF Research Database (Denmark)

Novitsky, Andrey; Galynsky, Vladimir M.; Zhukovsky, Sergei

2012-01-01

The electronic Lorentz theory is employed to explain the optical properties of planar split-ring metamaterials. Starting from the dynamics of individual free carriers, the electromagnetic response of an individual split-ring meta-atom is determined, and the effective permittivity tensor...... of the metamaterial is calculated for normal incidence of light. Whenever the split ring lacks in-plane mirror symmetry, the corresponding permittivity tensor has a crystallographic structure of an elliptically dichroic medium, and the metamaterial exhibits optical properties of planar chiral structures. Its...... transmission spectra are different for right-handed versus left-handed circular polarization of the incident wave, so the structure changes its transmittance when the direction of incidence is reversed. The magnitude of this change is shown to be related to the geometric parameters of the split ring...

Geogenic sources of benzene in aquifers used for public supply, California

Science.gov (United States)

Landon, Matthew K.; Belitz, Kenneth

2012-01-01

Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium 1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

Current understandings and perspectives on non-cancer health effects of benzene: A global concern

Energy Technology Data Exchange (ETDEWEB)

Bahadar, Haji [International Campus, Tehran University of Medical Sciences (Iran, Islamic Republic of); Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Mostafalou, Sara [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Abdollahi, Mohammad, E-mail: Mohammad.Abdollahi@UToronto.Ca [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of)

2014-04-15

Objective: Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored. Methodology: A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of “benzene toxic health effects”, “environmental volatile organic compounds”, “diabetes mellitus and environmental pollutants”, “breast cancer and environmental pollution”, “prevalence of lung cancer”, and “diabetes prevalence”. More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study. Results: Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory. Conclusion: Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up. - Highlights: • Benzene is a volatile organic compound and established blood carcinogen. • Exposure to benzene needs to be

Whole-body ring-shaped confocal photoacoustic computed tomography of small animals in vivo

Science.gov (United States)

Xia, Jun; Chatni, Muhammad R.; Maslov, Konstantin; Guo, Zijian; Wang, Kun; Anastasio, Mark; Wang, Lihong V.

2012-05-01

We report a novel small-animal whole-body imaging system called ring-shaped confocal photoacoustic computed tomography (RC-PACT). RC-PACT is based on a confocal design of free-space ring-shaped light illumination and 512-element full-ring ultrasonic array signal detection. The free-space light illumination maximizes the light delivery efficiency, and the full-ring signal detection ensures a full two-dimensional view aperture for accurate image reconstruction. Using cylindrically focused array elements, RC-PACT can image a thin cross section with 0.10 to 0.25 mm in-plane resolutions and 1.6 s/frame acquisition time. By translating the mouse along the elevational direction, RC-PACT provides a series of cross-sectional images of the brain, liver, kidneys, and bladder.

Towards an Understanding of Radiative Factors on Planetary Rings: a Perspective from Cassini CIRS Observations at Saturn Equinox

Science.gov (United States)

Brooks, Shawn M.; Spilker, L.; Edgington, S. G.; Déau, E.; Pilorz, S. H.

2012-10-01

Since arriving at Saturn in 2004, Cassini's Composite Infrared Spectrometer has recorded tens of millions of spectra of Saturn’s rings (personal communication, M. Segura). CIRS records far infrared radiation (16.7-1000 microns) at focal plane 1 (FP1). Thermal emission from Saturn’s rings peaks at FP1 wavelengths. CIRS spectra are well characterized as blackbody emission at an effective temperature Te, multiplied by a scalar factor related to ring emissivity (Spilker et al. [2005, 2006]). CIRS can therefore characterize the rings' temperature and study the thermal environment to which the ring particles are subject. We focus on CIRS data from the 2009 Saturnian equinox. As the Sun's disk crossed the ring plane, CIRS obtained several radial scans of the rings at a variety of phase angles, local hour angles and distances. With the Sun's rays striking the rings at an incidence angle of zero, solar heating is virtually absent, and thermal radiation from Saturn and sunlight reflected by Saturn dominate the thermal environment. These observations present an apparent paradox. Equinox data show that the flux of thermal energy radiated by the rings is roughly equivalent to or even exceeds the energy incident upon them as prescribed by thermal models (Froidevaux [1981], Ferrari and Leyrat [2006], Morishima et al. [2009, 2010]). This apparent energy excess is largest in the C ring and Cassini Division. Conservation principles suggest that models underestimate heating of the rings, as it is clearly unphysical for the rings to radiate significantly more energy than is incident upon them. In this presentation, we will attempt to resolve this paradox and determine what this can teach us about Saturn's rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2012 California Institute of Technology. Government sponsorship acknowledged.

Assessment of Benzene Exposures in the Working Environment at Gasoline Stations

Directory of Open Access Journals (Sweden)

Sunisa Chaiklieng

2015-07-01

Full Text Available This study aimed to investigate benzene exposure in the working environment of workers at gasoline stations. Ambient air (n=20 and inhaled air samples (n=101 of benzene were collected in the city of Khon Kaen, Thailand and analyzed with gas chromatography (GC-FID. Data records were also kept of the amounts of various petroleum products sold. The results of inhaled air benzene indicated the range concentration from 0.03 ppb to 65.71 ppb and showed significant differences between concentrations of each zone (p<0.05. The highest mean concentration was found in suburban stations (35.55 ppb, followed by urban stations (18.19 ppb, and rural stations (2.52 ppb. The highest mean concentration of ambient air was found in urban stations (45.55 ppb. Regarding different job functions, the benzene concentration of fueling workers in the inhalation zone (27.29 ppb was significantly higher than that of cashiers (0.56 ppb. The amounts of petroleum products with high benzene content sold were relatively consistent with inhaled benzene concentration, indicated by the significant differences between suburban and rural zones (p<0.05. In conclusion, this study found the inhaled air benzene concentration ranged 0.03 to 65.71 ppb depending on locations and job functions of workers. Therefore, workers should be protected of adversely affected health from long-term exposure by training on safe working practice and awareness of the different risks associated with their job functions, locations of stations and daily amounts of petroleum products sold.

Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling

International Nuclear Information System (INIS)

Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

2014-01-01

Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (V o,d ) initially increase and then decrease. The V o,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The V o,d of phenanthrene and benzene on the kerogen samples accounts for 23–46% and 36–65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling. -- Highlights: • The microporosity estimated by benzene vapor differs greatly from that by N 2 . • The micropore volume changes with kerogen maturation. • The phenanthrene or benzene sorption is related to the microporosity of kerogen. • Higher adsorption volume for benzene than for phenanthrene suggests molecular sieve effect. • The pore-filling plays an important role in the sorption of phenanthrene and benzene. -- The sorption behaviors of benzene and phenanthrene are related to the microporosity of the differently matured kerogen, indicating the importance of pore-filling

Design of a dual linear polarization antenna using split ring resonators at X-band

Science.gov (United States)

Ahmed, Sadiq; Chandra, Madhukar

2017-11-01

Dual linear polarization microstrip antenna configurations are very suitable for high-performance satellites, wireless communication and radar applications. This paper presents a new method to improve the co-cross polarization discrimination (XPD) for dual linear polarized microstrip antennas at 10 GHz. For this, three various configurations of a dual linear polarization antenna utilizing metamaterial unit cells are shown. In the first layout, the microstrip patch antenna is loaded with two pairs of spiral ring resonators, in the second model, a split ring resonator is placed between two microstrip feed lines, and in the third design, a complementary split ring resonators are etched in the ground plane. This work has two primary goals: the first is related to the addition of metamaterial unit cells to the antenna structure which permits compensation for an asymmetric current distribution flow on the microstrip antenna and thus yields a symmetrical current distribution on it. This compensation leads to an important enhancement in the XPD in comparison to a conventional dual linear polarized microstrip patch antenna. The simulation reveals an improvement of 7.9, 8.8, and 4 dB in the E and H planes for the three designs, respectively, in the XPD as compared to the conventional dual linear polarized patch antenna. The second objective of this paper is to present the characteristics and performances of the designs of the spiral ring resonator (S-RR), split ring resonator (SRR), and complementary split ring resonator (CSRR) metamaterial unit cells. The simulations are evaluated using the commercial full-wave simulator, Ansoft High-Frequency Structure Simulator (HFSS).

A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications

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Sangjin Jo

2014-01-01

Full Text Available We present a simple coplanar waveguide- (CPW- fed rectangular ring monopole antenna designed for dual-band wireless local area network (WLAN applications. The antenna is based on a simple structure composed of a CPW feed line and a rectangular ring. Dual-band WLAN operation can be achieved by controlling the distance between the rectangular ring and the ground plane of the CPW feed line, as well as the horizontal vertical lengths of the rectangular ring. Simulated and measured data show that the antenna has a compact size of 21.4×59.4 mm2, an impedance bandwidths of 2.21–2.70 GHz and 5.04–6.03 GHz, and a reflection coefficient of less than −10 dB. The antenna also exhibits an almost omnidirectional radiation pattern. This simple compact antenna with favorable frequency characteristics therefore is attractive for applications in dual-band WLAN.

