Crosslinking of SAVY-4000 O-rings as a Function of Aging Conditions

Energy Technology Data Exchange (ETDEWEB)

Van Buskirk, Caleb Griffith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-08

SAVY-4000 containers were developed as a part of DOE M 441.1-1 to protect workers who handle stored nuclear material from exposure due to loss of containment.1 The SAVY-4000 is comprised of three parts: a lid, a container, and a cross-linked fluoropolymer O-ring. Degradation of the O-ring during use could limit the lifetime of the SAVY-4000. In order to quantify the chemical changes of the Oring over time, the molecular weight between crosslinks was determined as a function of aging conditions using a swelling technique. Because the O-ring is a cross-linked polymer, it will absorb solvent into its matrix without dissolving. The relative amount of solvent uptake can be related to the degree of crosslinking using an equation developed by Paul Flory and John Rehner Jr3. This method was used to analyze O-ring samples aged under thermal and ionizing-radiation conditions. It was found that at the harsher thermal gaining conditions in absence of ionizing-radiation the average molecular weight between crosslinks decreased, indicating a rise in crosslinks, which may be attributable to advanced aging with no ionizing radiation present. Inversely, in the presence of ionizing radiation it was found that material has a higher level of cross-linking with age. This information could be used to help predict the lifetime of the O-rings in SAVY-4000 containers under service conditions.

FY2017 status report: Model 9975 O-ring fixture long-term leak performance

Energy Technology Data Exchange (ETDEWEB)

Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-07-27

A series of experiments to monitor the aging performance of Viton® GLT and GLT-S O-rings used in the Model 9975 shipping package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups with GLT O-rings were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, a smaller test matrix with fourteen additional tests was initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. Leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The 300 °F GLT O-ring fixtures failed after 2.8 to 5.7 years at temperature. The remaining GLT O-ring fixtures aging at 300 ºF were retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 9 to 10.5 years, or in GLT O-ring fixtures aging at 270 ºF for 5.7 years. These aging temperatures bound O-ring temperatures anticipated during normal storage in K-Area Complex (KAC). Leak test failures have been experienced in all of the GLT-S O-ring fixtures aging at 300 ºF and above. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 and 250 ºF for 6.9 to 7.5 years. Data from the O-ring fixtures are generally consistent with results from compression stress relaxation testing, and provide confidence in the predictive models based on those results

Helium and deuterium permeability in O-rings

International Nuclear Information System (INIS)

Lakner, J.F.

1976-01-01

To obtain more information on gas permeation through elastomeric O-rings, studies were performed on Parker Seal Company O-rings, Nos. 2-113, 2-006, 3-904, and 3-906, all made of a nitrile rubber. Also included in the tests was a valve packing (Autoclave Engineers) encased in AE Valve 20A-2142. Permeation experiments were run usually in duplicate to 82.7 MPa (12,000 psi) with helium and deuterium at room temperature. The data are extrapolated to give values for tritium

μ-Oxalato-κ4O1,O2:O1′,O2′-bis[aqua(2,2′-bipyridine-κN(nitrato-κ2O,O′lead(II

Directory of Open Access Journals (Sweden)

Gang-Hong Pan

2012-10-01

Full Text Available The title compound, [Pb2(C2O4(NO32(C10H8N22(H2O2], was synthesized hydrothermally. The binuclear complex molecule is centrosymmetric, the inversion centre being located at the mid-point of the oxalate C—C bond. The PbII ion is heptacoordinated by the O atom of one water molecule, two oxalate O atoms, two nitrate O atoms and two 2,2′-bipyridine N atoms, forming an irregular coordination environemnt. Intermolecular O—H...O hydrogen bonds between water molecules and oxalate and nitrate ions result in the formation of layers parallel to (010. π–π interactions between pyridine rings in adjacent layers, with centroid–centroid distances of 3.584 (2 Å, stabilize the structural set-up.

Noble gas bond and the behaviour of XeO3 under pressure.

Science.gov (United States)

Hou, Chunju; Wang, Xianlong; Botana, Jorge; Miao, Maosheng

2017-10-18

Over the past few decades, the concept of hydrogen bonds, in which hydrogen is electrophilic, has been extended to halogen bonds, chalcogen bonds and pnicogen bonds. Herein, we show that such a non-covalent bonding also exists in noble gas compounds. Using first principles calculations, we illustrate the OXe-O bond in molecular crystal XeO 3 and its effect on the behavior of this compound under pressure. Our calculations show that the covalent Xe-O bond lengths were elongated with increasing pressure and correspondingly the Xe-O stretching vibration frequencies were red shifted, which is similar to the change of H-bonds under pressure. The OXe-O bond and related hopping of O between neighboring Xe sites also correspond to the structural changes in the XeO 3 compounds at about 2 GPa. Our study extends the concept of hydrogen bonding to include all p-block elements and show a new bonding type for Noble gas elements in which it acts as an electrophilic species.

Contact mechanical analysis of O-ring stresses

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Kyu

2007-02-15

The purpose of this project is to develop the approximate solutions of contact traction and internal stress of an O-ring by using a two dimensional elasticity for enhancing the design and failure prediction technology. Investigated were the applicability of Lindley's formulae of contact force prediction and the Hertz theory. Three cases of O-ring installation were considered. The approximate solution of contact tractions and internal stresses of each case were derived. The key results are summarized as follows: 1. It is verified that Lindley's formulae predicts the relationship between the fractional compression and contact force. 2. In the case of Case I, II and III without internal pressure, it is found that a function form of the contact traction is the Hertzian. So it is possible to express the traction with a Hertzian form and correction factors. 3. The internal stresses are derived in the case of the Hertzian traction profile. The stresses at the center of O-ring show a satisfactory result when compared with the finite element result.

Hydrated aluminophosphate (AlPO/sub 4/. 1. 5H/sub 2/O) with PO/sub 4/, AlO/sub 4/ and AlO/sub 4/(H/sub 2/O)/sub 2/ groups and encapsulated water

Energy Technology Data Exchange (ETDEWEB)

Pluth, J.J.; Smith, J.V.

1986-09-15

Aluminium phosphate hydrate, AlPO/sub 4/ /sub ./ 1.5H/sub 2/O, M/sub r/=148.98, orthorhombic, Pbca, a=19.3525(13), b=9.7272(7), c=9.7621(8) A, V=1837.7(1) A/sup 3/, Z=16, D/sub x/=2.15 g cm/sup -3/, lambda(CuK..cap alpha..)=1.5418 A, ..mu..=68.2 cm/sup -1/, F(000)=1200, Tproportional to 295 K, R=0.033 for 1530 diffractions. A 4-connected framework contains PO/sub 4/ tetrahedra interposed between AlO/sub 4/ tetrahedra and AlO/sub 4/(H/sub 2/O)/sub 2/ octahedra at the nodes of cross-linked alternate 6/sup 3/ and 4.8/sup 2/ nets. A two-dimensional channel system, limited by 8-rings, lies between adjacent 6/sup 3/ nets. One H/sub 2/O of each octahedron lies in a 6-ring, and the other forms a continuous chain with a third H/sub 2/O which is held in place only by hydrogen bonds.

Fifth Interim Status Report: Model 9975 PCV O-Ring Fixture Long-Term Leak Performance

International Nuclear Information System (INIS)

Daugherty, W.; Hoffman, E.

2010-01-01

A series of experiments to monitor the aging performance of Viton reg. GLT O-rings used in the Model 9975 package has been ongoing for six years at the Savannah River National Laboratory. Sixty-seven mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 F. They were leak-tested initially and have been tested at nominal six month intervals to determine if they meet the criterion of leaktightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 F. High temperature aging continues for 36 GLT O-ring fixtures at 200--350 F. Room temperature leak test failures have been experienced in 5 of the GLT O-ring fixtures aging at 300 and 350 F, and in all 3 of the GLT O-ring fixtures aging at higher temperatures. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 30--48 months, which is still bounding to O-ring temperatures during storage in KAMS. High temperature aging continues for 6 GLT-S O-ring fixtures at 200--300 F. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 F. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 or 300 F for 19 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the O-rings displayed a compression set ranging from 51--95%. This is significantly greater than seen to date for packages inspected during KAMS field surveillance (23% average). For GLT O-rings, service life based on the room temperature leak rate criterion is comparable to that predicted by compression stress relaxation (CSR) data at higher temperatures (350--400 F). While there are no comparable failure data yet at aging temperatures below 300 F, extrapolations of the data for GLT O-rings suggests that CSR model predictions provide a conservative prediction of service

Tensile bond srength between composite resin using different adhesive systems Avaliação da resistência à ruptura por tração entre resina composta e diversos adesivos dentinários

Directory of Open Access Journals (Sweden)

Patrícia Dias

2002-11-01

Full Text Available The aim of this study was evaluate the tensile bond strength (TBS among nine adhesive systems and one composite resin. The groups were made as follows: Single Bond/3M (G1, Etch & Prime 3.0 /Degussa (G2, Bond 1/Jeneric/Pentron (G3, Prime & Bond 2.1/Dentsply (G4, OptiBond FL/Kerr (G5, Stae/SDI (G6, Snap Bond/ Copalite-Cooley & Cooley (G7, Prime & Bond NT/Dentsply (G8, Scotchbond Multi Purpose Plus/3M (G9. The control group (G10 was made only with the composite resin (Z100/3M. One hundred specimens were made, 10 for each group. There were significant differences on TBS among groups. G3 showed the hightest TBS in comparison to other tested groups. G10 presented higher TBS than all groups. O objetivo desta pesquisa foi investigar in vitro a resistência de união entre uma resina composta e nove sistemas adesivos dentinários. Os adesivos estudados foram assim agrupados: Single Bond/3M (G1, Etch & Prime 3.0/ Degussa (G2, Bond 1/Jeneric/Pentron (G3, Prime & Bond 2.1/Dentsply (G4, OptiBond FL/Kerr (G5, Stae/SDI (G6, Snap Bond/Copalite (G7, Prime & Bond NT/Dentsply (G 8, Scotchbond Multi Purpose Plus/3M (G9. O Grupo controle (G10. foi confeccionado somente com a resina composta (Z100/3M. Foram confeccionados 100 espécimes, 10 para cada grupo. Houve diferenças estatísticas significantes entre os grupos. O grupo 3 foi o que mostrou a mais alta resistência em comparação aos nove testados. O grupo controle (G10 apresentou a mais alta resistência entre todos os Grupos.  

A ROBUST EIGHT–MEMBERED RING MOTIF IN THE HYDROGEN-BONDED STRUCTURE OF -(PHENYLAMINOPYRIDINIUM- DI(METHANESULFONYLAMIDATE

Directory of Open Access Journals (Sweden)

Karna Wijaya

2002-03-01

Full Text Available The compound was prepared by dissolving 2-(phenylaminopyridine (0.52 g ; 3.0 mmol and di(methanesulfonylamine (0.51 g; 3.0 mmol in 5 mL methanol. Slow partial evaporation of the solvent at low tempertaure (-30 oC gave a yield of 0.66 g (64% and crystals suitable for X-ray study (m.p. 150-152 oC. The single crystal X-ray result showed that the crystal system was trikline with space group P. The crystal structure of the title compound 2-(phenylaminopyridinium-di(methane-sulfonylamidate forms a robust antidromic ring motif type. The structure testifies to the persistence of the  in question, which was previously detected as a robust supramolecular synthon in 2-aminopyridinium di(benzenesulfonylamidate and in a series of onium di(methane-sulfonylamidates.   Keywords: supramolecule, hydrogen-bond

Fragrance material review on anisyl alcohol (o-m-p-).

Science.gov (United States)

Scognamiglio, J; Jones, L; Letizia, C S; Api, A M

2012-09-01

A toxicologic and dermatologic review of anisyl alcohol (o-m-p-) when used as a fragrance ingredient is presented. Anisyl alcohol (o-m-p-) is a member of the fragrance structural group Aryl Alkyl Alcohols and is a primary alkyl alcohol. The AAAs are a structurally diverse class of fragrance ingredients that includes primary, secondary, and tertiary alkyl alcohols covalently bonded to an aryl (Ar) group, which may be either a substituted or unsubstituted benzene ring. The common structural element for the AAA fragrance ingredients is an alcohol group -C-(R1)(R2)OH and generically the AAA fragrances can be represented as an Ar-C-(R1)(R2)OH or Ar(-)Alkyl-C-(R1)(R2)OH group. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. A safety assessment of the entire Aryl Alkyl Alcohols will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all other branched chain saturated alcohols in fragrances. Copyright © 2011 Elsevier Ltd. All rights reserved.

Photosynthetic water oxidation: binding and activation of substrate waters for O-O bond formation.

Science.gov (United States)

Vinyard, David J; Khan, Sahr; Brudvig, Gary W

2015-01-01

Photosynthetic water oxidation occurs at the oxygen-evolving complex (OEC) of Photosystem II (PSII). The OEC, which contains a Mn4CaO5 inorganic cluster ligated by oxides, waters and amino-acid residues, cycles through five redox intermediates known as S(i) states (i = 0-4). The electronic and structural properties of the transient S4 intermediate that forms the O-O bond are not well understood. In order to gain insight into how water is activated for O-O bond formation in the S4 intermediate, we have performed a detailed analysis of S-state dependent substrate water binding kinetics taking into consideration data from Mn coordination complexes. This analysis supports a model in which the substrate waters are both bound as terminal ligands and react via a water-nucleophile attack mechanism.

Bond breaking and bond making in tetraoxygen: analysis of the O2(X3Sigma(g)-) + O2(X3Sigma(g)-) O4 reaction using the electron pair localization function.

Science.gov (United States)

Scemama, Anthony; Caffarel, Michel; Ramírez-Solís, Alejandro

2009-08-06

We study the nature of the electron pairing at the most important critical points of the singlet potential energy surface of the 2O2 O4 reaction and its evolution along the reaction coordinate using the electron pair localization function (EPLF) [Scemama, A.; Chaquin, P.; Caffarel, M. J. Chem. Phys. 2004, 121, 1725]. To do that, the 3D topology of the EPLF calculated with quantum Monte Carlo (at both variational and fixed-node-diffusion Monte Carlo levels) using Hartree-Fock, multiconfigurational CASSCF, and explicitly correlated trial wave functions is analyzed. At the O4 equilibrium geometry the EPLF analysis reveals four equivalent covalent bonds and two lone pairs on each oxygen atom. Along the reaction path toward dissociation it is found that the two oxygen-oxygen bonds are not broken simultaneously but sequentially, and then the lone pairs are rearranged. In a more general perspective, the usefulness of the EPLF as a unique tool to analyze the topology of electron pairing in nontrivial chemical bonding situations as well as to visualize the major steps involved in chemical reactivity is emphasized. In contrast with most standard schemes to reveal electron localization (atoms in molecules, electron localization function, natural bond orbital, etc.), the newly introduced EPLF function gives a direct access to electron pairings in molecules.

Design and syntheses of hybrid metal-organic materials based on K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] metallotectons

Science.gov (United States)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao; Wang, Wenqiang; Wang, Lei

2016-05-01

By using K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] (C2O42-=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C2O4)2(H2O)2}2]·(H-L1)2·H2O 1, [Fe(C2O4)Cl2]·(H2-L2)0.5·(L2)0.5·H2O 2, [{Fe(C2O4)1.5Cl2}2]·(H-L3)43, [Fe2(C2O4)Cl8]·(H2-L4)2·2H2O 4, K[Al(C2O4)3]·(H2-L5)·2H2O 5, K[Al(C2O4)3]·(H-L6)2·2H2O 6, K[Cr(C2O4)3]·2H2O 7, Na[Fe(C2O4)3]·(H-L6)2·2H2O 8 (with L1=4-dimethylaminopyridine, L2=2,3,5,6-tetramethylpyrazine, L3=2-aminobenzimidazole, L4=1,4-bis-(1H-imidazol-1-yl)benzene, L5=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L6=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C2O4)2(H2O)2]- unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C2O4)Cl2]- anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe2(C2O4)3Cl4]4- unit. Compound 4 features distinct [Fe2(C2O4)Cl8]4- units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C2O4)3]3- units and K+ cations. The 1D chains are further extended into 3D antionic H-bonded framework through O-H···O H-bonds. Compounds 6-8 show 2D [KAl(C2O4)3]2- layer, [KCr(C2O4)3]2- layer and [NaFe(C2O4)3]2- layer, respectively.

Irregular Aharonov–Bohm effect for interacting electrons in a ZnO quantum ring

International Nuclear Information System (INIS)

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

2017-01-01

The electronic states and optical transitions of a ZnO quantum ring containing few interacting electrons in an applied magnetic field are found to be very different from those in a conventional semiconductor system, such as a GaAs ring. The strong Zeeman interaction and the Coulomb interaction of the ZnO system, two important characteristics of the electron system in ZnO, exert a profound influence on the electron states and on the optical properties of the ring. In particular, our results indicate that the Aharonov–Bohm (AB) effect in a ZnO quantum ring strongly depends on the electron number. In fact, for two electrons in the ZnO ring, the AB oscillations become aperiodic, while for three electrons (interacting) the AB oscillations completely disappear. Therefore, unlike in conventional quantum ring topology, here the AB effect (and the resulting persistent current) can be controlled by varying the electron number. (paper)

Electrochemical performance and structure evolution of core-shell nano-ring α-Fe_2O_3@Carbon anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

2016-01-01

Core-shell nano-ring α-Fe_2O_3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe_2O_3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe_2O_3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe_2O_3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g"−"1 and retains 920/897 mAh g"−"1 after 200 cycles at 500 mA g"−"1 (0.5C). Even at 2000 mA g"−"1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g"−"1, and still maintains 630/610 mAh g"−"1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe_2O_3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe_2O_3 and facilitate the transportation of electrons and Li"+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe_2O_3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

Electrochemical performance and structure evolution of core-shell nano-ring α-Fe2O3@Carbon anodes for lithium-ion batteries

Science.gov (United States)

Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

2016-12-01

Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g-1 and retains 920/897 mAh g-1 after 200 cycles at 500 mA g-1 (0.5C). Even at 2000 mA g-1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g-1, and still maintains 630/610 mAh g-1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3 and facilitate the transportation of electrons and Li+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

N6,3′-cyclo-5′-O-Cyanomethylthymidine

Directory of Open Access Journals (Sweden)

Jingbo Sun

2010-06-01

Full Text Available The title compound, C19H20N4O4, is a cyclonucleoside with a C—N linkage. The furanose ring adopts a twist C3′-endo/C2′-exo (close to 3T2 conformation with a pseudorotational phase angle (P of 8.1° and puckering amplitude (vm of 30.6°. The orientation of the pyrimidine ring with respect to the sugar group is anti. One intramolecular C—H...O hydrogen bond is observed. The packing features an N—H...O hydrogen bond.

Cleavage of sp3 C-O bonds via oxidative addition of C-H bonds.

Science.gov (United States)

Choi, Jongwook; Choliy, Yuriy; Zhang, Xiawei; Emge, Thomas J; Krogh-Jespersen, Karsten; Goldman, Alan S

2009-11-04

(PCP)Ir (PCP = kappa(3)-C(6)H(3)-2,6-[CH(2)P(t-Bu)(2)](2)) is found to undergo oxidative addition of the methyl-oxygen bond of electron-poor methyl aryl ethers, including methoxy-3,5-bis(trifluoromethyl)benzene and methoxypentafluorobenzene, to give the corresponding aryloxide complexes (PCP)Ir(CH(3))(OAr). Although the net reaction is insertion of the Ir center into the C-O bond, density functional theory (DFT) calculations and a significant kinetic isotope effect [k(CH(3))(OAr)/k(CD(3))(OAr) = 4.3(3)] strongly argue against a simple insertion mechanism and in favor of a pathway involving C-H addition and alpha-migration of the OAr group to give a methylene complex followed by hydride-to-methylene migration to give the observed product. Ethoxy aryl ethers, including ethoxybenzene, also undergo C-O bond cleavage by (PCP)Ir, but the net reaction in this case is 1,2-elimination of ArO-H to give (PCP)Ir(H)(OAr) and ethylene. DFT calculations point to a low-barrier pathway for this reaction that proceeds through C-H addition of the ethoxy methyl group followed by beta-aryl oxide elimination and loss of ethylene. Thus, both of these distinct C-O cleavage reactions proceed via initial addition of a C(sp(3))-H bond, despite the fact that such bonds are typically considered inert and are much stronger than C-O bonds.

Cross-Dehydrogenative Coupling Reactions Between P(O)-H and X-H (X = S, N, O, P) Bonds.

Science.gov (United States)

Hosseinian, Akram; Farshbaf, Sepideh; Fekri, Leila Zare; Nikpassand, Mohammad; Vessally, Esmail

2018-05-26

P(O)-X (X = S, N, O, P) bond-containing compounds have extensive application in medicinal chemistry, agrochemistry, and material chemistry. These useful organophosphorus compounds also have many applications in organic synthesis. In light of the importance of titled compounds, there is continuing interest in the development of synthetic methods for P(O)-X bonds construction. In the last 4 years, the direct coupling reaction of P(O)-H compounds with thiols, alcohols, and amines/amides has received much attention because of the atom-economic character. This review aims to give an overview of new developments in cross-dehydrogenative coupling reactions between P(O)-H and X-H (X = S, N, O, P) bonds, with special emphasis on the mechanistic aspects of the reactions.

A novel stress distribution analytical model of O-ring seals under different properties of materials

International Nuclear Information System (INIS)

Wu, Di; Wang, Shao Ping; Wang, Xing Jian

2017-01-01

The elastomeric O-ring seals have been widely used as sealing elements in hydraulic systems. The sealing performance of O-ring seals is related to stress distribution. The stresses distribution depends on the squeeze rate and internal pressure, and would vary with properties of O-ring seals materials. Thus, in order to study the sealing performance of O-ring seals, it is necessary to describe the analytic relationship between stress distribution and properties of O-ring seals materials. For this purpose, a novel Stress distribution analytical model (SDAM) is proposed in this paper. The analytical model utilizes two stress complex functions to describe the stress distribution of O-ring seals. The proposed SDAM can express not only the analytical relationship between stress distribution and Young’s modulus, but also the one between stress distribution and Poisson’s ratio. Finally, compared results between finite element analysis and the SDAM validate that the proposed model can effectively reveal the stress distribution under different properties for O-ring materials

A novel stress distribution analytical model of O-ring seals under different properties of materials

Energy Technology Data Exchange (ETDEWEB)

Wu, Di; Wang, Shao Ping; Wang, Xing Jian [School of Automation Science and Electrical Engineering, Beihang University, Beijing (China)

2017-01-15

The elastomeric O-ring seals have been widely used as sealing elements in hydraulic systems. The sealing performance of O-ring seals is related to stress distribution. The stresses distribution depends on the squeeze rate and internal pressure, and would vary with properties of O-ring seals materials. Thus, in order to study the sealing performance of O-ring seals, it is necessary to describe the analytic relationship between stress distribution and properties of O-ring seals materials. For this purpose, a novel Stress distribution analytical model (SDAM) is proposed in this paper. The analytical model utilizes two stress complex functions to describe the stress distribution of O-ring seals. The proposed SDAM can express not only the analytical relationship between stress distribution and Young’s modulus, but also the one between stress distribution and Poisson’s ratio. Finally, compared results between finite element analysis and the SDAM validate that the proposed model can effectively reveal the stress distribution under different properties for O-ring materials.

Regulatory concerns for leakage testing of packagings with three O-ring closure seals

International Nuclear Information System (INIS)

Oras, J.J.; Towell, R.H.; Wangler, M.E.

1997-01-01

The American National Standard for Radioactive Materials--Leakage Tests on Packages for Shipment (ANSI N14.5) provides guidance for leakage rate testing to show that a particular packaging complies with regulatory requirements and also provides guidance in determining appropriate acceptance criteria. Recent radioactive packagings designs have incorporated three O-ring closure seals, the middle O-ring being the containment seal. These designs have the potential for false positive results of leakage rate tests. The volume between the containment O-ring and the inner O-ring is used for the helium gas required for the leakage rate tests to reduce both the amount of helium used and the time required to conduct the tests. A leak detector samples the evacuated volume between the outer O-ring and the containment O-ring. False positive results can be caused in two ways, a large leakage in the containment seal or leakage in the inner seal. This paper will describe the problem together with possible solutions/areas that need to be addressed in a Safety Analysis Report for Packagings before a particular packaging design can be certified for transport

4-Chloro-N-o-tolylbenzamide

Directory of Open Access Journals (Sweden)

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.

Tris-(hydroxyamino)triazines: high-affinity chelating tridentate O,N,O-hydroxylamine ligand for the cis-V(V)O2(+) cation.

Science.gov (United States)

Nikolakis, Vladimiros A; Exarchou, Vassiliki; Jakusch, Tamás; Woolins, J Derek; Slawin, Alexandra M Z; Kiss, Tamás; Kabanos, Themistoklis A

2010-10-14

The treatment of the trichloro-1,3,5-triazine with N-methylhydroxylamine hydrochloride results in the replacement of the three chlorine atoms of the triazine ring with the function -N(OH)CH(3) yielding the symmetrical tris-(hydroxyamino)triazine ligand H(3)trihyat. Reaction of the ligand H(3)trihyat with NaV(V)O(3) in aqueous solution followed by addition of Ph(4)PCl gave the mononuclear vanadium(V) compound Ph(4)P[V(V)O(2)(Htrihyat)] (1). The structure of compound 1 was determined by X-ray crystallography and indicates that this compound has a distorted square-pyramidal arrangement around vanadium. The ligand Htrihyat(2-) is bonded to vanadium atom in a tridentate fashion at the triazine ring nitrogen atom and the two deprotonated hydroxylamido oxygen atoms. The high electron density of the triazine ring nitrogen atoms, which results from the resonative contribution of electrons of exocyclic nitrogen atoms, leads to a very strong V-N bond. The cis-[V(V)O(2)(Htrihyat)](-) species exhibits high hydrolytic stability in aqueous solution over a wide pH range, 2.5-11.5, as was evidenced by potentiometry.

Bonding characteristics in NiAl intermetallics with O impurity: a first-principles computational tensile test

International Nuclear Information System (INIS)

Hu Xuelan; Zhang Ying; Lu Guanghong; Wang Tianmin

2009-01-01

We have performed a first-principles computational tensile test on NiAl intermetallics with O impurity along the [001] crystalline direction on the (110) plane to investigate the tensile strength and the bonding characteristics of the NiAl-O system. We show that the ideal tensile strength is largely reduced due to the presence of O impurity in comparison with pure NiAl. The investigations of the atomic configuration and bond-length evolution show that O prefers to bond with Al, forming an O-Al cluster finally with the break of O-Ni bonds. The O-Ni bonds are demonstrated to be weaker than the O-Al bonds, and the reduced tensile strength originates from such weaker O-Ni bonds. A void-like structure forms after the break of the O-Ni and some Ni-Al bonds. Such a void-like structure can act as the initial nucleation or the propagation path of the crack, and thus produce large effects on the mechanical properties of NiAl.

Self-Assembled Amphiphilic Water Oxidation Catalysts: Control of O-O Bond Formation Pathways by Different Aggregation Patterns.

Science.gov (United States)

Yang, Bing; Jiang, Xin; Guo, Qing; Lei, Tao; Zhang, Li-Ping; Chen, Bin; Tung, Chen-Ho; Wu, Li-Zhu

2016-05-17

The oxidation of water to molecular oxygen is the key step to realize water splitting from both biological and chemical perspective. In an effort to understand how water oxidation occurs on a molecular level, a large number of molecular catalysts have been synthesized to find an easy access to higher oxidation states as well as their capacity to make O-O bond. However, most of them function in a mixture of organic solvent and water and the O-O bond formation pathway is still a subject of intense debate. Herein, we design the first amphiphilic Ru-bda (H2 bda=2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts (WOCs) of formula [Ru(II) (bda)(4-OTEG-pyridine)2 ] (1, OTEG=OCH2 CH2 OCH2 CH2 OCH3 ) and [Ru(II) (bda)(PySO3 Na)2 ] (2, PySO3 (-) =pyridine-3-sulfonate), which possess good solubility in water. Dynamic light scattering (DLS), scanning electron microscope (SEM), critical aggregation concentration (CAC) experiments and product analysis demonstrate that they enable to self-assemble in water and form the O-O bond through different routes even though they have the same bda(2-) backbone. This work illustrates for the first time that the O-O bond formation pathway can be regulated by the interaction of ancillary ligands at supramolecular level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Symmetry and topology code of the cluster self-assembly of framework MT structures of alumophosphates AlPO4(H2O)2 (metavariscite and variscite) and Al2(PO4)2(H2O)3 (APC)

Science.gov (United States)

Ilyushin, G. D.; Blatov, V. A.

2017-03-01

The supramolecular chemistry of alumophosphates, which form framework 3D MT structures from polyhedral AlO4(H2O)2 clusters with octahedral O coordination (of M polyhedra) and PO4 and AlO4 with tetrahedral O coordination (of T polyhedra), is considered. A combinatorial-topological modeling of the formation of possible types of linear (six types) and ring (two types) tetrapolyhedral cluster precursors M2T2 from MT monomers is carried out. Different versions of chain formation from linked (MT)2 rings (six types) are considered. The model, which has a universal character, has been used to simulate the cluster selfassembly of the crystal structure of AlPO4(H2O)2 minerals (metavariscite, m-VAR, and variscite, VAR) and zeolite [Al2(PO4)2(H2O)2] · H2O (APC). A tetrapolyhedral linear precursor is established for m-VAR and a ring precursor (MT)2 is established for VAR and APC. The symmetry and topology code of the processes of crystal structure self-assembly from cluster precursors is completely reconstructed. The functional role of the O-H···O hydrogen bonds is considered for the first time. The cluster self-assembly model explains the specific features of the morphogenesis of single crystals: m-VAR prisms, flattened VAR octahedra, and needleshaped APC square-base prisms.

Design and syntheses of hybrid metal–organic materials based on K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] metallotectons

Energy Technology Data Exchange (ETDEWEB)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao, E-mail: dbwang@qust.edu.cn; Wang, Wenqiang; Wang, Lei, E-mail: inorchemwl@126.com

2016-05-15

By using K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] (C{sub 2}O{sub 4}{sup 2−}=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C_2O_4)_2(H_2O)_2}{sub 2}]·(H–L{sub 1}){sub 2}·H{sub 2}O 1, [Fe(C{sub 2}O{sub 4})Cl{sub 2}]·(H{sub 2}–L{sub 2}){sub 0.5}·(L{sub 2}){sub 0.5}·H{sub 2}O 2, [{Fe(C_2O_4)_1_._5Cl_2}{sub 2}]·(H–L{sub 3}){sub 4}3, [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]·(H{sub 2}–L{sub 4}){sub 2}·2H{sub 2}O 4, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H{sub 2}–L{sub 5})·2H{sub 2}O 5, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 6, K[Cr(C{sub 2}O{sub 4}){sub 3}]·2H{sub 2}O 7, Na[Fe(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 8 (with L{sub 1}=4-dimethylaminopyridine, L{sub 2}=2,3,5,6-tetramethylpyrazine, L{sub 3}=2-aminobenzimidazole, L{sub 4}=1,4-bis-(1H-imidazol-1-yl)benzene, L{sub 5}=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L{sub 6}=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O){sub 2}]{sup −} unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C{sub 2}O{sub 4})Cl{sub 2}]{sup -} anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe{sub 2}(C{sub 2}O{sub 4}){sub 3}Cl{sub 4}]{sup 4−} unit. Compound 4 features distinct [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]{sup 4−} units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C{sub 2}O{sub 4}){sub 3}]{sup 3−} units and K{sup +} cations. The 1D chains are further extended into 3D antionic H-bonded framework through O–H···O H-bonds. Compounds 6–8 show 2D [KAl(C{sub 2}O

Comparing Sources of Storm-Time Ring Current O+

Science.gov (United States)

Kistler, L. M.

2015-12-01

The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

Electronic parameters of Sr2Nb2O7 and chemical bonding

DEFF Research Database (Denmark)

Atuchin, V.V.; Grivel, Jean-Claude; Korotkov, A.S.

2008-01-01

/2)) and Delta(O-Sr) = BE(O 1s)-BE(Sr 3d(5/2)), were used to characterize the valence electron transfer on the formation of the Nb-O and Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and earlier published structural and XPS data for other Sr- or Nb...

Energy of Intramolecular Hydrogen Bonding in ortho-Hydroxybenzaldehydes, Phenones and Quinones. Transfer of Aromaticity from ipso-Benzene Ring to the Enol System(s

Directory of Open Access Journals (Sweden)

Danuta Rusinska-Roszak

2017-03-01

Full Text Available Intramolecular hydrogen bonding (HB is one of the most studied noncovalent interactions of molecules. Many physical, spectral, and topological properties of compounds are under the influence of HB, and there are many parameters used to notice and to describe these changes. Hitherto, no general method of measurement of the energy of intramolecular hydrogen bond (EHB has been put into effect. We propose the molecular tailoring approach (MTA for EHB calculation, modified to apply it to Ar-O-H∙∙∙O=C systems. The method, based on quantum calculations, was checked earlier for hydroxycarbonyl-saturated compounds, and for structures with resonance-assisted hydrogen bonding (RAHB. For phenolic compounds, the accuracy, repeatability, and applicability of the method is now confirmed for nearly 140 structures. For each structure its aromaticity HOMA indices were calculated for the central (ipso ring and for the quasiaromatic rings given by intramolecular HB. The comparison of calculated HB energies and values of estimated aromaticity indices allowed us to observe, in some substituted phenols and quinones, the phenomenon of transfer of aromaticity from the ipso-ring to the H-bonded ring via the effect of electron delocalization.

Deformation Characteristics and Sealing Performance of Metallic O-rings for a Reactor Pressure Vessel

Directory of Open Access Journals (Sweden)

Mingxue Shen

2016-04-01

Full Text Available This paper provides a reference to determine the seal performance of metallic O-rings for a reactor pressure vessel (RPV. A nonlinear elastic-plastic model of an O-ring was constructed by the finite element method to analyze its intrinsic properties. It is also validated by experiments on scaled samples. The effects of the compression ratio, the geometrical parameters of the O-ring, and the structure parameters of the groove on the flange are discussed in detail. The results showed that the numerical analysis of the O-ring agrees well with the experimental data, the compression ratio has an important role in the distribution and magnitude of contact stress, and a suitable gap between the sidewall and groove can improve the sealing capability of the O-ring. After the optimization of the sealing structure, some key parameters of the O-ring (i.e., compression ratio, cross-section diameter, wall thickness, sidewall gap have been recommended for application in megakilowatt class nuclear power plants. Furthermore, air tightness and thermal cycling tests were performed to verify the rationality of the finite element method and to reliably evaluate the sealing performance of a RPV.

Deformation characteristics and sealing performance of metallic-O-ring for a reactor pressure vessel

Energy Technology Data Exchange (ETDEWEB)

Shen, Ming Xue; Peng, Xudong; Xie, Linjun; Meng, Xiang Kai [Engineering Research Center of Process Equipment and Its Remanufacture, Ministry of Education, Zhejiang University of Technology, Hangzhou (China); Li, Xing Gen [Ningbo Tiansheng Sealing Packing Co., Ltd., Ningbo (China)

2016-04-15

This paper provides a reference to determine the seal performance of metallic O-rings for a reactor pressure vessel (RPV). A nonlinear elastic-plastic model of an O-ring was constructed by the finite element method to analyze its intrinsic properties. It is also validated by experiments on scaled samples. The effects of the compression ratio, the geometrical parameters of the O-ring, and the structure parameters of the groove on the flange are discussed in detail. The results showed that the numerical analysis of the O-ring agrees well with the experimental data, the compression ratio has an important role in the distribution and magnitude of contact stress, and a suitable gap between the sidewall and groove can improve the sealing capability of the O-ring. After the optimization of the sealing structure, some key parameters of the O-ring (i.e., compression ratio, cross-section diameter, wall thickness, sidewall gap) have been recommended for application in megakilowatt class nuclear power plants. Furthermore, air tightness and thermal cycling tests were performed to verify the rationality of the finite element method and to reliably evaluate the sealing performance of a RPV.

Helium/solid powder O-ring leakage correlation experiments using a radiotracer

International Nuclear Information System (INIS)

Bild, R.W.; Leisher, W.B.; Weissman, S.H.; Seya, M.