Benzene degradation coupled with chlorate reduction in soil column study

NARCIS (Netherlands)

Tan, N.C.G.; Doesburg, van W.C.J.; Langenhoff, A.A.M.; Stams, A.J.M.

2006-01-01

Perchlorate and chlorate are electron acceptors that during reduction result in the formation of molecular oxygen. The produced oxygen can be used for activation of anaerobic persistent pollutants, like benzene. In this study chlorate was tested as potential electron acceptor to stimulate benzene

Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009-12

Science.gov (United States)

Lorah, Michelle M.; Walker, Charles W.; Baker, Anna C.; Teunis, Jessica A.; Emily Majcher,; Brayton, Michael J.; Raffensperger, Jeff P.; Cozzarelli, Isabelle M.

2015-01-01

Wetlands at the Standard Chlorine of Delaware, Inc. Superfund Site (SCD) in New Castle County, Delaware, are affected by contamination with chlorobenzenes and benzene from past waste storage and disposal, spills, leaks, and contaminated groundwater discharge. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey began an investigation in June 2009 to characterize the hydrogeology and geochemistry in the wetlands and assess the feasibility of monitored natural attenuation and enhanced bioremediation as remedial strategies. Groundwater flow in the wetland study area is predominantly vertically upward in the wetland sediments and the underlying aquifer, and groundwater discharge accounts for a minimum of 47 percent of the total discharge for the subwatershed of tidal Red Lion Creek. Thus, groundwater transport of contaminants to surface water could be significant. The major contaminants detected in groundwater in the wetland study area included benzene, monochlorobenzene, and tri- and di-chlorobenzenes. Shallow wetland groundwater in the northwest part of the wetland study area was characterized by high concentrations of total chlorinated benzenes and benzene (maximum about 75,000 micrograms per liter [μg/L]), low pH, and high chloride. In the northeast part of the wetland study area, wetland groundwater had low to moderate concentrations of total chlorinated benzenes and benzene (generally not greater than 10,000 μg/L), moderate pH, and high sulfate concentrations. Concentrations in the groundwater in excess of 1 percent of the solubility of the individual chlorinated benzenes indicate that a contaminant source is present in the wetland sediments as dense nonaqueous phase liquids (DNAPLs). Consistently higher contaminant concentrations in the shallow wetland groundwater than deeper in the wetland sediments or the aquifer also indicate a continued source in the wetland sediments, which could include dissolution of DNAPLs and

Benzene observations and source appointment in a region of oil and natural gas development

Science.gov (United States)

Halliday, Hannah Selene

Benzene is a primarily anthropogenic volatile organic compound (VOC) with a small number of well characterized sources. Atmospheric benzene affects human health and welfare, and low level exposure (Atmospheric Observatory (PAO) in Colorado to investigate how O&NG development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's DISCOVER-AQ field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO. A limited information source attribution with the PAO dataset was completed using the EPA's positive matrix factorization (PMF) source receptor model. Six VOCs from the PTR-QMS measurement were used along with CO and NO for a total of eight chemical species. Six sources

Opening a spiropyran ring by way of an exciplex intermediate.

Science.gov (United States)

Benniston, Andrew C; Harriman, Anthony; Howell, Sarah L; Li, Peiyi; Lydon, Donocadh P

2007-02-02

A molecular dyad has been synthesized in which the main chromophore is a 1,4-diethynylated benzene residue terminated with pyrene moieties, this latter unit acting as a single chromophore. A spiropyran group has been condensed to the central phenylene ring so as to position a weak electron donor close to the pyrene unit. Illumination of the pyrene-based chromophore leads to formation of a fluorescent exciplex in polar solvents but pyrene-like fluorescence is observed in nonpolar solvents. The exciplex has a lifetime of a few nanoseconds and undergoes intersystem crossing to the pyrene-like triplet state with low efficiency. Attaching a 4-nitrobenzene group to the open end of the spiropyran unit creates a new route for decay of the exciplex whereby the triplet state of the spiropyran is formed. Nonradiative decay of this latter species results in ring opening to form the corresponding merocyanine species. Rate constants for the various steps have been obtained from time-resolved fluorescence spectroscopy carried out over a modest temperature range. Under visible light illumination, the merocyanine form reverts to the original spiropyran geometry so that the cycle is closed. Energy transfer from the pyrene chromophore to the merocyanine unit leads to an increased rate of ring closure and serves to push the steady-state composition in favor of the spiropyran form.

Crystal structures of salen-type ligands 2-[(1E-({1-(3-chlorophenyl-2-[(E-(2-hydroxybenzylideneamino]propyl}iminomethyl]phenol and 2-[(1E-({1-(4-chlorophenyl-2-[(E-(2-hydroxybenzylideneamino]propyl}iminomethyl]phenol

Directory of Open Access Journals (Sweden)

A. Gayathri

2017-12-01

Full Text Available The title compounds, C23H21ClN2O2, differ from each other only by the position of the Cl atom on the corresponding benzene ring: meta relative to the central sp3 C atom for (I and para for (II. In (I, the hydroxyphenyl rings are almost parallel, the dihedral angle between the mean planes being 9.2 (2°, but in (II, the relative position of the ring is different, characterized by a dihedral angle of 48.5 (1°. Compound (I features intramolecular O—H...N and intermolecular C—H...O hydrogen bonds, while in (II, intramolecular O—H...N, C—H...N hydrogen bonds and weak intermolecular C—H...π interactions are observed. Compound (I was refined as an inversion twin.

Study of orbit stability in the SSRF storage ring

International Nuclear Information System (INIS)

Dai Zhimin; Liu Guimin; Huang Nan

2003-01-01

In this paper, analysis of the beam orbit stability and conceptual study of the dynamic orbit feedback in the SSRF storage ring are presented. It is shown that beam orbit position movement at the photon source points is smaller than the orbit stability requirements in horizontal plane, but exceeds the orbit stability requirements in vertical plane. A dynamic global orbit feedback system, which consists of 38 high-bandwidth air-coil correctors and 40 high-precise BPMs, is proposed to suppress the vertical beam orbit position movement. Numerical simulations show that this dynamic orbit feedback system can stabilize the vertical beam orbit position movement in the frequency range up to 100 Hz

Story of skeletally substituted benzenes

Indian Academy of Sciences (India)

Unknown

values are extensively used to define aromaticity quantitatively.3 In a recent study on ... studies were directed to unravel the subtle ways in which the stability, reactivity, and ..... The singlet–triplet gaps of all the skeletally substituted benzenes ...

High-efficiency plasma catalytic removal of dilute benzene from air

International Nuclear Information System (INIS)

Fan, Hong-Yu; Shi, Chuan; Li, Xiao-Song; Zhao, De-Zhi; Xu, Yong; Zhu, Ai-Min

2009-01-01

Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min -1 flow rate, the energy cost was as low as 3.7 x 10 -3 kWh m -3 air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

Benzene - exposure and risk evaluation; Benzol - Exposition und Risikoabschaetzung

Energy Technology Data Exchange (ETDEWEB)

Eikmann, T. [Giessen Univ. (Germany). Hygiene-Institut und Umweltmedizin; Eikmann, S. [Gesellschaft fuer Umwelttoxikologie und Krankenhaushygiene mbH, Wetzlar (Germany); Goeen, T. [Technische Hochschule Aachen (Germany). Inst. fuer Hygiene und Arbeitsmedizin

2000-07-01

Benzene is one of the most important environmental carcinogens. Because of its potential to induce leukemia, benzene is noted as carcinogeneous hazardous substance in legal guidelines for occupational use and environmental contact. Epidemiological studies resulted to unit-risk values between 2.8 x 10{sup -6} to 30 x 10{sup -6} for lifelong exposure to 1 {mu}g/m{sup 3} benzene. In Germany, the average unit-risk was estimated to be 9 x 10{sup -6}. The general population is mainly exposed to benzene due to the emissions of motor vehicles. The average annual air concentration of benzene at main roads and in industrial areas are 5 to 30 {mu}g/m{sup 3}. Due to seasonal influences and special exposure situations distinctly higher peak concentrations are occurring. Regional differences, i.e. between rural and urban immission levels and between the concentration in air of the northern and southern part of Europe, are also recognizable. The life-style factor smoking increases the individual exposure distinctly, whereas contamination of the diet contribute little to the total uptake of benzene. The internal exposure of the general population varies due to living area, smoking habits and mobility. Individuals living in no-smoking buildings show benzene concentrations in blood of 15 to 170 ng/l, whereas the benzene level of persons with additional exposures (smoking, frequently use of motor vehicles, etc.) can reach approximately 1000 ng/l blood. Comparable conclusions result from data for the urinary levels of two sensitive metabolites of benzene: trans-, trans-muconic acid and S-phenylmercapturic acid. (orig.) [German] Benzol stellt aufgrund seines ubiquitaeren Auftretens und seiner Leukaemie verursachenden Wirkung eines der bedeutendsten Umweltkanzerogene dar. Es ist als krebserzeugender Gefahrstoff (Gefahrstoffverordnung: Gruppe II) und als eindeutig krebserzeugender Arbeitsstoff (Kategorie 1) ausgewiesen. Aus epidemiologischen Studien ergaben sich Unit

Degradative capacities and bioaugmentation potential of an anaerobic benzene-degrading bacterium strain DN11

Energy Technology Data Exchange (ETDEWEB)

Yuki Kasai; Yumiko Kodama; Yoh Takahata; Toshihiro Hoaki; Kazuya Watanabe [Marine Biotechnology Institute, Kamaishi (Japan)

2007-09-15

Azoarcus sp. strain DN11 is a denitrifying bacterium capable of benzene degradation under anaerobic conditions. The present study evaluated strain DN11 for its application to bioaugmentation of benzene-contaminated underground aquifers. Strain DN11 could grow on benzene, toluene, m-xylene, and benzoate as the sole carbon and energy sources under nitrate-reducing conditions, although o- and p-xylenes were transformed in the presence of toluene. Phenol was not utilized under anaerobic conditions. Kinetic analysis of anaerobic benzene degradation estimated its apparent affinity and inhibition constants to be 0.82 and 11 {mu}M, respectively. Benzene-contaminated groundwater taken from a former coal-distillation plant site in Aichi, Japan was anaerobically incubated in laboratory bottles and supplemented with either inorganic nutrients (nitrogen, phosphorus, and nitrate) alone, or the nutrients plus strain DN11, showing that benzene was significantly degraded only when DN11 was introduced. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments, and quantitative PCR revealed that DN11 decreased after benzene was degraded. Following the decrease in DN11 16S rRNA gene fragments corresponding to bacteria related to Owenweeksia hongkongensis and Pelotomaculum isophthalicum, appeared as strong bands, suggesting possible metabolic interactions in anaerobic benzene degradation. Results suggest that DN11 is potentially useful for degrading benzene that contaminates underground aquifers at relatively low concentrations. 50 refs., 6 figs., 1 tab.

Crystal structures of 2-benzylamino-4-(4-bromophenyl-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine-3-carbonitrile and 2-benzylamino-4-(4-chlorophenyl-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine-3-carbonitrile

Directory of Open Access Journals (Sweden)

R. A. Nagalakshmi

2015-01-01

Full Text Available In the title compounds, C24H22BrN3, (I, and C24H22ClN3, (II, the 2-aminopyridine ring is fused with a cycloheptane ring, which adopts a half-chair conformation. The planes of the phenyl and benzene rings are inclined to that of the central pyridine ring [r.m.s. deviations = 0.0083 (1 and 0.0093 (1 Å for (I and (II, respectively] by 62.47 (17 and 72.51 (14°, respectively, in (I, and by 71.44 (9 and 54.90 (8°, respectively, in (II. The planes of the aromatic rings are inclined to one another by 53.82 (17° in (I and by 58.04 (9° in (II. In the crystals of both (I and (II, pairs of N—H...Nnitrile hydrogen bonds link the molecules, forming inversion dimers with R22(12 ring motifs. In (I, the resulting dimers are connected through C—H...Br hydrogen bonds, forming sheets parallel to (10-1, and π–π interactions [inter-centroid distance = 3.7821 (16 Å] involving inversion-related pyridine rings, forming a three-dimensional network. In (II, the resulting dimers are connected through π–π interactions [inter-centroid distance = 3.771 (2 Å] involving inversion-related pyridine rings, forming a two-dimensional network lying parallel to (001.

4,6-Dibromo-N-{3-[(4,6-dibromo-2,3-dimethylphenylimino]butan-2-ylidene}-2,3-dimethylaniline

Directory of Open Access Journals (Sweden)

Lina Huang

2013-10-01

Full Text Available The title compound, C20H20Br4N2, is a product of the condensation reaction of 4,6-dibromo-2,3-dimethylaniline and butane-2,3-dione. The molecule has a center of symmetry at the mid-point of the central C—C bond. The dihedral angle between the benzene ring and the 1,4-diazabutadiene plane is 78.3 (2°. Niether hydrogen bonding nor aromatic stacking is observed in the crystal structure.

{N,N′-Bis[(E-3-phenylallylidene]ethane-1,2-diamine}dichloridozinc(II

Directory of Open Access Journals (Sweden)

Zhi-Dong Lin

2008-12-01

Full Text Available In the title compound, [ZnCl2(C20H20N2], the ZnII atom is four coordinated in a distorted tetrahedral geometry by two N atoms of the Schiff base ligand and by two Cl atoms. Edge-to-face C—H...π interactions exist between molecules, with a dihedral angle of 37.8 (1° between the benzene ring planes and a shortest H...centroid distance of 3.62 (5 Å.

Recent developments in out-of-plane metallocorrole chemistry across the periodic table.

Science.gov (United States)

Buckley, Heather L; Arnold, John

2015-01-07

This article presents a brief review of recent developments in metallocorrole chemistry, with a focus on species with significant displacement of the metal from the N4 plane of the corrole ring. Comparisons based on X-ray crystallographic data are made between a range of early and/or heavy transition metal, lanthanide, actinide, and main group metallocorrole species.

Mineral-like clathrate of cadmium cyanide with benzene

International Nuclear Information System (INIS)

Kitazava, T.; Nishimura, A.

1999-01-01

A new mineral-like clathrate of cadmium cyanide with benzene Cd(CN) 2 ·C 6 H 6 is prepared. Data of x-ray diffraction analysis show that benzene molecule is incorporated in cadmium cyanide lattice and a new mineral-like lattice of Cd(CN) 2 belongs to structures of cristobalite type. Clathrate Cd(CN) 2 ·C 6 H 6 crystallizes in trigonal space group R3m, a=8.953(4), c=21929(6) A [ru

Oxidative desulfurization of benzene fraction on transition metal oxides

Science.gov (United States)

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Science.gov (United States)

2010-07-01

... benzene). i = Individual batch of gasoline produced at the refinery from January 1, 2004 through December 31, 2005. n = Total number of batches of gasoline produced at the refinery from January 1, 2004... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading...

Palladium catalyzed direct oxidation of benzene with molecular oxygen to phenol

International Nuclear Information System (INIS)

Jintoku, Tetsuro; Takaki, Ken; Fujiwara, Yuzo; Fuchita, Yoshio; Hiraki, Katsuma.

1990-01-01

Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O 2 via direct activation of a C-H aromatic bond by the Pd(OAc) 2 /phenanthroline catalyst system. The evidence for direct oxidation of benzene by O 2 was obtained using 18 O and 2 H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph-Pd σ complex intermediates. (author)

Determination of benzene in different food matrices by distillation and isotope dilution HS-GC/MS

International Nuclear Information System (INIS)

Medeiros Vinci, Raquel; Canfyn, Michael; De Meulenaer, Bruno; Schaetzen, Thibault de; Van Overmeire, Ilse; De Beer, Jacques; Van Loco, Joris

2010-01-01

Benzene is classified by the IARC as carcinogenic to humans. Several sources may contribute for the occurrence of benzene in foods, such as, environmental contamination and the reaction of benzoate salts with ascorbic acid (naturally present or added as food additives). Matrix effect on benzene recovery (e.g. in fatty foods) and artefactual benzene formation from benzoate during analysis in the presence of ascorbate are some of the challenges presented when determining benzene in a wide range of foodstuffs. Design of experiment (DOE) was used to determine the most important variables in benzene recovery from headspace GC/MS. Based on the results of the DOE, a versatile method for the extraction of benzene from all kind of food commodities was developed. The method which consisted of distillation and isotope dilution HS-GC/MS was in-house validated. Artefactual benzene was prevented by addition of a borate buffer solution (pH 11) under distillation conditions. The method presented in this study allows the use of a matrix-independent calibration with detection limits below the legal limit established by the European Council for benzene in drinking water (1 μg L -1 ).

Determination of benzene in different food matrices by distillation and isotope dilution HS-GC/MS

Energy Technology Data Exchange (ETDEWEB)

Medeiros Vinci, Raquel [Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Canfyn, Michael [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium); De Meulenaer, Bruno [Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Schaetzen, Thibault de; Van Overmeire, Ilse; De Beer, Jacques [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium); Van Loco, Joris, E-mail: Joris.VanLoco@iph.fgov.BE [Food, Medicines and Consumer Safety, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels (Belgium)

2010-07-05

Benzene is classified by the IARC as carcinogenic to humans. Several sources may contribute for the occurrence of benzene in foods, such as, environmental contamination and the reaction of benzoate salts with ascorbic acid (naturally present or added as food additives). Matrix effect on benzene recovery (e.g. in fatty foods) and artefactual benzene formation from benzoate during analysis in the presence of ascorbate are some of the challenges presented when determining benzene in a wide range of foodstuffs. Design of experiment (DOE) was used to determine the most important variables in benzene recovery from headspace GC/MS. Based on the results of the DOE, a versatile method for the extraction of benzene from all kind of food commodities was developed. The method which consisted of distillation and isotope dilution HS-GC/MS was in-house validated. Artefactual benzene was prevented by addition of a borate buffer solution (pH 11) under distillation conditions. The method presented in this study allows the use of a matrix-independent calibration with detection limits below the legal limit established by the European Council for benzene in drinking water (1 {mu}g L{sup -1}).