1984-01-01

UO 2 definitely leaked past the O-ring in three of the tests confirming the major results of the previous work. Continuous leakage at these levels may require additional precautions under present regulatory policies. The mechanism and the time and particle size dependence for the leakage are not known, but there is some indication leakage is more likely at low temperatures. It is possible leakage is due to movement of the O-ring during temperature or pressure cycling at the beginning or end of a test. The radiotracer method involves less labor and is much less susceptible to contamination than the previous method. Future work will investigate leakage past lubricated O-rings and time dependence of leakage. 1 reference, 1 table

Low temperature bonding of heterogeneous materials using Al2O3 as an intermediate layer

DEFF Research Database (Denmark)

Sahoo, Hitesh Kumar; Ottaviano, Luisa; Zheng, Yi

2018-01-01

Integration of heterogeneous materials is crucial for many nanophotonic devices. The integration is often achieved by bonding using polymer adhesives or metals. A much better and cleaner option is direct wafer bonding, but the high annealing temperatures required make it a much less attractive...... atomic layer deposited Al2O3 an excellent choice for the intermediate layer. The authors have optimized the bonding process to achieve a high interface energy of 1.7 J/m2 for a low temperature annealing of 300 °C. The authors also demonstrate wafer bonding of InP to SiO2 on Si and GaAs to sapphire using...

New metal-organic polygons involving MM quadruple bonds: M8(O2CtBu)4(mu-SC4H2-3,4-{CO2}2)6 (M=Mo, W).

Science.gov (United States)

Byrnes, Matthew J; Chisholm, Malcolm H; Patmore, Nathan J

2005-12-12

The reactions between M2(O2CtBu)4, where M=Mo or W, and thienyl-3,4-dicarboxylic acid (0.5-1.5 equiv) in toluene proceed via a series of detectable intermediates to the compounds M8(O2CtBu)4(mu-SC4H2-3,4-{CO2}2)6, which are isolated as air-sensitive yellow (M=Mo) or red (M=W) powders and show parent molecular ions in their mass spectra (MALDI). The structure of the molybdenum complex was determined by single-crystal X-ray crystallography and shown to contain an unusual M8 polygon involving four Mo2 quadruply bonded units linked via the agency of the six 3,4-thienylcarboxylate groups. The structure has crystallographically imposed S4 symmetry and may be described in terms of a highly distorted tetrahedron of Mo2 units or a bisphenoid in which two Mo2 units are linked by a thienyldicarboxylate such that intramolecular Mo2...O bonding is present, while the other thienylcarboxylate bridges merely serve to link these two [Mo2]...[Mo2] units together. The color of the compounds arises from intense M2 delta-to-thienyl pi transitions and, in THF, the complexes are redox-active and show four successive quasi-reversible oxidation waves. The [M8]+ radical cations, generated by one-electron oxidation with AgPF6, are shown to be valence-trapped (class II) by UV-vis-near-IR and electron paramagnetic resonance spectroscopy. These results are supported by the electronic structure calculations on model compounds M8(O2CH)4(mu-SC4H2-3,4-{CO}2)6 employing density functional theory that reveal only a small splitting of the M2 delta manifold via mixing with the 3,4-thienylcarboxylate pi system.

Spatial structure of radio frequency ring-shaped magnetized discharge sputtering plasma using two facing ZnO/Al2O3 cylindrical targets for Al-doped ZnO thin film preparation

Directory of Open Access Journals (Sweden)

Takashi Sumiyama

2017-05-01

Full Text Available Spatial structure of high-density radio frequency ring-shaped magnetized discharge plasma sputtering with two facing ZnO/Al2O3 cylindrical targets mounted in ring-shaped hollow cathode has been measured and Al-doped ZnO (AZO thin film is deposited without substrate heating. The plasma density has a peak at ring-shaped hollow trench near the cathode. The radial profile becomes uniform with increasing the distance from the target cathode. A low ion current flowing to the substrate of 0.19 mA/cm2 is attained. Large area AZO films with a resistivity of 4.1 – 6.7×10-4 Ω cm can be prepared at a substrate room temperature. The transmittance is 84.5 % in a visible region. The surface roughnesses of AZO films are 0.86, 0.68, 0.64, 1.7 nm at radial positions of r = 0, 15, 30, 40 mm, respectively, while diffraction peak of AZO films is 34.26°. The grains exhibit a preferential orientation along (002 axis.

Long-Term Leak Tightness Of O-Ring Seals In The 9975 Shipping Package

International Nuclear Information System (INIS)

Hoffman, E.; Skidmore, E.; Daugherty, W.

2010-01-01

O-ring seals in the 9975 shipping package containment vessels are fabricated from a Viton GLT or GLT-S compound. Long-term testing of these O-rings has been performed to support service life predictions for packages used for long-term storage. Since the only criterion for O-ring performance is to maintain a leak-tight seal, leak testing is the primary indicator of service life. Fixtures have been aging at elevated temperatures to provide data for service life predictions. Limited leak test failures have been observed at the higher temperatures. This provides the opportunity for comparison to trends based on other O-ring properties, such as compression stress relaxation. Initial data suggest that the CSR data have some predictive value for a leak-tight service life, but other factors can complicate efforts to draw definitive conclusions.

Molecular dynamics simulation based on the multi-component molecular orbital method: Application to H5O2+,D5O2+,andT5O2+

International Nuclear Information System (INIS)

Ishimoto, Takayoshi; Koyama, Michihisa

2012-01-01

Graphical abstract: Molecular dynamics method based on multi-component molecular orbital method was applied to basic hydrogen bonding systems, H 5 O 2 + , and its isotopomers (D 5 O 2 + andT 5 O 2 + ). Highlights: ► Molecular dynamics method with nuclear quantum effect was developed. ► Multi-component molecular orbital method was used as ab initio MO calculation. ► Developed method applied to basic hydrogen bonding system, H 5 O 2 + , and isotopomers. ► O ⋯ O vibrational stretching reflected to the distribution of protonic wavefunctions. ► H/D/T isotope effect was also analyzed. - Abstract: We propose a molecular dynamics (MD) method based on the multi-component molecular orbital (MC M O) method, which takes into account the quantum effect of proton directly, for the detailed analyses of proton transfer in hydrogen bonding system. The MC M O based MD (MC M O-MD) method is applied to the basic structures, H 5 O 2 + (called “Zundel ion”), and its isotopomers (D 5 O 2 + andT 5 O 2 + ). We clearly demonstrate the geometrical difference of hydrogen bonded O ⋯ O distance induced by H/D/T isotope effect because the O ⋯ O in H-compound was longer than that in D- or T-compound. We also find the strong relation between stretching vibration of O ⋯ O and the distribution of hydrogen bonded protonic wavefunction because the protonic wavefunction tends to delocalize when the O ⋯ O distance becomes short during the dynamics. Our proposed MC M O-MD simulation is expected as a powerful tool to analyze the proton dynamics in hydrogen bonding systems.

C=C bond cleavage on neutral VO3(V2O5)n clusters.

Science.gov (United States)

Dong, Feng; Heinbuch, Scott; Xie, Yan; Bernstein, Elliot R; Rocca, Jorge J; Wang, Zhe-Chen; Ding, Xun-Lei; He, Sheng-Gui

2009-01-28

The reactions of neutral vanadium oxide clusters with alkenes (ethylene, propylene, 1-butene, and 1,3-butadiene) are investigated by experiments and density function theory (DFT) calculations. Single photon ionization through extreme ultraviolet radiation (EUV, 46.9 nm, 26.5 eV) is used to detect neutral cluster distributions and reaction products. In the experiments, we observe products (V(2)O(5))(n)VO(2)CH(2), (V(2)O(5))(n)VO(2)C(2)H(4), (V(2)O(5))(n)VO(2)C(3)H(4), and (V(2)O(5))(n)VO(2)C(3)H(6), for neural V(m)O(n) clusters in reactions with C(2)H(4), C(3)H(6), C(4)H(6), and C(4)H(8), respectively. The observation of these products indicates that the C=C bonds of alkenes can be broken on neutral oxygen rich vanadium oxide clusters with the general structure VO(3)(V(2)O(5))(n=0,1,2...). DFT calculations demonstrate that the reaction VO(3) + C(3)H(6) --> VO(2)C(2)H(4) + H(2)CO is thermodynamically favorable and overall barrierless at room temperature. They also provide a mechanistic explanation for the general reaction in which the C=C double bond of alkenes is broken on VO(3)(V(2)O(5))(n=0,1,2...) clusters. A catalytic cycle for alkene oxidation on vanadium oxide is suggested based on our experimental and theoretical investigations. The reactions of V(m)O(n) with C(6)H(6) and C(2)F(4) are also investigated by experiments. The products VO(2)(V(2)O(5))(n)C(6)H(4) are observed for dehydration reactions between V(m)O(n) clusters and C(6)H(6). No product is detected for V(m)O(n) clusters reacting with C(2)F(4). The mechanisms of the reactions between VO(3) and C(2)F(4)/C(6)H(6) are also investigated by calculations at the B3LYP/TZVP level.

Co-occurring species differ in tree-ring δ18O trends.

Science.gov (United States)

John D. Marshall; Robert A. Monserud

2006-01-01

The stable oxygen isotope ratio (δ18O) of tree-ring cellulose is jointly determined by the δ18O of xylem water, the δ18O of atmospheric water vapor, the humidity of the atmosphere and perhaps by species-specific differences in leaf structure and function. Atmospheric...

Electrochemical performance and structure evolution of core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon anodes for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Sun, Yan-Hui, E-mail: sunyanhui0102@163.com; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

2016-12-30

Core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe{sub 2}O{sub 3} nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe{sub 2}O{sub 3} (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe{sub 2}O{sub 3} during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g{sup −1} and retains 920/897 mAh g{sup −1} after 200 cycles at 500 mA g{sup −1} (0.5C). Even at 2000 mA g{sup −1} (2C), the electrode delivers the initial capacities of 1400/900 mAh g{sup −1}, and still maintains 630/610 mAh g{sup −1} after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe{sub 2}O{sub 3}@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe{sub 2}O{sub 3} and facilitate the transportation of electrons and Li{sup +} ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe{sub 2}O{sub 3}@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

{open_quotes}O{close_quotes} ring sealed process tube, Phase II, test project

Energy Technology Data Exchange (ETDEWEB)

Johnson, R.E.

1951-04-09

The {open_quotes}O{close_quotes} ring seal has been proposed to replace the van stone flange and the bellows thermal expansion assembly currently used on the existing Hanford piles to achieve water and gas seals, respectively. Possible advantages of the {open_quotes}O{close_quotes} ring seal are: (1) simplification of component parts and elimination of van stone corrosion; (2) simplification of maintenance; (3) lower costs of initial erection; (4) increased strength. This test supplements Test Project No. 27 (a preliminary thermal cycling test) in applying the {open_quotes}O{close_quotes} ring seal assembly to actual pile operating conditions.

Eleventh interim status report: Model 9975 O-Ring fixture long-term leak performance

Energy Technology Data Exchange (ETDEWEB)

Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-08-01

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF.

Impact of SiO2 on Al–Al thermocompression wafer bonding

International Nuclear Information System (INIS)

Malik, Nishant; Finstad, Terje G; Schjølberg-Henriksen, Kari; Poppe, Erik U; Taklo, Maaike M V

2015-01-01

Al–Al thermocompression bonding suitable for wafer level sealing of MEMS devices has been investigated. This paper presents a comparison of thermocompression bonding of Al films deposited on Si with and without a thermal oxide (SiO 2 film). Laminates of diameter 150 mm containing device sealing frames of width 200 µm were realized. The wafers were bonded by applying a bond force of 36 or 60 kN at bonding temperatures ranging from 300–550 °C for bonding times of 15, 30 or 60 min. The effects of these process variations on the quality of the bonded laminates have been studied. The bond quality was estimated by measurements of dicing yield, tensile strength, amount of cohesive fracture in Si and interfacial characterization. The mean bond strength of the tested structures ranged from 18–61 MPa. The laminates with an SiO 2 film had higher dicing yield and bond strength than the laminates without SiO 2 for a 400 °C bonding temperature. The bond strength increased with increasing bonding temperature and bond force. The laminates bonded for 30 and 60 min at 400 °C and 60 kN had similar bond strength and amount of cohesive fracture in the bulk silicon, while the laminates bonded for 15 min had significantly lower bond strength and amount of cohesive fracture in the bulk silicon. (paper)

Insights into the Electronic Structure of Ozone and Sulfur Dioxide from Generalized Valence Bond Theory: Bonding in O3 and SO2.

Science.gov (United States)

Takeshita, Tyler Y; Lindquist, Beth A; Dunning, Thom H

2015-07-16

There are many well-known differences in the physical and chemical properties of ozone (O3) and sulfur dioxide (SO2). O3 has longer and weaker bonds than O2, whereas SO2 has shorter and stronger bonds than SO. The O-O2 bond is dramatically weaker than the O-SO bond, and the singlet-triplet gap in SO2 is more than double that in O3. In addition, O3 is a very reactive species, while SO2 is far less so. These disparities have been attributed to variations in the amount of diradical character in the two molecules. In this work, we use generalized valence bond (GVB) theory to characterize the electronic structure of ozone and sulfur dioxide, showing O3 does indeed possess significant diradical character, whereas SO2 is effectively a closed shell molecule. The GVB results provide critical insights into the genesis of the observed difference in these two isoelectronic species. SO2 possesses a recoupled pair bond dyad in the a"(π) system, resulting in SO double bonds. The π system of O3, on the other hand, has a lone pair on the central oxygen atom plus a pair of electrons in orbitals on the terminal oxygen atoms that give rise to a relatively weak π interaction.

Bond length effects during the dissociation of O2 on Ni(1 1 1)

International Nuclear Information System (INIS)

Shuttleworth, I.G.

2015-01-01

Graphical abstract: - Highlights: • The dissociation of O 2 on Ni(1 1 1) has been investigated using the Nudged Elastic Band (NEB) technique. • An exceptional correlation has been identified between the O/Ni bond order and the O 2 bond length for a series of sterically different reaction paths. • Direct magnetic phenomena accompany these processes suggesting further mechanisms for experimental control. - Abstract: The interaction between O 2 and Ni(1 1 1) has been investigated using spin-polarised density functional theory. A series of low activation energy (E A = 103–315 meV) reaction pathways corresponding to precursor and non-precursor mediated adsorption have been identified. It has been seen that a predominantly pathway-independent correlation exists between O−Ni bond order and the O 2 bond length. This correlation demonstrates that the O−O interaction predominantly determines the bonding of this system

Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

Energy Technology Data Exchange (ETDEWEB)

Roth, Justine P. [Johns Hopkins Univ., Baltimore, MD (United States)

2015-03-03

Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

The Role of Ionospheric O+ in Forming the Storm-time Ring Current

Science.gov (United States)

Kistler, L. M.; Mouikis, C.; Menz, A.; Bingham, S.

2017-12-01

During storm times, the particle pressure that creates the storm-time ring current in the inner magnetosphere can be dominated by O+. This is surprising, as the immediate source for the ring current is the nightside plasma sheet, and O+ is usually not the dominant species in the plasma sheet. In this talk we examine the many factors that lead to this result. The O+ outflow is enhanced during geomagnetically active times. The transport paths of O+ and H+ are different, such that the O+ that reaches the near-earth plasma sheet is more energetic than H+. The source spectrum in the near-earth plasma sheet can be harder for O+ than for H+, perhaps due to substorm injections, so that the more energetic plasma has a higher O+/H+ ratio. And finally the plasma sheet O+ can be more abundant towards the beginning of the storm, when the convection is largest, so the enhanced O+ is brought the deepest into the inner magnetosphere. We will discuss the interrelationships between these different effects as well as the ways in which O+ itself may influence the system.

Bonding and M?ssbauer Isomer Shifts in (Tl,Pb) - 1223 Cuprate

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

By using the chemical bond theory of dielectric description,the chemical bond parameters of (Tl,Pb) - 1223 was calculated.The results show that the Sr-O,Tl-O,and Ca-O types of bond have higher ionic character and the Cu-O types of bond have more covalent character.M?ssbauer isomer shifts of 57Fe and 119Sn doped in (Tl,Pb) -1223 were calculated by using the chemical environmental factor,he,defined by covalency and electronic polarizability.Four valence state tin and three valence iron sites were identified in 57Fe,and 119Sn doped (Tl,Pb) -1223 superconductor.We conclude that all of the Fe atoms substitute the Cu at square planar Cu (1) site,whereas Sn prefers to substitute the square pyramidal Cu (2) site.

Control of chemical bonding of the ZnO surface grown by molecular beam epitaxy

International Nuclear Information System (INIS)

Ogata, K.; Komuro, T.; Hama, K.; Koike, K.; Sasa, S.; Inoue, M.; Yano, M.

2004-01-01

Toward the fabrication of enzyme modified field effect transistors (EnFETs) as one of organic/inorganic hybridized structures, surface bonding of the ZnO grown by molecular beam epitaxy was controlled by ex situ treatments. Angle resolved X-ray photoelectron spectroscopy (XPS) measurement revealed that O-H bonds exist at the surface of ZnO. It was found that the number of O-H bond could be changed with reversibility using plasma and thermal treatments

Effect of increasing concentration of Na2O on structural, elastic and optical properties of (90  -  x)GeO2-xNa2O-10PbO glass system in the germanate anomaly region

Science.gov (United States)

Zainudin, C. N.; Hisam, R.; Yusof, M. I. M.; Yahya, A. K.; Halimah, M. K.

2017-10-01

Ternary germanate glasses (90  -  x)GeO2-xNa2O-10PbO (x  =  10-30 mol%) have been prepared by the melt-quenching method. Density, ρ increased with Na2O content up to maxima at 20 mol% while molar volume, V a showed an opposite trend to the density, with a minima at 20 mol% of Na2O content indicating the presence of the germanate anomaly. Ultrasonic velocity measurements showed both longitudinal, v l and shear, v s velocities increased up to 20 mol% before decreasing with further addition of Na2O. Independent longitudinal, L and shear, G moduli along with Young’s modulus, Y, mean sound velocity, v m, Debye temperature, θ D, and hardness, H recorded maximum values at 20 mol% of Na2O content which were suggested to be related to the germanate anomaly. Structural modification occurring due to conversion of six-membered GeO4 rings to three-membered rings of GeO4 changed bond density and compactness of the glass systems and caused the increase in rigidity and stiffness of the glasses. Beyond 20 mol% of Na2O, the decrease in the elastic moduli was due to depolymerization of the glass network. Meanwhile, optical energy gap, E opt exhibited a minima at 20 mol% whereas Urbach energy, E U and refractive index, n showed a maxima at the same concentration, thereby indicating variation in polarizability due to changes in concentration of bridging and non-bridging oxygen.

Bismuth-boron multiple bonding in BiB_2O"- and Bi_2B"-

International Nuclear Information System (INIS)

Jian, Tian; Cheung, Ling Fung; Chen, Teng-Teng; Wang, Lai-Sheng

2017-01-01

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB_2O"- and Bi_2B"-, containing triple and double B-Bi bonds are presented. The BiB_2O"- and Bi_2B"- clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB_2O"- ([Bi≡B-B≡O]"-) and Bi_2B"- ([Bi=B=Bi]"-), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Platinum Catalyzed Ring-Opening of 1,2-Cyclopropanated Sugars with O-Nucleophiles

DEFF Research Database (Denmark)

Beyer, Jürgen; Skaanderup, Philip Robert; Madsen, Robert

1999-01-01

In the presence of a catalytic amount of Zeise's dimer 1,2-cyclopropanated sugars undergo regioselective ring-opening at C-1 with O-nucleophiles including alcohols, phenols and water to produce 2-C-branched carbohydrates.......In the presence of a catalytic amount of Zeise's dimer 1,2-cyclopropanated sugars undergo regioselective ring-opening at C-1 with O-nucleophiles including alcohols, phenols and water to produce 2-C-branched carbohydrates....

First-principle study on bonding mechanism of ZnO by LDA+U method

International Nuclear Information System (INIS)

Zhou, G.C.; Sun, L.Z.; Zhong, X.L.; Chen Xiaoshuang; Wei Lu; Wang, J.B.

2007-01-01

The electronic structure and the bonding mechanism of ZnO have been studied by using the Full-Potential Linear Augmented Plane Wave (FP-LAPW) method within the density-functional theory (DFT) based on LDA+U exchange correlation potential. The valence and the bonding charge density are calculated and compared with those derived from LDA and GGA to describe the bonding mechanism. The charge transfer along with the bonding process is analyzed by using the theory of Atoms in Molecules (AIM). The bonding, the topological characteristics and the p-d coupling effects on the bonding mechanism of ZnO are shown quantitatively with the critical points (CPs) along the bonding trajectory and the charge in the atomic basins. Meanwhile, the bonding characteristics for wurtzite, zinc blende and rocksalt phase of ZnO are discussed systematically in the present paper

B2O3/SiO2 substitution effect on structure and properties of Na2O-CaO-SrO-P2O5-SiO2 bioactive glasses from molecular dynamics simulations.

Science.gov (United States)

Ren, Mengguo; Lu, Xiaonan; Deng, Lu; Kuo, Po-Hsuen; Du, Jincheng

2018-05-23

The effect of B2O3/SiO2 substitution in SrO-containing 55S4.3 bioactive glasses on glass structure and properties, such as ionic diffusion and glass transition temperature, was investigated by combining experiments and molecular dynamics simulations with newly developed potentials. Both short-range (such as bond length and bond angle) and medium-range (such as polyhedral connection and ring size distribution) structures were determined as a function of glass composition. The simulation results were used to explain the experimental results for glass properties such as glass transition temperature and bioactivity. The fraction of bridging oxygen increased linearly with increasing B2O3 content, resulting in an increase in overall glass network connectivity. Ion diffusion behavior was found to be sensitive to changes in glass composition and the trend of the change with the level of substitution is also temperature dependent. The differential scanning calorimetry (DSC) results show a decrease in glass transition temperature (Tg) with increasing B2O3 content. This is explained by the increase in ion diffusion coefficient and decrease in ion diffusion energy barrier in glass melts, as suggested by high-temperature range (above Tg) ion diffusion calculations as B2O3/SiO2 substitution increases. In the low-temperature range (below Tg), the Ea for modifier ions increased with B2O3/SiO2 substitution, which can be explained by the increase in glass network connectivity. Vibrational density of states (VDOS) were calculated and show spectral feature changes as a result of the substitution. The change in bioactivity with B2O3/SiO2 substitution is discussed with the change in pH value and release of boric acid into the solution.

Manganese-Oxygen Intermediates in O-O Bond Activation and Hydrogen-Atom Transfer Reactions.

Science.gov (United States)

Rice, Derek B; Massie, Allyssa A; Jackson, Timothy A

2017-11-21

Biological systems capitalize on the redox versatility of manganese to perform reactions involving dioxygen and its derivatives superoxide, hydrogen peroxide, and water. The reactions of manganese enzymes influence both human health and the global energy cycle. Important examples include the detoxification of reactive oxygen species by manganese superoxide dismutase, biosynthesis by manganese ribonucleotide reductase and manganese lipoxygenase, and water splitting by the oxygen-evolving complex of photosystem II. Although these enzymes perform very different reactions and employ structurally distinct active sites, manganese intermediates with peroxo, hydroxo, and oxo ligation are commonly proposed in catalytic mechanisms. These intermediates are also postulated in mechanisms of synthetic manganese oxidation catalysts, which are of interest due to the earth abundance of manganese. In this Account, we describe our recent efforts toward understanding O-O bond activation pathways of Mn III -peroxo adducts and hydrogen-atom transfer reactivity of Mn IV -oxo and Mn III -hydroxo complexes. In biological and synthetic catalysts, peroxomanganese intermediates are commonly proposed to decay by either Mn-O or O-O cleavage pathways, although it is often unclear how the local coordination environment influences the decay mechanism. To address this matter, we generated a variety of Mn III -peroxo adducts with varied ligand environments. Using parallel-mode EPR and Mn K-edge X-ray absorption techniques, the decay pathway of one Mn III -peroxo complex bearing a bulky macrocylic ligand was investigated. Unlike many Mn III -peroxo model complexes that decay to oxo-bridged-Mn III Mn IV dimers, decay of this Mn III -peroxo adduct yielded mononuclear Mn III -hydroxo and Mn IV -oxo products, potentially resulting from O-O bond activation of the Mn III -peroxo unit. These results highlight the role of ligand sterics in promoting the formation of mononuclear products and mark an important

Activation of a Carbon-Oxygen Bond of Benzofuran by Precoordination of Manganese to the Carbocyclic Ring: A Model for Hydrodeoxygenation.

Science.gov (United States)

Zhang; Watson; Dullaghan; Gorun; Sweigart

1999-08-01

Stable unsaturated heterocycles such as benzofuran are difficult to remove from petroleum by conventional catalytic hydrotreating. However, in a model system, coordination of Mn(CO)(3)(+) to the aromatic ring of benzofuran activates the C-O bond towards insertion of [Pt(PPh(3))(2)] [Eq. (1)]. The insertion is preceded by precoordination to the furan C=C bond; thus, the 2,3-dihydro analogue of 1, which lacks this double bond, does not undergo insertion of the Pt moiety.

Poly[aqua(μ3-pyridazine-4-carboxylato-κ2O:O:O′lithium

Directory of Open Access Journals (Sweden)

Wojciech Starosta

2011-04-01

Full Text Available The structure of the title compound, [Li(C5H3N2O2(H2O]n, is composed of centrosymmetric dimers in which two LiI ions are bridged by a carboxylate O atom, each donated by a ligand, acting in a bidentate mode. The second carboxylato O atoms bridge the dimers to LiI ions in adjacent dimers, forming molecular layers parallel to (001. Each LiI ion is coordinated by two bridging carboxylate O atoms, a bridging carboxylate O atom donated by the adjacent dimer and an aqua O atom, resulting in a distorted tetrahedral coordination geometry. The layers are held together by O—H...N hydrogen bonds in which coordinated water O atoms act as donors and ligand hetero-ring N atoms as acceptors.

Initial Reactivity of Linkages and Monomer Rings in Lignin Pyrolysis Revealed by ReaxFF Molecular Dynamics.

Science.gov (United States)

Zhang, Tingting; Li, Xiaoxia; Guo, Li

2017-10-24

The initial conversion pathways of linkages and their linked monomer units in lignin pyrolysis were investigated comprehensively by ReaxFF MD simulations facilitated by the unique VARxMD for reaction analysis. The simulated molecular model contains 15 920 atoms and was constructed on the basis of Adler's softwood lignin model. The simulations uncover the initial conversion ratio of various linkages and their linked aryl monomers. For linkages and their linked monomer aryl rings of α-O-4, β-O-4 and α-O-4 & β-5, the C α /C β ether bond cracking dominates the initial pathway accounting for at least up to 80% of their consumption. For the linkage of β-β & γ-O-α, both the C α -O ether bond cracking and its linked monomer aryl ring opening are equally important. Ring-opening reactions dominate the initial consumption of other 4-O-5, 5-5, β-1, β-2, and β-5 linkages and their linked monomers. The ether bond cracking of C α -O and C β -O occurs at low temperature, and the aryl ring-opening reactions take place at relatively high temperature. The important intermediates leading to the stable aryl ring opening are the phenoxy radicals, the bridged five-membered and three-membered rings and the bridged six-membered and three-membered rings. In addition, the reactivity of a linkage and its monomer aryl ring may be affected by other linkages. The ether bond cracking of α-O-4 and β-O-4 linkages can activate its neighboring linkage or monomer ring through the formed phenoxy radicals as intermediates. The important intermediates revealed in this article should be of help in deepening the understanding of the controlling mechanism for producing aromatic chemicals from lignin pyrolysis.

Adaptação transcultural para o português brasileiro do Parental Bonding Instrument (PBI Cross-cultural adaptation of Parental Bonding Instrument (PBI to Brazilian Portuguese

Directory of Open Access Journals (Sweden)

Simone Hauck

2006-08-01

Full Text Available OBJETIVO: O artigo apresenta a adaptação transcultural do Parental Bonding Instrument, um questionário auto-aplicável desenvolvido em 1979 e usado desde então para avaliar a percepção da qualidade do vínculo com os pais até os 16 anos. MÉTODO: Foram realizadas as etapas de equivalência conceitual, equivalência dos itens, equivalência semântica, equivalência operacional, equivalência funcional e aprovação da versão final pelo autor original do instrumento. RESULTADOS: Os critérios de equivalência foram satisfeitos, tendo a versão final sido aprovada pelo autor do instrumento original. CONCLUSÃO: A adaptação do Parental Bonding Instrument disponibiliza para uso um instrumento que já demonstrou ser extremamente útil em pesquisas de risco e resiliência nas últimas décadas, ao avaliar a percepção de características do comportamento dos pais tradicionalmente associadas ao desenvolvimento da personalidade.OBJETIVE: This article aims to present a cross-cultural adaptation of the Parental Bonding Instrument to Brazilian Portuguese. It is a self-administered questionnaire developed in 1979, which has been used since then to measure the subjective experience of being parented to the age of 16 years. METHOD: The following steps were performed: conceptual equivalence, item equivalence, semantic equivalence, operational equivalence, functional equivalence, and approval of the final version by the author of the original instrument. RESULTS: The study has reached the objectives of equivalence, and the final Brazilian Portuguese version has been approved by the original author. CONCLUSION: The study provides a Brazilian Portuguese version of an instrument that has been proven extremely useful in risk and resilience researches over the past decades, assessing the perception of parental characteristics traditionally related to personality development.

Nitrilotris(methylenephosphonato)potassium K[μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3}H{sub 4}]: Synthesis, structure, and the nature of the K–O chemical bond

Energy Technology Data Exchange (ETDEWEB)

Somov, N. V., E-mail: somov@phys.unn.ru [Lobachevsky State University of Nizhni Novgorod (Russian Federation); Chausov, F. F., E-mail: xps@ftiudm.ru [Russian Academy of Sciences, Physical-Technical Institute, Ural Branch (Russian Federation); Zakirova, R. M., E-mail: ftt@udsu.ru [Udmurt State University (Russian Federation)

2016-07-15

The crystal structure of nitrilotris(methylenephosphonato)potassium K[μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3}H{sub 4}]—a three-dimensional coordination polymer—was determined. The potassium atom is coordinated by seven oxygen atoms belonging to the six nearest ligand molecules, resulting in distorted monocapped octahedral coordination geometry. The complex contains the four-membered chelate ring K–O–P–O. The K–O chemical bond is predominantly ionic. Meanwhile, the bonds of the potassium atom with some oxygen atoms have a noticeable covalent component. In addition to coordination bonds, the molecules in the crystal packing are linked by hydrogen bonds.

Avaliação da utilização dos adesivos dentinários na microinfiltração marginal de resinas compostas = Evaluation of use of dentin bond on the marginal microleakege of composites

Directory of Open Access Journals (Sweden)

Peixe, Simone

2006-01-01

Full Text Available O objetivo deste trabalho foi o de avaliar a microinfiltração marginal em restaurações de resina composta quando utilizados adesivos dentinários de um mesmo fabricante e associação com os adesivos de fabricantes diferentes. Foram realizados 40 preparos classe II tipo slot vertical, com pontas diamantadas 1094 (K. G. Sorensen nas proximais dos terceiros molares. As restaurações foram divididas em 4 grupos; restaurações com Prime & Bond e TPH (G1, Single Bond e TPH (G2, Single Bond e Z 100 (G3, Prime & Bond e Z 100 (G4. Após a confecção das restaurações, estas foram submetidas à ciclagem térmica, em água a 5°C ± 2°C e 55°C ± 2°C, com o tempo de permanência de 30 segundos, num total de 500 ciclos. As amostras foram imersas no corante, nitrato de prata 50%, em temperatura ambiente por 24 horas em câmara escura, sendo posteriormente colocadas em uma solução fotoreveladora sob luz fluorescente por 6 horas. Foram realizados dois cortes no centro da restauração, no sentido ocluso-gengival. A análise da microinfiltração foi realizada em lupa esterioscópica Zeiss com 50 vezes de aumento, seguindo scores de 0 a 3 graus. Os dados obtidos foram submetidos à análise não paramétrica de Kruskal-Wallis, revelando que os valores medianos (G1 = 3; G2 = 3; G3 = 2. 5; G4 = 1 diferem estatisticamente ao nível de significância de 5%. Mediante ao teste de comparação múltipla de Dunn (5% G4 foi superior aos outros grupos em termos de microinfiltração marginal

Aging and lifetime prediction of O-ring seals

International Nuclear Information System (INIS)

Koemmling, Anja

2017-01-01

In some applications, elastomer seals have to remain leak tight over extended time periods (up to several decades) as an exchange of the seals is not practical. Therefore, it is necessary to be able to predict the lifetime of such seals reliably. For this reason, ageing experiments with O-rings and sheets based on hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene propylene diene rubber (EPDM) and fluorocarbon rubber (FKM) were performed over up to two years at different temperatures. For investigating the changes of material properties during ageing, measurements of i.a. hardness and tensile behaviour as well as dynamic-mechanical and thermogravimetric analyses were conducted. For assessing the relaxation and recovery behaviour of the ageing seals, compression stress relaxation and compression set experiments were performed. Furthermore, leakage rate was measured to detect seal failure. By examining the aged samples, both the property changes and the responsible degradation mechanisms were characterised. Additionally, the most suitable approach for lifetime predictions should be determined using the large database of results from different test methods performed at several ageing times and temperatures. This included identifying an end-of-lifetime criterion that correlates with leakage and thus seal failure. Regarding the property changes and degradation mechanisms of HNBR, a pronounced embrittlement was observed due to dominant crosslinking reactions during ageing. These also resulted in a decrease of oxygen permeability, leading to a reduction of the oxygen transport into the interior sample (mainly of the thicker O-rings). This resulted in diffusion-limited oxidation effects (DLO effects), meaning that the interior of the sample aged less strongly than regions close to the surface. During ageing of EPDM, both chain scission and crosslinking occurred, which became noticeable in deteriorated tensile properties and decreased compression force as well as

High-κ Al{sub 2}O{sub 3} material in low temperature wafer-level bonding for 3D integration application

Energy Technology Data Exchange (ETDEWEB)

Fan, J., E-mail: fanji@hust.edu.cn; Tu, L. C. [MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Tan, C. S. [School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2014-03-15

This work systematically investigated a high-κ Al{sub 2}O{sub 3} material for low temperature wafer-level bonding for potential applications in 3D microsystems. A clean Si wafer with an Al{sub 2}O{sub 3} layer thickness of 50 nm was applied as our experimental approach. Bonding was initiated in a clean room ambient after surface activation, followed by annealing under inert ambient conditions at 300 °C for 3 h. The investigation consisted of three parts: a mechanical support study using the four-point bending method, hermeticity measurements using the helium bomb test, and thermal conductivity analysis for potential heterogeneous bonding. Compared with samples bonded using a conventional oxide bonding material (SiO{sub 2}), a higher interfacial adhesion energy (∼11.93 J/m{sup 2}) and a lower helium leak rate (∼6.84 × 10{sup −10} atm.cm{sup 3}/sec) were detected for samples bonded using Al{sub 2}O{sub 3}. More importantly, due to the excellent thermal conductivity performance of Al{sub 2}O{sub 3}, this technology can be used in heterogeneous direct bonding, which has potential applications for enhancing the performance of Si photonic integrated devices.

Core level photoemission spectroscopy and chemical bonding in Sr2Ta2O7

DEFF Research Database (Denmark)

Atuchin, V. V.; Grivel, Jean-Claude; Zhang, Z. M.

2009-01-01

Electronic parameters of constituent element core levels of strontium pyrotantalate (Sr2Ta2O7) were measured with X-ray photoelectron spectroscopy (XPS). The Sr2Ta2O7 powder sample was synthesized using standard solid state method. The valence electron transfer on the formation of the Sr-O and Ta......-O bonds was characterized by the binding energy differences between the O 1s and cation core levels, Delta(O-Sr) = BE(O 1s) - BE(Sr 3d(5/2)) and Delta(O-Ta) = BE(O 1s) - BE(Ta 4f(7/2)). The chemical bonding effects were considered on the basis of our XPS results for Sr2Ta2O7 and earlier published...