(E-2-[(2,4,6-Trimethoxybenzylideneamino]phenolThis paper is dedicated to His Majesty King Bhumibol Adulyadej of Thailand on the occasion of his 86th birthday, which fell on December 5th, 2013.

Directory of Open Access Journals (Sweden)

Narissara Kaewmanee

2014-01-01

Full Text Available There are two independent molecules in the asymmetric unit of the title compound, C16H17NO4, with similar conformations but some differences in their bond angles. Each molecule adopts a trans configuration with respect to the methylidene C=N bond and is twisted with a dihedral angle between the two substituted benzene rings of 80.52 (7° in one molecule and 83.53 (7° in the other. All methoxy groups are approximately coplanar with the attached benzene rings, with Cmethyl—O—C—C torsion angles ranging from −6.7 (2 to 5.07 (19°. In the crystal, independent molecules are linked together by O—H...N and O—H...O hydrogen bonds and a π–π interaction [centroid–centroid distance of 3.6030 (9 Å], forming a dimer. The dimers are further linked by weak C—H...O interactions and another π–π interaction [centroid–centroid distance of 3.9452 (9 Å] into layers lying parallel to the ab plane.

Instrument for benzene and toluene emission measurements of glycol regenerators

International Nuclear Information System (INIS)

Hanyecz, Veronika; Szabó, Gábor; Mohácsi, Árpád; Puskás, Sándor; Vágó, Árpád

2013-01-01

We introduce an in-field and in-explosive atmosphere useable instrument, which can measure the benzene and toluene concentration in two gas and two glycol samples produced by natural gas dehydration units. It is a two-phase, on-line gas chromatograph with a photoacoustic spectroscopy based detector. The time resolution is 10 min per cycle and the minimum detectable concentrations are 2 mg m −3 for benzene, 3 mg m −3 for toluene in natural gas, and 5 g m −3 for benzene and 6 g m −3 for toluene in glycol. Test measurements were carried out at a dehydration plant belonging to MOL Hungarian Oil and Gas Company. Benzene and toluene emissions of gas dehydration unit are calculated from the measured values based on mass balance of a glycol regenerator. The relationship between the outdoor temperature and the measured concentration was observed which is caused by temperature-dependent operation of the whole dehydration unit. Emission decreases with increase of outdoor temperature. (paper)

An overview of published benzene exposure data by industry in China, 1960-2003.

Science.gov (United States)

Liang, You-Xin; Wong, Otto; Armstrong, Thomas; Ye, Xi-Biao; Miao, Li-Zhuang; Zhou, Yi-Mei; Wu, Qiang-En; Qian, Hao-Jun; Fu, Hua

2005-05-30

This article presents an overview of occupational benzene exposures in China based on data published in Chinese medical journals. The data were derived from 384 reports of benzene poisoning or industrial hygiene surveys published in Chinese medical journals between 1960 and 2003. The following information was extracted whenever available: industry, occupation, task, date, benzene levels, sampling location, workplace descriptions and, for case reports, medical diagnosis. Each paper provided one or more sets of benzene data, each set representing a sampling location or job title with one to several measurements including, mainly, breathing zone area concentration measurements, and much less frequently personal monitoring. Two criteria based on data quality were applied to select suitable data for analyses. The selected exposure data were analyzed by industry and time period. Nine hundred five sets of benzene measurements from 72 industries were reported in the 384 papers selected for this review, and 621 sets (68.6%) presented average benzene concentrations, which covered 55 industries. The distribution of the reported average benzene exposures was skewed with a median of 51.5 mg/m3. The average benzene concentrations were below 100 mg/m3 for 406 (65%) of the 621 reported average concentrations. The medians of the reported averages in mg/m3 for the five industries with the highest exposures were: 124.8 for leather products, 98.7 for electronic devices, 75.4 for machinery, 50.4 for shoes, and 50.3 for office supplies and sports equipment manufacturing. These data describe the concentrations and changing patterns of occupational benzene exposure by industry and time period in China.

Benzene exposure in the shoemaking industry in China, a literature survey, 1978-2004.

Science.gov (United States)

Wang, Laiming; Zhou, Yimei; Liang, Youxin; Wong, Otto; Armstrong, Thomas; Schnatter, A Robert; Wu, Qiangen; Fang, Jinbin; Ye, Xibiao; Fu, Hua; Irons, Richard D

2006-11-01

This article presents a summary of benzene exposure levels in the shoemaking industry in China reported in the Chinese medical literature between 1978 and 2004. A comprehensive search identified 182 papers reporting such exposure data. These papers could be classified into two categories: benzene poisoning case reports and industrial hygiene surveys. From each paper, the following information was abstracted whenever available: location and year of occurrence, occupation and/or task involved, benzene content in adhesives/solvents, work environment, working conditions, working hours, diagnosis, and air monitoring data of benzene. A total of 333 benzene measurements (88 averages, 116 minimums, 129 maximums) in the shoemaking industry were reported in the 182 papers identified. The data were analyzed in terms of geographical location, time period, type of ownership (state, township, or foreign), type of report (benzene poisoning reports vs. industrial hygiene surveys), and job title (work activity) or process. The reported data covered a wide range; some measurements were in excess of 4500 mg/m(3). Thirty-five percent of the reported benzene concentrations were below 40 mg/m(3), which was the national occupational exposure limit (OEL) for benzene between 1979 and 2001. The remaining 65% measurements, which exceeded the national OEL in effect at the time, and were distributed as follows: 40-100 mg/m(3), 11%; 100-300 mg/m(3), 21%; 300-500 mg/m(3), 13%; and 500+ mg/m(3), 20%. However, only 24% of the reported measurements after 2002 were below 6 mg/m(3), i.e., Permissible Concentration-Time Weighted Average (PC-TWA) and 10 mg/m(3), i.e., Permissible Concentration-Short Term Exposure Limit (PC-STEL), the newly amended benzene OELs in effect after May 2002. The data demonstrated that the majority of the facilities in the shoemaking industry reported in the literature were not in compliance of the OEL for benzene in effect at the time. Overall, the data show a clear downward

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Science.gov (United States)

2010-07-01

... baseline? 80.1285 Section 80.1285 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline... credits. (b) For U.S. Postal delivery, the benzene baseline application shall be sent to: Attn: MSAT2...

Crystal structure of (E)-3-fluoro-N-((5-nitrothiophen-2-yl)methylene)aniline

Energy Technology Data Exchange (ETDEWEB)

Karataş, Şadiye; Tanak, Hasan, E-mail: hasantanak@gmail.com [Amasya University, Department of Physics, Faculty of Arts and Sciences (Turkey); Ağar, Ayşen Alaman [Ondokuz Mayıs University, Department of Chemistry, Faculty of Arts and Sciences (Turkey)

2016-05-15

The structure of the title compound C{sub 11}H{sub 7}FN{sub 2}O{sub 2}S was characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2{sub 1}/n with Z = 12, i.e. with three molecules in asymmetric unit. The molecules are not planar: the dihedral angles between the planes of thiophene and the benzene rings are 42.3(3)°, 42.0(3)°, and 48.9(2)°. In the crystal, intermolecular C–H···F interactions link the molecules through R{sub 2}{sup 2} (14) ring motif. The crystal packing is also stabilized by π···π interactions.

Bis[4′-(4-cyanophenyl-2,2′:6′,2′′-terpyridine]cobalt(II dichloride

Directory of Open Access Journals (Sweden)

Kun Qian

2009-11-01

Full Text Available The title complex, [Co(C22H14N42]Cl2, has been synthesized by a solvothermal reaction of the 4′-(4-cyanophenyl-2,2′:6′,2′′-terpyridine ligand with CoCl2·6H2O. The cobalt(II ion is six-coordinated by two tridentate ligands in a distorted octahedral geometry. The benzene rings form dihedral angles of 30.02 (7 and 30.26 (7° with the mean planes of the terpyridine ring systems. The chloride anions are statistically disordered over two positions with refined site occupancies of 0.601 (2 and 0.399 (2.

(S,S,S,S-Nebivolol hydrochloride hemihydrate

Directory of Open Access Journals (Sweden)

Yoann Rousselin

2012-12-01

Full Text Available The asymmetric unit of the title hydrated salt, C22H26F2NO4+·Cl−·0.5H2O, consists of an (S,S,S,S-nebivolol {nebivol = bis[2-(6-fluoro-3,4-dihydro-2H-1-benzopyran-2-yl-2-hydroxyethyl]ammonium} cation, a chloride anion and a half-occupancy water molecule. The dihedral angle between the mean planes of the benzene rings is 50.34 (12°. The pyran rings adopt half-chair conformations. The crystal packing features O—H...O hydrogen bonds and weak N—H...Cl, O—H...Cl, and O—H...Cl interactions, producing layers along (010.

(E-1-(2,4-Dimethylquinolin-3-yl-3-(4-methylphenylprop-2-en-1-one

Directory of Open Access Journals (Sweden)

R. Prasath

2012-05-01

Full Text Available In the title compound, C21H19NO, there are two molecules in the asymmetric unit (Z′ = 2. There are π–π interactions between these two molecules [centroid–centroid distance = 3.678 (2 Å], as well as a weak C—H...O interaction. The conformation adopted by the two molecules is such that the quinoline mean plane and the benzene ring are almost perpendicular [89.04 (5 and 76.89 (4°]. In each molecule, the methyl group of the tolyl ring is disordered over two conformations, with occupancy ratios of 0.56 (3:0.44 (3 and 0.65 (3:0.35 (3.

Gene expression profile in bone marrow and hematopoietic stem cells in mice exposed to inhaled benzene

International Nuclear Information System (INIS)

Faiola, Brenda; Fuller, Elizabeth S.; Wong, Victoria A.; Recio, Leslie

2004-01-01

Acute myeloid leukemia and chronic lymphocytic leukemia are associated with benzene exposure. In mice, benzene induces chromosomal breaks as a primary mode of genotoxicity in the bone marrow (BM). Benzene-induced DNA lesions can lead to changes in hematopoietic stem cells (HSC) that give rise to leukemic clones. To gain insight into the mechanism of benzene-induced leukemia, we investigated the DNA damage repair and response pathways in total bone marrow and bone marrow fractions enriched for HSC from male 129/SvJ mice exposed to benzene by inhalation. Mice exposed to 100 ppm benzene for 6 h per day, 5 days per week for 2 week showed significant hematotoxicity and genotoxicity compared to air-exposed control mice. Benzene exposure did not alter the level of apoptosis in BM or the percentage of HSC in BM. RNA isolated from total BM cells and the enriched HSC fractions from benzene-exposed and air-exposed mice was used for microarray analysis and quantitative real-time RT-PCR. Interestingly, mRNA levels of DNA repair genes representing distinct repair pathways were largely unaffected by benzene exposure, whereas altered mRNA expression of various apoptosis, cell cycle, and growth control genes was observed in samples from benzene-exposed mice. Differences in gene expression profiles were observed between total BM and HSC. Notably, p21 mRNA was highly induced in BM but was not altered in HSC following benzene exposure. The gene expression pattern suggests that HSC isolated immediately following a 2 weeks exposure to 100 ppm benzene were not actively proliferating. Understanding the toxicogenomic profile of the specific target cell population involved in the development of benzene-associated diseases may lead to a better understanding of the mechanism of benzene-induced leukemia and may identify important interindividual and tissue susceptibility factors

Formation of reactive metabolites from benzene

International Nuclear Information System (INIS)

Snyder, R.; Jowa, L.; Witz, G.; Kalf, G.; Rushmore, T.

1986-01-01

Rat liver mitoplasts were incubated first with [ 3 H]dGTP, to form DNA labeled in G, and then with [ 14 C]benzene. The DNA was isolated and upon isopycnic density gradient centrifugation in CsCl yielded a single fraction of DNA labeled with both [ 3 H] and [ 14 C]. These data are consistent with the covalent binding of one or more metabolites of benzene to DNA. The DNA was enzymatically hydrolyzed to deoxynucleosides and chromatographed to reveal at least seven deoxyguanosine adducts. Further studies with labeled deoxyadenine revealed one adduct on deoxyadenine. [ 3 H]Deoxyguanosine was reacted with [ 14 C]hydroquinone or benzoquinone. The product was characterized using uv, fluorescence, mass and NMR spectroscopy. A proposed structure is described. (orig.)

Radiation chemistry of a mixture of benzene and cyclohexane in presence of triphenyl stibine

Energy Technology Data Exchange (ETDEWEB)

Nazir, S B; Rai, R S [Birla Inst. of Tech. and Science, Pilani (India). Dept. of Chemistry

1976-08-01

Following previously reported work (Peterson et al. J. Phys. Chem.; 71: 4506 (1967)) on the radiolysis of triphenyl stibine in benzene from which it was concluded that the energy is absorbed by benzene and excited benzene molecules transfer their energy to the metal phenyl which does not decompose due to quenching and since benzene is a protective agent for cyclohexane against ..gamma.. radiation, a system consisting of benzene, cyclohexane and triphenyl stibine has been used to study the energy transfer processes and the nature of protection. It was found that /sup 60/C0 ..gamma.. radiolysis of cyclohexane in presence of 1 x 10/sup -2/M triphenyl stibine formed two isomers of pentane and hexane and hexene, methylcyclopentane, benzene and cyclohexene. G values of these products, except those of hexene and methylcyclopentane are negligible. All products except these two are eliminated in the radiolysis of this system in presence of benzene. G values of these products are reduced considerably. The mechanism of formation of these compounds and a sponge type protection have been postulated to explain the results.

Electric currents induced by twisted light in Quantum Rings.

Science.gov (United States)

Quinteiro, G F; Berakdar, J

2009-10-26

We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

40 CFR 80.1290 - How are standard benzene credits generated?

Science.gov (United States)

2010-07-01

... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading... approved under § 80.1340. (b) [Reserved] (c)(1) The number of standard benzene credits generated shall be... the nearest gallon. Fractional values shall be rounded down if less than 0.50, and rounded up if...

29 CFR 1910.1028 - Benzene.

Science.gov (United States)

2010-07-01

...) Scope and application. (1) This section applies to all occupational exposures to benzene. Chemical...-general, and paragraph (e)(6) accuracy of monitoring. Engineering and work practice controls shall be used... wholesale customers. Container means any barrel, bottle, can, cylinder, drum, reaction vessel, storage tank...

Renovation of the sealing planes of WWER-400 reactors pressure vessel

International Nuclear Information System (INIS)

Jablonicky, P.; Pilat, P.

2007-01-01

An article describes technical solution for renovation of the sealing planes of WWER-440 reactor's pressure vessel. Four nickel sealing rings placed in four concentric grooves are providing hermetic sealing between the vessel and the lid of this type of the reactor. Impeccable seal of the reactor's pressure vessel, where the fission reaction takes place, represents a basic security factor for safe electric energy production. Principle of renovation of the reactor's pressure vessel and lid sealing planes is based on mechanical enlargement of defective grooves and following cladding of the new material by TIG welding. Final step for renovation includes machining of new grooves according to geometrical and surface quality requirements (Authors)

Damping the e-p instability in the SNS accumulator ring

Science.gov (United States)

Evans, N. J.; Deibele, C.; Aleksandrov, A.; Xie, Z.

2018-03-01

A broadband, digital damper system for both transverse planes developed for the SNS accumulator ring has recently damped the first indications of the broadband 50-150 MHz e-p instability in a 1.2 MW neutron production beam. This paper presents details of the design and operation of the SNS damper system as well as results of active damping of the e-p instability in the SNS ring showing a reduction in power of betatron oscillation over the 10-300 MHz band of up to 70%. The spectral content of the beam during operation, with and without the damper system is presented and performance of the damper system is evaluated.

Single-Frequency Nd:YAG Ring Lasers with Corner Cube Prism

Science.gov (United States)

Wu, Ke-Ying; Yang, Su-Hui; Zhao, Chang-Ming; Wei, Guang-Hui

2000-10-01

We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single-frequency generating power. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix.

Reverse isotope dilution method for determining benzene and metabolites in tissues

International Nuclear Information System (INIS)

Bechtold, W.E.; Sabourin, P.J.; Henderson, R.F.

1988-01-01

A method utilizing reverse isotope dilution for the analysis of benzene and its organic soluble metabolites in tissues of rats and mice is presented. Tissues from rats and mice that had been exposed to radiolabeled benzene were extracted with ethyl acetate containing known, excess quantities of unlabeled benzene and metabolites. Butylated hydroxytoluene was added as an antioxidant. The ethyl acetate extracts were analyzed with semipreparative reversed-phase HPLC. Isolated peaks were collected and analyzed for radioactivity (by liquid scintillation spectrometry) and for mass (by UV absorption). The total amount of each compound present was calculated from the mass dilution of the radiolabeled isotope. This method has the advantages of high sensitivity, because of the high specific activity of benzene, and relative stability of the analyses, because of the addition of large amounts of unlabeled carrier analogue

2,4,6-Trimethyl-3,5-bis[(phenylcarbonothioylsulfanylmethyl]benzyl benzenecarbodithioate

Directory of Open Access Journals (Sweden)

M. Kannan

2010-06-01

Full Text Available In the title compound C33H30S6, the three pendant methylene benzodithioate groups lie to one side of the central benzene ring in a cis-cis-cis `tripod' arrangement. The dihedral angles between the central benzene ring and the three pendant rings are 72.54 (4, 89.68 (4 and 86.74 (4°. In the crystal structure, one of the benzene rings is disordered over two orientations in a 0.559 (13:0.441 (13 ratio.

A Low-Profile and Compact Split-Ring Antenna with Horizontally Polarized Omnidirectional Radiation

Directory of Open Access Journals (Sweden)

Kittima Lertsakwimarn

2015-01-01

Full Text Available This paper presents a low-profile and compact printed antenna having an omnidirectional radiation pattern with horizontal polarization to the ground. The proposed antenna consists of an inner small fed ring, an outer coupled split ring, and a ground plane. The overall dimension of the proposed antenna is 45 mm × 50.5 mm × 11.6 mm (0.138λ0 × 0.155λ0 × 0.036λ0. The −10-dB S11 of the antenna covers the 920-MHz RFID band, and the gain is about 1.45 dBi in the parallel direction to the ground plane. The measured results show good agreements with the simulated results. Furthermore, the reasons for the low-profile structure and the omnidirectional radiation pattern are also discussed.