Determinação da tensão de aderência do bambu-concreto Determination of the bamboo-concrete bond stress

Directory of Open Access Journals (Sweden)

Ligia P. Mesquita

2006-06-01

Full Text Available Apresenta-se e se discute, neste trabalho, o estudo da aderência entre o bambu e o concreto; através de dois estudos baseados em uma programação estatística de experimento, em que no primeiro se investigaram as influências da dimensão da seção transversal das varetas de bambu e da resistência do concreto na aderência bambu-concreto e, no segundo, avaliou-se o efeito da colocação de pinos artificiais nas varetas de bambu. Em cada estudo realizaram-se 10 réplicas para cada combinação de fatores, resultando no total de 159 ensaios de arrancamento. Curvas tensão de aderência versus deslocamento relativo bambu-concreto, são apresentadas e discutidas, e a tensão de aderência de cálculo é calculada e comparada com os valores sugeridos por normas internacionais para barras lisas de aço. Constatou-se, na primeira fase da investigação, que apenas a resistência do concreto influencia na aderência bambu-concreto e que esta tensão é apenas 20% inferior que a do aço liso-concreto; já na segunda fase verificou-se que os pinos de bambu e de aço elevam a capacidade de transferência de tensões bambu-concreto, de forma significativa.This paper presents and discusses a study about the bamboo-concrete bond stress. Based on a statistical design of experiment, the investigation was divided in two steps: the first one, where the effects of the concrete compressive strength and the dimensions of the bamboo-splint cross-section were investigated; and the second, where the effect of artificial pins studding in the bamboo splints were evaluated. In both steps, ten replicates for each factor combination were done, resulting in 159 push-out tests. Bond stress versus relative displacement curves were presented and discussed. In addition, the design bond stresses of bamboo-concrete were calculated and their values were compared with those specified by International Building Codes for smooth steel and concrete. In the first step, it was

Effect of BSO addition on Cu-O bond of GdBa{sub 2}Cu{sub 3}O{sub 7-x} films with varying thickness probed by extended x-ray absorption fine structure

Energy Technology Data Exchange (ETDEWEB)

Jeon, H. K.; Lee, J. K.; Yang, D. S.; Kang, B. [Chungbuk National University, Cheongju (Korea, Republic of); Kang, W. N. [Dept. of Physics, Sungkyunkwan University, Suwon (Korea, Republic of)

2016-12-15

We investigated the relation between the Cu-O bond length and the superconducting properties of BaSnO{sub 3} (BSO)-added GdBa{sub 2}Cu{sub 3}O{sub 7-x} (GdBCO) thin films by using extended x-ray absorption fine structure (EXAFS) spectroscopy. 4 wt.% BaSnO{sub 3} (BSO) added GdBa{sub 2}Cu{sub 3}O{sub 7-x} (GdBCO) thin films with varying thickness from 0.2 μm to 1.0 μm were fabricated by using pulsed laser deposition (PLD) method. The transition temperature (T{sub c}) and the residual resistance ratio (RRR) of the GdBCO films increased with increasing thickness up to 0.8 μm, where the crystalline BSO has the highest peak intensity, and then decreased. This uncommon behaviors of T{sub c} and RRR are likely to be created by the addition of BSO, which may change the ordering of GdBCO atomic bonds. Analysis from the Cu K-edge EXAFS spectroscopy showed an interesting thickness dependence of ordering behavior of BSO-added GdBCO films. It is noticeable that the ordering of Cu-O bond and the transition temperature are found to show opposite behaviors in the thickness dependence. Based on these results, the growth of BSO seemingly have evident effect on the alteration of the local structure of GdBCO film.

Tree-ring C-H-O isotope variability and sampling

International Nuclear Information System (INIS)

Leavitt, Steven W.

2010-01-01

In light of the proliferation of tree-ring isotope studies, the magnitude and cause of variability of tree-ring δ 13 C, δ 18 O and δ 2 H within individual trees (circumferential) and among trees at a site is examined in reference to field and laboratory sampling requirements and strategies. Within this framework, this paper provides a state-of-knowledge summary of the influence of 'juvenile' isotope effects, ageing effects, and genetic effects, as well as the interchangeability of species, choice of ring segment to analyze (whole ring, earlywood or latewood), and the option of sample pooling. The range of isotopic composition of the same ring among trees at a site is ca. 1-3 per mille for δ 13 C, 1-4 per mille δ 18 O, and 5-30 per mille for δ 2 H, whereas the circumferential variability within a tree is lower. A standard prescription for sampling and analysis does not exist because of differences in field environmental circumstances and mixed findings represented in relevant published literature. Decisions in this regard will usually be tightly constrained by goals of the study and project resources. Sampling 4-6 trees at a site while avoiding juvenile effects in rings near the pith seems to be the most commonly used methodology, and although there are some reasoned arguments for analyzing only latewood and developing separate isotope records from each tree, the existence of some contradictory findings together with efforts to reduce cost and effort have prompted alternate strategies (e.g., most years pooled with occasional analysis of rings in the sequence separately for each tree) that have produced useful results in many studies.

Muon-oxygen bonding in V2O3

International Nuclear Information System (INIS)

Chan, K.C.B.; Lichti, R.L.; Boekema, C.

1986-01-01

A muon site search using calculated internal fields has been performed for V 2 O 3 , where purely dipolar fields allow a site determination free from covalent complications. The obtained sites are a subset of the Rodriguez and Bates sites found in α-Fe 2 O 3 and indicate muon oxygen bond formation. The sites missing at low temperatures are consistent with the vanadium pairing mechanism for the metal-to-insulator (corundum-to-monoclinic) phase transition. (orig.)

Hydrogenation/Deoxygenation (H/D Reaction of Furfural-Acetone Condensation Product using Ni/Al2O3-ZrO2 Catalyst

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Adam Mahfud

2016-08-01

Full Text Available The catalytic hydrogenation/deoxygenation (H/D reaction was carried out using Ni/Al2O3-ZrO2 catalyst. The 10% (wt/wt of Ni were impregnated on Al2O3-ZrO2 (10NiAZ by wet impregnation method followed by calcination and reduction. X-Ray diffraction analysis showed that Nideposited on the surface, with specific surface areas (SBET was 48.616 m2/g. Catalyst performance were evaluated for H/D reaction over furfural-acetone condensation products, mixture of 2-(4-furyl-3-buten-2-on and 1,5-bis-(furan-2-yl-pentan-3-one. The reaction was carried out in a batch, performed at 150°C for 8 hours. The H/D reaction gave alkane derivatives C8 and C10 by hydrogenation process followed by ring opening of furan in 15.2% yield. While, oxygenated product C10-C13 were also detected in 17.2% yield. The increasing of pore volume of 10NiAZ might enhance catalyst activity over H/D reaction. The alkene C=C bond was easy to hydrogenated under this condition by the lower bond energy gap.

Uma investigação sobre os co-movimentos na volatilidade dos par bonds latino-americanos

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Igor A.C. de Morais

2001-04-01

Full Text Available Este artigo procura aplicar o método de quase-máxima verossimilhança para estimar a volatilidade estocástica multivariada não-estacionária dos preços de compra dos par bonds de quatro países latino-americanos - México, Brasil, Argentina e Venezuela - no período de 9-8-1994 a 15-9-1999. O objetivo é analisar possíveis movimentos comuns nestas variâncias. Os testes feitos revelam que a volatilidade nos modelos univariados não apresentam inclinação, mas possuem alta persistência. A formulação multivariada relaciona bem os dados, obtendo estimativas consistentes e revelando a existência de um comportamento ao longo do tempo similar entre as volatilidades das quatro séries.This paper uses a quasi-maximum likelihood procedure to estimate the non-stationary stochastic volatility for the par bonds of four Latin American countries: Brazil, Argentina, Mexico and Venezuela. The aim is to investigate the possible presence of co-movements in volatility across countries. The estimation period goes from August 1994 to September 1999, including, therefore, the Asian and Russian crises. The estimated volatility for the univariate model does not show any slope and is highly persistent. The multivariate model gives a good fit to the data and shows that there is common movement.

Charge transfer and bond lengths in YBa2Cu3-xMxO6+y

International Nuclear Information System (INIS)

Jorgensen, J.D.; Rhyne, J.J.; Neumann, D.A.; Miceli, P.F.; Tarascon, J.M.; Greene, L.H.; Barboux, P.

1989-01-01

We discuss the effects of doping on the Cu chain sites in YBa 2 Cu 3-x M x O 6+y . The relationship between bond lengths obtained from neutron scattering and charge transfer is evaluated in terms of bond valence. In particular, it is concluded that removing an oxygen from the chains transfers one electron to the planes. 24 refs., 3 figs

Evolution of the bonding mechanism of ZnO under isotropic compression: A first-principles study

International Nuclear Information System (INIS)

Zhou, G.C.; Sun, L.Z.; Wang, J.B.; Zhong, X.L.; Zhou, Y.C.

2008-01-01

The electronic structure and the bonding mechanism of ZnO under isotropic pressure have been studied by using the full-potential linear augmented plane wave (FP-LAPW) method within the density-functional theory (DFT) based on LDA+U exchange correlation (EXC) potential. We used the theory of Atoms in Molecules (AIM) method to analyze the change of the charge transfer and the bonding strength under isotropic pressure. The results of the theoretical analysis show that charge transfer between Zn and O atomic basins nearly linearly increases with the increasing pressure. Charge density along the Zn-O bond increases under the high pressure. The bonding strength and the ionicity of Zn-O bond also increase with the increasing pressure. The linear evolution process of the bonding mechanism under isotropic pressure was shown clearly in the present paper

A concepção das mães sobre o desenvolvimento da comunicação mãe-bebê

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Maria C. D. P. Lyra

Full Text Available Comparamos duas abordagens teórico-metodológicas distintas e investigamos a concepção que mães apresentam acerca do processo de desenvolvimento da comunicação mãe-bebê. Lyra e colaboradores propõem o modelo EEA, que integra uma seqüência de três padrões de organização do desenvolvimento da comunicação, denominados estabelecimento, extensão e abreviação (EEA. Esse modelo está baseado na observação longitudinal e na análise microgenética de estudos de caso a partir da perspectiva dos sistemas dinâmicos. Utilizando o procedimento de classificação múltipla, investigamos como esses três períodos do desenvolvimento da comunicação (EEA são conceituados pelas mães. Foram pesquisadas 48 mães pertencentes a dois níveis sócio-econômicos. Os resultados encontrados fortalecem o modelo EEA, confirmando: a distinção entre as trocas face-a-face e aquelas mediadas pelo objeto (MOB; a diferenciação dos três períodos do desenvolvimento da comunicação (EEA em ambas as trocas; e a distribuição ordenada (axial desses três períodos, exceto, nesse último caso, para as trocas MOB, quando analisadas separadamente.

Permeability test and fuzzy orthogonal analysis of hydrogenated nitrile O-ring

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Qin Hu

2015-03-01

Full Text Available In the high temperature, high pressure and high corrosive environment of the oil and gas drilling downhole, the weatherability of rubber sealing material has a great influence on the production safety. In order to study the important degree of every key environmental factor in downhole influencing the sealing performance of rubber sealing material, a new device of simulating downhole environment is designed to test the permeability of O-ring. The sample is hydrogenated nitrile O-ring and orthogonal experiment method is used to do nine tests by getting three levels from temperature, pressure and CO2 volume fraction. Test adopts fuzzy orthogonal method to analyze the main effects and the interaction between two factors, taking tensile strength, diameter variety rate and pH value of indicator as evaluation index. The results show that: the environmental factor influencing the sealing performance of hydrogenated nitrile O-ring from high to low by turns is temperature, pressure and CO2 volume fraction, while the interaction between temperature and pressure is the most significant. It provides a new way to study the influence of downhole complex environment on the performance of rubber sealing material. Moreover, the results have important reference value to further study the failure mechanism of rubber sealing ring in many environmental factors and the rational use in engineering.

Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

KAUST Repository

Elshewy, Ahmed M.

2013-12-01

Oxygen and Nitrogen containing compounds are of utmost importance due to their interesting and diverse biological activities. The construction of the C-O and C–N bonds is of significance as it opens avenues for the introduction of ether and amine linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts or ligands in many cases. Thus, it is a challenge to develop alternative, milder, cheaper and more reproducible methodologies for the construction of these types of bonds. Herein, we introduce a new efficient ligand free catalytic system for C-O and C-N bond formation reactions.

3,4-O-Isopropylidene-2-C-methyl-d-galactonolactone

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N. Dai

2010-02-01

Full Text Available X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title molecule, C10H16O6, in which the 1,5-lactone ring exists in a boat conformation. The use of d-galactose in the synthesis determined the absolute stereochemistry. The crystal exists as O—H...O hydrogen-bonded layers in the ab plane, with each molecule acting as a donor and acceptor for two hydrogen bonds.

Radiation-induced O-glycoside bond scission in carbohydrates

International Nuclear Information System (INIS)

Kisel', R.M.

2005-01-01

Regularities in formation of products resulting from O-glycoside bond cleavage on radiolysis of aqueous solutions of (-methyl-D-glucopyranoside (I), 3-O-methylglucopyranose (II), maltose and lactose were studied. Oxygen and quinones were shown to inhibit radiation-induced homolytic destruction processes taking place in glycosides. The data obtained in this study enabled the authors to demonstrate an important role played by fragmentation reaction of C-2 radicals generated from the starting substances in formation of final radiolysis products. (authors)

Crystal structure of diquabis (3-hydroxybenzoato-κO)bis(nicotinamide-κN)zinc(II)

International Nuclear Information System (INIS)

Sahin, O.; Buyukgungor, O.; Koese, D. A.; Necefoglu, H.

2010-01-01

The title compound, [Zn(C 7 H 5 O 3 ) 2 (C 6 H 6 N 2 O) 2 (H 2 O) 2 ], is a two-dimensional hydrogen-bonded supramolecular complex. The Zn I I ion resides on the centre of symmetry and is in an octahedral coordination environment comprising two pyridyl N atoms, two carboxylate O atoms and two O atoms from water molecules. Intermolecular N-H...O and O-H...O hydrogen bonds produce R 1 1 (6), R 2 2 (7), R 2 2 (8), R 2 2 (16), R 2 2 (20), R 2 2 (22) and R 3 3 (30) rings which lead to a one-dimensional polymeric chains. An extensive two-dimensional network of N-H...O, O-H...O, C-H...O hydrogen bonds, and C-H...π interactions are responsible for crystal stabilization.

Leak Rate Performance of Silicone Elastomer O-Rings Contaminated with JSC-1A Lunar Regolith Simulant

Science.gov (United States)

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

Contamination of spacecraft components with planetary and foreign object debris is a growing concern. Face seals separating the spacecraft cabin from the debris filled environment are particularly susceptible; if the seal becomes contaminated there is potential for decreased performance, mission failure, or catastrophe. In this study, silicone elastomer O-rings were contaminated with JSC- 1A lunar regolith and their leak rate performance was evaluated. The leak rate values of contaminated O-rings at four levels of seal compression were compared to those of as-received, uncontaminated, O-rings. The results showed a drastic increase in leak rate after contamination. JSC-1A contaminated O-rings lead to immeasurably high leak rate values for all levels of compression except complete closure. Additionally, a mechanical method of simulant removal was examined. In general, this method returned the leak rate to as-received values.

The electrical properties of low pressure chemical vapor deposition Ga doped ZnO thin films depending on chemical bonding configuration

Energy Technology Data Exchange (ETDEWEB)

Jung, Hanearl [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Doyoung [School of Electrical and Electronic Engineering, Ulsan College, 57 Daehak-ro, Nam-gu, Ulsan 680-749 (Korea, Republic of); Kim, Hyungjun, E-mail: hyungjun@yonsei.ac.kr [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2014-04-01

Highlights: • Undoped and Ga doped ZnO thin films were deposited using DEZ and TMGa. • Effects of Ga doping using TMGa in Ga doped ZnO were investigated. • Degraded properties from excessive doping were analyzed using chemical bondings. - Abstract: The electrical and chemical properties of low pressure chemical vapor deposition (LP-CVD) Ga doped ZnO (ZnO:Ga) films were systematically investigated using Hall measurement and X-ray photoemission spectroscopy (XPS). Diethylzinc (DEZ) and O{sub 2} gas were used as precursor and reactant gas, respectively, and trimethyl gallium (TMGa) was used as a Ga doping source. Initially, the electrical properties of undoped LP-CVD ZnO films depending on the partial pressure of DEZ and O{sub 2} ratio were investigated using X-ray diffraction (XRD) by changing partial pressure of DEZ from 40 to 140 mTorr and that of O{sub 2} from 40 to 80 mTorr. The resistivity was reduced by Ga doping from 7.24 × 10{sup −3} Ω cm for undoped ZnO to 2.05 × 10{sup −3} Ω cm for Ga doped ZnO at the TMG pressure of 8 mTorr. The change of electric properties of Ga doped ZnO with varying the amount of Ga dopants was systematically discussed based on the structural crystallinity and chemical bonding configuration, analyzed by XRD and XPS, respectively.

(Carbonato-κ(2)O,O')bis-(5,5'-dimethyl-2,2'-bipyridyl-κ(2)N,N')cobalt(III) bromide trihydrate.

Science.gov (United States)

Arun Kumar, Kannan; Meera, Parthsarathi; Amutha Selvi, Madhavan; Dayalan, Arunachalam

2012-04-01

In the title complex, [Co(CO(3))(C(12)H(12)N(2))(2)]Br·3H(2)O, the Co(III) cation has a distorted octa-hedral coordination environment. It is chelated by four N atoms of two different 5,5'-dimethyl-2,2'-bipyridyl (dmbpy) ligands in axial and equatorial positions, and by two O atoms of a carbonate anion completing the equatorial positions. Although the water mol-ecules are disordered and their H atoms were not located, there are typical O⋯O distances between 2.8 and 3.0 Å, indicating O-H⋯O hydrogen bonding. The crystal packing is consolidated by C-H⋯O and C-H⋯Br hydrogen bonds, as well as π-π stacking inter-actions between adjacent pyridine rings of the dmbpy ligands, with centroid-centroid distances of 3.694 (3) and 3.7053 (3) Å.

Resistência de união à dentina de quatro sistemas adesivos Bond strength of four adhesive systems to dentin

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Marcela Rocha de Oliveira Carrilho

2002-09-01

Full Text Available O objetivo do presente estudo foi avaliar a resistência adesiva de quatro sistemas adesivos, composicionalmente diferentes, aplicados à dentina humana. Doze dentes terceiros molares humanos tiveram o esmalte oclusal removido para exposição de uma superfície plana de dentina, na qual foram realizados os procedimentos de adesão. Os dentes foram aleatoriamente divididos em quatro grupos, considerando-se o sistema adesivo e a resina composta a serem empregados: Grupo 1 - Single Bond + P60 (SB; Grupo 2 - Bond 1 + Surefil (B1; Grupo 3 - Prime & Bond NT + Alert (NT e Grupo 4 - Prime & Bond 2.1 + TPH (2.1. Após 24 h de armazenagem em água destilada a 37ºC, os dentes foram seccionados, longitudinalmente, em cortes perpendiculares entre si, para que fossem obtidos espécimes em formato de um paralelogramo com secção transversal retangular de 0,8 mm² de área e 10 mm de comprimento, em média. Os espécimes foram submetidos ao teste de microtração. A análise de variância (alfa = 0,05 demonstrou não haver diferença significante entre os valores médios de resistência obtidos pelos quatro adesivos, embora a análise dos espécimes que sofreram fratura precoce tenha evidenciado menor sensibilidade para o sistema SB.The purpose of the present study was to evaluate the bond strength of four adhesive systems to dentin. Twelve human third molars had their occlusal enamel removed in order to expose a flat dentinal surface, on which the adhesive procedures were carried out. The teeth were divided into four groups, according to the employed adhesive system and composite resin: Group 1 - Single Bond + P60 (SB; Group 2 - Bond 1 + Surefil (B1; Group 3 - Prime & Bond NT + Alert (NT; and Group 4 - Prime & Bond 2.1 + TPH (2.1. After 24 h in distilled water at 37ºC, the teeth were longitudinally sectioned in two perpendicular directions in order to obtain parallelogram-shaped specimens with a cross-sectional area of 0.8 mm² and 10 mm of length, on the

Infrared spectroscopic investigation of M(H2PO4)2x2H2O (M=Mg, Mn, Cd) dehydration products

International Nuclear Information System (INIS)

Pechkovskij, V.V.; Dzyuba, E.D.; Mel'nikova, R.Ya.; Salonets, G.I.; Kovalishina, V.I.; Malashonok, I.E.

1982-01-01

Using the method of IR spectroscopy the composition of products separated at different stages of M(H 2 PO 4 ) 2 x2H 2 O dehydration, where M=Mg, Mn, Cd, has been investigated. It is shown that cation influence is expressed in strengthening of bond of proton-containing groups in the structure of initial compounds from magnesium to cadmium. A supposition is made that the difference in bond character of the groups more evidently expressed for partially dehydrated products of the composition M(H 2 PO 4 ) 2 , conditions a possibility of dehydration in two directions- with the formation of intermediate phase MH 2 P 2 O 7 or with separation of three phosphoric acid

Avaliação da resistência adesiva e do padrão de descolagem de diferentes sistemas de colagem de braquetes associados à clorexidina Evaluation of the bond strength and debonding pattern of different bracket bonding systems associated with chlorhexidine

Directory of Open Access Journals (Sweden)

Jorge Luís de Oliveira Ribeiro

2008-08-01

Full Text Available OBJETIVOS: o objetivo deste estudo in vitro foi avaliar a resistência adesiva e o padrão de descolagem de diferentes sistemas de colagem de braquetes (Sistema Transbond XT / 3M-Unitek e Sistema Enlight / Ormco cujos respectivos adesivos foram pré-misturados ao verniz de clorexidina (Cervitec / Ivoclar-Vivadent. METODOLOGIA: a amostra utilizada foi constituída por 60 pré-molares humanos, extraídos por indicações ortodônticas, incluídos em cilindros de PVC e divididos aleatoriamente em quatro grupos: grupo 1 - Sistema Transbond XT conforme prescrito pelo fabricante; grupo 2 - Sistema Transbond XT associado a verniz de clorexidina; grupo 3 - Sistema Enlight conforme prescrito pelo fabricante; grupo 4 - Sistema Enlight associado a verniz de clorexidina. A resistência adesiva foi avaliada pelo teste de cisalhamento na máquina de ensaios universal EMIC (0,5mm/min; o padrão de descolagem foi avaliado, através da lupa estereoscópica STEMI 2000-C / Zeiss (20x, pela observação do Índice de Adesivo Remanescente (IAR na superfície do esmalte dentário, após a descolagem dos braquetes. RESULTADOS: não houve diferença estatisticamente significante (p AIM: The objective of this in vitro study was to evaluate the bond strength and the debonding pattern of different bracket bonding systems (Transbond XT System / 3M-Unitek and Enlight System / Ormco whose respective adhesives were pre-mixed with chlorhexidine varnish (Cervitec / Ivoclar-Vivadent. METHODS: The sample used consisted of sixty human pre-molars extracted for orthodontic purposes, included in PVC cylinder and randomly divided in four experimental groups: group 1 - Transbond XT System according to the manufacturer’s instructions; group 2 - Transbond XT System combined with chlorhexidine varnish; group 3 - Enlight System according to the manufacturer’s instructions; group 4 - Enlight System combined with chlorhexidine varnish. The bond strength evaluation was obtained through

A mão que desenha o corpo: O lago da lua

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Vinícius Lopes Passos

2003-10-01

Full Text Available Em O lago da lua, Paula Tavares, escritora angolana radicada em Portugal, amalgama corpo e poesia, resultando num trabalho delicado, pulsante e, por vezes, agressivo, em que o feminino comparece na linguagem da memória, nomeando o mundo de dentro e de fora, misturando o universo africano com o europeu. O embaralhamento das tradições revela o sensível e o cognoscível, bem cosidos num texto poético particular, cujas imagens conduzem o leitor para o tempo contemplativo da arte – no caso a poesia – mas também para o tempo investigativo e analítico da razão, em suas insuspeitas relações. O propósito aqui é apresentar uma breve leitura deste livro da autora, enfatizando a relação poesia e erotismo como agregadora de valores estéticos.

Valence electron structure and properties of the ZrO2

Institute of Scientific and Technical Information of China (English)

2008-01-01

To reveal the properties of ZrO2 at the atom and electron levels, the valence elec- tron structures of three ZrO2 phases were analyzed on the basis of the empirical electron theory of solids and molecules. The results showed that the hybridization levels of Zr and O atoms in the m-ZrO2 were the same as those in the t-ZrO2, while those in the c-ZrO2 rose markedly. The electron numbers and bond energies on the strongest covalent bonds in the m-ZrO2 phase were the greatest, the values were 0.901106 and 157.5933 kJ/mol, respectively. Those in the t-ZrO2 phase took second place, which were 0.722182 and 123.9304 kJ/mol, and those in the c-ZrO2 phase were the smallest, which were 0.469323 and 79.0289 kJ/mol. According to the product of the bond energy on the strongest covalent bond and equivalent bond number (this value reflected the crystal cohesive energy), the order from the greatness to smallness was the c-ZrO2> t-ZrO2 > m-ZrO2. This showed that the m-phase bonds were the tightest, their energy was the smallest, the crystal cohe- sive energy of the m-phase was the largest, and the m-phase existed most stably at room temperature. So it must need energy or higher temperature to take apart the stronger covalent bonds to form a new phase.

Valence electron structure and properties of the ZrO2

Institute of Scientific and Technical Information of China (English)

LI JinPing; MENG SongHe; HAN JieCai; ZHANG XingHong

2008-01-01

To reveal the properties of ZrO2 at the atom and electron levels, the valence elec-tron structures of three ZrO2 phases were analyzed on the basis of the empirical electron theory of solids and molecules. The results showed that the hybridization levels of Zr and O atoms in the m-ZrO2 were the same as those in the t-ZrO2, while those in the c-ZrO2 rose markedly. The electron numbers and bond energies on the strongest covalent bonds in the m-ZrO2 phase were the greatest, the values were 0.901106 and 157.5933 kJ/mol, respectively. Those in the t-ZrO2 phase took second place, which were 0.722182 and 123.9304 kJ/mol, and those in the c-ZrO2 phase were the smallest, which were 0.469323 and 79.0289 kJ/mol. According to the product of the bond energy on the strongest covalent bond and equivalent bond number (this value reflected the crystal cohesive energy), the order from the greatness to smallness was the c-ZrO2 t-ZrO2 m-ZrO2. This showed that the m-phase bonds were the tightest, their energy was the smallest, the crystal cohe-sive energy of the m-phase was the largest, and the m-phase existed most stably at room temperature. So it must need energy or higher temperature to take apart the stronger covalent bonds to form a new phase.

A two-dimensional CdII coordination polymer: poly[diaqua[μ3-5,6-bis(pyridin-2-ylpyrazine-2,3-dicarboxylato-κ5O2:O3:O3,N4,N5]cadmium

Directory of Open Access Journals (Sweden)

Monserrat Alfonso

2016-09-01

Full Text Available The reaction of 5,6-bis(pyridin-2-ylpyrazine-2,3-dicarboxylic acid with cadmium dichloride leads to the formation of the title two-dimensional coordination polymer, [Cd(C16H8N4O4(H2O2]n. The metal atom is sevenfold coordinated by one pyrazine and one pyridine N atom, two water O atoms, and by two carboxylate O atoms, one of which bridges two CdII atoms to form a Cd2O2 unit situated about a centre of inversion. Hence, the ligand coordinates to the cadmium atom in an N,N′,O-tridentate and an O-monodentate manner. Within the polymer network, there are a number of O—H...O hydrogen bonds present, involving the water molecules and the carboxylate O atoms. There are also C—H...N and C—H...O hydrogen bonds present. In the crystal, the polymer networks lie parallel to the bc plane. They are aligned back-to-back along the a axis with the non-coordinating pyridine rings directed into the space between the networks.

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

Science.gov (United States)

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

2014-01-20

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

Density functional theory investigation of the geometric and electronic structures of [UO2(H2O)m(OH)n](2 - n) (n + m = 5).

Science.gov (United States)

Ingram, Kieran I M; Häller, L Jonas L; Kaltsoyannis, Nikolas

2006-05-28

Gradient corrected density functional theory has been used to calculate the geometric and electronic structures of the family of molecules [UO2(H2O)m(OH)n](2 - n) (n + m = 5). Comparisons are made with previous experimental and theoretical structural and spectroscopic data. r(U-O(yl)) is found to lengthen as water molecules are replaced by hydroxides in the equatorial plane, and the nu(sym) and nu(asym) uranyl vibrational wavenumbers decrease correspondingly. GGA functionals (BP86, PW91 and PBE) are generally found to perform better for the cationic complexes than for the anions. The inclusion of solvent effects using continuum models leads to spurious low frequency imaginary vibrational modes and overall poorer agreement with experimental data for nu(sym) and nu(asym). Analysis of the molecular orbital structure is performed in order to trace the origin of the lengthening and weakening of the U-O(yl) bond as waters are replaced by hydroxides. No evidence is found to support previous suggestions of a competition for U 6d atomic orbitals in U-O(yl) and U-O(hydroxide)pi bonding. Rather, the lengthening and weakening of U-O(yl) is attributed to reduced ionic bonding generated in part by the sigma-donating ability of the hydroxide ligands.

catena-Poly[lead(II-[μ-2,4-diamino-6-(piperidin-1-ylpyrimidine N-oxide-κ2O:O]di-μ-iodido

Directory of Open Access Journals (Sweden)

Maryam Ranjbar

2009-07-01

Full Text Available The N-oxide O atom of the minoxidil unit in the 1/1 adduct with lead(II iodide, [PbI2(C9H15N5O]n, bridges two PbII atoms, as do each of the I atoms. The bridging interactions give rise to a linear chain motif that propagates along the a axis of the orthorhombic unit cell. The coordination sphere around the six-coordinate PbII atom is a distorted ψ-monocapped octahedron in which the stereochemically active lone pair caps one of the faces defined by the O and I atoms forming the longer Pb—O or Pb—I bonds. The PbII atom lies on a mirror plane; the mirror plane is perpendicular to the pyrimidine ring and it bisects the piperidine ring. The aromatic ring is disordered about the mirror plane with respect to the 1-nitrogen and 5-carbon atoms.

Secagem de fatias de abacaxi in natura e pré-desidratadas por imersão-impregnação: cinética e avaliação de modelos Assessment of convective drying models for fresh and osmo-dehydrated pineapple rings

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Rafael Gomes Dionello

2009-03-01

Full Text Available O presente estudo teve como objetivos investigar o efeito da impregnação de sacarose e de açúcar invertido na taxa de secagem por convecção de abacaxi e avaliar a adequação de nove modelos matemáticos na descrição das curvas de secagem. Os testes experimentais foram feitos empregando-se coroas circulares de abacaxi in natura e pré-desidratadas por imersão-impregnação em soluções de sacarose (0,40, 0,44 e 0,47 g.mL-1 e em xarope de açúcar invertido. A pré-desidratação osmótica foi realizada a 40 e 50 ºC, por 2 horas, sob agitação de 60 min-1. A secagem por convecção foi feita em secador do tipo gabinete com bandejas, a 60 ºC e 1,25 m.s-1. O grau de ajuste dos modelos foi avaliado por meio do coeficiente de determinação, da raiz do erro quadrático médio, do erro percentual absoluto médio e por análise de dispersão de resíduos. As maiores taxas de secagem foram obtidas para amostras in natura; naquelas pré-desidratadas osmoticamente, o aumento da concentração da solução ocasionou a diminuição da taxa de secagem. O modelo de Wang e Singh foi o que melhor descreveu a secagem por convecção de coroas circulares de abacaxi.The effect of glucose and invert sugar impregnation on the convective drying rate of pineapple and the suitability of nine mathematical models to describe the drying curves were investigated. Tests were conducted using fresh pineapple rings and samples which were pre-treated by osmotic dehydration in sucrose solutions (0.40, 0.44, and 0.47 g mL-1 and in invert sugar syrup. Osmotic pre-treatments were performed at 40 and 50 ºC for 2 hours at 60 min-1. The convective drying was performed in a tray cabinet dryer using heated ambient air at 60 ºC and 1.25 m.s-1. The adjustment levels of the models were based on the correlation coefficient, the root mean square error, mean absolute percentage error, and residual plot analysis. The highest rates of convective drying were obtained for the fresh

Effective tuning of electron charge and spin distribution in a dot-ring nanostructure at the ZnO interface

Science.gov (United States)

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

2018-05-01

Electronic states and the Aharonov-Bohm effect in ZnO quantum dot-ring nanostructures containing few interacting electrons reveal several unique features. We have shown here that in contrast to the dot-rings made of conventional semiconductors, such as InAs or GaAs, the dot-rings in ZnO heterojunctions demonstrate several unique characteristics due to the unusual properties of quantum dots and rings in ZnO. In particular the energy spectra of the ZnO dot-ring and the Aharnov-Bohm oscillations are strongly dependant on the electron number in the dot or in the ring. Therefore even small changes of the confinement potential, sizes of the dot-ring or the magnetic field can drastically change the energy spectra and the behavior of Aharonov-Bohm oscillations in the system. Due to this interesting phenomena it is possible to effectively control with high accuracy the electron charge and spin distribution inside the dot-ring structure. This controlling can be achieved either by changing the magnetic field or the confinement potentials.

Potassium (2,2'-bipyridine-κN,N')bis-(carbonato-κO,O')cobaltate(III) dihydrate.

Science.gov (United States)

Wang, Jian-Fei; Lin, Jian-Li

2010-09-30

In the title compound, K[Co(CO(3))(2)(C(10)H(8)N(2))]·2H(2)O, the Co(III) atom is coordinated by two bipyridine N atoms and four O atoms from two bidentate chelating carbonate anions, and thus adopts a distorted octa-hedral N(2)O(4) environment. The [Co(bipy)(CO(3))(2)](-) (bipy is 2,2'-bipyridine) -units are stacked along [100] via π-π stacking inter-actions, with inter-planar distances between the bipyridine rings of 3.36 (4) and 3.44 (6) Å, forming chains. Classical O-H⋯O hydrogen-bonding inter-actions link the chains, forming channels along (100) in which the K(+) ions reside and leading to a three-dimensional supra-molecular architecture.

Crystal structure of (2-formylphenolato-κ2O,O′oxido(2-{[(2-oxidoethylimino]methyl}phenolato-κ3O,N,O′vanadium(V

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Sowmianarayanan Parimala

2015-05-01

Full Text Available In the unsymmetrical title vanadyl complex, [V(C9H9NO2(C7H5O2O], one of the ligands (2-formylphenol is disordered over two sets of sites, with an occupancy ratio of 0.55 (2:0.45 (2. The metal atom is hexacoordinated, with a distorted octahedral geometry. The vanadyl O atom (which subtends the shortest V—O bond occupies one of the apical positions and the remaining axial bond (the longest in the polyhedron is provided by the (disordered formyl O atoms. The basal plane is defined by the two phenoxide O atoms, the iminoalcoholic O and the imino N atom. The planes of the two benzene rings are almost perpendicular to each other, subtending an interplanar angle of 84.1 (2° between the major parts. The crystal structure features weak C—H...O and C—H...π interactions, forming a lateral arrangement of adjacent molecules.

Topology-energy relationships and lowest energy configurations for pentagonal dodecahedral (H2O)20X clusters, X=empty, H2O, NH3, H3O+: The importance of O-topology

Science.gov (United States)

Anick, David J.

2010-04-01

For (H2O)20X water clusters consisting of X enclosed by the 512 dodecahedral cage, X=empty, H2O, NH3, and H3O+, databases are made consisting of 55-82 isomers optimized via B3LYP/6-311++G∗∗. Correlations are explored between ground state electronic energy (Ee) or electronic energy plus zero point energy (Ee+ZPE) and the clusters' topology, defined as the set of directed H-bonds. Linear regression is done to identify topological features that correlate with cluster energy. For each X, variables are found that account for 99% of the variance in Ee and predict it with a rms error under 0.2 kcal/mol. The method of analysis emphasizes the importance of an intermediate level of structure, the "O-topology," consisting of O-types and a list of O pairs that are bonded but omitting H-bond directions, as a device to organize the databases and reduce the number of structures one needs to consider. Relevant variables include three parameters, which count the number of H-bonds having particular donor and acceptor types; |M|2, where M is the cluster's vector dipole moment; and the projection of M onto the symmetry axis of X. Scatter diagrams for Ee or Ee+ZPE versus |M| show that clusters fall naturally into "families" defined by the values of certain discrete parameters, the "major parameters," for each X. Combining "family" analysis and O-topologies, a small group of clusters is identified for each X that are candidates to be the global minimum, and the minimum is determined. For X=H3O+, one cluster with central hydronium lies just 2.08 kcal/mol above the lowest isomer with surface hydronium. Implications of the methodology for dodecahedral (H2O)20(NH4+) and (H2O)20(NH4+)(OH-) are discussed, and new lower energy isomers are found. For MP2/TZVP, the lowest-energy (H2O)20(NH4+) isomer features a trifurcated H-bond. The results suggest a much more efficient and comprehensive way of seeking low-energy water cluster geometries that may have wide applicability.

Influência da adição de carga inorgânica aos sistemas adesivos na resistência adesiva à dentina = Influence of filler addition to bonding agents on dentin bond strength

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Cesar, Patricia Desiderio

2005-01-01

Full Text Available O objetivo desse estudo foi avaliar o papel da presença ou não de partículas de carga nos sistemas adesivos sobre a resistência adesiva à dentina. Foram utilizados 70 dentes bovinos, divididos em 7 grupos, que foram embutidos em resina acrílica e desgastados até a exposição de uma área plana de dentina. Todos os espécimes receberam o condicionamento ácido e aplicação dos sistemas adesivos, contendo ou não as partículas de carga, de acordo com as instruções do fabricante: Prime & Bond 2. 1 (sem carga – SC, Prime & Bond NT (com carga – CC, Prime & Bond 2. 1 + 10% de SiO² (CC, One Step (SC, One Step Plus (CC, Sigle Bond (SC e Single Bond +10% de SiO² (CC. Cilindros de resina composta TPH Spectrum foram realizados sobre a área de adesão. Os espécimes foram armazenados por 24 a 37C°, e então submetidos ao teste de cisalhamento. Os dados obtidos foram submetidos à análise estatística, empregando- se o teste de análise de variância paramétrica, seguida pelo teste de Tukey a um nível de significância de 5%. Concluiu-se que, para todos os sistemas adesivos testados, a adição de partículas de carga não resultou em diferenças significativas na força de adesão. Porém, entre as marcas comerciais, observamos diferenças significativas, o que demonstra a influência dos demais componentes na eficiência adesiva

Insegurança alimentar, vínculo mãe-filho e desnutrição infantil em área de alta vulnerabilidade social Food insecurity, mother-child bonding and child malnutrition in a high social vulnerability area

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Viviane Laudelino Vieira

2010-06-01

Full Text Available OBJETIVO: analisar a insegurança alimentar e o vínculo inadequado mãe-filho como dois potenciais determinantes da desnutrição em crianças de quatro a seis anos de idade. MÉTODOS: estudo de caso-controle desenvolvido em Escolas Municipais de Educação Infantil (EMEIs no Jardim Jaqueline, área de alta vulnerabilidade social do município de São Paulo, Brasil. Foram aplicados a Escala Brasileira de Insegurança Alimentar e o Protocolo de Avaliação do Vínculo Mãe-filho, além de coletadas informações biológicas e socio-econômicas. Para verificação dos efeitos de cada variável independente e controle dos efeitos das demais variáveis incluídas no modelo, foi utilizado o modelo de regressão logística múltipla. RESULTADOS: verificou-se que tanto a insegurança alimentar familiar (OR=3,6 como o vínculo inadequado mãe-filho (OR=9,4 estiveram associados com a desnutrição infantil (pOBJECTIVES: to investigate food insecurity and inadequate bonding between mother and child as two potential factors determining malnutrition among children aged between four and six years. METHODS: a case-control study was conducted in Municipal Primary Schools in Jardim Jaqueline, a highly underprivileged neighborhood of the municipality of São Paulo, Brazil. The Brazilian Food Insecurity Scale and the Mother-Child Bonding Evaluation Protocol were applied and biological and socio-economic data collected. The multiple logistic regression model was used to confirm the effect of each independent variable and to control for other variables included in the model. RESULTS: both family food insecurity (OR=3.6 and inadequate mother-child bonding (OR=9.4 were confirmed to be associated with child malnutrition (p<0.05, even when controlled for weight at birth, age, and marital and employment status of mother. CONCLUSIONS: both family food insecurity (OR=3.6 and inadequate mother-child bonding (OR=9.4 were shown to be factors determining the occurrence of

Long-term evaluation of fluoroelastomer O-rings in UF6

International Nuclear Information System (INIS)

Russell, R.G.; Otey, M.G.; Dippo, G.L.

1986-01-01

A major component in the gaseous centrifuge enrichment plant (GCEP) was fluoroelastomer O-rings, which were used to seal the uranium hexafluoride (UF 6 ) gas system. A program utilizing accelerated test conditions was used to help identify the best material out of four selected candidates and to predict the service life of these materials at GCEP conditions. The tests included accelerated temperatures, mechanical stress, and UF 6 exposure. Data were evaluated using the Newman--Keuls 1 ranking system to identify the best material and a zero-order reaction rate equation to help predict service life. This presentation includes a description of the test facility, the materials tested, the types of tests, objectives of the study, service life predictions, and conclusions. The O-rings are predicted to last approx. 30 years, and a high-molecular-weight polymer had the best performance ranking

Structure of Ga2O3(ZnO)6: a member of the homologous series Ga2O3(ZnO)m

International Nuclear Information System (INIS)

Michiue, Yuichi; Kanke, Yasushi; Kimizuka, Noboru

2008-01-01

The structure of Ga 2 O 3 (ZnO) 6 was determined using singlecrystal X-ray diffraction techniques in the space group Cmcm. The metal ion sublattice resembles some of the Zn ions in the wurtzite ZnO structure. The oxygen ion sublattice in Ga 2 O 3 (ZnO) 6 also resembles some of the O ions in ZnO. Structural relationships between Ga 2 O 3 (ZnO) 6 and ZnO are discussed, illustrating the process for obtaining the centrosymmetric Ga 2 O 3 (ZnO) 6 structure from the noncentrosymmetric ZnO. Structures of phases in the homologous series Ga 2 O 3 (ZnO) m are predicted on the basis of the structural data for Ga 2 O 3 (ZnO) 6 . The structures of even m are constructed by simply extending the structure units seen in Ga 2 O 3 (ZnO) 6 , while those of odd m consist of structure units which are of different types from those used for even m. (orig.)

Bonding of NH{sub 3}, CO, and NO to NiO and Ni-doped MgO: a problem for density functional theory

Energy Technology Data Exchange (ETDEWEB)

Pacchioni, Gianfranco [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca (Italy); Di Valentin, Cristiana [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca (Italy); Dominguez-Ariza, David [Departament de Quimica FIsica i Centre de Recerca en Quimica Teorica, Universitat de Barcelona i Parc Cientific de Barcelona, C/ Marti i Franques 1, E-08028 Barcelona (Spain); Illas, Francesc [Departament de QuImica FIsica i Centre de Recerca en Quimica Teorica, Universitat de Barcelona i Parc CientIfic de Barcelona, C/ Marti i Franques 1, E-08028 Barcelona (Spain); Bredow, Thomas [Theoretische Chemie, Universitaet Hannover, Am Kleinen Felde 30, 30167 Hannover (Germany); Kluener, Thorsten [Department Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Staemmler, Volker [Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

2004-07-07

Recent experimental results (Hoeft et al 2001 Phys. Rev. Lett. 87 086101) have questioned the capability of current theoretical methods for describing the bonding of NH{sub 3}, CO, and NO with the NiO(100) surface. We show that these systems do indeed represent a challenge to theory. For different reasons, density functional theory (DFT) fails in describing the bonding of these molecules to the NiO surface. The gradient-corrected functionals which work better for the properties of NH{sub 3}/NiO and CO/NiO (energies, geometries, vibrations) provide wrong answers for NO/NiO and vice versa. This is not due to the well-known difficulty as regards DFT describing the insulating character of NiO. In fact, exactly the same problem is found for isolated Ni{sup 2+} impurities in MgO. A correct description of the bonding of both closed-shell (NH{sub 3} and CO) and open-shell (NO) molecules to Ni{sub x}Mg{sub 1-x}O is obtained only after inclusion of dynamical correlation and dispersion forces via wavefunction-based methods. However, even with correlated calculations some uncertainties exist regarding the predicted value of the energy of adsorption of NO on NiO. While CASPT2 calculations reach reasonable agreement with experiment, the results of approximate coupled-cluster calculations (the multi-configuration coupled-electron-pair approach) substantially underestimate the adsorption energy.

Phase diagrams of systems of Sr2V2O7-M2V2O7 and of Ba2V2O7-M2V2O7 (M=Ca,Cd)

International Nuclear Information System (INIS)

Fotiev, A.A.; Zhuravlev, V.D.; Zhukov, V.P.

1982-01-01

Using the methods of X-ray phase and differential thermal anlyses phase equilibria in the systems Sr 2 V 2 O 7 -M 2 V 2 O 7 and Ba 2 V 2 O 7 -M 2 V 2 O 7 , where M--Ca, Cd, are studied, their phase diagrams being built. New double pyrovanadates Mosub(0.5)Srsub(1.5)Vsub(2)Osub(7) and MBaV 2 O 7 are found [ru

Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

Science.gov (United States)

Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

2017-06-01

Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

Perovskite BaBiO3 Transformed Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence.

Science.gov (United States)

Li, Hong; Zhao, Qing; Liu, Bo-Mei; Zhang, Jun-Ying; Li, Zhi-Yong; Guo, Shao-Qiang; Ma, Ju-Ping; Kuroiwa, Yoshihiro; Moriyoshi, Chikako; Zheng, Li-Rong; Sun, Hong-Tao

2018-04-14

Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Here we present the successful synthesis of stoichiometric layered BaBiO2.5 enabled by a non-topotactic phase transformation of perovskite BaBiO3. By analysing the synchrotron X-ray diffraction data using the maximum entropy method/Rietveld technique, we find that Bi forms unusual chemical bondings with four oxygen atoms, featuring one ionic bonding and three covalent bondings that results in an asymmetric coordination geometry. A broad range of photophysical characterizations reveal that this peculiar structure shows near-infrared luminescence differing from conventional Bi-bearing systems. Experimental and theoretical results lead us to propose the excitonic nature of luminescence. Our work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. We envisage that this work could inspire interest for the exploration of a range of materials containing heavier p-block elements, offering prospects for the finding of systems with unusual properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced photocatalytic degradation of Amaranth dye on mesoporous anatase TiO2: evidence of C-N, N[double bond, length as m-dash]N bond cleavage and identification of new intermediates.

Science.gov (United States)

Naik, Amarja P; Salkar, Akshay V; Majik, Mahesh S; Morajkar, Pranay P

2017-07-01

The photocatalytic degradation mechanism of Amaranth, a recalcitrant carcinogenic azo dye, was investigated using mesoporous anatase TiO 2 under sunlight. Mesoporous anatase TiO 2 of a high photocatalytic activity has been synthesized using a sol-gel method and its photocatalytic activity for the degradation of Amaranth dye has been evaluated with respect to Degussa P25. The effect of bi-dentate complexing agents like oxalic acid, ethylene glycol and urea on the surface properties of TiO 2 catalyst has been investigated using TG-DTA, FTIR, HR-TEM, SAED, PXRD, EDS, UV-DRS, PL, BET N 2 adsorption-desorption isotherm studies and BJH analysis. The influence of catalyst properties such as the mesoporous network, pore volume and surface area on the kinetics of degradation of Amaranth as a function of irradiation time under natural sunlight has been monitored using UV-Vis spectroscopy. The highest rate constant value of 0.069 min -1 was obtained for the photocatalytic degradation of Amaranth using TiO 2 synthesized via a urea assisted sol-gel synthesis method. The effect of the reaction conditions such as pH, TiO 2 concentration and Amaranth concentration on the photodegradation rate has been investigated. The enhanced photocatalytic activity of synthesized TiO 2 in comparison with P25 is attributed to the mesoporous nature of the catalyst leading to increased pore diameter, pore volume, surface area and enhanced charge carrier separation efficiency. New intermediates of photocatalytic degradation of Amaranth, namely, sodium-3-hydroxynaphthalene-2,7-disulphonate, 3-hydroxynaphthalene, sodium-4-aminonaphthalenesulphonate and sodium-4-aminobenzenesulphonate have been identified using LC-ESI-MS for the very first time, providing direct evidence for simultaneous bond cleavage pathways (-C-N-) and (-N[double bond, length as m-dash]N-). A new plausible mechanism of TiO 2 catalysed photodegradation of Amaranth along with the comparison of its toxicity to that of its degradation

O método simplex generalizado

OpenAIRE

Cardoso, Domingos Moreira

1992-01-01

Apresenta-se um novo método para a resolução de problemas de Programação Linear, que se designa por método simplex generalizado, por se considerar que generaliza o método simplex clássico. Com efeito, as sucessivas soluções admissíveis, que se vão determinando ao longo da sua aplicação, podem pertencer ao interior relativo de faces de dimensão superior a zero, fazendo-se os respectivos deslocamentos, entre estas faces, através de faces que, incluindo as anteriores, têm um...

Density Functional Study of Structures and Electron Affinities of BrO4F/BrO4F-

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Wei Li

2009-07-01

Full Text Available The structures, electron affinities and bond dissociation energies of BrO4F/BrO4F− species have been investigated with five density functional theory (DFT methods with DZP++ basis sets. The planar F-Br…O2…O2 complexes possess 3A' electronic state for neutral molecule and 4A' state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabatic electron affinity (EAad, the vertical electron affinity (EAvert, and the vertical detachment energy (VDE. The EAad value predicted by B3LYP method is 4.52 eV. The bond dissociation energies De (BrO4F → BrO4-mF + Om (m = 1-4 and De- (BrO4F- → BrO4-mF- + Om and BrO4F- → BrO4-mF + Om- are predicted. The adiabatic electron affinities (EAad were predicted to be 4.52 eV for F-Br…O2…O2 (3A'← 4A' (B3LYP method.

Incorporation of TiO2 nanotubes in a polycrystalline zirconia: Synthesis of nanotubes, surface characterization, and bond strength.

Science.gov (United States)

Dos Santos, Angélica Feltrin; Sandes de Lucena, Fernanda; Sanches Borges, Ana Flávia; Lisboa-Filho, Paulo Noronha; Furuse, Adilson Yoshio

2018-04-05

Despite numerous advantages such as high strength, the bond of yttria-stabilized zirconia polycrystal (Y-TZP) to tooth structure requires improvement. The purpose of this in vitro study was to evaluate the incorporation of TiO 2 nanotubes into zirconia surfaces and the bond strength of resin cement to the modified ceramic. TiO 2 nanotubes were produced by alkaline synthesis, mixed with isopropyl alcohol (50 wt%) and applied on presintered zirconia disks. The ceramics were sintered, and the surfaces were characterized by confocal laser microscopy, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) analysis. For bond strength, the following 6 groups (n=16) were evaluated: without TiO 2 and Single Bond Universal; with TiO 2 nanotubes and Single Bond Universal; without TiO 2 nanotubes and Z-prime; with TiO 2 nanotubes and Z-prime; without TiO 2 and Signum Zirconia Bond; with TiO 2 and Signum Zirconia Bond. After sintering, resin cement cylinders, diameter of 1.40 mm and 1 mm in height, were prepared and polymerized for 20 seconds. Specimens were stored in water at 37°C for 30 days and submitted to a shear test. Data were analyzed by 2-way ANOVA and Tukey honest significant difference (α=.05) tests. EDS analysis confirmed that nanoagglomerates were composed of TiO 2 . The shear bond strength showed statistically significant differences among bonding agents (P<.001). No significant differences were found with the application of nanotubes, regardless of the group analyzed (P=.682). The interaction among the bonding agent factors and addition of nanotubes was significant (P=.025). Nanotubes can be incorporated into zirconia surfaces. However, this incorporation did not improve bond strength. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Quantitative Evidence for Lanthanide-Oxygen Orbital Mixing in CeO2, PrO2, and TbO2.

Science.gov (United States)

Minasian, Stefan G; Batista, Enrique R; Booth, Corwin H; Clark, David L; Keith, Jason M; Kozimor, Stosh A; Lukens, Wayne W; Martin, Richard L; Shuh, David K; Stieber, S Chantal E; Tylisczcak, Tolek; Wen, Xiao-Dong

2017-12-13

Understanding the nature of covalent (band-like) vs ionic (atomic-like) electrons in metal oxides continues to be at the forefront of research in the physical sciences. In particular, the development of a coherent and quantitative model of bonding and electronic structure for the lanthanide dioxides, LnO 2 (Ln = Ce, Pr, and Tb), has remained a considerable challenge for both experiment and theory. Herein, relative changes in mixing between the O 2p orbitals and the Ln 4f and 5d orbitals in LnO 2 are evaluated quantitatively using O K-edge X-ray absorption spectroscopy (XAS) obtained with a scanning transmission X-ray microscope and density functional theory (DFT) calculations. For each LnO 2 , the results reveal significant amounts of Ln 5d and O 2p mixing in the orbitals of t 2g (σ-bonding) and e g (π-bonding) symmetry. The remarkable agreement between experiment and theory also shows that significant mixing with the O 2p orbitals occurs in a band derived from the 4f orbitals of a 2u symmetry (σ-bonding) for each compound. However, a large increase in orbital mixing is observed for PrO 2 that is ascribed to a unique interaction derived from the 4f orbitals of t 1u symmetry (σ- and π-bonding). O K-edge XAS and DFT results are compared with complementary L 3 -edge and M 5,4 -edge XAS measurements and configuration interaction calculations, which shows that each spectroscopic approach provides evidence for ground state O 2p and Ln 4f orbital mixing despite inducing very different core-hole potentials in the final state.

2,4-Dichloro-N-o-tolylbenzamide

Directory of Open Access Journals (Sweden)

Aamer Saeed

2009-07-01

Full Text Available In the title compound, C14H11Cl2NO, the central C—C(O—N—C amide unit makes dihedral angles of 68.71 (11 and 54.92 (12°, respectively, with the dichlorobenzene and tolyl rings. The two aromatic rings are inclined at 16.25 (17°. In the crystal, N—H...O hydrogen bonds link molecules into zigzag chains propagating in [001]. C—H...Cl contacts link these chains and additional C—H...O contacts generate stacks down b. Weak C—H...π and C—Cl...π interactions [Cl...centroid distance = 3.5422 (15 Å] may also stabilize the structure.

Arder de mão

OpenAIRE

Jacinto, João, 1966-

2013-01-01

Tese de doutoramento, Belas-Artes (Desenho), Universidade de Lisboa, Faculdade de Belas-Artes, 2013 Num século abstracto, como o séc.XX o foi, persistiram alguns intensos «olhar o rosto». Em quatro estúdios excessivos de pó, de tinta e de desordem, Antonin Artaud, Alberto Giacometi, Frank Auerbach e Leon Kossoff continuaram dia a dia a escavar o rosto, o mesmo rosto reclamando uma habilidade total e não condicionada da mão. Como que a verificar se o rosto ainda lá estava, se era possível o...

O texto eletrônico hipertextualizado: a máquina, o autor e o leitor

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Emanoel Cesar Pires de Assis

2012-09-01

Full Text Available http://dx.doi.org/10.5007/2176-8552.2011nesp1p110 O leitor de uma narrativa tradicional está temporalmente marcado por uma estrutura de começo, meio e fim. Já o leitor interativo-imersivo da narrativa eletrônica experimenta temporalidades narrativas múltiplas; diríamos mais, além de múltiplas elas podem ser análogas e/ou contraditórias, uma vez que a estrutura descentralizada da leitura hipertextual desloca espaço e tempo, dando ao leitor a experiência de uma leitura topográfica; ou seja, visual e estruturalmente concebida como se fosse a leitura de um mapa, onde não há um ponto inicial estabelecido, mas, sim, vários caminhos que podem ser seguidos. Ao deslocar o tempo, a leitura hipertextual torna-se um presente constante e contínuo. Assim: “O leitor eletrônico lê e não conclui sua leitura no tempo. O que faz é experimentar constantemente, em releituras sucessivas, possibilidades narrativas alternativas em uma vasta dimensão espacial e em um eterno presente” (BELLEI, 2002, p. 122.

Structure of Na/sub 2/As/sub 4/O/sub 11/

Energy Technology Data Exchange (ETDEWEB)

Driss, A.; Jouini, T.; Omezzine, M.

1988-05-15

Disodium tetraarsenate, M/sub r/=521.66, monoclinic, C2/c, a=9.049(3), b=8.287(3), c=11.508(5) A, ..beta..=102.74(4)/sup 0/, V=842(2) A/sup 3/, Z=4, D/sub m/=4.06 (by flotation), D/sub x/=4.11 Mg m/sup -3/, lambda(AgK anti ..cap alpha..)=0.5608 A, ..mu..=8.6 mm/sup -1/, F(000)=968, room temperature, final R=0.046 and ..omega..R=0.048 for 1153 independent reflections. The main feature of this structure is the existence of the first three-dimensional anion (As/sub 4/O/sub 11/)/sub n//sup 2n-/ in the chemistry of the condensed arsenates. It has the lowest O/As ratio (2.75) of the known arsenates showing marked condensation: all the O atoms are shared except one per AsO/sub 4/ tetrahedron. The structural unit is the As/sub 4/O/sub 15/ ring with point symmetry 2, built up from alternate AsO/sub 4/ tetrahedra and AsO/sub 6/ octahedra sharing corners. In addition, the two octahedra share one O atom located on the 2 axis. The As/sub 4/O/sub 15/ ring derives from the known centrosymmetric As/sub 4/O/sub 14/ ring by the cleavage of one As-O-As linkage between the two octahedra of the ring to form two new As-O-As linkages with AsO/sub 4/ tetrahedra connecting two rings, leading to a decrease of the O/As ratio. The As/sub 4/O/sub 15/ rings are further linked by sharing edges of AsO/sub 6/ octahedra to form a three-dimensional framework. This completes the set of the already known arrangements of the As/sub 4/O/sub 14/ ring (isolated units, infinite chains, layers).

Ab Initio Study of the Dynamical Si–O Bond Breaking Event in α-Quartz

International Nuclear Information System (INIS)

Su Rui; Zhang Hong; Han Wei; Chen Jun

2015-01-01

The Si–O bond breaking event in the α-quartz at the first triplet (T_1) excitation state is studied by using ab initio molecular dynamics (AIMD) and nudged elastic band calculations. A meta-stable non-bridging oxygen hole center and E′ center (NBOHC-E′) is observed in the AIMD which consists of a broken Si–O bond with a Si–O distance of 2.54 Å. By disallowing the re-bonding of the Si and O atoms, another defect configuration (III-Si/V-Si) is obtained and validated to be stable at both ground and excitation states. The NBOHC-E′ is found to present on the minimal energy pathway of the initial to III-Si/V-Si transition, showing that the generating of the NBOHC-E′ is an important step of the excitation induced structure defect. The energy barriers to produce the NBOHC-E′ and III-Si/V-Si defects are calculated to be 1.19 and 1.28 eV, respectively. The electronic structures of the two defects are calculated by the self-consistent GW calculations and the results show a clear electron transition from the bonding orbital to the non-bonding orbital. (paper)

Poly[[aqua(μ2-4,4′-bipyridine-κ2N:N′[μ3-3-bromo-2-(carboxylatomethylbenzoato-κ3O1:O1′:O2]cadmium] monohydrate

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Yangmei Liu

2012-08-01

Full Text Available In the title compound, {[Cd(C9H5BrO4(C10H8N2(H2O]·H2O}n, the CdII atom has a distorted octahedral coordination geometry. Two N atoms from two 4,4′-bipyridine (bipy ligands occupy the axial positions, while the equatorial positions are furnished by three carboxylate O atoms from three 3-bromo-2-(carboxylatomethylbenzoate (bcb ligands and one O atom from a water molecule. The bipy and bcb ligands link the CdII atoms into a three-dimensional network. O—H...O hydrogen bonds and π–π interactions between the pyridine and benzene rings [centroid–centroid distance = 3.736 (4 Å] are present in the crystal.

A relação assimétrica médico-paciente: repensando o vínculo terapêutico Asymmetric doctor-patient relationship: rethinking the therapeutic bond

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Andrea Caprara

2004-01-01

Full Text Available A relação médico-paciente é uma temática que hoje encontra um renovado interesse na produção cientifica, na formação e prática clínica com a aplicação de técnicas comunicacionais que podem proporcionar uma melhor qualidade na relação. O presente artigo, por meio de uma revisão da literatura e da apresentação dos resultados de uma pesquisa que realizamos sobre a relação entre médicos e pacientes no Programa de Saúde da Família no Estado do Ceará, se propõe a refletir sobre quais os fatores que estão na raiz desta problemática. Uma melhor relação médico-paciente não tem somente efeitos positivos na satisfação dos usuários e na qualidade dos serviços de saúde, mas exerce também uma influência direta sobre o estado de saúde dos pacientes. Esta demanda exige a implementação de mudanças visando à aquisição de competências na formação dos médicos.Doctor-patient relationship encounters a renewed interest in scientific production, medical education, and clinical practice, with the application of communication techniques that improve the quality of communication. The present article discusses about factors affecting the relationship through a literature review and the research results on doctor-patient relationship in the Family Health Program of the Ceará State. A better doctor-patient relationship doesn't have only positive effects on users' satisfaction and health services quality, but it influences directly the health state of patients. This demand requires the introduction of changes seeking the acquisition of competences in doctors' training.

The plasmasheet H+ and O+ contribution on the storm time ring current

Science.gov (United States)

Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

2015-12-01

The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

Nossa notação m' na prova de Rorschach: ampliação e restrição do fator m de Klopfer

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Aníbal Silveira

1972-06-01

Full Text Available Julgamos oportuna e necessária a diferenciação de fatores "movimento" efetuada por Klopfer, entre os quais a categoria a que denominou "movimento inanimado", como integrante do grupo "movimentos menores". O significado particular de semelhantes fatores foi claramente acentuado por Piotrowski quando redefiniu todos os elementos psicodiagnósticos. E acreditamos que o próprio Rorschach faria essa diversificação de determinantes. Pessoalmente, utilizamos a categoria m de Klopfer e de Piotrowski de modo algo diverso. Por um lado, não incluimos aí máscara, nem mímica expressiva, nem expressões emocionais, nem movimentos parciais. Por outro, classificamos nesse grupo movimento humano ou de animal, toda vez que não resulte diretamente da configuração da mancha como elemento formal, mas da reação subjetiva do examinando ante a cinestesia percebida. Como condição básica para a classificação, é indispensável que esteja clara a sensação de tensão muscular — como é exigido desde Rorschach para M;e como traço comum a todas as interpretações da rubrica — sejam abstrações, sejam seres inanimados: (a intenção, bloqueio, incapacidade, por exemplo, ou (b atividade de elementos da natureza. Devido a esse caráter subjetivo, anotamos m'em vez de m. Essas duas maneiras (a e (b de o probando interpretar movimento, já encontramos em Rorschach, respectivamente nos Exemplosdo Psychodiagnostik e da Contribuição póstuma. E tanto uma como outra podem decorrer, em última análise, quer de fuga ante estímulos emocionais, quer de capacidade mental muito elevada.

REVIEW OF AGING DATA ON EPDM O-RINGS IN THE H1616 SHIPPING PACKAGE

Energy Technology Data Exchange (ETDEWEB)

Skidmore, E.

2012-03-27

Currently, all H1616 shipping package containers undergo annual re-verification testing, including containment vessel leak testing to verify leak-tightness (<1 x 10{sup -7} ref cc/sec air) as per ANSI N14.5. The purpose of this literature review is to supplement aging studies currently being performed by SRNL on the EPDM O-rings to provide the technical basis for extending annual re-verification testing for the H1616 shipping package and to predict the life of the seals at bounding service conditions. The available data suggest that the EPDM O-rings can retain significant mechanical properties and sealing force at or below bounding service temperatures (169 F or 76 C) beyond the 1 year maintenance period. Interpretation of available data suggests that a service life of at least 2 years and potentially 4-6 years may be possible at bounding temperatures. Seal lifetimes at lower, more realistic temperatures will likely be longer. Being a hydrocarbon elastomer, EPDM O-rings may exhibit an inhibition period due to the presence of antioxidants. Once antioxidants are consumed, mechanical properties and seal performance could decline at a faster rate. Testing is being performed to validate the assumptions outlined in this report and to assess the long-term performance of O-ring seals under actual service conditions.

Effects of variation in background mixing ratios of N2, O2, and Ar on the measurement of δ18O-H2O and δ2H-H2O values by cavity ring-down spectroscopy

Science.gov (United States)

Johnson, Jennifer E.; Rella, Chris W.

2017-08-01

Cavity ring-down spectrometers have generally been designed to operate under conditions in which the background gas has a constant composition. However, there are a number of observational and experimental situations of interest in which the background gas has a variable composition. In this study, we examine the effect of background gas composition on a cavity ring-down spectrometer that measures δ18O-H2O and δ2H-H2O values based on the amplitude of water isotopologue absorption features around 7184 cm-1 (L2120-i, Picarro, Inc.). For background mixtures balanced with N2, the apparent δ18O values deviate from true values by -0.50 ± 0.001 ‰ O2 %-1 and -0.57 ± 0.001 ‰ Ar %-1, and apparent δ2H values deviate from true values by 0.26 ± 0.004 ‰ O2 %-1 and 0.42 ± 0.004 ‰ Ar %-1. The artifacts are the result of broadening, narrowing, and shifting of both the target absorption lines and strong neighboring lines. While the background-induced isotopic artifacts can largely be corrected with simple empirical or semi-mechanistic models, neither type of model is capable of completely correcting the isotopic artifacts to within the inherent instrument precision. The development of strategies for dynamically detecting and accommodating background variation in N2, O2, and/or Ar would facilitate the application of cavity ring-down spectrometers to a new class of observations and experiments.

Isolation and X-ray structures of four Rh(PCP) complexes including a Rh(I) dioxygen complex with a short O-O bond

KAUST Repository

Hayashi, Yukiko

2013-07-01

The reaction of RhCl3·H2O with tBu2P(CH2)5PtBu 2 afforded several complexes including [RhIII(H)Cl{ tBu2- P(CH2)2CH(CH2) 2PtBu2}] (1), [RhIIIHCl 2{tBu2P(CH2)5P tBu2}]2 (2), [RhICl{ tBu2P(CH2)2CH=CHCH2P tBu2}] (3) and [RhICl{tBu 2PCH2C(O)CH=CHCH2PtBu2}] (4). X-ray crystal structures of 3 and 4 showed that the C=C bond on the C 5 unit of tBu2P(CH2) 5PtBu2 is bound to Rh(I) in a η2 configuration. In 4, the Rh atom has a trigonal pyramidal coordination geometry. The X-ray crystal structure of 2 consists of two rhodium( III) centers bridged by two tBu2P(CH2)5P tBu2 ligands with two phosphorus atoms, one from each ligand, trans to one another. The crystal structure of the rhodium oxygen adduct with 1,3-bis(di-t-butylphosphinomethyl) benzene [RhO2{ tBu2PCH2(C6H3)CH 2PtBu2}] (5) was also investigated. In this species the O2 is η2 coordinated to the Rh(I) center with asymmetric Rh-O bond lengths (2.087(7) and 1.998(8) Å). The O-O bond distance is short (1.337(11) Å) with νO-O of 990.5 cm -1. DFT calculations on complex 5 yielded two η2- O2 structures that differed in energy by only 0.76 kcal/mol. The lower energy one (5a) had near C2 symmetry, and had nearly equal Rh-O bond lengths, while the higher energy structure (5b) had near Cs symmetry and generally good agreement with the experimental structure. The calculated UV-Vis and IR spectra of complex 5 are in excellent agreement with experiment. © 2012 Elsevier Ltd. All rights reserved.

Isolation and X-ray structures of four Rh(PCP) complexes including a Rh(I) dioxygen complex with a short O-O bond

KAUST Repository

Hayashi, Yukiko; Szalda, David J.; Grills, David C.; Hanson, Jonathan C.; Huang, Kuo-Wei; Muckerman, James T.; Fujita, Etsuko

2013-01-01

The reaction of RhCl3·H2O with tBu2P(CH2)5PtBu 2 afforded several complexes including [RhIII(H)Cl{ tBu2- P(CH2)2CH(CH2) 2PtBu2}] (1), [RhIIIHCl 2{tBu2P(CH2)5P tBu2}]2 (2), [RhICl{ tBu2P(CH2)2CH=CHCH2P tBu2}] (3) and [RhICl{tBu 2PCH2C(O)CH=CHCH2PtBu2}] (4). X-ray crystal structures of 3 and 4 showed that the C=C bond on the C 5 unit of tBu2P(CH2) 5PtBu2 is bound to Rh(I) in a η2 configuration. In 4, the Rh atom has a trigonal pyramidal coordination geometry. The X-ray crystal structure of 2 consists of two rhodium( III) centers bridged by two tBu2P(CH2)5P tBu2 ligands with two phosphorus atoms, one from each ligand, trans to one another. The crystal structure of the rhodium oxygen adduct with 1,3-bis(di-t-butylphosphinomethyl) benzene [RhO2{ tBu2PCH2(C6H3)CH 2PtBu2}] (5) was also investigated. In this species the O2 is η2 coordinated to the Rh(I) center with asymmetric Rh-O bond lengths (2.087(7) and 1.998(8) Å). The O-O bond distance is short (1.337(11) Å) with νO-O of 990.5 cm -1. DFT calculations on complex 5 yielded two η2- O2 structures that differed in energy by only 0.76 kcal/mol. The lower energy one (5a) had near C2 symmetry, and had nearly equal Rh-O bond lengths, while the higher energy structure (5b) had near Cs symmetry and generally good agreement with the experimental structure. The calculated UV-Vis and IR spectra of complex 5 are in excellent agreement with experiment. © 2012 Elsevier Ltd. All rights reserved.

Structural change of NaO1/2-WO3-NbO5/2-LaO3/2-PO5/2 glass induced by electrochemical substitution of sodium ions with protons.

Science.gov (United States)

Ishiyama, Tomohiro; Yamaguchi, Takuya; Nishii, Junji; Yamashita, Toshiharu; Kawazoe, Hiroshi; Kuwata, Naoaki; Kawamura, Junichi; Omata, Takahisa

2015-05-28

Structural changes of 35NaO1/2-1WO3-8NbO5/2-5LaO3/2-51PO5/2 glass (1W-glass) before and after the electrochemical substitution of sodium ions with protons by alkali-proton substitution (APS) are studied by Raman and (31)P magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies. The glass before APS consists of (PO3(-))8.6(P2O7(4-)) chains on average and the terminal Q(1) units (-O-PO3(3-)) are bound to MO6 octahedra (M denotes niobium or tungsten) through P-O-M bonds. Some non-bridging oxygens (NBOs) in the MO6 octahedra are present in addition to the bridging oxygens (BOs) in P-O-M bonds. APS induces fragmentation of the phosphate chains because the average chain length decreases to (PO3(-))3.7(P2O7(4-)) after APS, despite the total number of modifier cations of sodium and lanthanum ions and protons being unaffected by APS. This fragmentation is induced by some of the NBOs in the MO6 octahedra before APS, changing to BOs of the newly formed M-O-P bonds after APS, because of the preferential formation of P-OH bonds over M-OH ones in the present glass. We show that APS under the conditions used here is not a simple substitution of sodium ions with protons, but it is accompanied by the structural relaxation of the glass to stabilize the injected protons.

Variations of force constants, M-O distances and bond order in solid solutions between Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Fadini, A [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

1977-12-01

In solid solutions between the 1:1 ordered perovskites Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/ (system Ba/sub 2/MgUsub(1-x)Wsub(x)O/sub 6/) the force constants of the UO/sub 6/ and WO/sub 6/ octahedras are variied. The valence force constants fsub(MO) tend to adjust for each x. The bond order and the M-O distances are reported as well.

Hydrogen-bonded Three-Dimensional Networks Encapsulating One-dimensional Covalent Chains: [Cu(3-ampy)(H2O)4](SO4)·(H2O) (3-ampy = 3-Aminopyridine)

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

A three-dimensional complex [Cu(3-ampy)(H2O)4](SO4)·(H2O) (3-ampy = 3-aminopyridine) has been synthesized. Crystallographic data: C5H16CuN2O9S, Mr = 343.80, triclinic, space group P, a = 7.675(2), b = 8.225(3), c = 10.845(3) (A), α= 86.996(4), β = 76.292(4),γ = 68.890(4)°, V = 620.0(3) (A)3, Z = 2, Dc = 1.841 g/cm3, F(000) = 354 and μ = 1.971 mm-1. The structure was refined to R = 0.0269 and wR = 0.0659 for 1838 observed reflections (I ＞ 2σ(Ⅰ)). The structure consists of [Cu(3-ampy)(H2O)4]2+ cations, SO42- anions and lattice water molecules. 3-Ampy acting as a bidentate bridging ligand generates a 1D covalent chain. A supramolecular 2D framework is formed through π-π stacking of pyridine rings. The lattice water molecules and SO42- anions are located between the adjacent 2D frameworks. The hydrogen bonding interactions from lattice water molecules and SO42- anions to coordinate water extend the 2D framework into a 3D network.