2-[2-Chloro-5-(trifluoromethylphenyl]hexahydropyrimidine monohydrate

Directory of Open Access Journals (Sweden)

Reza Kia

2008-09-01

Full Text Available The molecule of the title compound, C11H12ClF3N2·H2O, is a substituted hexahydropyrimidine. There are two crystallographically independent molecules (A and B and two water molecules in the asymmetric unit of the title compound. Intermolecular C—H...Cl (× 2, C—H...F, and C—H...N (× 2 hydrogen bonds generate S(5 ring motifs. The dihedral angle between the two benzene rings is 8.17 (11°. The F atoms in molecule B are disordered over four positions with refined site-occupancies of ca 0.35/0.19/0.29/0.17 for the four components. In the crystal structure, molecules are arranged into one-dimensional extended chains along the c axis and are further stacked along the a axis by directed four-membered O—H...O—H interactions, forming two-dimensional networks parallel to the ac plane. The short distances between the centroids of the benzene rings (3.8002–3.8327 Å indicate the existence of π–π interactions. In addition, the crystal structure is further stabilized by N—H...O, O—H...N (× 4, N—H...Cl and C—H...O (× 2 hydrogen-bonding interactions.

Benzene levels in ambient air and breath of smokers and nonsmokers in urban and pristine environments

Energy Technology Data Exchange (ETDEWEB)

Wester, R.C.; Maibach, H.I.; Gruenke, L.D.; Craig, J.C.

1986-01-01

Benzene levels in human breath and in ambient air were compared in the urban area of San Francisco (SF) and in a more remote coastal pristine setting of Stinson Beach, Calif. (SB). Benzene analysis was done by gas chromatography-mass spectroscopy (GC-MS). Ambient benzene levels were sevenfold higher in SF (2.6 +/- 1.3 ppb, n = 25) than SB (0.38 +/- 0.39 ppb, n = 21). In SF, benzene in smokers' breath (6.8 +/- 3.0 ppb) was greater than in nonsmokers' breath (2.5 +/- 0.8 ppb) and smokers' ambient air (3.3 +/- 0.8 ppb). In SB the same pattern was observed: benzene in smokers' breath was higher than in nonsmokers' breath and ambient air. Benzene in SF nonsmokers' breath was greater than in SB nonsmokers' breath. Marijuana-only smokers had benzene breath levels between those of smokers and nonsmokers. There was little correlation between benzene in breath and number of cigarettes smoked, or with other benzene exposures such as diet. Of special interest was the finding that benzene in breath of SF nonsmokers (2.5 +/- 0.8 ppb) was greater than that in nonsmokers ambient air (1.4 +/- 0.1 ppb). The same was true in SB, where benzene in nonsmokers breath was greater than ambient air (1.8 +/- 0.2 ppb versus 1.0 +/- 0.1 ppb on d 1 and 1.3 +/- 0.3 ppb versus 0.23 +/- 0.18 ppb on d 2). This suggests an additional source of benzene other than outdoor ambient air.

Critical issues in benzene toxicity and metabolism: the effect of interactions with other organic chemicals on risk assessment.

Science.gov (United States)

Medinsky, M A; Schlosser, P M; Bond, J A

1994-11-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several investigators have demonstrated that a combination of metabolites (hydroquinone and phenol, for example) is necessary to duplicate the hematotoxic effect of benzene. Enzymes implicated in the metabolic activation of benzene and its metabolites include the cytochrome P450 monooxygenases and myeloperoxidase. Since benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. Other organic molecules that are substrates for cytochrome P450 can inhibit the metabolism of benzene. For example, toluene has been shown to inhibit the oxidation of benzene in a noncompetitive manner. Enzyme inducers, such as ethanol, can alter the target tissue dosimetry of benzene metabolites by inducing enzymes responsible for oxidation reactions involved in benzene metabolism. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes, such as enzymatic oxidation, and deactivation processes, like conjugation and excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Synchronization in a Random Length Ring Network for SDN-Controlled Optical TDM Switching

DEFF Research Database (Denmark)

Kamchevska, Valerija; Cristofori, Valentina; Da Ros, Francesco

2016-01-01

. In addition, we propose a novel synchronization algorithm that enables automatic synchronization of software defined networking controlled all-optical TDM switching nodes connected in a ring network. Besides providing synchronization, the algorithm also can facilitate dynamic slot size change and failure......In this paper we focus on optical time division multiplexed (TDM) switching and its main distinguishing characteristics compared with other optical subwavelength switching technologies. We review and discuss in detail the synchronization requirements that allow for proper switching operation...... detection. We experimentally validate the algorithm behavior and achieve correct operation for three different ring lengths. Moreover, we experimentally demonstrate data plane connectivity in a ring network composed of three nodes and show successful wavelength division multiplexing space division...

THE RINGS OF CHARIKLO UNDER CLOSE ENCOUNTERS WITH THE GIANT PLANETS

Energy Technology Data Exchange (ETDEWEB)

Araujo, R. A. N.; Sfair, R.; Winter, O. C., E-mail: ran.araujo@gmail.com, E-mail: rsfair@feg.unesp.br, E-mail: ocwinter@gmail.com [UNESP - Univ. Estadual Paulista, Grupo de Dinâmica Orbital e Planetologia, CEP 12516-410, Guaratingueta, SP (Brazil)

2016-06-20

The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approach to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.

Pharmacological characterization and modeling of the binding sites of novel 1,3-bis(pyridinylethynyl)benzenes as metabotropic glutamate receptor 5-selective negative allosteric modulators

DEFF Research Database (Denmark)

Mølck, Christina; Harpsøe, Kasper; Gloriam, David E

2012-01-01

)pyridine (MPEP)-derived negative allosteric modulators, 2-, 3-, and 4-BisPEB, have been characterized. 2-, 3-, and 4-BisPEB are 1,3-bis(pyridinylethynyl)-benzenes and differ only by the position of the nitrogen atoms in the pyridine rings. Despite their high structural similarity, 2-BisPEB [1,3-bis(pyridin-2......-ylethynyl)-benzene, nitrogen atoms in ortho positions], with an IC(50) value in the nanomolar range, is significantly more potent than the 3- and 4-pyridyl analogs. Mutational analysis, directed by a previously published mGluR5 homology model, was used to determine key residues for the ligand...... that the higher potency of 2-BisPEB is due to hydrogen bonding to Ser809 because the S809A mutation made 2-BisPEB equipotent to 3- and 4-BisPEB (IC(50), 1-2.5 µM). The potency of MPEP was also greatly affected by S809A (52-fold), suggesting that a Ser809-mediated hydrogen bond is also a key interaction between...

Antimalarial activity of compounds comprising a primary benzene sulfonamide fragment.

Science.gov (United States)

Andrews, Katherine T; Fisher, Gillian M; Sumanadasa, Subathdrage D M; Skinner-Adams, Tina; Moeker, Janina; Lopez, Marie; Poulsen, Sally-Ann

2013-11-15

Despite the urgent need for effective antimalarial drugs with novel modes of action no new chemical class of antimalarial drug has been approved for use since 1996. To address this, we have used a rational approach to investigate compounds comprising the primary benzene sulfonamide fragment as a potential new antimalarial chemotype. We report the in vitro activity against Plasmodium falciparum drug sensitive (3D7) and resistant (Dd2) parasites for a panel of fourteen primary benzene sulfonamide compounds. Our findings provide a platform to support the further evaluation of primary benzene sulfonamides as a new antimalarial chemotype, including the identification of the target of these compounds in the parasite. Copyright © 2013 Elsevier Ltd. All rights reserved.

Utilization of alternative fuels and materials in cement kiln towards emissions of benzene, toluene, ethyl-benzene and xylenes (BTEX

Directory of Open Access Journals (Sweden)

Muliane Ulfi

2018-01-01

Full Text Available Co-processing in cement industry has benefits for energy conservation and waste recycling. Nevertheless, emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX tend to increase compared to a non co-processing kiln. A study was conducted in kiln feeding solid AFR (similar to municipal solid waste, MSW having production capacity 4600-ton clinker/day (max. 5000 ton/day and kiln feeding biomass having production capacity 7800-ton clinker/day (max. 8000 ton/day. The concentration of VOCs emissions tends to be higher at the raw mill on rather than the raw mill off. At the raw mill on, concentration of total volatile organic carbon (VOCs emission from cement kiln stack feeding Solid AFR 1, biomass, Solid AFR 2, and mixture of Solid AFR and biomass is 16.18 mg/Nm3, 16.15 mg/Nm3, 9.02 mg/Nm3, and 14.11 mg/Nm3 respectively. The utilization of biomass resulted in the lower fraction of benzene and the higher fraction of xylenes in the total VOCs emission. Operating conditions such as thermal substitution rate, preheater temperature, and kiln speed are also likely to affect BTEX emissions.