Photoelectron spectroscopy of B4O4-: Dual 3c-4e π hyperbonds and rhombic 4c-4e o-bond in boron oxide clusters

Science.gov (United States)

Tian, Wen-Juan; Zhao, Li-Juan; Chen, Qiang; Ou, Ting; Xu, Hong-Guang; Zheng, Wei-Jun; Zhai, Hua-Jin; Li, Si-Dian

2015-04-01

Gas-phase anion photoelectron spectroscopy (PES) is combined with global structural searches and electronic structure calculations at the hybrid Becke 3-parameter exchange functional and Lee-Yang-Parr correlation functional (B3LYP) and single-point coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)) levels to probe the structural and electronic properties and chemical bonding of the B4O40/- clusters. The measured PES spectra of B4O4- exhibit a major band with the adiabatic and vertical detachment energies (ADE and VDE) of 2.64 ± 0.10 and 2.81 ± 0.10 eV, respectively, as well as a weak peak with the ADE and VDE of 1.42 ± 0.08 and 1.48 ± 0.08 eV. The former band proves to correspond to the Y-shaped global minimum of Cs B4O4- (2A″), with the calculated ADE/VDE of 2.57/2.84 eV at the CCSD(T) level, whereas the weak band is associated with the second lowest-energy, rhombic isomer of D2h B4O4- (2B2g) with the predicted ADE/VDE of 1.43/1.49 eV. Both anion structures are planar, featuring a B atom or a B2O2 core bonded with terminal BO and/or BO2 groups. The same Y-shaped and rhombic structures are also located for the B4O4 neutral cluster, albeit with a reversed energy order. Bonding analyses reveal dual three-center four-electron (3c-4e) π hyperbonds in the Y-shaped B4O40/- clusters and a four-center four-electron (4c-4e) π bond, that is, the so-called o-bond in the rhombic B4O40/- clusters. This work is the first experimental study on a molecular system with an o-bond.

Photoelectron spectroscopy of B4O4 (-): Dual 3c-4e π hyperbonds and rhombic 4c-4e o-bond in boron oxide clusters.

Science.gov (United States)

Tian, Wen-Juan; Zhao, Li-Juan; Chen, Qiang; Ou, Ting; Xu, Hong-Guang; Zheng, Wei-Jun; Zhai, Hua-Jin; Li, Si-Dian

2015-04-07

Gas-phase anion photoelectron spectroscopy (PES) is combined with global structural searches and electronic structure calculations at the hybrid Becke 3-parameter exchange functional and Lee-Yang-Parr correlation functional (B3LYP) and single-point coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)) levels to probe the structural and electronic properties and chemical bonding of the B4O4 (0/-) clusters. The measured PES spectra of B4O4 (-) exhibit a major band with the adiabatic and vertical detachment energies (ADE and VDE) of 2.64 ± 0.10 and 2.81 ± 0.10 eV, respectively, as well as a weak peak with the ADE and VDE of 1.42 ± 0.08 and 1.48 ± 0.08 eV. The former band proves to correspond to the Y-shaped global minimum of Cs B4O4 (-) ((2)A″), with the calculated ADE/VDE of 2.57/2.84 eV at the CCSD(T) level, whereas the weak band is associated with the second lowest-energy, rhombic isomer of D2h B4O4 (-) ((2)B2g) with the predicted ADE/VDE of 1.43/1.49 eV. Both anion structures are planar, featuring a B atom or a B2O2 core bonded with terminal BO and/or BO2 groups. The same Y-shaped and rhombic structures are also located for the B4O4 neutral cluster, albeit with a reversed energy order. Bonding analyses reveal dual three-center four-electron (3c-4e) π hyperbonds in the Y-shaped B4O4 (0/-) clusters and a four-center four-electron (4c-4e) π bond, that is, the so-called o-bond in the rhombic B4O4 (0/-) clusters. This work is the first experimental study on a molecular system with an o-bond.

Intermolecular and very strong intramolecular C-SeO/N chalcogen bonds in nitrophenyl selenocyanate crystals.

Science.gov (United States)

Wang, Hui; Liu, Ju; Wang, Weizhou

2018-02-14

Single-crystal X-ray diffraction reveals that polymorphic ortho-nitrophenyl selenocyanate (o-NSC, crystals 1a and 1b) and monomorphic para-nitrophenyl selenocyanate (p-NSC, crystal 2) crystals are all stabilized mainly by intermolecular and very strong intramolecular C-SeO/N chalcogen bonds, as well as by other different interactions. Thermogravimetric (TG) and differential scanning calorimetry thermogram (DSC) analyses show that the starting decomposition temperatures and melting points of the three crystals are different, following the order 1b > 1a > 2, which is consistent with the structural characteristics of the crystals. In addition, atoms in molecules (AIM) and natural bond orbital (NBO) analyses indicate that the total strengths of the C-SeO and C-SeN chalcogen bonds decrease in the order 1b > 1a > 2. This study could be significant for engineering functional crystals based on robust C-SeO and C-SeN chalcogen bonds, and for designing drugs containing selenium as well as understanding their interaction in biosystems.

Gestão da informação utilizando o método infomapping

Directory of Open Access Journals (Sweden)

Marta Lígia Pomim Valentim

Full Text Available A gestão da informação é extremamente importante para as organizações. O mapeamento informacional é um instrumento que pode ser utilizado no âmbito da gestão da informação. Para realizar o mapeamento informacional, pode-se utilizar o método denominado "Infomapping", criado por Burk Jr. e Horton Jr., que se constitui em uma valiosa ferramenta para gerenciar os recursos de informação de uma organização. Ele permite descobrir com exatidão o grau de desconhecimento que se tem sobre as fontes, serviços e sistemas com os quais se desenvolve o trabalho informacional da organização. O processo consiste em criar um levantamento de todas as informações, que supostamente constituem-se num recurso informacional gerado internamente ou produzido externamente, que impactam diretamente as atividades corporativas.

A Study for Shelf Life Evaluation of Rubber O-ring

International Nuclear Information System (INIS)

Jung, Sun Chul; Kim, Jong Seog

2005-01-01

Non-metallic materials stored in warehouses in nuclear power plants have shelf life. The shelf life means the maximum storage time allowable such that the install life of the material is not affected. Materials whose shelf lives expire are generally discarded. unless the shelf lives of these materials can be extended by reducing the install life. Examples of this case are rubber materials. Rubber materials are widely used for sealing of various machines. There are various life evaluation methods for rubber material. For example, the compression set is generally used for evaluation the aging condition of rubber materials used for sealing. A compression set value can be calculated according to the ASTM D395. We have tried the compression set test by using specimens with 6.99mm diameter O-ring even when ASTM D 395 recommends the use of bar specimen. Test results and comparison between O-ring and reference data of EPRI NP-6608 are presented below

Phase relations in the M2MoO4 - Ag2MoO4 - Hf(MoO4)2 (M=Li, Na) systems

International Nuclear Information System (INIS)

Bazarova, Zh.G.; Bazarov, B.G.; Balsanova, L.V.

2002-01-01

The M 2 MoO 4 - Ag 2 MoO 4 - Hf(MoO 4 ) 2 (M=Li, Na) systems were studied by X-ray diffraction and differential thermal analyses in the subsolidus area (450 - 500 Deg C) for the first time. The formation of the binary compound with the variable composition Li 4-x Hf 1+0.2x (MoO 4 ) 4 (0 ≤ x ≤ 0.6) in the Li 2 MoO 4 - Hf(MoO 4 ) 2 system and the ternary molybdates Li 4 Ag 2 Hf(MoO 4 ) 5 (S 1 ) and Na 2 Ag 2 Hf(MoO 4 ) 4 (S 2 ) was established and the thermal characteristics of the prepared compounds were examined. The new binary molybdate Ag 2 Hf(MoO 4 ) 3 was prepared by the reaction between Ag 2 MoO 4 and Hf(MoO 4 ) 2 [ru

Influência da adição de carga inorgânica aos sistemas adesivos dentinários na microinfiltração marginal = Influence of inorganic filler addition to dentin bonding systemson marginal microleakage

Directory of Open Access Journals (Sweden)

Yoshida, Kellyn Roberta Ayumi

2005-01-01

Full Text Available O objetivo deste estudo foi avaliar os efeitos da adição de carga inorgânica aos adesivos dentinários sobre a microinfiltração marginal. Para tal, oitenta incisivos bovinos receberam preparos classe V na junção amelo-cementária e foram divididos em oito grupos, cada qual recebendo versões com e sem carga de diferentes sistemas adesivos, segundo as recomendações dos fabricantes. Os seguintes Grupos foram avaliados: OS – One Step (Sem Carga – SC, OSP – One Step Plus (Com Carga – CC, PB – Prime & Bond 2. 1 (SC, PBNT – Prime & Bond NT (CC, ST – Stae (SC, STM – Stae + 10% de partículas SiO2 com tamanho de 0,01 µm (CC, SB – Single Bond (SC, SBC – Single Bond 10% de partículas SiO2 com tamanho de 0,01 µm (CC. As cavidades foram restauradas com dois incrementos de Z250. Os dentes foram imersos em água destilada a 37ºC por 24 horas e submetidos a 500 ciclos térmicos (5 e 55ºC. A microinfiltração foi avaliada quantitativamente pelo método do nitrato de prata seguido pela diafanização. Os dados foram submetidos à ANOVA paramétrica a um fator e ao teste de Tukey (a = 5%, obtendo-se um valor de p = 0,00. As médias (± desvio padrão observadas para cada Grupo foram: SB: 1,07 (± 0,20a; OS: 1,25 (± 0,49ab; OSP: 1,64 (± 0,59ab; SBC: 1,69 (± 1,07ab; PBNT: 2,21 (± 0,98ab; PB: 2,60 (± 1,45bc; ST: 3,70 (± 1,29c; STC: 3,86 (± 1,11c. Os Grupos acompanhados das mesmas letras não apresentam diferenças significantes. Podemos concluir que a adição de partículas de carga não influenciou de forma significativa a microinfiltração marginal. Foram constatadas diferenças significativas entre os sistemas adesivos de diferentes marcas

Enhanced bonding between TiO2-Graphene oxide

DEFF Research Database (Denmark)

Naknikham, Usuma; Buffa, Vittorio; Yue, Yuanzheng

analysis. Besides, the study of Ti-O-C and Ti-C interface bonding was carried out using XPS. The band-gap energy was determined using a UV-VIS spectrophotometer equipped with an integrating sphere. Thus, it was possible for us to determine the reactivity of the new photocatalysts under the visible light...... as photocatalysts, which can efficiently react with organic species under solar light and can enhance the adsorption of water pollutants [3]. Many studies have shown that TiO2-GO heterostructures can quickly mineralize organic dyes in solution under UV-light. However, it is not clear if these materials can provide...... the same performances under sunlight and with complex real water systems. Hence, this research aims to study the photocatalystic property on GO-TiO2 composites with aqueous solutions of selected emerging pollutants under visible light. The samples were synthesized via the in-situ sol-gel nucleation...

High precision measurements of 16O12C17O using a new type of cavity ring down spectrometer

Science.gov (United States)

Daëron, M.; Stoltmann, T.; Kassi, S.; Burkhart, J.; Kerstel, E.

2016-12-01

Laser absorption techniques for the measurement of isotopologue abundances in gases have been dripping into the geoscientific community over the past decade. In the field of carbon dioxide such instruments have mostly been restricted to measurements of the most abundant stable isotopologues. Distinct advantages of CRDS techniques are non-destructiveness and the ability to resolve isobaric isotopologues. The determination of low-abundance isotopologues is predominantly limited by the linewidth of the probing laser, laser jitter, laser drift and system stability. Here we present first measurements of 16O12C17O abundances using a new type of ultra-precise cavity ring down spectrometer. By the use of Optical Feedback Frequency Stabilization, we achieved a laser line width in the sub-kHz regime with a frequency drift of less than 20 Hz/s. A tight coupling with an ultra-stable ring down cavity combined with a frequency tuning mechanism which enables us to arbitrarily position spectral points (Burkart et al., 2013) allowed us to demonstrate a single-scan (2 minutes) precision of 40 ppm on the determination of the 16O12C17O abundance. These promising results imply that routine, direct, high-precision measurements of 17O-anomalies in CO2 using this non-destructive method are in reach. References:Burkart J, Romanini D, Kassi S; Optical feedback stabilized laser tuned by single-sideband modulation; Optical Letters 12:2062-2063 (2013)

Extended O-Doped Polycyclic Aromatic Hydrocarbons.

Science.gov (United States)

Stassen, Daphné; Demitri, Nicola; Bonifazi, Davide

2016-05-10

The synthesis of O-doped benzorylenes, in which peripheral carbon atoms have been replaced by oxygen atoms, has been achieved for the first time. This includes key high-yielding ring-closure steps which, through intramolecular C-O bond formation, allow stepwise planarization of oligonaphthalenes. Single-crystal X-ray diffraction showed that the tetraoxa derivative forms remarkable face-to-face π-π stacks in the solid state, a favorable solid-state arrangement for organic electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of Chemical Bond Properties and Mssbauer Spectroscopy in YBa2Cu3O7

Institute of Scientific and Technical Information of China (English)

高发明; 李东春; 张思远

2003-01-01

Chemical bond properties of YBa2Cu3O7 were studied by using the average band-gap model. The calculated results show that the covalency of Cu(1)-O bond is 0.406, and one of Cu(2)-O is 0.276. Mssbauer isomer shifts of 57Fe in Y-123 were calculated by the chemical surrounding factor hv defined by covalency and electronic polarizability. The charge-state and site of Fe were determined. The relation between the coupling constant of electron-phonon interaction and covalency is employed to explain that the Cu(2)-O plane is more important than the Cu(1)-O chain on the superconductivity in the Y-123 compounds.

Competition between weak OH···π and CH··O hydrogen bonds: THz spectroscopy of the C2H2—H2O and C2H4—H2O complexes

DEFF Research Database (Denmark)

Andersen, Jonas; Heimdal, Jimmy; Nelander, B.

2017-01-01

an intermolecular CH⋯O hydrogen-bonded configuration of C2v symmetry with the H2O subunit acting as the hydrogen bond acceptor. The observation and assignment of two large-amplitude donor OH librational modes of the C2H4—H2O complex at 255.0 and 187.5 cm−1, respectively, confirms an intermolecular OH⋯π hydrogen...

A study on the method for estimating the life time of O-rings made of NBR used in sealing air operating cylinders

International Nuclear Information System (INIS)

Fujii, Yuzo; Mitsuta, Yasumasa

2003-01-01

At nuclear power plants, a large number of O-rings made of rubber are attached to safety related machines and apparatus for sealing two metallic components. O-rings degrade during the long term exposure in environmental conditions in use, and finally lose the requested functions. Therefore it is important to exchange them in a proper period based on the precise life time estimation. This study aimed at to investigate the method for estimating the life time of O-rings made of NBR (acrylonitrile butadiene rubber) attached to the air cylinders which drive the dampers of ventilation systems in nuclear power plants. It has been conducted as follows: (1) After confirming that the main cause of degradation of O-rings is thermo-oxidation reaction, thermally accelerated aging tests were carried out for O-rings with three different temperatures. (2) It was certified that the elongation values of O-rings obtained by the tests could be fitted by the Arrhenius rule, and then the life time of O-rings was estimated using the Arrhenius rule. (3) In order to validate the reliability of this estimation, we measured the elongation values of the O-rings which had been actually used at nuclear power plants, and compared them to the predicted elongation values obtained by the above estimation. The average and standard deviation of the values which is calculated by the equation {(measured value-predicted value)/ predicted value} are 11% and 8%, respectively and there are small errors between the measured value and the predicted values. As a result we can judge that good estimation of life time of O-rings can be done by the above method. (author)

Synthesis and characterization of dinuclear complexes containing the Fe(III)-F...(H2O)M(II) motif

DEFF Research Database (Denmark)

Ghiladi, M; Jensen, K.B.; Jiang, Jianzhong

1999-01-01

.818(2), 1.902(2) Å) and one of them is strongly hydrogen bonded to the water molecule on the adjacent Cu atom (F-H...O 2.653(4) Å). The metal ions in the aquafluoride complexes [(bpbp)Fe(F)2M(H2O)2][BF4]2, M=Fe or Co, are weakly antiferromagnetically coupled (J=-8 and -10 cm-1 respectively) and in [(bpbp...

Informações contábil-financeiras e custo de captação em mercados de bonds

Directory of Open Access Journals (Sweden)

Maurício Ribeiro do Valle

2002-12-01

Full Text Available O artigo discute a questão do conteúdo informacional de números contábil-financeiros e analisa a relação entre estas informações e o custo de captação das maiores empresas do setor Papel & Celulose que obtiveram recursos nos mercados americano e internacional de bonds durante o período 1991-98. Os indicadores contábil-financeiros analisados mostraram que as empresas brasileiras não apresentaram um elevado desempenho como as empresas que captaram recursos com um baixo custo, mas, também, não apresentaram características semelhantes às empresas - americanas e canadenses com profundos problemas financeiros - que captaram a um alto custo nos mercados estudados.The article concerns the information provided by accounting/financial variables and analyzes the relationship between this information and the cost of funding for the largest Pulp and Paper companies that raised capital in the U.S. and international bond markets in the period 1991-98. The analyzed accounting/financial variables showed that Brazilian companies neither performed as well as the companies that raised capital with a low cost, nor presented the same characteristics as the companies - American and Canadian companies with large financial problems - that raised capital with a high cost in the studied markets.

Effect of Surface Treatment on Shear Bond Strength between Resin Cement and Ce-TZP/Al2O3

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Jong-Eun Kim

2016-01-01

Full Text Available Purpose. Although several studies evaluating the mechanical properties of Ce-TZP/Al2O3 have been published, to date, no study has been published investigating the bonding protocol between Ce-TZP/Al2O3 and resin cement. The aim of this study was to evaluate the shear bond strength to air-abraded Ce-TZP/Al2O3 when primers and two different cement types were used. Materials and Methods. Two types of zirconia (Y-TZP and Ce-TZP/Al2O3 specimens were further divided into four subgroups according to primer application and the cement used. Shear bond strength was measured after water storage for 3 days or 5,000 times thermocycling for artificial aging. Results. The Y-TZP block showed significantly higher shear bond strength than the Ce-TZP/Al2O3 block generally. Primer application promoted high bond strength and less effect on bond strength reduction after thermocycling, regardless of the type of cement, zirconia block, or aging time. Conclusions. Depending on the type of the primer or resin cement used after air-abrasion, different wettability of the zirconia surface can be observed. Application of primer affected the values of shear bond strength after the thermocycling procedure. In the case of using the same bonding protocol, Y-TZP could obtain significantly higher bond strength compared with Ce-TZP/Al2O3.

Indium-Catalyzed Annulation of o-Acylanilines with Alkoxyheteroarenes: Synthesis of Heteroaryl[b]quinolines and Subsequent Transformation to Cryptolepine Derivatives

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Kyohei Yonekura

2018-04-01

Full Text Available We disclose herein the first synthetic method that is capable of offering heteroaryl[b]quinolines (HA[b]Qs with structural diversity, which include tricyclic and tetracyclic structures with (benzothienyl, (benzofuranyl, and indolyl rings. The target HA[b]Q is addressed by the annulation of o-acylanilines and MeO–heteroarenes with the aid of an indium Lewis acid that effectively works to make two different types of the N–C and C–C bonds in one batch. A series of indolo[3,2-b]quinolines prepared here can be subsequently transformed to structurally unprecedented cryptolepine derivatives. Mechanistic studies showed that the N–C bond formation is followed by the C–C bond formation. The indium-catalyzed annulation reaction thus starts with the nucleophilic attack of the NH2 group of o-acylanilines to the MeO-connected carbon atom of the heteroaryl ring in an SNAr fashion, and thereby the N–C bond is formed. The resulting intermediate then cyclizes to make the C–C bond through the nucleophilic attack of the heteroaryl-ring-based carbon atom to the carbonyl carbon atom, providing the HA[b]Q after aromatizing dehydration.

Photoelectron spectroscopy of B4O4−: Dual 3c-4e π hyperbonds and rhombic 4c-4e o-bond in boron oxide clusters

International Nuclear Information System (INIS)

Tian, Wen-Juan; Chen, Qiang; Ou, Ting; Li, Si-Dian; Zhao, Li-Juan; Xu, Hong-Guang; Zheng, Wei-Jun; Zhai, Hua-Jin

2015-01-01

Gas-phase anion photoelectron spectroscopy (PES) is combined with global structural searches and electronic structure calculations at the hybrid Becke 3-parameter exchange functional and Lee-Yang-Parr correlation functional (B3LYP) and single-point coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)) levels to probe the structural and electronic properties and chemical bonding of the B 4 O 4 0/− clusters. The measured PES spectra of B 4 O 4 − exhibit a major band with the adiabatic and vertical detachment energies (ADE and VDE) of 2.64 ± 0.10 and 2.81 ± 0.10 eV, respectively, as well as a weak peak with the ADE and VDE of 1.42 ± 0.08 and 1.48 ± 0.08 eV. The former band proves to correspond to the Y-shaped global minimum of C s B 4 O 4 − ( 2 A″), with the calculated ADE/VDE of 2.57/2.84 eV at the CCSD(T) level, whereas the weak band is associated with the second lowest-energy, rhombic isomer of D 2h B 4 O 4 − ( 2 B 2g ) with the predicted ADE/VDE of 1.43/1.49 eV. Both anion structures are planar, featuring a B atom or a B 2 O 2 core bonded with terminal BO and/or BO 2 groups. The same Y-shaped and rhombic structures are also located for the B 4 O 4 neutral cluster, albeit with a reversed energy order. Bonding analyses reveal dual three-center four-electron (3c-4e) π hyperbonds in the Y-shaped B 4 O 4 0/− clusters and a four-center four-electron (4c-4e) π bond, that is, the so-called o-bond in the rhombic B 4 O 4 0/− clusters. This work is the first experimental study on a molecular system with an o-bond

Direct bonding of ALD Al₂O₃ to silicon nitride thin films

DEFF Research Database (Denmark)

Laganà, Simone; Mikkelsen, E. K.; Marie, Rodolphe

2017-01-01

microscopy (TEM) by improving low temperature annealing bonding strength when using atomic layer deposition of aluminum oxide. We have investigated and characterized bonding of Al2O3-SixNy (low stress silicon rich nitride) and Al2O3-Si3N4 (stoichiometric nitride) thin films annealed from room temperature up......O3 can be bonded to. Preliminary tests demonstrating a well-defined nanochannel system with-100 nm high channels successfully bonded and tests against leaks using optical fluorescence technique and transmission electron microscopy (TEM) characterization of liquid samples are also reported. Moreover...

Evaluation of biaxial flexural strength and modulus of filled and unfilled adhesive systems = Avaliação da resistência flexural biaxial e módulo de flexão de sistemas adesivos

Directory of Open Access Journals (Sweden)

Liberti, Michele Santana

2009-01-01

Full Text Available Objetivo: O objetivo deste estudo foi avaliar a resistência flexural e o módulo de flexão de dois sistemas adesivos, através de ensaio de resistência flexural biaxial. Metodologia: Os adesivos (Pentron Clinical Technologies estudados foram: Bond 1 (B1 e NanoBond (NB. Treze discos de cada adesivo foram preparados com dimensões aproximadas de 6,1 mm de diâmetro e 0,6 mm de espessura. Os discos de adesivos foram confeccionados utilizando-se moldes de teflon e fotopolimerizados com aparelho XL 3000 (3M ESPE. Após armazenamento por 10 dias, os discos foram testados em máquina universal de ensaio (Instron 5844, com velocidade de 1,27 mm/min. Os dados foram submetidos à análise de variância (1 fator ao nível de significância de 0,05. Resultados: Os valores médios (±DP de resistência flexural para os adesivos foram (em MPa: B1- 89,7±7,6 e NB- 131,1±9,5. Os valores médios de módulo flexural (±DP foram (em MPa: B1- 1999,9±258,4 e NB- 2314,5±271,0. Conclusão: O adesivo contendo partículas de carga (NB mostrou maiores valores de resistência flexural e módulo de flexão que o adesivo B1

Alfabetização no Espírito Santo: o método mútuo ou monitorial

OpenAIRE

Gontijo,Cláudia Maria Mendes

2011-01-01

Este texto tem por finalidade analisar o Regimento Interno das Aulas Publicas de 1.as Letras da Província do Espírito Santo e o método de ensino da leitura e da escrita concretizado nesse Regimento. Para desenvolvimento do estudo, utilizamos a pesquisa documental. O artigo conclui que o uso do método mútuo possibilitou a permanência de modelos tradicionais de ensino da leitura e da escrita baseados no estudo sistemático das letras, das sílabas, da frase e, finalmente, da leitura de textos rel...

Rotational Isomers, Intramolecular Hydrogen Bond, and IR Spectra of o-Vinylphenol Homologs

Science.gov (United States)

Glazunov, V. P.; Berdyshev, D. V.; Balaneva, N. N.; Radchenko, O. S.; Novikov, V. L.

2018-03-01

The ν(OH) stretching-mode bands in solution IR spectra of five o-vinylphenol (o-VPh) homologs in the slightly polar solvents CCl4 and n-hexane were studied. Several rotamers with free OH groups were found in solutions of o-VPh and its methyl-substituted derivatives in n-hexane. The proportion of rotamers in o-VPh homologs with intramolecular hydrogen bonds (IHBs) O-H...π varied from 22 to 97% in the gas and cyclohexane according to B3LYP/cc-pVTZ calculations. The theoretically estimated effective enthalpies -ΔH of their IHBs varied in the range 0.20-2.24 kcal/mol.

Synthesis of hybrid cellulose nanocomposite bonded with dopamine SiO2/TiO2 and its antimicrobial activity

Science.gov (United States)

Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Jaehwan; Kim, Joo-Hyung

2015-04-01

Organic-inorganic hybrid material based cellulose was synthesized by the sol-gel approach. The explosion of activity in this area in the past decade has made tremendous progress in industry or academic both fundamental understanding of sol-gel process and applications of new functionalized hybrid materials. In this present research work, we focused on cellulose-dopamine functionalized SiO2/TiO2 hybrid nanocomposite by sol-gel process. The cellulose-dopamine hybrid nanocomposite was synthesized via γ-aminopropyltriethoxysilane (γ-APTES) coupling agent by in-situ sol-gel process. The chemical structure of cellulose-amine functionalized dopamine bonding to cellulose structure with covalent cross linking hybrids was confirmed by FTIR spectral analysis. The morphological analysis of cellulose-dopamine nanoSiO2/TiO2 hybrid nanocomposite materials was characterized by XRD, SEM and TEM. From this different analysis results indicate that the optical transparency, thermal stability, control morphology of cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite. Furthermore cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite was tested against pathogenic bacteria for antimicrobial activity.

Linear-to-λ-Shape P-O-P Bond Transmutation in Polyphosphates with Infinite (PO3)∞ Chain.

Science.gov (United States)

Wang, Ying; Li, Lin; Han, Shujuan; Lei, Bing-Hua; Abudoureheman, Maierhaba; Yang, Zhihua; Pan, Shilie

2017-09-05

A new metal polyphosphate, α-CsBa 2 (PO 3 ) 5 , exhibiting the first example of a linear P-O-P bond angle in a one-dimensional (PO 3 ) ∞ chain has been reported. Interestingly, α → β phase transition occurs in CsBa 2 (PO 3 ) 5 along with the P-O-P bonds varying from linear to λ-shape, suggesting that α-CsBa 2 (PO 3 ) 5 with unfavorable linear P-O-P bonds is more stable at ambient temperature.

Extrusão do anel intra-estromal corneano e vascularização do túnel Extrusion and vascularization of the intrastromal corneal ring tunnel

Directory of Open Access Journals (Sweden)

Larissa Casteluber

2007-12-01

Full Text Available O objetivo deste trabalho é relatar e discutir os aspectos de um caso clínico em que foi observada a formação de neovascularização no túnel do anel intra-estromal corneano. Trata-se de paciente com ectasia corneana 4 anos após LASIK, comprovada pela paquimetria e topografia, e submetido ao implante de anel intra-estromal corneano. No terceiro ano de acompanhamento após implante do anel intraestromal, com o paciente em uso de lente de contato gelatinosa, verificou-se extrusão de um segmento e neovascularização no túnel. Removeu-se o segmento afetado, realizou-se fotocoagulação vascular, observando-se regressão completa do quadro neovascular.The purpose of this paper is to describe the clinical aspects of one case with deep corneal vascularization after corneal ring implantation to treat corneal ectasia due to LASIK 4 years before. The corneal ectasia diagnostic was performed by corneal pachimetry and topography. Intrastromal corneal ring segment was implanted. On the third year of follow-up, extrusion of one segment was noted and deep corneal neovascularization was found. The segment was removed, laser photocoagulation was applied and complete vascular regression was observed.

Lubrication of ceramics in ring/cylinder applications

International Nuclear Information System (INIS)

Gaydos, P.A.; Dufrane, K.F.

1989-01-01

In support of efforts to apply ceramics to advanced heat engines, a study was performed of the wear mechanisms of ceramics at the ring/cylinder interface. A laboratory apparatus was constructed to reproduce most of the conditions of an actual engine but used easily prepared ring and cylinder specimens to facilitate their fabrication. Plasma-sprayed coatings of Cr 2 O 3 and hypersonic flame-sprayed coatings of cobalt-bonded WC performed particularly well as ring coatings. Similar performance was obtained with these coatings operating against SiC, Si 3 N 4 , SiC whisker-reinforced Al 2 O 3 and Cr 2 O 2 coatings. The study demonstrated the critical need for lubrication and evaluated the performance of two available lubricants

Climate and Streamflow Reconstruction on the São Francisco Basin, Brazil, Using Tree-Ring Data

Science.gov (United States)

Pereira, G. D. A.; Barbosa, A. C. M. C.; Granato-Souza, D.; Stahle, D. W.; Torbenson, M.; dos Santos, R. M.; Rodrigues Alves Delfino Barbosa, J. P.

2017-12-01

The São Francisco River crosses the most drought-prone region of Brazil and regional economic dynamics are dependent on the water availability in the basin. The seasonally dry forests are widely distributed in the basin, where Cedrela fissilis Vell (cedro) are frequently found. This semi-arid region provides a favorable setting where the deciduous cedro trees form well-defined semi-ring porous annual rings that can be exactly crossdated and used to build climate sensitive chronologies. Therefore, we have developed chronologies of cedro from seasonally dry forest fragments of three sites located in the middle-sector of the São Francisco River basin and south limit of the Brazilian Drought Polygon. The samples were analyzed according to standard procedures: sample preparation, ring count, crossdating and measurement of the tree rings. Dating quality was tested using the computer program COFECHA and ring-width time series where detrended and standardized to produce the final index chronology using the ARSTAN program. The results show that crossdating within and among trees from different sites demonstrate the potential to expand the spatial sampling. The tree-ring chronologies are sensitive with wet season precipitation totals (October - March), and can explain approximately 40% of the variance (1961-2015). Significant correlation was also observed with total annual discharge of the Rio São Francisco River measured at Barra (r=0.48; 1961-2015). However, the correlation disapears after 1993 (r=0.64 for 1961-1993, but r=-0.004 for 1994-2015) and we suspect that the stream gage at Barra has been impacted by human activity. Tree-ring chronologies can provide important information on climate and streamflow variability of São Francisco River, where hydrological records are often short and discontinuous. This chronology is now being extended with 150-yr old trees from the region and may be used to reconstruct climate and streamflow records back to the pre

O episódio de Freud com a cocaína: o médico e o monstro

Directory of Open Access Journals (Sweden)

Decio Gurfinkel

2008-09-01

Full Text Available O objetivo do trabalho é uma avaliação dos possíveis "restos" que o episódio de Freud com a cocaína tenha deixado para a criação da psicanálise, realizada através do reexame retrospectivo, crítico e analítico desse episódio. O resultado desta avaliação pôs em destaque quatro elementos: o surgimento de um Freud psiquiatra e farmacologista e o progressivo abandono desta via; o surgimento da adicção como objeto de investigação; o modelo da auto-administração como método de pesquisa; e a crença e abandono subseqüente de um projeto de "cura mágica".

New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

International Nuclear Information System (INIS)

Weng Shengfeng; Wang, Yun-Hsin; Lee, Chi-Shen

2012-01-01

Two novel materials, [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1-bar (No. 2); compound 2 crystallized in monoclinic space group P2 1 /c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of Cu II ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d 1 excited state and two levels of the 4f 1 ground state ( 2 F 5/2 and 2 F 7/2 ). Compounds 1b and 2 containing Ce III ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers. - Graphical Abstract: [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2)—with 1D and 2D structures were synthesized and characterized. Highlights: ► Two MOF – [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2) – with 1D and 2D structures. ► The adjacent chains of the 1D framework were correlated with each other through an oxalate ligand to form a 2D layer structure. ► The source of the oxalate ligand was the decomposition in situ of citric acid oxidized in the presence of Cu II ions.

Bismuth-boron multiple bonding in BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}

Energy Technology Data Exchange (ETDEWEB)

Jian, Tian; Cheung, Ling Fung; Chen, Teng-Teng; Wang, Lai-Sheng [Department of Chemistry, Brown University, Providence, RI (United States)

2017-08-01

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}, containing triple and double B-Bi bonds are presented. The BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -} clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB{sub 2}O{sup -} ([Bi≡B-B≡O]{sup -}) and Bi{sub 2}B{sup -} ([Bi=B=Bi]{sup -}), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Oxygen isotopes in tree rings record variation in precipitation δ18O and amount effects in the south of Mexico.

Science.gov (United States)

Brienen, Roel J W; Hietz, Peter; Wanek, Wolfgang; Gloor, Manuel

2013-12-01

[1] Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings ( δ 18 O tr ). Interannual variation in δ 18 O tr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ 13 C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ 18 O tr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18 O-depleted rain in the region and seem to have affected the δ 18 O tr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ 18 O tr of M . acantholoba can be used as a proxy for source water δ 18 O and that interannual variation in δ 18 O prec is caused by a regional amount effect. This contrasts with δ 18 O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in

Avaliação comparativa da perda de retenção de quatro sistemas de encaixes do tipo ERA e O-Ring empregados sob overdentures em função do tempo de uso Comparative evaluation of retention loss in four types of attachments used on overdentures in function of time of use

Directory of Open Access Journals (Sweden)

Wellington Cardoso Bonachela

2003-03-01

Full Text Available O objetivo deste trabalho foi avaliar e comparar a capacidade retentiva entre dois sistemas O-ring e O-SO (Grupo I e dois sistemas ERA - cápsulas de retenção cinza e brancas - (Grupo II, em função simulada, com ciclos de inserção e remoção, do início, 6 meses, 1, 2, 3, 4 e 5 anos depois. Dois implantes do tipo Brånemark foram fixados em duas bases metálicas trapezoidais, sendo os testes de inserção e remoção feitos numa máquina de costura ajustada para este propósito, usando um sistema de correias e polias, movendo um virabrequim. Uma platina de delineador foi usada para fixação dos corpos de prova às bases metálicas na máquina de costura. Os testes de resistência ao movimento axial das cápsulas por tensão foram feitos numa máquina de ensaios universal em períodos de tempo pré-estabelecidos, antes e após o término do ciclo na máquina de costura. Baseado nos resultados, esse estudo pôde concluir que houve perda de retenção de todos os sistemas testados, porém o sistema ERA apresentou, desde o início, maior retenção quando comparado aos outros sistemas e a cápsula cinza mostrou o melhor resultado no final da simulação.The aim of this study was to evaluate and compare the retentive capacity between two O-ring and O-SO system (Group I, and two ERA system types - white and gray retention caps - (Group II, respectively, in simulated function in database, 6 months, 1, 2, 3, 4, and 5 years later, with insertion and removal cycles. Two Brånemark implants were fixed in two trapezoidal metallic bases for the tests. Removal and insertion tests were done in a sewing machine, adjusted for this purpose using a belt and a pulley system, moving a steel crankshaft. A delineator platinum hold was used for body trial fixation to the metallic base of the sewing machine. Resistance test to axial movement of the caps by tension was done in a Universal test machine in an established period of time, before and after the cycle

Insertion reactions into Pd[bond]O and Pd[bond]N bonds: preparation of alkoxycarbonyl, carbonato, carbamato, thiocarbamate, and thioureide complexes of palladium(II).

Science.gov (United States)

Ruiz, José; Martínez, M Teresa; Florenciano, Félix; Rodríguez, Venancio; López, Gregorio; Pérez, José; Chaloner, Penny A; Hitchcock, Peter B

2003-06-02

Mononuclear palladium hydroxo complexes of the type [Pd(N[bond]N)(C(6)F(5))(OH)] [(N[bond]N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me(2)bipy), 1,10-phenanthroline (phen), or N,N,N',N'-tetramethylethylenediamine (tmeda)] have been prepared by reaction of [Pd(N[bond]N)(C(6)F(5))(acetone)]ClO(4) with KOH in methanol. These hydroxo complexes react, in methanol, with CO (1 atm, room temperature) to yield the corresponding methoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)Me)]. Similar alkoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)R)] (N[bond]N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me, Et, or (i)Pr) are obtained when [Pd(N[bond]N)(C(6)F(5))Cl] is treated with KOH in the corresponding alcohol ROH and CO is bubbled through the solution. The reactions of [Pd(N[bond]N)(C(6)F(5))(OH)] (N[bond]N = bipy or Me(2)bipy) with CO(2), in tetrahydrofuran, lead to the formation of the binuclear carbonate complexes [(N[bond]N)(C(6)F(5))Pd(mu-eta(2)-CO(3))Pd(C(6)F(5))(N[bond]N)]. Complexes [Pd(N[bond]N)(C(6)F(5))(OH)] react in alcohol with PhNCS to yield the corresponding N-phenyl-O-alkylthiocarbamate complexes [Pd(N[bond]N)(C(6)F(5))[SC(OR)NPh

X-ray photoelectron spectra structure and chemical bonding in AmO2

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Teterin Yury A.

2015-01-01

Full Text Available Quantitative analysis was done of the X-ray photoelectron spectra structure in the binding energy range of 0 eV to ~35 eV for americium dioxide (AmO2 valence electrons. The binding energies and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the Am63O216 and AmO8 (D4h cluster reflecting Am close environment in AmO2 were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-~15 eV binding energy and the inner (~15 eV-~35 eV binding energy valence molecular orbitals. The filled Am 5f electronic states were shown to form in the AmO2 valence band. The Am 6p electrons participate in formation of both the inner and the outer valence molecular orbitals (bands. The filled Am 6p3/2 and the O 2s electronic shells were found to make the largest contributions to the formation of the inner valence molecular orbitals. Contributions of electrons from different molecular orbitals to the chemical bond in the AmO8 cluster were evaluated. Composition and sequence order of molecular orbitals in the binding energy range 0-~35 eV in AmO2 were established. The experimental and theoretical data allowed a quantitative scheme of molecular orbitals for AmO2, which is fundamental for both understanding the chemical bond nature in americium dioxide and the interpretation of other X-ray spectra of AmO2.

Crystallographic and infrared spectroscopic study of bond distances in Ln[Fe(CN)6].4H2O (Ln=lanthanide)

International Nuclear Information System (INIS)

Zhou Xianju; Wong, W.-T.; Faucher, Michele D.; Tanner, Peter A.

2008-01-01

Along with crystallographic data of Ln[Fe(CN) 6 ].4H 2 O (Ln=lanthanide), the infrared spectra are reassigned to examine bond length trends across the series of Ln. The changes in mean Ln-O, Ln-N, C≡N and Fe-C distances are discussed and the bond natures of Ln-N and Ln-O are studied by bond length linear or quadratic fitting and comparisons with relevant ionic radii. The two different C≡N bond distances have been simulated by the covalo-electrostatic model. - Graphical abstract: Crystallographic and FTIR data for Ln[Fe(CN) 6 ].4H 2 O enable the changes in Ln-O, Ln-N, C≡N and Fe-C distances to be determined and modeled across the lanthanide series

Crystal structure and spectroscopic analysis of a new oxalate-bridged MnII compound: catena-poly[guanidinium [[aquachloridomanganese(II]-μ2-oxalato-κ4O1,O2:O1′,O2′] monohydrate

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Hiba Sehimi

2016-05-01

Full Text Available As part of our studies on the synthesis and the characterization of oxalate-bridged compounds M–ox–M (ox = oxalate dianion and M = transition metal ion, we report the crystal structure of a new oxalate-bridged MnII phase, {(CH6N3[Mn(C2O4Cl(H2O]·H2O}n. In the compound, a succession of MnII ions (situated on inversion centers adopting a distorted octahedral coordination and bridged by oxalate ligands forms parallel zigzag chains running along the c axis. These chains are interconnected through O—H...O hydrogen-bonding interactions to form anionic layers parallel to (010. Individual layers are held together via strong hydrogen bonds involving the guanidinium cations (N—H...O and N—H...Cl and the disordered non-coordinating water molecule (O—H...O and O—H...Cl, as well as by guanidinium π–π stacking. The structural data were confirmed by IR and UV–Visible spectroscopic analysis.

Influence of silicon dangling bonds on germanium thermal diffusion within SiO{sub 2} glass

Energy Technology Data Exchange (ETDEWEB)

Barba, D.; Martin, F.; Ross, G. G. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Cai, R. S.; Wang, Y. Q. [The Cultivation Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Demarche, J.; Terwagne, G. [LARN, Centre de Recherche en Physique de la Matière et du Rayonnement (PMR), University of Namur (FUNDP), B-5000 Namur (Belgium); Rosei, F. [INRS Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel-Boulet, Varennes, Québec J3X 1S2 (Canada); Center for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec H3A 2K6 (Canada)

2014-03-17

We study the influence of silicon dangling bonds on germanium thermal diffusion within silicon oxide and fused silica substrates heated to high temperatures. By using scanning electron microscopy and Rutherford backscattering spectroscopy, we determine that the lower mobility of Ge found within SiO{sub 2}/Si films can be associated with the presence of unsaturated SiO{sub x} chemical bonds. Comparative measurements obtained by x-ray photoelectron spectroscopy show that 10% of silicon dangling bonds can reduce Ge desorption by 80%. Thus, the decrease of the silicon oxidation state yields a greater thermal stability of Ge inside SiO{sub 2} glass, which could enable to considerably extend the performance of Ge-based devices above 1300 K.

Effect of irradiation mode and filling technique on resin/dentin bonding strength in class I cavities Efeito do modo de ativação e da técnica restauradora na resistência de união entre compósito e dentina em cavidades classe I

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Alex José Souza dos Santos

2004-09-01

Full Text Available Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm² for 40 s or Soft-Start (250 mW/cm² for 10 s + 600 mW/cm² for 30 s modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1. The teeth were stored in water at 37ºC for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm² were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05. Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p Fatores como o modo de ativação, a técnica restauradora e a configuração cavitária podem afetar a resistência adesiva à dentina. Este estudo avaliou os efeitos dos modos de ativação e das técnicas restauradoras na resistência de união compósito/dentina na parede vestibular de restaurações classe I. O esmalte oclusal dos dentes foi removido para expor uma superfície dentinária planificada. Cavidades oclusais (4 x 3 x 3 mm foram preparadas em dentina. O adesivo Single Bond foi aplicado de acordo com as instruções do fabricante, e o compósito TPH Spectrum, inserido através de três diferentes técnicas: oblíqua incremental, horizontal

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].

Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

Science.gov (United States)

Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

2015-12-01

As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

Nickel-Catalyzed C sp2 –C sp3 Cross-Coupling via C–O Bond Activation

KAUST Repository

Guo, Lin

2016-06-13

A new and efficient nickel-catalyzed alkylation of CAr-O electrophiles with B-alkyl-9-BBNs is described. The transformation is characterized by its functional group tolerance and provides a practical and versatile access to various Csp2-Csp3 bonds through Csp2-O substitution, without the restriction of β-hydride elimination. Moreover, the advantage of the newly developed method was demonstrated in a selective and sequential C-O bond activation process. © 2016 American Chemical Society.

Electronic Structure and Bonding Situation in M2O2 (M=Be,Mg,Ca) Rhombic Clusters.

Czech Academy of Sciences Publication Activity Database

Li, W.-L.; Lu, J.-B.; Zhao, L.; Ponec, Robert; Cooper, D.L.; Li, J.; Frenking, G.

Roč. 122, č. 10 ( 2018 ), s. 2816-2822 ISSN 1089-5639 Grant - others:NNSFCH(CN) 21590792; NNSFCH(CN) 21433005; NNSFCH(CN) 21703099; JPY NSF(CN) BK20170964; NTU(CN) 39837123 Institutional support: RVO:67985858 Keywords : electronic structures * M2O2n clustery * theoretical isnights Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.847, year: 2016

Electronic structure of Ti/sub 2/O/sub 3/, V/sub 2/O/sub 3/, and Cr/sub 2/O/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Bondarenko, T N; Zhurakovskii, E A; Dzeganovskii, V P [AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya

1975-11-01

Electronic structure of oxides Ti/sub 2/O/sub 3/, V/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/ was elucidated by means of X-ray and ESCA methods and the results were compared with the data obtained by other methods and with the available models of electronic structures. Energy diagram of V/sub 2/O/sub 3/ and common energy scale of X-ray spectra of Ti and Cr in Ti/sub 2/O/sub 3/ and Cr/sub 2/O/sub 3/ are presented. X-ray spectra show that these oxides possess the states which are related genetically to the M4p-states i.e. the X-ray data complement essentially to the result of optical and electrophysical measurements. MO and M/sub 2/O/sub 3/ compounds in the region of Fermi level have overlapping emission and absorption spectra which is specific to the matters with the metallic type of bonding. Actually TiO, VO, Ti/sub 2/O/sub 3/ and V/sub 2/O/sub 3/ have metallic type of bonding. However such overlap was observed in Cr/sub 2/O/sub 3/ as well whose forbidden zone according to photoconductivity measurments is about 3 eV. Absence of energy gap between emission and absorption spectra in Cr/sub 2/O/sub 3/ may be explained by traces of impurities which convert dielectrics conductors - impurities act as agents caus:ng filling or generation of vacancies rather than independent allowing additives. On the other hand this may be due to the defects in Cr/sub 2/O/sub 3/ lattice which may cause appearance of excited states in forbidden zone. These investigations enable to draw energy diagram of V/sub 2/O/sub 3/ and to combine the spectra of M in Ti/sub 2/O/sub 3/ into common energy scheme. Analysis of the diagram and combined spectra revealed great similarity in the electronic structures of M/sub 2/O/sub 3/ oxides (M - Ti, V, Cr) .

Room temperature direct bonding of LiNbO3 crystal layers and its application to high-voltage optical sensing

International Nuclear Information System (INIS)

Tulli, D; Janner, D; Pruneri, V

2011-01-01

LiNbO 3 is a crystal widely used in photonics and acoustics, for example in electro-optic modulation, nonlinear optical frequency conversion, electric field sensing and surface acoustic wave filtering. It often needs to be combined with other materials and used in thin layers to achieve the adequate device performance. In this paper, we investigate direct bonding of LiNbO 3 crystals with other dielectric materials, such as Si and fused silica (SiO 2 ), and we show that specific surface chemical cleaning, together with Ar or O 2 plasma activation, can be used to increase the surface free energy and achieve effective bonding at room temperature. The resulting hybrid material bonding is very strong, making the dicing and grinding of LiNbO 3 layers as thin as 15 µm possible. To demonstrate the application potentials of the proposed bonding technique, we have fabricated and characterized a high-voltage field sensor with high sensitivity in a domain inverted and bonded LiNbO 3 waveguide substrate

Butane-1,4-diammonium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6cadmate(II dihydrate

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Najmeh Firoozi

2008-10-01

Full Text Available In the title compound, (C4H14N2[Cd(C7H3NO42]·2H2O, the CdII ion is coordinated by four O atoms [Cd—O = 2.2399 (17–2.2493 (17 Å] and two N atoms [Cd—N = 2.3113 (15 and 2.3917 (15 Å] from two tridentate pyridine-2,6-dicarboxylato ligands in a distorted octahedral geometry. The uncoordinated water molecules are involved in O—H...O and N—H...O hydrogen bonds, which contribute to the formation of a three-dimensional supramolecular structure, along with π–π stacking interactions [centroid–centroid distances of 3.5313 (13 and 3.6028 (11 Å between the pyridine rings of neighbouring dianions].

Buthalital and methitural – 5,5-substituted derivatives of 2-thiobarbituric acid forming the same type of hydrogen-bonded chain

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Thomas Gelbrich

2017-12-01

Full Text Available The molecule of buthalital, (I [systematic name: 5-(2-methylpropyl-5-(prop-2-en-1-yl-2-sulfanylidene-1,3-diazinane-4,6-dione], C11H16N2O2S, exhibits a planar pyrimidine ring, whereas the pyrimidine ring of methitural, (II [systematic name: 5-(1-methylbutyl-5-[2-(methylsulfanylethyl]-2-sulfanylidene-1,3-diazinane-4,6-dione], C12H20N2O2S2, is slightly puckered. (I and (II contain the same hydrogen-bonded chain structure in which each molecule is connected, via four N—H...O=C hydrogen bonds, to two other molecules, resulting in a hydrogen-bonded chain displaying a sequence of R22(8 rings. The same type of N—H...O=C hydrogen-bonded chain has previously been found in several 5,5-disubstituted derivatives of barbituric acid which are chemically closely related to (I and (II.

Structure of ferroelastic K3H(SeO4)2

International Nuclear Information System (INIS)

Ichikawa, M.; Sato, S.; Komukae, M.; Osaka, T.

1992-01-01

Tripotassium hydrogenbis(selenate), K 3 H(SeO 4 ) 2 , M r = 404.2, monoclinic, A2/a, a = 10.1291 (8), b = 5.9038 (5), c = 14.961 (1) A, β = 103.640 (8) 0 , V = 869.5 (1) A 3 , Z = 4, D x = 3.086 Mg m -3 , λ(Mo Kα) = 0.71073 A, μ = 9.86 mm -1 , F(000) = 760, T = 299 K, R(F) = 0.0294 for 1670 unique reflections. K 3 H(SeO 4 ) 2 is isomorphous with most M 3 H(XO 4 ) 2 -type crystals (M=K,Rb and Cs; Cs; X = S and Se); two SeO 4 groups are connected by a crystallographically symmetric hydrogen bond into a dimer. The bond distances and angles in the SeO 4 group are similar to those in Rb 3 H(SeO 4 ) 2 and Rb 3 D(SeO 4 ) 2 . The hydrogen-bond length, 2.524 (5) A, is the shortest among the members of the M 3 H(SeO 4 ) 2 family exhibiting the low-temperature phase transition. (orig.)

Avaliação do Índice de Remanescente Adesivo utilizando braquetes com e sem tratamento na base e a interação com três sistemas de colagem Evaluation of Adhesive Remnant Index using conventional mesh bases and sandblasted orthodontic bracket bases and three bonding systems

Directory of Open Access Journals (Sweden)

Lilian Maria Brisque Pignatta

2009-02-01

Full Text Available OBJETIVO: avaliar o Índice de Remanescente Adesivo (IRA em dentes bovinos após a descolagem de braquetes com e sem tratamento na base. METODOLOGIA: foram utilizados três sistemas de colagem ortodôntica para os dois padrões de base. Os dentes bovinos foram divididos em seis grupos de 40, de acordo com a base do braquete e o sistema de colagem. Vinte e quatro horas após a colagem foram realizados os testes de compressão em uma máquina de ensaios. A avaliação do IRA foi realizada em um estereomicroscópio por três examinadores calibrados. Foi utilizado o teste não paramétrico de Kruskal-Wallis, seguido do método de Dunn, para fazer as comparações múltiplas entre todos os grupos. RESULTADOS E CONCLUSÕES: observou-se que o tratamento das bases dos braquetes com óxido de alumínio não foi determinante para o aumento da adesividade entre o braquete e o adesivo. O grupo em que se utilizou braquetes com tratamento na base e adesivo TXT (3M-Unitek + Transbond Plus SEP (3M-Unitek apresentou a maior parte das fraturas na interface dente-adesivo (escore 4.AIM: To assess the Adhesive Remnant Index (ARI in bovine teeth after debonding mesh bases and sandblasted orthodontic bracket bases. METHODS: Were used three bonding systems for the two standards of base. The bovine teeth were divided into 6 groups of 40, according to the bracket base and to the bonding system. Twenty four hours after bonding they had been carried through shear bond strength tests in a universal testing machine. The assessment of ARI was performed in a stereomicroscopy by three calibrated examiners. It was used the non-parametric Kruskall-Wallis test, followed by Dunn's method, to do the multiple comparisons among all groups. RESULTS AND CONCLUSIONS: It was observed that the aluminum oxide sandblasting bracket bases was not determinative to the increase of the adhesiveness between bracket and adhesive. The group where it was used sandblasted orthodontic bracket bases and

Mode structure in an optically pumped D2O far infrared ring laser

International Nuclear Information System (INIS)

Yuan, D.C.; Soumagne, G.; Siegrist, M.R.

1989-07-01

The mode structures in an optically pumped D 2 O far infrared ring laser and a corresponding linear resonator have been compared. While single mode operation can be obtained over the whole useful pressure range in the ring structure, this is only possible at pressures greater than 8 Torr in the linear resonator case. A numerical model predicts quite well the pulse shape, pressure dependence and influence of the resonator quality in the ring cavity. (author) 12 figs., 8 refs

O Conhecimento profissional na formação do professor de música

OpenAIRE

Madeira, Ana Ester Correia

2016-01-01

Resumo Apresentação do livro Professional Knowledge in Music Teacher Education. Este é o primeiro livro que trata do conhecimento profissional do professor de música. Reúne 13 capítulos organizados em três partes com diferentes finalidades, os quais são escritos por autores de diversos países. Eles apresentam as muitas formas de definir o termo "conhecimento profissional" no ensino de música, sua importância para a formação do educador musical, sua aplicação nas pesquisas realizadas na área e...

O Conhecimento profissional na formação do professor de música

OpenAIRE

Madeira, Ana Ester Correia

2017-01-01

Resumo Apresentação do livro Professional Knowledge in Music Teacher Education. Este é o primeiro livro que trata do conhecimento profissional do professor de música. Reúne 13 capítulos organizados em três partes com diferentes finalidades, os quais são escritos por autores de diversos países. Eles apresentam as muitas formas de definir o termo "conhecimento profissional" no ensino de música, sua importância para a formação do educador musical, sua aplicação nas pesquisas realizadas na área e...

Ambientes virtuais e mídias de comunicação, abordando a explosão das mídias na sociedade da informação e seu impacto na aprendiza-gem - o uso do WhatsApp como plataforma de m-learning

Directory of Open Access Journals (Sweden)

Paulo Cesar Pereira

2016-09-01

Full Text Available Este trabalho tem como objetivo verificar o atual uso e desenvolvimento das plataformas denominadas m-learning, suas vantagens e desafios a serem enfrentados para a sua disseminação na educação à distância. Descreve brevemente a evolução dos ambientes de aprendizagem através do uso das Tecnologias de Informação e Comunicação e avalia a possibilidade de utilização da tecnologia de computação móvel no auxílio ao processo de aprendizagem. O trabalho foi realizado através de pesquisa exploratória, de campo e bibliográfica, consistindo no levantamento do conhecimento bibliográfico disponível em produções atuais e no levantamento das percepções de professores de diversos níveis de formação, vinculação, tempo de docência e idades a respeito do uso de ambientes de m-Learning, em especial o Wattsapp. Por meio do desenvolvimento do presente estudo, foi possível observar que o uso do m-learningainda está em fase embrionária no contexto brasileiro, mas o uso de dispositivos móveis na educação é algo que não deve ser ignorado ou pensado como improvável em pouco tempo, pois atualmente, alunos e professores buscam a interação pessoal, entre si, permitida por esta tecnologia, muito além de ser somente um distribuidor de conteúdos educacionais.

Relaxation of the chemical bond skin chemisorption size matter ZTP mechanics H2O myths

CERN Document Server

Sun, Chang Q

2014-01-01

The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band, and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behav...

The Hydrogen Bonded Structures of Two 5-Bromobarbituric Acids and Analysis of Unequal C5–X and C5–X′ Bond Lengths (X = X′ = F, Cl, Br or Me in 5,5-Disubstituted Barbituric Acids

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Thomas Gelbrich

2016-04-01

Full Text Available The crystal structure of the methanol hemisolvate of 5,5-dibromobarbituric acid (1MH displays an H-bonded layer structure which is based on N–H∙∙∙O=C, N–H∙∙∙O(MeOH and (MeOHO–H∙∙∙O interactions. The barbiturate molecules form an H-bonded substructure which has the fes topology. 5,5′-Methanediylbis(5-bromobarbituric acid 2, obtained from a solution of 5,5-dibromobarbituric acid in nitromethane, displays a N–H···O=C bonded framework of the sxd type. The conformation of the pyridmidine ring and the lengths of the ring substituent bonds C5–X and C5–X′ in crystal forms of 5,5-dibromobarbituric acid and three closely related analogues (X = X′ = Br, Cl, F, Me have been investigated. In each case, a conformation close to a C5-endo envelope is correlated with a significant lengthening of the axial C5–X′ in comparison to the equatorial C5–X bond. Isolated molecule geometry optimizations at different levels of theory confirm that the C5-endo envelope is the global conformational energy minimum of 5,5-dihalogenbarbituric acids. The relative lengthening of the axial bond is therefore interpreted as an inherent feature of the preferred envelope conformation of the pyrimidine ring, which minimizes repulsive interactions between the axial substituent and pyrimidine ring atoms.

Nitrile/Buna N Material Failure Assessment for an O-Ring used on the Gaseous Hydrogen Flow Control Valve (FCV) of the Space Shuttle Main Engine

Science.gov (United States)

Wingard, Doug

2006-01-01

After the rollout of Space Shuttle Discovery in April 2005 in preparation for return-to-flight, there was a failure of the Orbiter (OV-103) helium signature leak test in the gaseous hydrogen (GH2) system. Leakage was attributed to the Flow Control Valve (FCV) in Main Engine 3. The FCV determined to be the source of the leak for OV-103 is designated as LV-58. The nitrile/Buna N rubber O-ring seal was removed from LV-58, and failure analysis indicated radial cracks providing leak paths in one quadrant. Cracks were eventually found in 6 of 9 FCV O-rings among the three Shuttle Orbiters, though none were as severe as those for LV-58, OV-103. Testing by EM10 at MSFC on all 9 FCV O- rings included: laser dimensional, Shore A hardness and properties from a dynamic mechanical analyzer (DMA) and an Instron tensile machine. The following test data was obtained on the cracked quadrant of the LV-58, OV-103 O-ring: (1) the estimated compression set was only 9.5%, compared to none for the rest of the O-ring; (2) Shore A hardness for the O.D. was higher by almost 4 durometer points than for the rest of the O-ring; and (3) DMA data showed that the storage/elastic modulus E was almost 25% lower than for the rest of the O-ring. Of the 8 FCV O-rings tested on an Instron, 4 yielded tensile strengths that were below the MIL spec requirement of 1350 psi-a likely influence of rubber cracking. Comparisons were made between values of modulus determined by DNA (elastic) and Instron (Young s). Each nitrile/Buna N O-ring used in the FCV conforms to the MIL-P-25732C specification. A number of such O-rings taken from shelf storage at MSFC and Kennedy Space Center (KSC) were used to generate a reference curve of DMA glass transition temperature (Tg) vs. shelf storage time ranging from 8 to 26 years. A similar reference curve of TGA onset temperature (of rubber weight loss) vs. shelf storage time was also generated. The DMA and TGA data for the used FCV O-rings were compared to the reference

Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

Science.gov (United States)

Thorne, Richard M.; Horne, Richard B.

1994-01-01

Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

(E,E-6,6′-Dimethoxy-2,2′-[o-phenylenebis(nitrilomethylidyne]diphenol

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Yong Wang

2009-04-01

Full Text Available In the title compound, C22H20N2O4, the central benzene ring forms dihedral angles of 3.2 (2 and 61.1 (1° with the two outer substituted benzene rings. Intramolecular O—H...N hydrogen bonds are formed by both hydroxyl groups.

Molecular magnetism of M6 hexagon ring in D(3d) symmetric [(MCl)6(XW9O33)2](12-) (M = Cu(II) and Mn(II), X = Sb(III) and As(III)).

Science.gov (United States)

Yamase, Toshihiro; Ishikawa, Hirofumi; Abe, Hiroko; Fukaya, Keisuke; Nojiri, Hiroyuki; Takeuchi, Hideo

2012-04-16

) cylindrical geometry, is demonstrated by the polarization mechanism based on the point-dipole approximation, which provides a decrease of the ferromagnetic interaction due to the out-of-cylinder deviation of the Cu atoms for 1. The different nature of the magnetic exchange interaction in 3 and 4 is understood by the combined effect of the out-of plane deviation (the largest for 4) of the Mn atoms from the Mn(μ(3)-O)(2)Mn least-squares plane and the antiferromagnetic contribution arising from the large Mn-O-Mn bond angle. The primary contribution to D is discussed in terms of the magnetic dipole-dipole interaction between the electrons located on the magnetic sites in the M(6) hexagon. © 2012 American Chemical Society

Dicarbonyl[2-hydroxy-3,5,7-tris(morpholinomethylcyclohepta-2,4,6-trienonato(1–-κ2O1,O2]rhodium(I

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G. Steyl

2008-12-01

Full Text Available In the title compound, [Rh(C22H32N3O5(CO2], the RhI atom is coordinated by two carbonyl ligands and two tropolonate O atoms in a distorted square-planar geometry. It is an example of a new type of tropolone derivative that has not been characterized via solid-state methods. Weak intramolecular C—H...N and intermolecular C—H...O hydrogen bonds, and π–π stacking interactions between the tropolone rings [centroid–centroid distance = 3.590 (8 Å] are observed in the crystal structure.

Synthesis of the EF-ring of ciguatoxin 3C based on the [2,3]-Wittig rearrangement and ring-closing olefin metathesis.

Science.gov (United States)

Goto, Akiyoshi; Fujiwara, Kenshu; Kawai, Ayako; Kawai, Hidetoshi; Suzuki, Takanori

2007-12-20

The EF-ring segment of ciguatoxin 3C, a causative toxin of ciguatera fish poisoning, was synthesized in three major steps: 1,4-addition for the C20O-C27 bond connection, chirality transferring anti selective [2,3]-Wittig rearrangement for the construction of the anti-2-hydroxyalkyl ether part, and ring-closing olefin metathesis for the F-ring formation.

Density functional theory study of the structural and bonding mechanism of molecular oxygen (O2) with C3Si

Science.gov (United States)

Parida, Saroj K.; Behera, C.; Sahu, Sridhar

2018-07-01

The investigations of pure and heteroatom doped carbon clusters have created great interest because of their enormous prospective applications in various research zones, for example, optoelectronics, semiconductors, material science, energy storage devices, astro-science and so on. In this article, the interaction of molecular oxygen (O2) with C3Si has explored within a density functional theory (DFT). Different possible types of structure for C3SiO2 have collected. Among five different kinds of structure, the structure-1a, 1A1 is more energetically stable. The nature of the bonding of O2 and C3Si, in C3SiO2 has been studied by using Bader's topological analysis of the electron charge density distribution ρ(r) , Laplacian ∇2 ρ(r) and total energy density H(r) at the bond critical points (BCPs) of the structures within the framework of the atoms in molecules theory (AIM). The bonding mechanism of O2 and C3Si in C3SiO2 prompts to the fundamental understanding of the interaction of C3Si with oxygen molecule. It is interesting to note that, two types of bonding mechanism are established in same C3SiO2 system such as (i) shared-kind interactions (ii) closed-shell interactions. From various kinds of structure, Csbnd C bonds in all structures are shown as shared-kind interactions whereas Csbnd Si, Osbnd O bonds are classified as closed-shell type interactions with a certain degree of covalent character.

O estudante de Medicina e o médico recém-formado frente à morte e ao morrer

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Gustavo Nader Marta

Full Text Available A compreensão do papel da morte como uma condição intrínseca e inegável da vida sempre foi de grande relevância para o mundo ocidental, levando a diferentes atitudes, especialmente entre aqueles que precisam encarar a morte como parte de sua rotina profissional. Isto é particularmente aplicável aos médicos, que, muitas vezes, se acham diante da responsabilidade de tomar decisões sobre as condições de saúde e a vida de seus pacientes. Os objetivos deste estudo foram verificar o comportamento do estudante de Medicina e do médico recém-formado diante da morte e do morrer, identificar as condições e deficiências da relação médico-paciente-morrer-morte, comparar tais posturas entre os estudantes de Medicina e os médicos recém-formados, e propor atividades que possibilitem a sensibilização quanto aos processos internos com base em teoria, prática e desenvolvimento pessoal. Isso foi feito por meio da aplicação de questionários aos 100 alunos do terceiro ano e aos 120 residentes do CCMB-PUC-SP.

Precipitação média anual e vazão específica média de longa duração, na Bacia do São Francisco Specific yield discharge and mean precipitation in São Francisco Basin

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Fernando F. Pruski

2004-12-01

Full Text Available O Rio São Francisco abrange uma área de drenagem da ordem de 640.000 km² e é responsável pela sustentabilidade de 503 municípios situados na bacia, onde vivem cerca de 14 milhões de pessoas. Neste trabalho analisou-se a variação da precipitação média anual e da vazão específica média de longa duração na Bacia do São Francisco. Foram analisados os dados hidrológicos de 178 estações pluviométricas e 77 estações fluviométricas, sendo a vazão específica média de longa duração obtida dividindo-se a vazão média anual pela área de drenagem da estação fluviométrica considerada e a precipitação média em cada área de drenagem, calculada pelo método do Polígono de Thiessen. Os resultados obtidos permitiram as seguintes conclusões: as precipitações diminuem da nascente para a foz do São Francisco, e as vazões específicas médias de longa duração diminuem ao longo do Rio São Francisco, sendo a máxima vazão específica igual a 22,61 L s-1 km-2, em Iguatama, primeira estação situada neste, e a mínima, igual a 4,22 L s-1 km-2, em Traipu, última estação desse rio.The São Francisco River drains an area of 640,000 km² and is responsible for the sustainability of the 503 municipalities in the basin where 14 million people live. This study was undertaken to investigate the mean precipitation and the specific yield discharge in the São Francisco Basin. The analysis was made considering 178 rain-gauge stations and 77 stations to measure stream flow. The specific yield discharge was obtained by dividing the mean annual discharge by the drainage area upstream from the station, and the mean precipitation in the upstream area from each station was obtained by the Thiessen polygon method. The results indicated that the mean precipitation decreased from the Upper São Francisco to Lower São Francisco, and the specific yield discharge decreases along the river, the maximum specific discharge was 22.6 L s-1 km-2

Effect of tooth age on bond strength to dentin Efeito da idade na resistência de união

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Marcelo Giannini

2003-12-01

Full Text Available This in vitro study evaluated the effect of tooth age on the tensile bond strength of Prime & Bond NT adhesive system to dentin. Human third molars from the five age groups were analyzed: A- 17 to 20yrs, B- 21 to 30yrs, C- 31 to 40yrs, D- 41 to 50yrs and E- 51 to 63yrs. The occlusal enamel was removed using a diamond saw under water cooling and the dentin surface was wet-ground with 600-grit SiC paper to obtain flat surfaces. The adhesive system was applied according to the manufacturer's instructions and a 6-mm high resin "crown" was built-up with resin composite. Teeth were stored for 24 hours in distilled water at 37ºC and prepared for micro-tensile testing. Each specimen was mounted in a testing jig attached to a universal testing machine and stressed in tension at a crosshead speed of 0.5mm/min until failure. The means of tensile bond strength were (MPa: A- 21.42 ± 7.52ª; B- 30.13 ± 10.19ª; C- 31.69 ± 11.78ª; D- 30.69 ± 8.47ª and E- 35.66 ± 9.54ª. No statistically significant difference was observed among the age groups (p > 0.05. The results suggested that the tensile bond strength of the adhesive system was not significantly affected by dentin aging.Este estudo avaliou, in vitro, o efeito da idade na resistência à tração do sistema adesivo Prime & Bond NT no substrato dentinário. Foram utilizados terceiros molares humanos de cinco faixas etárias: A- 17 a 20, B- 21 a 30, C- 31 a 40, D- 41 a 50 e E- 51 a 63. O esmalte oclusal foi removido utilizando disco de diamante e a superfície dentinária abrasionada e planificada com lixa de SiC (600 sob refrigeração. O sistema adesivo foi aplicado de acordo com as recomendações do fabricante e um bloco de resina composta de 6 mm de altura foi confeccionado na superfície dentinária. Os dentes foram armazenados em água por 24 horas a 37ºC e preparados para o ensaio de micro-tração. Cada espécime foi fixado no dispositivo de micro-tração que estava acoplado a uma m

[Effect of TiO2-SiO2-SnOx film with different firing temperatures on bond strength of low-fusing dental porcelain to pure titanium].

Science.gov (United States)

Zhang, Zichuan; Zhang, Pei

2015-07-01

To evaluate the influence of TiO(2)-SiO(2)-SnOx nano-coatings with different firing temperatures on the bond strength of low-fusing dental porcelain to pure titanium. The surface of pure titanium was coated uniformly with TiO(2)-SiO(2)-SnOx nano-coatings by solution-gelatin (Sol-Gel) technology and then fired at 300 °C (group A) or 750 °C (group B) for 1 h. The specimens without any coatings were the control group (group C). There were 10 specimens in each group. Dental porcelain was sintered on the surface of titanium specimens. Surface roughness and contact angle of the coatings were also detected. The titanium-porcelain bond strength was investigated according to YY 0621-2008 standards using three-point flexure bond test. The phase composition of the TiO(2)-SiO(2)-SnOx nano-coatings was characterized by X-ray diffraction(XRD). The interface of titanium-porcelain and TiO(2)-SiO(2)-SnOx nano-coatings were observed using scanning electron microscope (SEM). No rutile phase was found in these specimens of group A and group B. The surface roughness of group A, B, C was (0.97 ± 0.06), (0.99 ± 0.03), (0.96 ± 0.07) µm, respectively. No significant difference was found among the three groups. Compared with that of group C (64.37° ± 3.01°), contact angles detected in group A (52.04° ± 3.15°) and group B (85.27° ± 4.17°) were significantly different (P porcelain in group A [(35.66 ± 2.65) MPa] was significantly increased compared with those in group B [(26.18 ± 2.22) MPa] and group C [(31.66 ± 3.52) MPa]. SEM photomicrographs of titanium-porcelain interface morphology of the specimens before porcelain sintering showed that TiO(2)-SiO(2)-SnOx nano-coatings in group A were compact and homogeneous with petty cracks and those in group B was loose and arranged disorderly. TiO(2)-SiO(2)-SnOx nano-coating fired at 300 °C is significantly effective in improving the titanium-porcelain bond strength.

Electrically detected magnetic resonance study of the Ge dangling bonds at the Ge(1 1 1)/GeO2 interface after capping with Al2O3 layer

International Nuclear Information System (INIS)

Paleari, S.; Molle, A.; Accetta, F.; Lamperti, A.; Cianci, E.; Fanciulli, M.

2014-01-01

The electrical activity of Ge dangling bonds is investigated at the interface between GeO 2 -passivated Ge(1 1 1) substrate and Al 2 O 3 grown by atomic layer deposition, by means of electrically detected magnetic resonance spectroscopy (EDMR). The Al 2 O 3 /GeO 2 /Ge stacked structure is promising as a mobility booster for the post-Si future electronic devices. EDMR proved to be useful in characterizing interface defects, even at the very low concentrations of state-of-the-art devices ( 10 cm −2 ). In particular, it is shown that capping the GeO 2 -passivated Ge(1 1 1) with Al 2 O 3 has no impact on the microstructure of the Ge dangling bond.

Televisão e argumentação: episteme e métodos

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Luís Carlos Lopes

2011-01-01

Full Text Available Este artigo discute as possíveis imbricações entre as proposições das teorias da argumentação e a pesquisa compreensiva dos significados sociais da televisão. O autor propõe uma crítica humanista às teorias sobre as máquinas de comunicar de nosso tempo, considerando-as como portadoras da essência da comunicação humana. Funda sua análise no exame do pathos aristotélico, em contraponto ao ethos e aologos, também do mesmo filósofo. Faz a discussão dos aportes para o mesmo tema das teorias da argumentação contemporâneas, sobretudo, das proposições de Philippe Breton. Conclui com a sugestão de adoção do paradigma da argumentação como base epistemológica e suporte metodológico do campo da comunicação como um todo e dos estudos específicos sobre a comunicação televisiva.

r m o gemson

Indian Academy of Sciences (India)

Home; Journals; Sadhana. R M O GEMSON. Articles written in Sadhana. Volume 41 Issue 12 December 2016 pp 1473-1490. A heuristic reference recursive recipe for adaptively tuning the Kalman filter statistics part-1: formulation and simulation studies · M R ANANTHASAYANAM M SHYAM MOHAN NAREN NAIK R M O ...