Upstream petroleum industry glycol dehydrator benzene emissions status report

International Nuclear Information System (INIS)

1999-07-01

The population of dehydrators referred to are located in the Western Sedimentary Basin in northeast British Columbia, Alberta and Saskatchewan, and includes units installed at wellsites, compressor stations, gas plants, central crude oil treating facilities, and reservoir or salt cavern gas storage facilities. Benzene emissions from the still column vent on glycol dehydrators occur as a result of glycol's strong affinity for aromatic hydrocarbons, including benzene. A study was carried out to: 1) develop a list of oil and gas companies operating in Canada, 2) develop an equipment and benzene emissions inventory of glycol dehydrators, 3) develop a database in Microsoft Access format to gather and maintain inventory and emission data, 4) evaluate and validate at least 10% of the reported data, 5) develop a list of companies that manufacture dehydrators and incinerators to determine how many new dehydrators were sold for use in Canada in 1998, and 6) prepare a report summarizing findings and recommendations. The companies included in the survey were the oil and gas companies identified by the Nickels' Oil and Gas Index and others provided by CAPP, CGA, and SEPAC. The project was carried out to gather glycol dehydrator equipment and still column vent benzene emissions information. 8 refs

4-(4-Bromophenyl-7,7-dimethyl-2-methylamino-3-nitro-7,8-dihydro-4H-chromen-5(6H-one including an unknown solvate

Directory of Open Access Journals (Sweden)

S. Antony Inglebert

2014-05-01

Full Text Available In the title compound, C18H19BrN2O4, the chromene unit is not quite planar (r.m.s. deviation = 0.199 Å, with the methyl C atoms lying 0.027 (4 and 1.929 (4 Å from the mean plane of the chromene unit. The six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation, with the dimethyl-substituted C atom as the flap. The methylamine and nitro groups are slightly twisted from the chromene moiety, with C—N—C—O and O—N—C—C torsion angles of 2.7 (4 and −0.4 (4°, respectively. The dihedral angle between the mean plane of the chromene unit and the benzene ring is 85.61 (13°. An intramolecular N—H...O hydrogen bond generates an S(6 ring motif, which stabilizes the molecular conformation. In the crystal, molecules are linked via N—H...O hydrogen bonds, forming hexagonal rings lying parallel to the ab plane. A region of disordered electron density, most probably disordered ethanol solvent molecules, occupying voids of ca 432 Å3 for an electron count of 158, was treated using the SQUEEZE routine in PLATON [Spek (2009. Acta Cryst. D65, 148–155]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

Crystal structure of a diaryl carbonate: 1,3-phenylene bis(phenyl carbonate

Directory of Open Access Journals (Sweden)

Marina A. Solomos

2017-12-01

Full Text Available The whole molecule of the title compound, C20H14O6, is generated by mirror symmetry, the mirror bisecting the central benzene ring. The carbonate groups adopt an s-cis-s-cis conformation, with torsion angles of 58.7 (2 and 116.32 (15°. The crystal structure of 1,3-phenylene bis(phenyl carbonate contains no strong hydrogen bonds, though weak C—H...O and offset π–π interactions are observed, forming layers parallel to the ac plane.

Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations; Exposition par inhalation au benzene, toluene, ethylbenzene et xylenes (BTEX) dans l'air. Source, mesures et concentrations

Energy Technology Data Exchange (ETDEWEB)

Del Gratta, F.; Durif, M.; Fagault, Y.; Zdanevitch, I

2004-12-15

This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.

Science.gov (United States)

Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

2014-01-01

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2 m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. © 2013, National Ground Water Association.

Unleaded gasoline with reduction in benzene and aromatics

International Nuclear Information System (INIS)

Ahmed, I.

2003-01-01

The trend today is towards making gasoline more environment and human friendly or in other words making gasoline a really clean fuel. This paper covers the ill effects of benzene and aromatics and the driving force behind their reduction in gasoline worldwide. It addresses health concerns specifically, and the theme is unleaded gasoline without simultaneously addressing reduction in benzene and aromatics is more harmful. The paper cites worldwide case studies, and also the World Bank (WB), Government of Pakistan (GoP), and United Nations (UN) efforts in this area in Pakistan. (author)

Canadian soil quality guidelines for the protection of environmental and human health : benzene

Energy Technology Data Exchange (ETDEWEB)

Potter, K.

2005-07-01

This report presented soil quality guidelines for benzene to protect humans and ecological receptors in 4 types of land uses: agricultural; residential and parklands; commercial and industrial. The chemical and physical properties of benzene were reviewed, as well as the sources and emissions of benzene in Canada. The distribution and behaviour of benzene in the environment was examined, and the toxicological effects of benzene on microbial processes, plants, animals and humans were reviewed. It was noted that the background information and rationale for the derivation of Canadian Soil Quality Guidelines for this substance were originally published in 1999 by the Canadian Council of Ministers of the Environment (CCME) in Canadian Environmental Quality Guidelines. These guidelines have since been revised to reflect new data and lessons learned during the development of the Canada-wide Standard for Petroleum Hydrocarbons in Soil (CCME 2000). Modifications in this report included the derivation of guidelines for different soil textures and depths. Behaviour and effects in biota were reviewed, including soil microbial processes; terrestrial plants; terrestrial invertebrates; livestock and wildlife; and bioaccumulation. Behaviour and effects in humans and mammalian species were examined. The derivation of environmental soil quality guidelines was outlined. Recommendations for Canadian soil quality guidelines were presented. It was concluded that there is a lack of studies on the toxic effects of benzene on livestock, mammalian wildlife and birds and that studies on the metabolism of benzene in mammals and birds as well as invertebrates are needed. In addition, research is needed on the effects of benzene on nitrogen fixation, nitrification, nitrogen mineralization, decomposition and respiration. 118 refs., 3 tabs., 2 figs.

Surface silylation of natural mesoporous/macroporous diatomite for adsorption of benzene.

Science.gov (United States)

Yu, Wenbin; Deng, Liangliang; Yuan, Peng; Liu, Dong; Yuan, Weiwei; Liu, Peng; He, Hongping; Li, Zhaohui; Chen, Fanrong

2015-06-15

Naturally occurring porous diatomite (Dt) was functionalized with phenyltriethoxysilane (PTES), and the PTES-modified diatomite (PTES-Dt) was characterized using diffuse reflectance Fourier transform infrared spectroscopy, nitrogen adsorption, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. After silylation, a functional group (-C6H5, phenyl) was successfully introduced onto the surface of Dt. PTES-Dt exhibited hydrophobic properties with a water contact angle (WCA) as high as 120°±1°, whereas Dt was superhydrophilic with a WCA of 0°. The benzene adsorption data on both Dt and PTES-Dt fit well with the Langmuir isotherm equation. The Langmuir adsorption capacity of benzene on PTES-Dt is 28.1 mg/g, more than 4-fold greater than that on Dt. Moreover, the adsorption kinetics results show that equilibrium was achieved faster for PTES-Dt than for Dt, over the relative pressure range of 0.118-0.157. The excellent benzene adsorption performance of PTES-Dt is attributed to strong π-system interactions between the phenyl groups and the benzene molecules as well as to the macroporosity of the PTES-Dt. These results show that the silylated diatomite could be a new and inexpensive adsorbent suitable for use in benzene emission control. Copyright © 2015 Elsevier Inc. All rights reserved.

Optics design of Intrabeam Scattering dominated damping rings

CERN Document Server

Antoniou, Fanouria; Papaphilippou, Ioannis

A e+/e- linear collider, the Compact Linear Collider (CLIC) is under design at CERN, aiming to explore the terascale particle physics regime. The collider has been optimized at 3 TeV center of mass energy and targets a luminosity of 1034 cm-2 s-1. In order to achieve this high luminosity, high intensity bunches with ultra low emittances, in all three planes, are required. The generation of ultra low emittance is achieved in the Damping Rings (DR) complex of the collider. The large input beam emittances, especially the ones coming from the positron source, and the requirement of ultra low emittance production in a fast repetition time of 20 ms, imply that the beam damping is done in two stages. Thus, a main-damping ring (DR) and a predamping ring (PDR) are needed, for each particle species. The high bunch brightness gives rise to several collective effects, with Intra-beam scattering (IBS) being the main limitation to the ultra-low emittance. This thesis elaborates the lattice design and non-linear optimizatio...

5-Chloro-2-methyl-3-phenylsulfonyl-1-benzofuran

Directory of Open Access Journals (Sweden)

Hong Dae Choi

2008-07-01

Full Text Available The title compound, C15H11ClO3S, was prepared by the oxidation of 5-chloro-2-methyl-3-phenylsulfanyl-1-benzofuran with 3-chloroperoxybenzoic acid. There are two symmetry-independent molecules in the asymmetric unit. The dihedral angles formed by the phenyl ring and the plane of the benzofuran system are 77.80 (8 and 78.34 (8°. The crystal structure is stabilized by aromatic π–π stacking interactions between the furan ring and the benzene rings of neighbouring benzofuran fragments from two symmetry-independent molecules; the centroid–centroid distances within the stacks are 3.689 (4, 3.702 (4, 3.825 (4 and 3.826 (4 Å. Additionally, the stacked molecules exhibit inter- and intramolecular C—H...O interactions.

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

Science.gov (United States)

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

2008-10-01

The asymmetric unit of the title compound, {[Cu(CO(3))(C(14)H(14)N(4))(1.5)] x 0.5 C(14)H(14)N(4) x 5 H(2)O}(n), contains one Cu(II) cation in a slightly distorted square-pyramidal coordination environment, one CO(3)(2-) anion, one full and two half 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands, one half-molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)(1.5)](n) molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 A. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu(II) atom is completed by two O atoms of the CO(3)(2-) anion. The framework is further strengthened by extensive O-H...O and O-H...N hydrogen bonds involving the water molecules, the O atoms of the CO(3)(2-) anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures.

Benzene emission from the actual car fleet in relation to petrol composition in Denmark

International Nuclear Information System (INIS)

Palmgren, F.; Hansen, A.B.; Berkowicz, R.; Skov, H.

2001-01-01

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO x from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NO x . The decreasing trends of NO x and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period. (Author)

Critical issues in benzene toxicity and metabolism: the effect of interactions with other organic chemicals on risk assessment.

OpenAIRE

Medinsky, M A; Schlosser, P M; Bond, J A

1994-01-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several inve...

Plane grating monochromators for synchrotron radiation

International Nuclear Information System (INIS)

Howells, M.R.

1979-01-01

The general background and theoretical basis of plane grating monochromators (PGM's) is reviewed and the particular case of grazing incidence PGM's suitable for use with synchrotron radiation is considered in detail. The theory of reflection filtering is described and the problem of the finite source distance is shown to be of special importance with high brightness storage rings. The design philosophy of previous instruments is discussed and a new scheme proposed, aimed at dealing with the problem of the finite source distance. This scheme, involving a parabolic collimating mirror fabricated by diamond turning, is considered in the context of Wolter-type telescopes and microscopes. Some practical details concerning an instrument presently under construction using the new design are presented

The use of biomonitoring data in exposure and human health risk assessment: benzene case study.

Science.gov (United States)

Arnold, Scott M; Angerer, Juergen; Boogaard, Peter J; Hughes, Michael F; O'Lone, Raegan B; Robison, Steven H; Schnatter, A Robert

2013-02-01

Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10(-5) excess cancer risk (2.9 µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.

Monitoring benzene formation from benzoate in model systems by proton transfer reaction-mass spectrometry

Science.gov (United States)

Aprea, Eugenio; Biasioli, Franco; Carlin, Silvia; Märk, Tilmann D.; Gasperi, Flavia

2008-08-01

The presence of benzene in food and in particular in soft drinks has been reported in several studies and should be considered in fundamental investigations about formation of this carcinogen compound as well as in quality control. Proton transfer reaction-mass spectrometry (PTR-MS) has been used here for rapid, direct quantification of benzene and to monitor its formation in model systems related to the use of benzoate, a common preservative, in presence of ascorbic acid: a widespread situation that yields benzene in, e.g., soft drinks and fruit juices. Firstly, we demonstrate here that PTR-MS allows a rapid determination of benzene that is in quantitative agreement with independent solid phase micro-extraction/gas chromatography (SPME/GC) analysis. Secondly, as a case study, the effect of different sugars (sucrose, fructose and glucose) on benzene formation is investigated indicating that they inhibit its formation and that this effect is enhanced for reducing sugars. The sugar-induced inhibition of benzene formation depends on several parameters (type and concentration of sugar, temperature, time) but can be more than 80% in situations that can be expected in the storage of commercial soft drinks. This is consistent with the reported observations of higher benzene concentrations in sugar-free soft drinks.

Positronium quenching in liquid and solid octanol and benzene

DEFF Research Database (Denmark)

Shantarovich, V.P.; Mogensen, O.E.; Goldanskii, V.I.

1970-01-01

The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase.......The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase....

Crystal structure of 26-(4-methylphenyl-8,11,14,17-tetraoxa-28-azatetracyclo[22.3.1.02,7.018,23]hexacosa-2,4,6,18(23,19,21,24(1,25,27-nonaene

Directory of Open Access Journals (Sweden)

T. Thanh Van Tran

2016-05-01

Full Text Available The title compound, C30H29NO4, is a tetracyclic system containing a 4-arylpyridine fragment, two benzene rings and an aza-17-crown-5 ether moiety, in a bowl-like arrangement. The pyridine ring is inclined to the 4-methylphenyl ring by 26.64 (6°, and by 57.43 (6 and 56.81 (6° to the benzene rings. The benzene rings are inclined to one another by 88.32 (6°. In the crystal, molecules are linked by pairs of C—H...N hydrogen bonds, forming inversion dimers with an R22(14 ring motif. The dimers are linked via a number of C—H...π interactions, forming a three-dimensional architecture.

Benzene-induced genotoxicity in mice in vivo detected by the alkaline comet assay

DEFF Research Database (Denmark)

Tuo, J; Loft, S; Thomsen, M S

1996-01-01

was further increased to 5.4-fold and 6.6-fold of the control values, respectively (p propylene glycol (5 microliters/g b.wt., twice with a 60-min interval), a selective CYP2E1 inhibitor, reduced the increase in the tail length by about half at all doses in both cell types (p ...The myelotoxic and genotoxic effects of benzene have been related to oxidative DNA damage after metabolism by CYP2E1. Single cell gel electrophoresis (alkaline comet assay) detects DNA damage and may thus be a convenient method for the study of benzene genotoxicity. Benzene exposure to NMRI mice.......01). By comparing our data with those from genotoxicity studies on benzene using other methods, we conclude that the 'alkaline comet assay' is a sensitive method to detect DNA damage induced by benzene. We also infer that CYP2E1 contributes, at least partly, to the formation of the 'comet'-inducing metabolites...

Omnidirectional piezo-optical ring sensor for enhanced guided wave structural health monitoring

International Nuclear Information System (INIS)

Giurgiutiu, Victor; Roman, Catalin; Lin, Bin; Frankforter, Erik

2015-01-01

This paper presents a novel method for the detection of ultrasonic waves from acoustic emission events using piezoelectric wafer ac3tive sensors (PWAS) and optical fiber Bragg grating (FBG) sensing combined with mechanical resonance amplification principles. The method is best suited for detecting the out-of-plane motion of the AE wave with preference for a certain frequency that can be adjusted by design. Several issues are discussed: (a) study the mode shapes of the sensors under different resonance frequencies in order to understand the behavior of the ring in a frequency band of interest; (b) comparison of analytical results and mode shapes with FEM predictions; (c) choice of the final piezo-optical ring sensor shape; (d) testing of the piezo-optical ring sensor prototype; (e) discussion of the ring-sensor test results in comparison with conventional results from PWAS and FBG sensors mounted directly on the test structure. The paper ends with summary, conclusions, and suggestions for further work. (paper)

Size distribution of carbon layer planes in biochar from different plant type of feedstock with different heating temperatures.

Science.gov (United States)

Lu, Guan-Yang; Ikeya, Kosuke; Watanabe, Akira

2016-11-01

Biochar application to soil is a strategy to decelerate the increase in the atmospheric carbon concentration. The composition of condensed aromatic clusters appears to be an important determinant of the degradation rate of char in soil. The objective of the present study was to determine the size distribution of carbon layer planes in biochars produced from different types of feedstock (a broadleaf and a coniferous tree and two herbs) using different heating treatment temperatures (HTT; 400 °C-800 °C) using X-ray diffraction 11 band profile analysis. (13)C nuclear magnetic resonance with the phase-adjusted spinning side bands of the chars indicated different spectral features depending on the HTT and similar carbon composition among the plant types at each HTT. Both the content and composition of carbon layer planes in biochar produced using the same HTT were also similar among the plant types. The carbon layer plane size in the 400 °C and 600 °C chars was distributed from 0.24 to 1.68 or 1.92 nm (corresponding to 37 or 52 rings) with the mean size of 0.79-0.92 and 0.80-1.14 nm, respectively. The carbon layer planes in the 800 °C chars ranged from 0.72-0.96 nm (7-14 rings) to 2.64-3.60 nm (91-169 rings) and the mean values were 1.47-1.89 nm. The relative carbon layer plane content in the 600 °C and 800 °C chars was typically 2 and 3 times that in the 400 °C chars. These results indicate the progression of the formation and/or the size development of graphite-like structures, suggesting that a char produced at a higher HTT would have better carbon sequestrating characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gravitational Couplings for Gop-Planes and y-Op-Planes

OpenAIRE

Giraldo, Juan Fernando Ospina

2000-01-01

The Wess-Zumino actions for generalized orientifold planes (GOp-planes) and y-deformed orientifold planes (yOp-planes) are presented and two series power expantions are realized from whiches processes that involves GOp-planes,yOp-planes, RR-forms, gravitons and gaugeons, are obtained. Finally non-standard GOp-planes and y-Op-planes are showed.