Positronium formation and hydrated positron reactions in H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−

DEFF Research Database (Denmark)

Mogensen, O. E.; Pedersen, Niels Jørgen

1986-01-01

Angular correlation of annihilation photons were measured for H2O, D2O, 1.74 M PPS/H2O and 1.74 M PPS/D2O solutions of Cl−, Br− and I−. The three components of the angular correlation spectra for D2O and H2O were nearly identical in shape. The positronium (Ps) yields for the H2O and D2O solutions...... before annihilation (lifetime 400 ps) was determined for the three halides in the four solvents. Simple kinetic equations (“trapping model”) with time dependent rate constant, solved analytically, could explain the [X−, e+] formation in H2O fairly well for concentrations below 0.03 M X−, if a diffusion...... controlled reaction with positron diffusion constant D = 5 × 10−5 cm2/s and reaction radius R = 1 nm were assumed. The three halides gave roughly identical [X−, e+] formation below 0.03 M X−. The difference between the four solutions could be explained partly only in terms of viscosity change for the model...

Tensile bond strength of self-etching versus total-etching adhesive systems under different dentinal substrate conditions Resistência de união à tração de sistemas adesivos autocondicionantes versus de condicionamento total, em diferentes condições de substrato dentinário

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Alexandre Henrique Susin

2007-03-01

Full Text Available The use of acid etchants to produce surface demineralization and collagen network exposure, allowing adhesive monomers interdiffusion and consequently the formation of a hybrid layer, has been considered the most efficient mechanism of dentin bonding. The aim of this study was to compare the tensile bond strength to dentin of three adhesive systems, two self-etching ones (Clearfil SE Bond - CSEB and One Up Bond F - OUBF and one total-etching one (Single Bond - SB, under three dentinal substrate conditions (wet, dry and re-wet. Ninety human, freshly extracted third molars were sectioned at the occlusal surface to remove enamel and to form a flat dentin wall. The specimens were restored with composite resin (Filtek Z250 and submitted to tensile bond strength testing (TBS in an MTS 810. The data were submitted to two-way ANOVA and Tukey's test (p = 0.05. Wet dentin presented the highest TBS values for SB and CSEB. Dry dentin and re-wet produced significantly lower TBS values when using SB. OUBF was not affected by the different conditions of the dentin substrate, producing similar TBS values regardless of the surface pretreatments.O uso de condicionadores ácidos para desmineralizar a superfície dental e expor a rede de fibras colágenas para interdifusão dos monômeros adesivos e conseqüente formação da camada híbrida tem sido considerado o mais eficiente mecanismo de adesão dos agentes de união. O objetivo deste estudo foi comparar a resistência de união à dentina de três sistemas adesivos, dois autocondicionantes (Clearfil SE Bond - CSEB e One Up Bond F - OUBF e um de condicionamento total (Single Bond - SB, sob três diferentes condições de substrato dentinário (úmido, seco e reidratado. Noventa terceiros molares humanos recém-extraídos foram cortados na superfície oclusal, para se remover o esmalte e formar uma parede plana de dentina. Os espécimes foram restaurados com resina composta (Filtek Z250 e submetidos ao teste de

Interfaces da relação entre o médico e a dupla mãe-filho em um hospital público

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Ondina Lúcia Ceppas Resende

2013-06-01

Full Text Available OBJETIVO: Investigar a percepção dos médicos sobre a experiência de atenderem ambulatorialmente crianças com doença ocular grave e como compreendem sua interferência na relação mãe-filho. MÉTODOS: Foram realizadas entrevistas semiestruturadas com os oftalmologistas (setores de retina, glaucoma, segmento anterior e oftalmopediatria e observação das consultas ambulatoriais durante três meses. RESULTADOS: Idealização da figura do médico e da mãe; dificuldades na hora de transmitir o diagnóstico; e reconhecimento de que o profissional interfere na relação da dupla durante seus encontros. CONCLUSÃO: O desafio do médico está em dar as informações sobre diagnóstico e tratamento; ter disponibilidade para escutar, esclarecer e orientar e nos casos graves mostrar que a criança tem outras potencialidades além da visão.

Effect of La2O3 addition on interface chemistry between 4YSZ top layer and Ni based alloy bond coat in thermal barrier coating by EB PVD.

Science.gov (United States)

Park, Chan-Young; Yang, Young-Hwan; Kim, Seong-Won; Lee, Sung-Min; Kim, Hyung-Tae; Jang, Byung-Koog; Lim, Dae-Soon; Oh, Yoon-Suk

2014-11-01

The effect of a 5 mol% La2O3 addition on the forming behavior and compositional variation at interface between a 4 mol% Yttria (Y2O3) stabilized ZrO2 (4YSZ) top coat and bond coat (NiCrAlY) as a thermal barrier coating (TBC) has been investigated. Top coats were deposited by electron beam physical vapor deposition (EB PVD) onto a super alloy (Ni-Cr-Co-Al) substrate without pre-oxidation of the bond coat. Top coats are found to consist of dense columnar grains with a thin interdiffusion layer between metallic bond coats. In the as-received 4YSZ coating, a thin interdiffusion zone at the interface between the top and bond coats was found to consist of a Ni-Zr intermetallic compound with a reduced quantity of Y, Al or O elements. On the other hand, in the case of an interdiffusion area of 5 mol% La2O3-added 4YSZ coating, it was found that the complicated composition and structure with La-added YSZ and Ni-Al rich compounds separately. The thermal conductivity of 5 mol% La2O3-added 4YSZ coating (- 1.6 W/m x k at 1100 degrees C) was lower than a 4YSZ coating (- 3.2 W/m x k at 1100 degrees C) alone.

O método de pontos

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Waldir Mantovani

1990-01-01

Full Text Available O método de pontos foi usado em diversas situações, comparado com outros métodos, modificado e amplamente discutido e criticado, podendo-se ter através da revisão bibliográfica uma visão de suas vantagens e limitações, salientando-se naquelas a sua rapidez, precisão e pouca perturbação causada na vege tação e nestas, o diâmetro da agulha e a ação do vento. Neste trabalho está sendo introduzido e discutido um novo índice, denominado ín dice de cobertura (IC, obtido da soma dos valores absolutos de freqüência, que representa a cobertura e de vigor, associado à biomassa.The point method has been utilized in many situations, with or without modifications; it has also been compared to other methods and critically discussed. A review of the literature reveals the advantages (speed precision, minimum disturbance of the stand and disadvantages (dependence on diameter of the needle, wind action. A new index is introduced and discussed. It is referred to as the cover index (CI and is obtained by summing absolute frequency, which represents cover, and absolute vigor, which is associated with biomass.

Seleção de métodos para modularização no desenvolvimento de produtos: revisão sistemática

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Monique Sonego

2016-06-01

Full Text Available Resumo A estratégia de modularização em produtos é mencionada como razão de diversos benefícios para as empresas. Este artigo tem como objetivo identificar na literatura os métodos para desenvolvimento da modularização em produtos com o intuito de avaliar sua aplicabilidade e ferramentas utilizadas, visando facilitar a escolha do método para cada empresa. Para atingir estes objetivos foi realizada uma revisão sistemática de acordo com a repetibilidade e importância indicada nos artigos. Como resultado foram identificados seis diferentes métodos para modularização de produtos. Como contribuição do artigo destacam-se a análise dos métodos com relação às etapas para formação dos módulos (decomposição, integração e avaliação bem como a análise com relação a parâmetros de classificação quanto à área de atuação de cada método (variedade, geração e ciclo de vida. Por fim, este estudo oferece um guia para as empresas, contextualizando ambientes de aplicação e relacionando conhecimentos necessários para aplicação dos métodos.

X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes

Energy Technology Data Exchange (ETDEWEB)

Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

2006-09-27

Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

Phase relations in the systems M2MoO4-Cr2(MoO4)3-Zr(MoO4)2 (M=Li, Na, or Rb)

International Nuclear Information System (INIS)

Bazarov, B.G.; Chimitova, O.D.; Bazarova, Ts.T.; Arkhincheeva, S.I.; Bazarova, Zh.G.

2008-01-01

Phase equilibria in the systems M 2 MoO 4 -Cr 2 (MoO 4 ) 3 -Zr(MoO 4 ) 2 (M=Li, Na, or Rb) were investigated by X-ray powder diffraction analysis, DTA, and IR spectroscopy. The subsolidus structure of the phase diagrams of the systems under study was established. Two phases are formed in the Rb 2 MoO 4 -Cr 2 (MoO 4 ) 3 -Zr(MoO 4 ) 2 system with the molar ratios of the starting components equal to 5:1:1 (S 2 ) and 1:1:1 (S 1 ). Proceeding from isostructural character of Rb 5 FeHf(MoO 4 ) 6 and S 2 , the unit cell parameters are determined for S 2 [ru

Investigation on pseudosymmetry, twinning and disorder in crystal structure determinations: Ba(H2O)M2III[PO3(OH)]4 (M=Fe, V) as examples

International Nuclear Information System (INIS)

Sun Wei; Huang Yaxi; Pan Yuanming; Mi Jinxiao

2012-01-01

Twinning commonly occurs in monoclinic crystals with dimensionally similar a and c axes and results in pseudo-orthorhombic symmetries with overlapping diffractions. For example, twinning in the new synthetic compound Ba(H 2 O)Fe 2 [PO 3 (OH)] 4 , which varies in space group from P2 1 to P2 1 /c with approximately equal a and c axial lengths, gives rise to a pseudosymmetry of C222 1 . Similarly, the related compound Ba(H 2 O)V 2 [PO 3 (OH)] 4 is commonly twinned and varies in space groups as well, arising from ordered to disordered distributions of the barium cations and water molecules in the cavities. Moreover, analyses of these and other twinned structures show that the small average standard uncertainty of bond distances is a sensitive criterion for structure determinations, especially for those involving crystal twinning as well as order–disorder. A proper structure determination leads to small standard uncertainties of the atomic displacement parameters, which further result in the small standard uncertainties of bond distances. - Graphical abstract: Ba(H 2 O)M 2 III [PO 3 (OH)] 4 (M=Fe, V) varies in space group from P2 1 to P2 1 /c, arising from ordered to disordered distributions of Ba 2+ and H 2 O in the cavities. Highlights: ► Twinning commonly occurs in monoclinic crystals with a≈c. ► Overlapping diffractions from twin domains hamper with the determination of real space groups. ► Conventional criteria for evaluating the real space groups are not effective in this case. ► Small standard uncertainty of bond distances is proposed as a sensitive criterion. ► Using this criterion we determined the order–disorder structures of Ba(H 2 O)M 2 III [PO 3 (OH)] 4 (M=Fe, V) from twinned crystals.

Supra-molecular hydrogen-bonding patterns in the N(9)-H protonated and N(7)-H tautomeric form of an N(6) -benzoyl-adenine salt: N (6)-benzoyl-adeninium nitrate.

Science.gov (United States)

Karthikeyan, Ammasai; Jeeva Jasmine, Nithianantham; Thomas Muthiah, Packianathan; Perdih, Franc

2016-02-01

In the title molecular salt, C12H10N5O(+)·NO3 (-), the adenine unit has an N (9)-protonated N(7)-H tautomeric form with non-protonated N(1) and N(3) atoms. The dihedral angle between the adenine ring system and the phenyl ring is 51.10 (10)°. The typical intra-molecular N(7)-H⋯O hydrogen bond with an S(7) graph-set motif is also present. The benzoyl-adeninium cations also form base pairs through N-H⋯O and C-H⋯N hydrogen bonds involving the Watson-Crick face of the adenine ring and the C and O atoms of the benzoyl ring of an adjacent cation, forming a supra-molecular ribbon with R 2 (2)(9) rings. Benzoyl-adeninum cations are also bridged by one of the oxygen atoms of the nitrate anion, which acts as a double acceptor, forming a pair of N-H⋯O hydrogen bonds to generate a second ribbon motif. These ribbons together with π-π stacking inter-actions between the phenyl ring and the five- and six-membered adenine rings of adjacent mol-ecules generate a three-dimensional supra-molecular architecture.

Uma formalização da mão invisível

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Eleutério F. S. Prado

2006-03-01

Full Text Available No artigo, busca-se reconstruir a noção de mão invisível da Economia Política Clássica e, em particular, de Adam Smith, a fim de demarcar seu significado, conceitual e formalmente. No presente texto, entretanto, o conceito não designa a coordenação ótima dos planos de agentes mercantis dotados de racionalidade perfeita, mas sim o processo de auto-organização inerente à concorrência de capitais. Após uma seção inicial em que se discute o conceito historicamente, constrói-se um modelo orientado temporalmente, o qual imediatamente reclama uma explicitação da dinâmica da mobilidade do capital que ocorre ante as variações das taxas de lucros setoriais. A formalização da mão invisível é feita, então, com base na chamada dinâmica de replicação, construída originalmente, no campo da biologia matemática, para mostrar o processo de reprodução e competição de certas espécies animais.In this paper, I intend to reconstruct the invisible hand notion created by Classical Political Economy and, in special, by Adam Smith, in order to circumscribe its significance, conceptually and formally. In the text, meanwhile, this concept do not designate the best coordination of agents plans, all of them endowed with perfect rationality, but the self-organization process inherent to the competition of capitals. After a section where this concept is discussed historically, I construct a time oriented model that requires, immediately, a formalization of capital mobility process which occurs in face of profit variations in the productive sectors. Then, the required formalization is done applying the so called replication dynamics that were constructed in the field of mathematic biology to represent the reproduction and competition process of certain animals' species.

Crystal structure of diaquabis(N,N-diethylnicotinamide-κN1bis(2,4,6-trimethylbenzoato-κO1cobalt(II

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Gülçin Şefiye Aşkın

2016-04-01

Full Text Available The centrosymmetric molecule in the monomeric title cobalt complex, [Co(C10H11O22(C10H14N2O2(H2O2], contains two water molecules, two 2,4,6-trimethylbenzoate (TMB ligands and two diethylnicotinamide (DENA ligands. All ligands coordinate to the CoII atom in a monodentate fashion. The four O atoms around the CoII atom form a slightly distorted square-planar arrangement, with the distorted octahedral coordination sphere completed by two pyridine N atoms of the DENA ligands. The dihedral angle between the planar carboxylate group and the adjacent benzene ring is 84.2 (4°, while the benzene and pyridine rings are oriented at a dihedral angle of 38.87 (10°. The water molecules exhibit both intramolecular (to the non-coordinating carboxylate O atom and intermolecular (to the amide carbonyl O atom O—H...O hydrogen bonds. The latter lead to the formation of layers parallel to (100, enclosing R44(32 ring motifs. These layers are further linked via weak C—H...O hydrogen bonds, resulting in a three-dimensional network. One of the two ethyl groups of the DENA ligand is disordered over two sets of sites with an occupancy ratio of 0.490 (13:0.510 (13.

Avaliação da resistência ao cisalhamento de braquetes colados com resinas ortodônticas fluoretadas Evaluation of shear bond strength of brackets bonded with orthodontic fluoride-releasing composite resins

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Marcia Cristina Rastelli

2010-06-01

Full Text Available OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos colados com resinas que contêm flúor, comparando-as a uma resina convencional; e analisar a quantidade de adesivo remanescente na superfície do esmalte. MÉTODOS: sessenta pré-molares foram divididos aleatoriamente em 3 grupos: Grupo I - Concise (3M, Grupo II - Ultrabond (Aditek do Brasil e Grupo III - Rely-a-Bond (Reliance. Após a colagem dos braquetes, as amostras foram termocicladas (500 ciclos nas temperaturas de 5°C e 55°C. Após 48 horas, foram submetidas aos ensaios mecânicos de cisalhamento na direção oclusocervical, com velocidade de carga de 0,5mm/min, em uma máquina MTS 810. RESULTADOS: foram observadas resistências médias ao cisalhamento de 24,54±6,98MPa para o Grupo I, de 11,53±6,20MPa para o Grupo II e de 16,46±5,72MPa para o Grupo III. A Análise de Variância determinou diferença estatística entre as médias de resistência ao cisalhamento entre os grupos (p OBJECTIVE: To evaluate the shear bond strength of stainless steel brackets bonded with fluoride releasing composite resins, comparing them with a conventional resin and to analyze the amount of resin left on the enamel surface. METHODS: Sixty premolars were randomly divided into three groups: Group I - Concise (3M, Group II - Ultrabond (Aditek do Brasil and Group III - Rely-a-Bond (Reliance. After bonding, the samples were thermocycled (500 cycles at 5ºC and 55ºC temperatures. After 48 hours they were subjected to shear bond strength testing, in the occluso-gingival direction, using an MTS 810 Universal Testing Machine with load speed of 0.5 mm/min. RESULTS: The results demonstrated a mean shear bond strength of 24.54 ± 6.98 MPa for Group I, 11.53 ± 6.20 MPa for Group II, and 16.46 ± 5.72 MPa for Group III. Analysis of Variance (ANOVA determined a statistical difference in the mean shear bond strengths between groups (p < 0.001. The Tukey test evidenced that the averages of the

A percepção de pacientes sobre a comunicação não verbal na assistência médica

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Luiza Augusta Rosa Rossi-Barbosa

Full Text Available A confiança no médico e o sucesso terapêutico dependem, além de outros fatores, de uma boa comunicação entre profissional de saúde e paciente. O presente estudo buscou conhecer a percepção dos pacientes sobre aspectos da comunicação não verbal que influenciam a consolidação da confiança no médico. Trata-se de um estudo transversal, descritivo e analítico, com amostra aleatória de pacientes alocada em locais públicos da cidade. Foram realizadas 182 entrevistas com pessoas de idades entre 18 e 88 anos, registrando-se preferência pelo perfil mais tradicionalista do profissional, com roupas brancas, cabelos aparados e sem acessórios. O uso de maquiagem e acessórios (brincos, pulseiras, etc. para mulheres é aceito com moderação. Existe restrição ao uso de piercings, tatuagens e brincos em homens, especialmente pela população idosa. Confirmando a importância da aparência na comunicação médico-paciente, o estudo destaca a necessidade da inserção do tema nos currículos médicos, uma vez que esses aspectos são pouco discutidos na formação do profissional médico, o que permitirá reflexões sobre aspectos não verbais da comunicação na relação médico-paciente e poderá influenciar positivamente as atitudes dos novos profissionais.

Nickel-Catalyzed C–O Bond-Cleaving Alkylation of Esters: Direct Replacement of the Ester Moiety by Functionalized Alkyl Chains

KAUST Repository

Liu, Xiangqian; Jia, Jiaqi; Rueping, Magnus

2017-01-01

Two efficient protocols for the nickel-catalyzed aryl–alkyl cross-coupling reactions using esters as coupling components have been established. The methods enable the selective oxidative addition of nickel to acyl C–O and aryl C–O bonds and allow the aryl–alkyl cross-coupling via decarbonylative bond cleavage or through cleavage of a C–O bond with high efficiency and good functional group compatibility. The protocols allow the streamlined, unconventional utilization of widespread ester groups and their precursors, carboxylic acids and phenols, in synthetic organic chemistry.

Nickel-Catalyzed C–O Bond-Cleaving Alkylation of Esters: Direct Replacement of the Ester Moiety by Functionalized Alkyl Chains

KAUST Repository

Liu, Xiangqian

2017-06-07

Two efficient protocols for the nickel-catalyzed aryl–alkyl cross-coupling reactions using esters as coupling components have been established. The methods enable the selective oxidative addition of nickel to acyl C–O and aryl C–O bonds and allow the aryl–alkyl cross-coupling via decarbonylative bond cleavage or through cleavage of a C–O bond with high efficiency and good functional group compatibility. The protocols allow the streamlined, unconventional utilization of widespread ester groups and their precursors, carboxylic acids and phenols, in synthetic organic chemistry.

Cocrystals of 6-propyl-2-thiouracil: N-H···O versus N-H···S hydrogen bonds.

Science.gov (United States)

Tutughamiarso, Maya; Egert, Ernst

2011-11-01

In order to investigate the relative stability of N-H···O and N-H···S hydrogen bonds, we cocrystallized the antithyroid drug 6-propyl-2-thiouracil with two complementary heterocycles. In the cocrystal pyrimidin-2-amine-6-propyl-2-thiouracil (1/2), C(4)H(5)N(3)·2C(7)H(10)N(2)OS, (I), the `base pair' is connected by one N-H···S and one N-H···N hydrogen bond. Homodimers of 6-propyl-2-thiouracil linked by two N-H···S hydrogen bonds are observed in the cocrystal N-(6-acetamidopyridin-2-yl)acetamide-6-propyl-2-thiouracil (1/2), C(9)H(11)N(3)O(2)·2C(7)H(10)N(2)OS, (II). The crystal structure of 6-propyl-2-thiouracil itself, C(7)H(10)N(2)OS, (III), is stabilized by pairwise N-H···O and N-H···S hydrogen bonds. In all three structures, N-H···S hydrogen bonds occur only within R(2)(2)(8) patterns, whereas N-H···O hydrogen bonds tend to connect the homo- and heterodimers into extended networks. In agreement with related structures, the hydrogen-bonding capability of C=O and C=S groups seems to be comparable.

Unprecedented connection mode of [V{sub 16}Sb{sub 4}O{sub 42}(H{sub 2}O)]{sup 8-} cluster anions by Mn{sup 2+} centered complexes. Solvothermal synthesis and properties of {[Mn(teta)]_4V_1_6Sb_4O_4_2(H_2O)}{sub n}.[(H{sub 2}O){sub 12}]{sub n}

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Maren; Naether, Christian; Bensch, Wolfgang [Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel (Germany); Leusen, Jan van; Koegerler, Paul [Institute of Inorganic Chemistry, RWTH Aachen University, Aachen (Germany)

2017-11-17

The new compound {[Mn(teta)]_4V_1_6Sb_4O_4_2}{sub n}.[(H{sub 2}O){sub 12}]{sub n} (teta = triethylenetetraamine) was synthesized under solvothermal conditions. The crystal structure features the high nuclearity [V{sub 16}{sup IV}Sb{sub 4}{sup III}O{sub 42}(H{sub 2}O)]{sup 8-} cluster anion, which consists of two rings composed of 8 edge-sharing VO{sub 5} polyhedra. The rings are perpendicular to each other generating four niches, which are occupied by two VO{sub 5} pyramids and two handle-like Sb{sub 2}O{sub 5} units. The two unique anions are each surrounded by eight Mn{sup 2+} centered complexes via Mn-O{sub term}-V bonds. Such an expansion has never been observed in heterometal polyoxovanadate chemistry. The connection mode between cluster anions and complex cations generates two individual layers stacked onto each other. Between the layers weak Sb..O contacts are observed. The crystal water molecules are mainly located in the empty space between the layers. Upon heating H{sub 2}O molecules are removed, while the crystal structure remains intact. The magnetic behavior is dominated by strong antiferromagnetic exchange interactions between the central V{sup 4+} ions, while the interaction between the cluster anion and central Mn{sup 2+} ions is significantly less pronounced. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Crystal structure of 1,2,3,5-di-O-methylene-α-d-xylofuranose

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Ioannis Tiritiris

2015-11-01

Full Text Available The title compound, C7H10O5, was synthesized by reaction of d-xylose with paraformaldehyde. In the crystal, the central part of the molecule consists of a five-membered C4O ring with an envelope conformation, with the methine C atom adjacent to the O atom being the flap. The protected O atoms of both cyclic acetal groups are oriented so that the four chiral C atoms of the furanose part show an R configuration. C—H...O hydrogen bonds are present between adjacent molecules, generating a three-dimensional network.

Synthesis and 3D Network Architecture of 1- and 16-Hydrated Salts of 4-Dimethylaminopyridinium Decavanadate, (DMAPH6[V10O28]·nH2O

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Eduardo Sánchez-Lara

2016-05-01

Full Text Available Two hybrid materials based on decavanadates (DMAPH6[V10O28]·H2O, (1 and (DMAPH6[V10O28]·16H2O, (2 (where DMAPH = 4-dimethylaminopyridinium were obtained by reactions under mild conditions at T = 294 and 283 K, respectively. These compounds are pseudopolymorphs, which crystallize in monoclinic P 2 1 / n and triclinic P 1 ¯ space groups. The structural analysis revealed that in both compounds, six cations DMAPH+ interact with decavanadate anion through N-H∙∙∙Odec hydrogen bonds; in 2, the hydrogen-bonding association of sixteen lattice water molecules leads to the formation of an unusual network stabilized by decavanadate clusters; this hydrogen-bond connectivity is described using graph set notation. Compound 2 differs basically in the water content which in turn increases the π∙∙∙π interactions coming from pyridinium rings. Elemental and thermal analysis (TGA/DSC as well as FT-IR, FT-Raman, for 1 and 2 are consistent with both structures and are also presented.

Instrumentos de avaliação do vínculo entre mãe e bebê

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Jaqueline Galdino Albuquerque Perrelli

2014-09-01

Full Text Available Objetivo: Identificar os instrumentos utilizados na avaliação do vínculo entre mãe e bebê com até um ano de vida, descrevê-los e fornecer informações sobre suas medidas de confiabilidade, validade e adaptação para o contexto brasileiro. Fonte de dados: Trata-se de um estudo de revisão integrativa realizado com base nas publicações contidas nas bases de dados PUBMED, LILACS, ScienceDirect, PsycINFO e CINAHL. Utilizaram-se os descritores mother-child relations e mother infant relationship, e as expressões validity, reliability e scale. Selecionaram-se 23 pesquisas, que foram lidas em sua integralidade. Síntese dos dados: Foram identificados 13 instrumentos de avaliação do apego entre mãe e bebê: sete escalas, três questionários, dois inventários e um método de observação. Do total de ferramentas analisadas, o Prenatal Attachment Inventory apresentou maior validade e confiabilidade para analisar a relação entre a mãe e o feto durante a gestação. Quanto ao período puerperal, foram encontrados melhores coeficientes de consistência interna para o Maternal Attachment Inventory e o Postpartum Bonding Questionnaire. Além disso, esse último revelou elevada sensibilidade para identificar disfunções leves e graves nas relações afetivas entre mãe e bebê. Conclusões: Verificou-se que a maioria dos instrumentos é confiável para estudar o fenômeno em questão. Contudo, foram evidenciadas limitações com relação à validade de construto e de critério. Ademais, apenas dois estão traduzidos e adaptados para a população de mulheres e crianças brasileiras, sendo portanto uma lacuna encontrada na produção científica nessa área.

A recriação mítica do mundo e o mito da primavera

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Luciane Ferreira

2012-04-01

Full Text Available O presente artigo tem como objetivo primordial compartilhar as ideias apresentadas no terceiro capítulo da pesquisa monográfica: O Mito da Primavera no conto A Mulher Ramada, de Marina Colasanti, cujo, os argumentos teóricos míticos tornaram-se os fundamentos analíticos, bem como os pontos de embasamento da estrutura metodológica desta investigação; Mielietinsk, Eliade Mirceia, Northrop Frye, Manfred Luker, proporcionaram a contextualização do objeto de pesquisa sob a perspectiva mítica, que se apresenta nesta produção trazendo um novo olhar de origem /recriação do universo, desta maneira realiza um resgate reflexivo sobre a relação homem-natureza, e sua evolução temporária.Palavras-chave: letras; literatura; teoria mítica; recriação; mito da primavera.

O conceito de felicidade na mídia e o estímulo ao consumo permanente: a felicidade não tem preço?

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Medeiros, Caciane Souza de

2009-01-01

Full Text Available Neste artigo tratamos de refletir sobre o conceito de felicidade na mídia e sua relação com o consumo imerso em uma rede discursiva movimentada sob a égide da informação. Trabalhamos com o conceito de felicidade nas condições de ser feliz, estar feliz e ter felicidade pontuando uma leitura discursiva que se constitui na relação entre o ser, constitutivo da subjetividade, e o ter: próprio da constituição da ordem social que se repete no discurso da mídia como globalizada e que toma, nas diferentes formas de expressar, uma mesma ideologia consumista

Structural relaxation and colour in the spinel-magnesiochromite (MgAl2O4-MgCr2O4) and gahnite-zincochromite (ZnAl2O4-ZnCr2O4) solid solution series

Science.gov (United States)

Hålenius, U.; Andreozzi, G. B.; Skogby, H.

2009-04-01

.5 %, respectively, is determined. Based on a Cr-O bond distance for the CrO6 polyhedron in magnesiochromite and zincochromite of 1.995 and 1.991 Å respectively (O'Neill and Dollase, 1994) and applying the ligand field relationship 10Dq?C×R-5 (R equals the M-O distance of the MO6-polyhedron), Cr-O bond distances in gahnite and spinel with Cr-contents at trace levels are determined to 1.959 and 1.969 Å, respectively. These M-O bond distances are considerably longer than the M-O distances determined for end member gahnite and spinel by XRD-methods (1.9137 and 1.9280 Å, respectively; O'Neill and Dollase, 1994) and shows that there is considerable structural relaxation of M-O bonds in the two present spinel series. The relaxation parameter, ɛ, determined from the optical absorption spectra is 0.59 and 0.63 for the ZnAl2-2xCr2xO4 and MgAl2-2xCr2xO4 and series, respectively. These values are lower than those suggested from X-ray absorption spectroscopy (Juhin et al. 2007), which may be explained by second nearest neighbour interactions. In contrast to what may be expected, the interelectronic repulsion parameter, B, for V ICr3+ decreases with increasing Cr-content and apparent Cr-O bond length in both of the present spinel series . This indicates that interactions between Cr-atoms in neighbouring octahedra become important at increasing Cr-content and result in more covalent Cr-O bonds. This in turn suppresses the energy of 4A2g -4T2g (4F) transition (and calculated 10Dq-values) in octahedrally coordinated Cr3+. Consequently, the values of structural relaxation parameters determined from the optical absorption spectra must be regarded as minimum numbers. Literature Juhin, A., Calas, G., Cabaret, D. and Galoisy, L. (2007): Structural relaxation around Cr3+ in MgAl2O4. Physical Review, B76, 054105. O'Neill, H.St.C. and Dollase, W.A. (1994): Crystal structures and cation distributions in simple spinels from powder XRD structure refinements: MgCr2O4, ZnCr2O4, Fe3O4 and the temperature

Syntheses and characterizations of secondary Pb-O bonding supported Pb(II)-sulfonate complexes

Science.gov (United States)

Huang, Guo-Zhen; Zou, Xin; Zhu, Zhi-Biao; Deng, Zhao-Peng; Huo, Li-Hua; Gao, Shan

2018-06-01

The reaction of Pb(II) salts and mono- or disulfonates leads to the formation of eight new Pb(II)-mono/disulfonate complexes, [Pb(L1)(H2O)]2 (1), [Pb4(L2)2(AcO)2]n·5nH2O (2), [Pb(L3)(H2O)]2 (3), [Pb(HL4)(H2O)2]n·nH2O (4), [Pb(HL5)(H2O)2]n·2nH2O (5), [Pb(H2L6)(H2O)]n·nDMF·2nH2O (6), [Pb2(H3L7)4(H2O)6]·2H2O (7) and [Pb(H2L7)(H2O)]n·nH2O (8) (H2L1= 2-hydroxy-5-methyl-benzenesulfonic acid, H3L2= 2-hydroxyl-5-methyl- 1,3-benzenedisulfonic acid, H2L3= 2-hydroxy-5-nitro-benzenesulfonic acid, H3L4= 2-hydroxyl-5-bromo-1,3- benzenedisulfonic acid, H3L5= 2-hydroxyl-5-carboxyl-benzenesulfonic acid, H4L6= 2,5-dihydroxyl-3-carboxyl- benzenesulfonic acid, H4L7= 2,4-dihydroxyl-5-carboxyl-benzenesulfonic acid, DMF = N,N'-dimethyl-formamide, AcO- = acetate), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. In view of the primary Pb-O bonds, these eight complexes exhibit diverse dinuclear (1, 3 and 7), helical chain (4), wave-like chain (5), linear chain (6), zigzag chain (8) and layer structure (2), in which the Pb(II) cations present different hemi-directed geometries. Taking the secondary Pb-O bonds into account, chain structure for complex 7, layer motifs for complexes 1 and 3-6, as well as 3-D framework for complex 8 are observed with Pb(II) cations showing more intricate holo-directed geometries. The various coordination modes of these seven different mono/disulfonate anions are responsible for the formation of these multiple structures. Furthermore, the introduction of hydroxyl and carboxyl groups increases the coordination ability of sulfonate to the p-block metal cation. Luminescent analyses indicate that complex 7 presents purple emission at 395 nm at room temperature.

THE REACTION BETWEEN ZnO AND MOLTEN NA2S2O7 OR K2S2O7 FORMING NA2Zn(SO4)2 OR K2Zn(SO4)2, STUDIED BY RAMAN SPECTROSCOPY AND X-RAY DIFFRACTION

DEFF Research Database (Denmark)

Berg, Rolf W.; Thorup, Niels

2005-01-01

Reactions between solid ZnO and molten Na2S2O7 or K2S2O7 at 500 are shown by Raman spectroscopy to be 1:1 reactions leading to solns. By lowering the temp. of the soln. melts, colorless crystals form. Raman spectra of the crystals are given and tentatively assigned. Crystal structures of the mon...... the three-dimensional network of the M2Zn(SO4)2 structures. Bond distances and angles compare well with literature values. Empirical correlations between S-O bond distances and av. O-S-O bond angles follow a previously found trend....

Structure of glasses of the TeO2-MoO3 system

International Nuclear Information System (INIS)

Dimitriev, Y.; Dimitrov, V.; Bart, J.C.J.

1981-01-01

Structural models for glasses of the TeO 2 -MoO 3 system are suggested. On the basis of X-ray and infrared spectral investigations, by comparing with known crystalline structures of TeO 2 , MoO 3 and Te 2 MoO 7 9t 2 M, it is shown that the glasses from TeO 2 to Te 2 MoO 7 possess [TeO 4 ] and [MoO 5 ] groups as basic structural units. The latter are connected to form [Mo 2 O 8 ] complexes. The glasses in the MoO 3 -rich compositional range are built up of [TeO 3 ] and [MoO 6 ] polyhedra. The glass-formation tendency is discussed in relation to the role of the free electron pair and the disruption of secondary and weak primary bonds in the crystals. (author)

A perspectiva das mães sobre o óbito infantil: uma investigação além dos números

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Lúcia Maria Horta de Figueiredo Goulart

Full Text Available Estudo qualitativo realizado em Belo Horizonte, Minas Gerais, Brasil, com objetivo de investigar a morte infantil sob a perspectiva das mães. Foram entrevistadas 16 mães que haviam perdido seus bebês, a maioria no período neonatal. As entrevistas foram analisadas tomando-se como principais categorias a percepção do processo saúde-doença-morte, a relação médico-paciente e a qualidade da assistência. A descontinuidade entre o pré-natal e o parto, as dificuldades enfrentadas para a realização do parto, a peregrinação das gestantes, a falta de comunicação com os profissionais de saúde, a dissociação entre as condições hospitalares oferecidas e as necessidades percebidas, foram algumas das situações evidenciadas. Medo, solidão, abandono, insegurança, impotência foram sentimentos que acompanharam as mães por ocasião do parto e durante o curto período de vida da criança. A iniqüidade de direitos, como categoria mais abrangente, permeou os diversos depoimentos, revelando um processo de exclusão das mães e de suas crianças enquanto usuárias do sistema público de saúde.

Resistência ao cisalhamento da colagem com compósitos utilizando potencializador de adesão Shear bond strength of composites using an adhesion booster

Directory of Open Access Journals (Sweden)

Edivaldo de Morais

2011-10-01

Full Text Available OBJETIVO: avaliar a resistência ao cisalhamento dos compósitos Transbond XT e Concise Ortodôntico utilizando o potencializador de adesão Ortho Primer. MÉTODOS: a amostra consistiu de 90 incisivos bovinos divididos em seis grupos (n=15. Todos os dentes receberam profilaxia com pedra-pomes e condicionamento do esmalte com ácido fosfórico. No Grupo I, utilizou-se Transbond XT de maneira convencional. O Grupo II foi semelhante ao I, porém, aplicou-se o Ortho Primer ao invés do XT Primer. No Grupo III, após condicionamento, o esmalte foi contaminado com saliva, aplicou-se o Ortho Primer e colagem com Transbond XT. No Grupo IV, utilizou-se o Concise Ortodôntico de maneira convencional. O Grupo V foi semelhante ao IV, porém, utilizou-se o Ortho Primer ao invés da resina fluida. No Grupo VI, após condicionamento, o esmalte foi contaminado com saliva, aplicou-se o Ortho Primer e colagem com Concise. Os corpos de prova foram armazenados em água destilada em estufa a 37ºC por 24h e submetidos ao ensaio de resistência ao cisalhamento. Os dados foram submetidos à ANOVA e ao teste de Tukey (5%. RESULTADOS: a resistência da colagem no Grupo IV foi estatisticamente superior à dos Grupos II, III e VI (p0,05. O Transbond XT e o Concise utilizados convencionalmente obtiveram os maiores valores adesivos. O Ortho Primer em esmalte seco atuou efetivamente como agente de união dos compósitos avaliados. Em esmalte contaminado, a colagem com Concise obteve baixa resistência adesiva.OBJECTIVE: The aim of this study was to evaluate the shear bond strength of the Transbond XT and Concise Orthodontics composites using the Ortho Primer adhesion booster. METHODS: The sample consisted of 90 bovine incisors divided in 6 groups (n=15. All teeth were submitted to prophylaxes with pumice stone and etching with phosphoric acid. In Group I the Transbond XT was used conventionally. Group II was similar to Group I, however, Ortho Primer was used instead of XT

Bonded stacked-ring insulator for the Antares electron gun

International Nuclear Information System (INIS)

Stine, R.D.; Allen, G.R.; Eaton, E.; Weinstein, B.

1982-01-01

A large diameter insulator utilizing epoxy bonding which has sufficient mechanical strength to support the 3000 kg cathode/grid assembly was developed. Bonding the insulator simplifies the handling and reduces the number of 0-ring seals to a minimum. We have described the material selection, bonding techniques and electrical design approach

Ni2Sr(PO42·2H2O

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Lahcen El Ammari

2010-12-01

Full Text Available The title compound, dinickel(II strontium bis[orthophosphate(V] dihydrate, was obtained under hydrothermal conditions. The crystal structure consists of linear chains ∞1[NiO2/2(OH22/2O2/1] of edge-sharing NiO6 octahedra (overline{1} symmetry running parallel to [010]. Adjacent chains are linked to each other through PO4 tetrahedra (m symmetry and arranged in such a way to build layers parallel to (001. The three-dimensional framework is accomplished by stacking of adjacent layers that are held together by SrO8 polyhedra (2/m symmetry. Two types of O—H...O hydrogen bonds involving the water molecule are present, viz. one very strong hydrogen bond perpendicular to the layers and weak trifurcated hydrogen bonds parallel to the layers.

K0.78Na0.22MoO2AsO4

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Ahmed Driss

2013-08-01

Full Text Available The title compound, potassium sodium dioxidomolybdenum(VI arsenate, K0.78Na0.22MoO2AsO4, was synthesized by a solid-state reaction route. The structure is built up from corner-sharing MoO6 octahedra and AsO4 tetrahedra, creating infinite [MoAsO8]∞ chains running along the b-axis direction. As, Mo and all but one O atom are on special positions (4c with m symmetry and K (occupancy 0.78 is on a position (4a of -1 in the tunnels. The possible motion of the alkali cations has been investigated by means of the bond-valance sum (BVS model. The simulation shows that the Na+ motion appears to be easier mainly along the b-axis direction. Structural relationships between the different compounds of the AMoO2AsO4 (A = Ag, Li, Na, K, Rb series and MXO8 (M = V; X = P, As chains are discussed.

Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds

Energy Technology Data Exchange (ETDEWEB)

Wang, Meng [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Gutiérrez, Oliver Y. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Camaioni, Donald M. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Lercher, Johannes A. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 85748 Garching Germany

2018-03-06

Pd/C catalyzes C-O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by methanol in H2. The aromatic C-O bond is cleaved by reductive methanolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with methanol to form a ketal, which generates methoxycyclohexene by eliminating phenol or an alkanol. Subsequent hydrogenation leads to methoxycyclohexane.

O terror e a mídia: o neoconservadorismo norte-americano e o islã radical

OpenAIRE

Ortunes, Leandro

2013-01-01

Esta dissertação tem como objeto de estudo a construção da imagem do neoconservadorismo norte-americano e do Islã radical na mídia. Através de uma fundamentação teórica sobre os choques culturais e os confrontos armados entre Ocidente e Oriente, mais precisamente entre Estados Unidos e países com grande atuação islâmica na forma de governo; apresentaremos os pontos de divergência e possíveis similaridades destes dois grupos. Com esta fundamentação, observaremos as divergências e as superficia...

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}].

Atomic resolution chemical bond analysis of oxygen in La2CuO4

Science.gov (United States)

Haruta, M.; Nagai, T.; Lugg, N. R.; Neish, M. J.; Nagao, M.; Kurashima, K.; Allen, L. J.; Mizoguchi, T.; Kimoto, K.

2013-08-01

The distorted CuO6 octahedron in La2CuO4 was studied using aberration-corrected scanning transmission electron microscopy at atomic resolution. The near-edge structure in the oxygen K-edge electron energy-loss spectrum was recorded as a function of the position of the electron probe. After background subtraction, the measured spectrum image was processed using a recently developed inversion process to remove the mixing of signals on the atomic columns due to elastic and thermal scattering. The spectra were then compared with first-principles band structure calculations based on the local-density approximation plus on-site Coulomb repulsion (LDA + U) approach. In this article, we describe in detail not only anisotropic chemical bonding of the oxygen 2p state with the Cu 3d state but also with the Cu 4p and La 5d/4f states. Furthermore, it was found that buckling of the CuO2 plane was also detectable at the atomic resolution oxygen K-edge. Lastly, it was found that the effects of core-hole in the O K-edge were strongly dependent on the nature of the local chemical bonding, in particular, whether it is ionic or covalent.

Experimentally calibrated computational chemistry of tryptophan hydroxylase: Trans influence, hydrogen-bonding, and 18-electron rule govern O-2-activation

DEFF Research Database (Denmark)

Haahr, Lærke Tvedebrink; Kepp, Kasper Planeta; Boesen, Jane

2010-01-01

with the experimental value (0.25 mm/s) which we propose as the structure of the hydroxylating intermediate, with the tryptophan substrate well located for further reaction 3.5 Å from the ferryl group. Based on the optimized transition states, the activation barriers for the two paths (glu and his) are similar, so......Insight into the nature of oxygen activation in tryptophan hydroxylase has been obtained from density functional computations. Conformations of O2-bound intermediates have been studied with oxygen trans to glutamate and histidine, respectively. An O2-adduct with O2 trans to histidine (Ohis...... towards the cofactor and a more activated O–O bond (1.33 Å) than in Oglu (1.30 Å). It is shown that the cofactor can hydrogen bond to O2 and activate the O–O bond further (from 1.33 to 1.38 Å). The Ohis intermediate leads to a ferryl intermediate (Fhis) with an isomer shift of 0.34 mm/s, also consistent...

Safe-by-Design CuO Nanoparticles via Fe-Doping, Cu-O Bond Length Variation, and Biological Assessment in Cells and Zebrafish Embryos.

Science.gov (United States)

Naatz, Hendrik; Lin, Sijie; Li, Ruibin; Jiang, Wen; Ji, Zhaoxia; Chang, Chong Hyun; Köser, Jan; Thöming, Jorg; Xia, Tian; Nel, Andre E; Mädler, Lutz; Pokhrel, Suman

2017-01-24

The safe implementation of nanotechnology requires nanomaterial hazard assessment in accordance with the material physicochemical properties that trigger the injury response at the nano/bio interface. Since CuO nanoparticles (NPs) are widely used industrially and their dissolution properties play a major role in hazard potential, we hypothesized that tighter bonding of Cu to Fe by particle doping could constitute a safer-by-design approach through decreased dissolution. Accordingly, we designed a combinatorial library in which CuO was doped with 1-10% Fe in a flame spray pyrolysis reactor. The morphology and structural properties were determined by XRD, BET, Raman spectroscopy, HRTEM, EFTEM, and EELS, which demonstrated a significant reduction in the apical Cu-O bond length while simultaneously increasing the planar bond length (Jahn-Teller distortion). Hazard screening was performed in tissue culture cell lines and zebrafish embryos to discern the change in the hazardous effects of doped vs nondoped particles. This demonstrated that with increased levels of doping there was a progressive decrease in cytotoxicity in BEAS-2B and THP-1 cells, as well as an incremental decrease in the rate of hatching interference in zebrafish embryos. The dissolution profiles were determined and the surface reactions taking place in Holtfreter's solution were validated using cyclic voltammetry measurements to demonstrate that the Cu + /Cu 2+ and Fe 2+ /Fe 3+ redox species play a major role in the dissolution process of pure and Fe-doped CuO. Altogether, a safe-by-design strategy was implemented for the toxic CuO particles via Fe doping and has been demonstrated for their safe use in the environment.

Anatomía de leño de Maytenus vitis-idaea y M. viscifolia (Celastraceae

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Ana María Giménez

2012-12-01

Full Text Available Es objetivo del trabajo describir el leño de Maytenus vitis-idaea Griseb. y M. viscifolia Griseb. (Celastraceae y determinar rasgos ecoanatómicos. Las muestras fueron recolectadas del bosque natural en la localidad Guampacha, Sierras de Guasayán, Santiago del Estero, Argentina (distrito chaqueño serrano. Cinco individuos de cada especie fueron seleccionados al azar, obteniéndose una rodaja a 0.3 m. En las descripciones del leño se usó la terminología del Comité de Nomenclatura de IAWA. Los rasgos fundamentales del leño de Maytenus se resumen en: poros pequeños, numerosos, vasos pequeños, miembros de vasos cortos y anillos de crecimiento angostos. El leño de las dos especies estudiadas se caracteriza por presentar porosidad difusa a semicircular, anillos de crecimiento tipo 5b; poros numerosos y pequeños, parénquima axial de distribución apotraqueal en bandas discontinuas de una sola hilera de células, con tendencia a reticulado; escaso paratraqueal unilateral y difuso en agregados, radios heterogéneos; presencia de fibrotraqueidas. Las principales diferencias anatómicas radican en el tipo de poros, fundamentalmente solitarios en M. vitis-idaea y la presencia de radios de mayor longitud en M. viscifolia. Ambas maderas presentan rasgos xerofiticos notorios.Wood anatomy of Maytenus vitis-idaea. y M. viscifolia (Celastraceae. Is objective of this study to describe the wood anatomy of Maytenus vitis-idaea Griseb. and M. viscifolia Griseb. (Celastraceae and to determine ecoanatomy features. The samples were collected from natural forest in Guampacha, Guasayán, Santiago del Estero, Argentina (Chaco Serrano district. Five individuals were randomly selected; being obtained a track to 0.3 m. IAWA Committee on Nomenclature terminology was used in wood descriptions. Xylem features of Maytenus be summarized as: numerous small pores, short vessel members and growth rings narrow. The wood of the two species were characterized by diffuse to

Synthesis and crystal structure of Na6[(UO2)3O(OH)3(SeO4)2]2·10H2O

International Nuclear Information System (INIS)

Baeva, E.Eh.; Serezhkina, L.B.; Virovets, A.V.; Peresypkina, E.V.

2006-01-01

The complex Na 6 [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 2 ·10H 2 O (I) is synthesized and studied by monocrystal X-ray diffraction. The compound crystallizes in the orthorhombic crystal system with the unit cell parameters: a=14.2225(7) A, b=18.3601(7) A, c=16.5406(6) A, V=4319.2(3) A 3, Z=4, space group Cmcm, R 1 =0.0406. Compound I is found to be a representative of the crystal-chemical group A 3 M 3 M 3 2 T 2 3 (A=UO 2 2+ , M 3 =O 2- , M 2 =OH - , T 3 =SeO 4 2- ) of the uranyl complexes; it contains layer uranium-containing groups [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 3- . These layers are linked to form a three-dimensional cage through bonds formed by the sodium atoms with the oxygen atoms of the uranyl ions and SeO 4 groups that belong to different layers [ru

A comunicação do diagnóstico "sombrio" na relação médico-paciente entre estudantes de Medicina: uma experiência de dramatização na educação médica

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Natalia Braga Hortêncio Jucá

Full Text Available O objetivo do trabalho foi apresentar a dramatização como prática para a humanização da relação médico- paciente entre estudantes do terceiro semestre do curso de Medicina da Universidade Estadual do Ceará (Uece. Por meio de metodologia qualitativa, aplicaram-se perguntas referentes aos sentimentos vivenciados enquanto na posição de médicos e de pacientes, e à vivência com a técnica, após a mesma ser apresentada em sala de aula (n=24.Os dados permitiram identificar que os temas abordados se referiam a doenças graves e perdas. Em relação aos sentimentos, no papel tanto de paciente quanto de médico, demonstraram angústia, impotência, apreensão,medo e ansiedade. Expressaram dificuldades frente ao diagnóstico e à transmissão de má notícia, ao mesmo tempo em que valorizaram a construção do vínculo médico-paciente. Frente à experiência, destacaram a técnica como geradora de auto conhecimento e vivência da futura profissão. Estudos prospectivos devem ser realizados para avaliar o impacto dessa estratégia na humanização da relação médico- paciente e educação médica, explorando o máximo de potencialidade frente às suas limitações.

Crystal structure of bis{2-[(E-(4-fluorobenzyliminomethyl]phenolato-κ2N,O}nickel(II

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Amalina Mohd Tajuddin

2014-10-01

Full Text Available The asymmetric unit of the title complex, [Ni(C14H11FNO2], contains one-half of the molecule with the NiII cation lying on an inversion centre coordinated by a bidentate Schiff base anion. The cationic NiII center is in a distorted square-planar coordination environment chelated by the imine N and phenolate O donor atoms of the two Schiff base ligands. The N and O donor atoms of the two ligands are mutually trans with Ni—N and Ni—O bond lengths of 1.9242 (10 and 1.8336 (9 Å, respectively. The fluorophenyl ring is almost orthogonal to the coordination plane and makes a dihedral angle of 82.98 (7° with the phenolate ring. In the crystal, molecules are linked into screw chains by weak C—H...F hydrogen bonds. Additional C—H...π contacts arrange the molecules into sheets parallel to the ac plane.

Microsolvation effect and hydrogen-bonding pattern of taurine-water TA-(H2O)n (n = 1-3) complexes.

Science.gov (United States)

Dai, Yumei; Wang, Yuhua; Huang, Zhengguo; Wang, Hongke; Yu, Lei

2012-01-01

The microsolvation of taurine (TA) with one, two or three water molecules was investigated by a density functional theory (DFT) approach. Quantum theory of atoms in molecules (QTAIM) analyses were employed to elucidate the hydrogen bond (H-bond) interaction characteristics in TA-(H(2)O)(n) (n = 1-3) complexes. The results showed that the intramolecular H-bond formed between the hydroxyl and the N atom of TA are retained in most TA-(H(2)O)(n) (n = 1-3) complexes, and are strengthened via cooperative effects among multiple H-bonds from n = 1-3. A trend of proton transformation exists from the hydroxyl to the N atom, which finally results in the cleavage of the origin intramolecular H-bond and the formation of a new intramolecular H-bond between the amino and the O atom of TA. Therefore, the most stable TA-(H(2)O)(3) complex becomes a zwitterionic complex rather than a neutral type. A many-body interaction analysis showed that the major contributors to the binding energies for complexes are the two-body energies, while three-body energies and relaxation energies make significant contributions to the binding energies for some complexes, whereas the four-body energies are too small to be significant.

Absence of magnetic long-range order in Y2CrSbO7 : Bond-disorder-induced magnetic frustration in a ferromagnetic pyrochlore

Science.gov (United States)

Shen, L.; Greaves, C.; Riyat, R.; Hansen, T. C.; Blackburn, E.

2017-09-01

The consequences of random nonmagnetic-ion dilution for the pyrochlore family Y2(M 1 -xN x)2O7 (M = magnetic ion, N = nonmagnetic ion) have been investigated. As a first step, we experimentally examine the magnetic properties of Y2CrSbO7 (x =0.5 ), in which the magnetic sites (Cr3 +) are percolative. Although the effective Cr-Cr spin exchange is ferromagnetic, as evidenced by a positive Curie-Weiss temperature, ΘCW ≃19.5 K , our high-resolution neutron powder diffraction measurements detect no sign of magnetic long-range order down to 2 K. In order to understand our observations, we construct a lattice model to numerically study the bond disorder introduced by the ionic size mismatch between M and N , which reveals that the bond disorder percolates at xb ≃0.23 , explaining the absence of magnetic long-range order. This model could be applied to a series of frustrated magnets with a pyrochlore sublattice, for example, the spinel compound Zn (Cr1 -xGax )2O4 , wherein a Néel to spin glass phase transition occurs between x =0.2 and 0.25 [Lee et al., Phys. Rev. B 77, 014405 (2008), 10.1103/PhysRevB.77.014405]. Our study stresses the non-negligible role of bond disorder on magnetic frustration, even in ferromagnets.

O mercado dos detergentes máquina roupa : a pressão promocional

OpenAIRE

Róis, Marta Alexandra Grangeiro

2012-01-01

Projecto de Mestrado em Economia da Empresa e da Concorrência / Classificação JEL: L81, Q51 O presente estudo tem como objetivo principal analisar a evolução da pressão promocional no mercado dos detergentes máquina roupa, com especial ênfase no canal dinâmico. Para tal foi utilizado o modelo de análise estrutural proposto por Porter (1980), mais conhecido pelo modelo das cinco forças. Com base na informação disponível sobre o mercado foram analisadas as cinco forças das quais foi possí...

Bonding of composites in different industries; Collage des composites dans diverses industries

Energy Technology Data Exchange (ETDEWEB)

Cognard, Ph. [societe Bostik Findley, La Defense 2, 92 (France)

2005-03-01

The walls of vanes of wind-mills are generally carried out in bonded sandwich materials. The interior tighteners can be bonded too to the exterior panels. For these bonding, epoxides or polyurethanes with two components hardening at ambient temperature, at high mechanical resistance and great durability are used. For the bonds of vanes on the turbine, the vanes are bonded on metallic rings with special epoxide adhesives, with two components, able to support high stresses, having a shear resistance of 30 MPa, a very good fatigue resistance for supporting a lot of turns under alternated bending stresses. These wind-mills have to support service temperature of -40 C to +80 C. (O.M.)

Influence of hydration on ion-biomolecule interactions: M(+)(indole)(H2O)(n) (M = Na, K; n = 3-6).

Science.gov (United States)

Ke, Haochen; Lisy, James M

2015-10-14

The indole functional group can be found in many biologically relevant molecules, such as neurotransmitters, pineal hormones and medicines. Indole has been used as a tractable model to study the hydration structures of biomolecules as well as the interplay of non-covalent interactions within ion-biomolecule-water complexes, which largely determine their structure and dynamics. With three potential binding sites: above the six- or five-member ring, and the N-H group, the competition between π and hydrogen bond interactions involves multiple locations. Electrostatic interactions from monovalent cations are in direct competition with hydrogen bonding interactions, as structural configurations involving both direct cation-indole interactions and cation-water-indole bridging interactions were observed. The different charge densities of Na(+) and K(+) give rise to different structural conformers at the same level of hydration. Infrared spectra with parallel hybrid functional-based calculations and Gibbs free energy calculations revealed rich structural insights into the Na(+)/K(+)(indole)(H2O)3-6 cluster ion complexes. Isotopic (H/D) analyses were applied to decouple the spectral features originating from the OH and NH stretches. Results showed no evidence of direct interaction between water and the NH group of indole (via a σ-hydrogen bond) at current levels of hydration with the incorporation of cations. Hydrogen bonding to a π-system, however, was ubiquitous at hydration levels between two and five.

Resultados a médio prazo do tratamento cirúrgico da dissecção aguda de aorta tipo A com o emprego da prótese intraluminal Surgical treatment of type a aortic dissection using intraluminal prosthesis medium term follow up

Directory of Open Access Journals (Sweden)

Jefferson Francisco de OLIVEIRA

2001-06-01

observamos formação de pseudo-aneurisma, migração e o gradiente máximo encontrado foi de 16 mmHg. Conclusão: O emprego da prótese intraluminal para o tratamento da dissecção aguda de aorta do tipo A nos proporciona uma anastomose rápida, segura e hem2ostática. Na avaliação pós-operatória e a médio prazo não observamos qualquer complicação relacionada ao emprego desta técnica.Introduction: The concept of intraluminal prosthesis was introduced by CARREL, in 1912. In 1978, DUREAU & ABLASA described the first case of type A acute aortic dissection treated with intraluminal prosthesis. This prosthesis was used in the eighties by several groups with good results. Several reports of complications (migration, embolism, stenosis, pseudoaneurysms formation made the surgical groups lose the enthusiasm with that technique. Objective: To evaluate the sutureless anastomosis using the intraluminal prosthesis in the treatment of type A acute aortic dissection. Material and Methods: During the period from July/1996 to November/1999, 64 patients with the diagnosis of type A acute aortic dissection were operated in our Service. In all the cases we used the intraluminal ring as the technique of suture. The average of age was of 56.3 years, and 89% of the patients were males. All the patients had systemic hypertension. In 26 patients we used only the intraluminal anastomosis. The proximal ring was placed above the coronary ostium and the distal ring was positioned close to the origin of the inominate artery. The aorta cross clamping time in these patients was 9 minutes, and the extracorporeal circulation average of time was 26 minutes. Only in 1 case there was a rupture of the ligature on the proximal ring, when we accomplished a radical surgery (Bentall-DeBonno, maintaining the distal ring. In 23 patients we did the aortoplasty and used a double patch of Dacron to prepare the aortic root, using the intraluminal ring in the distal anastomosis. We operated on the aortic arch

The role of uranium-arene bonding in H2O reduction catalysis

Science.gov (United States)

Halter, Dominik P.; Heinemann, Frank W.; Maron, Laurent; Meyer, Karsten

2018-03-01

The reactivity of uranium compounds towards small molecules typically occurs through stoichiometric rather than catalytic processes. Examples of uranium catalysts reacting with water are particularly scarce, because stable uranyl groups form that preclude the recovery of the uranium compound. Recently, however, an arene-anchored, electron-rich uranium complex has been shown to facilitate the electrocatalytic formation of H2 from H2O. Here, we present the precise role of uranium-arene δ bonding in intermediates of the catalytic cycle, as well as details of the atypical two-electron oxidative addition of H2O to the trivalent uranium catalyst. Both aspects were explored by synthesizing mid- and high-valent uranium-oxo intermediates and by performing comparative studies with a structurally related complex that cannot engage in δ bonding. The redox activity of the arene anchor and a covalent δ-bonding interaction with the uranium ion during H2 formation were supported by density functional theory analysis. Detailed insight into this catalytic system may inspire the design of ligands for new uranium catalysts.

Observation of Vacancies, Faults, and Superstructures in Ln5Mo2O12 (Ln = La, Y, and Lu) Compounds with Direct Mo-Mo Bonding.

Science.gov (United States)

Colabello, Diane M; Sobalvarro, Elizabeth M; Sheckelton, John P; Neuefeind, Joerg C; McQueen, Tyrel M; Khalifah, Peter G

2017-11-06

Among oxide compounds with direct metal-metal bonding, the Y 5 Mo 2 O 12 (A 5 B 2 O 12 ) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B 2 O 10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal-metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal-metal bonding have integer oxidation states resulting from the lifting of orbital degeneracy typically induced by the metal-metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln 5 Mo 2 O 12 (Ln = La-Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo 2 O 10 and LaO 6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1-2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La 5 Mo 2 O 11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. This represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one

Formation of ring marks in stocked tilapia juveniles (Oreochromis aureus/O. niloticus (Perciformes: Cichlidae

Directory of Open Access Journals (Sweden)

Ana L Ibañez

2007-12-01

Full Text Available Lake Metztitlán was dried up completely in the spring of 1998 and refilled in August of that year. In the period September-November, two cohorts of 1.6 million juveniles of a tilapia hybrid were stocked (Oreochromis aureus/O. niloticus, and monitored every month for one year. Since the date of birth of these juveniles was known, the analyses focused on whether the ring marks of the scales, sagittae and opercula or the circuli of the scales could be used to age them. The ring marks of the scales and opercula showed great variability, and the sagittae had a significant relationship with length, but it is unclear if at least the first ring mark could be formed at the hatchery and reflect changes in diet and/or tank movements in the fish farm. The circuli had a continuous regular behavior, with a formation rate of 10.38±0.93 and 11.38±0.95 circuli/month for the first and second cohorts, respectively. This proportion was maintained during the study period, and could be of help to calculate an approximate age of juveniles, especially in stocked fish that show multiple ring marks because of manipulation in fish farms and stocking events. Rev. Biol. Trop. 55 (3-4: 1005-1013. Epub 2007 December, 28.El lago de Metztitlán se secó completamente en la primavera de 1998, inundándose nuevamente en agosto del mismo año para ser repoblado entre septiembre y noviembre con 1.6 millones de jóvenes de un híbrido de tilapia (Oreochromis aureus/O. niloticus en dos periodos. Ambas cohortes fueron monitoreadas mensualmente durante un año. Debido a que la fecha de nacimiento era conocida, el objetivo del estudio fue evaluar si las marcas anulares de las escamas, las sagittae y los opérculos, o los circuli de las escamas pueden usarse para estimar la edad. Los anillos de las escamas y opérculos mostraron gran variabilidad, mientras que las de las sagittae se relacionaron significativamente con la longitud, sin embargo no quedó claro si al menos el primer

Facile solvothermal synthesis of abnormal growth of one-dimensional ZnO nanostructures by ring-opening reaction of polyvinylpyrrolidone

Energy Technology Data Exchange (ETDEWEB)

Xu, G., E-mail: gxu@alum.imr.ac.cn; Wang, X.L.; Liu, G.Z.

2015-02-28

Graphical abstract: - Highlights: • Facile solvothermal synthesis of ZnO nanostructures in super high alkaline alcoholic condition. • The exact role and chemical transformations of PVP in solvothermal synthesis of ZnO nanostructures was revealed. • Mechanism of abnormal growth of ZnO nanopyramids was proposed based on ring-opening reaction of PVP. - Abstract: Abnormal growth of one-dimensional (1-D) ZnO nanostructures (NSs) have been accomplished with the assistance of polyvinylpyrrolidone (PVP) under a super high alkaline alcoholic solvothermal condition. The products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ({sup 1}H NMR) spectroscopy. The effect of synthetic conditions, such as reaction temperature and the addition of PVP, on the morphologies of ZnO products were investigated. The results show that PVP molecules had the significant role in the transformation of morphologies of ZnO NSs ranging from nanorods, nanoparticles to pyramids, as well as flower-like assembly features. The possible growth mechanism of ZnO pyramids was proposed based on ring-opening reaction of PVP.

Voz cantada e a constituição da relação mãe-bebê

OpenAIRE

Mello,Enio Lopes; Maia,Suzana Magalhães; Andrada e Silva,Marta Assumpção de

2009-01-01

TEMA: refletir sobre uma faceta da constituição da relação mãe-bebê, que se fez presente no uso criativo da voz cantada da mãe, na comunicação com o seu bebê. PROCEDIMENTOS: o único sujeito desse estudo é uma mãe, que se submeteu a oito sessões de terapias corporais associadas à emissão da voz cantada, sempre dirigidas ao bebê; as sessões transcorreram com a possibilidade de expressão livre pela fala e gesto da mãe e a escuta do terapeuta. RESULTADOS: o quadro que a mãe apresentava em relação...

Formação integrada do ensino médio com a educação profissional: o que dizem as pesquisas

Directory of Open Access Journals (Sweden)

Josimar Aparecido Vieira

2016-07-01

Full Text Available O artigo aborda o estado de conhecimento sobre formação integrada do ensino médio com a educação profissional. Apresenta concepções de ensino integrado, análise sobre experiências de integração do ensino médio com a educação profissional enfocando suas dificuldades e entraves. São examinadas tentativas de organização do ensino integrado a partir das sínteses conclusivas dos estudos realizados. A fonte dos dados 16 trabalhos publicados pela ANPED (reuniões entre 2006 e 2013. Aponta princípios e dados que podem contribuir para a formação integrada do ensino médio com a educação profissional, e destaca que propostas desta natureza requerem integração epistemológica de conteúdos, de metodologias e de práticas educativas.

Nano-regime Length Scales Extracted from the First Sharp Diffraction Peak in Non-crystalline SiO2 and Related Materials: Device Applications

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Phillips James

2010-01-01

Full Text Available Abstract This paper distinguishes between two different scales of medium range order, MRO, in non-crystalline SiO2: (1 the first is ~0.4 to 0.5 nm and is obtained from the position of the first sharp diffraction peak, FSDP, in the X-ray diffraction structure factor, S(Q, and (2 the second is ~1 nm and is calculated from the FSDP full-width-at-half-maximum FWHM. Many-electron calculations yield Si–O third- and O–O fourth-nearest-neighbor bonding distances in the same 0.4–0.5 nm MRO regime. These derive from the availability of empty Si dπ orbitals for back-donation from occupied O pπ orbitals yielding narrow symmetry determined distributions of third neighbor Si–O, and fourth neighbor O–O distances. These are segments of six member rings contributing to connected six-member rings with ~1 nm length scale within the MRO regime. The unique properties of non-crystalline SiO2 are explained by the encapsulation of six-member ring clusters by five- and seven-member rings on average in a compliant hard-soft nano-scaled inhomogeneous network. This network structure minimizes macroscopic strain, reducing intrinsic bonding defects as well as defect precursors. This inhomogeneous CRN is enabling for applications including thermally grown ~1.5 nm SiO2 layers for Si field effect transistor devices to optical components with centimeter dimensions. There are qualitatively similar length scales in nano-crystalline HfO2 and phase separated Hf silicates based on the primitive unit cell, rather than a ring structure. Hf oxide dielectrics have recently been used as replacement dielectrics for a new generation of Si and Si/Ge devices heralding a transition into nano-scale circuits and systems on a Si chip.

Nickel-Catalyzed C sp2 –C sp3 Cross-Coupling via C–O Bond Activation

KAUST Repository

Guo, Lin; Hsiao, Chien-Chi; Yue, Huifeng; Liu, Xiangqian; Rueping, Magnus

2016-01-01

through Csp2-O substitution, without the restriction of β-hydride elimination. Moreover, the advantage of the newly developed method was demonstrated in a selective and sequential C-O bond activation process. © 2016 American Chemical Society.

Avaliação e comparação entre métodos de mensuração de pressão arterial sistólica em gatos hígidos conscientes

Directory of Open Access Journals (Sweden)

T.M. Anjos

2016-06-01

Full Text Available RESUMO Após validação de dois diferentes métodos de mensuração de pressão arterial sistólica (PAS não invasivos ou indiretos (oscilométrico e Doppler vascular com o invasivo ou direto (cateterização arterial - padrão ouro em 12 gatos hígidos anestesiados de mesma faixa etária, os métodos não invasivos foram avaliados e comparados em 24 gatos hígidos e conscientes, divididos em quatro grupos de idade. Em cada animal, procedeu-se à mensuração da pressão pelos métodos Doppler e oscilométrico. O método oscilométrico foi o primeiro a ser realizado, e, logo em seguida, o método Doppler. Os valores considerados foram obtidos das médias de sete medidas consecutivas para cada método, com intervalo de 30 segundos entre elas. A primeira medida e as medidas discrepantes (variação ˃ 20% PAS, obtidas com sinais óbvios de estresse e/ou com movimentação do animal, foram descartadas. Os métodos de mensuração oscilométrico e Doppler, embora tenham apresentado médias estatisticamente diferentes em todos os grupos, quando comparados em cada grupo, apresentaram uma correlação significativa, alta e positiva. Ou seja, sempre que for obtido um valor elevado por um método, o mesmo fato ocorrerá com o outro método e vice-versa. Clinicamente, a diferença observada não é relevante, uma vez que a diferença média dos valores obtida pelos dois métodos, em cada grupo, foi menor que 1,1%.

Study on leakage rates of high temperature water from wet-type transport casks for spent fuel. Pt. 2. Leakage rates from a scratch on O-ring surface and narrow wires adhering to O-ring surface

International Nuclear Information System (INIS)

Asano, R.; Aritomi, M.; Sudi, A.; Kohketsu, Y.

1997-01-01

A programme for enhancement of fuel burnup has been promoted in Japan as part of the sophisticated programme for light water reactors to reduce the fuel cost and the amount of spent fuel. As part of this fuel programme, a new wet-type transport cask has been developed to transport the high burnup fuels efficiently. The purpose of this work is to clarify the margin of safety in the evaluation of the release rate of radioactive materials from the wet-type transport cask into the environment and to establish a practical evaluation method for leakage rates on leak behaviour of high temperature water from the casks. In this paper, leakage rates of water under high pressures and at high temperatures are investigated from two kinds of leak path model. One is a disc with a scratch on the surface which simulates a defect on the seal surface of the O-ring flange and the other is narrow stainless steel wires installed on the O-ring surface which simulates hair adhering to the O-ring surface. From the results, an evaluation method for the leakage rate of water under high pressure and at high temperature from a non-circular leak path and multiple leak paths is proposed. (author)

Educação financeira para o ensino médio

OpenAIRE

Venturini, Rodrigo Cesar Pastrolin

2016-01-01

Este trabalho tem como objetivo destacar a importância do ensino e da aprendizagem da Matemática Financeira no Ensino Médio. Consideramos que este é um assunto de grande relevância no cotidiano dos jovens que provavelmente farão uso do sistema bancário e do comércio. Colocamos em discussão a situação atual do ensino da Matemática Financeira e apresentamos elementos para argumentação da sua importância no momento em que se elencam os conteúdos do Ensino Médio. Além disso, mos...

In vivo evaluation of CaO-SiO2-P2O5-B2O3 glass-ceramics coating on Steinman pins.

Science.gov (United States)

Lee, Jae Hyup; Hong, Kug Sun; Baek, Hae-Ri; Seo, Jun-Hyuk; Lee, Kyung Mee; Ryu, Hyun-Seung; Lee, Hyun-Kyung

2013-07-01

Surface coating using ceramics improves the bone bonding strength of an implant. We questioned whether a new type of glass-ceramics (BGS-7) coating (CaO-SiO2 -P2 O5 -B2 O3 ) would improve the osseointegration of Steinman pins (S-pins) both biomechanically and histomorphometrically. An in vivo study was performed using rabbits by inserting three S-pins into each iliac bone. The pins were 2.2-mm S-pins with a coating of 30-μm-thick BGS-7 and 550-nm-thick hydroxyapatite (HA), as opposed to an S-pin without coating. A tensile strength test and histomorphometrical evaluation was performed. In the 2-week group, the BGS-7 implant showed a significantly higher tensile strength than the S-pin. In the 4- and 8-week groups, the BGS-7 implants had significantly higher tensile strengths than the S-pins and HA implants. The histomorphometrical study revealed that the BGS-7 implant had a significantly higher contact ratio than the S-pin and HA implants in the 4-week group. The biomechanical and histomorphometrical tests showed that the BGS-7 coating had superior bone bonding properties than the groups without the coating from the initial stage of insertion. The BGS-7 coating of an S-pin will enhance the bone bonding strength, and there might also be an advantage in human bone bonding. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Nb 3d and O 1s core levels and chemical bonding in niobates

International Nuclear Information System (INIS)

Atuchin, V.V.; Kalabin, I.E.; Kesler, V.G.; Pervukhina, N.V.

2005-01-01

A set of available experimental data on binding energies of Nb 3d 5/2 and O 1s core levels in niobates has been observed with using energy difference (O 1s-Nb 3d 5/2 ) as a robust parameter for compound characterization. An empirical relationship between (O 1s-Nb 3d 5/2 ) values measured with XPS for Nb 5+ -niobates and mean chemical bond length L(Nb-O) has been discussed. A range of (O 1s-Nb 3d 5/2 ) values possible in Nb 5+ -niobates has been defined. An energy gap ∼1.4-1.8 eV is found between (O 1s-Nb 3d 5/2 ) values reasonable for Nb 5+ and Nb 4+ states in niobates

O mercado de música digital : um estudo sobre o comportamento do consumidor brasileiro

OpenAIRE

Martins, João Paulo Capelli; Slongo, Luiz Antonio

2014-01-01

A convergência entre tecnologia, Internet e música resultou em grandes desafios para a indústria fonográfica mundial. Apesar do crescimento no volume de receitas de música digital, a indústria fonográfica vem diminuindo significativamente nos últimos anos. Para atrair novos clientes e competir com outras formas de aquisição de música na rede, as gravadoras e os provedores de serviços de música on-line precisam descobrir quem são e como se comportam seus clientes em potencial. O objetivo deste...

Diaquabis[2-(2-hydroxyethylpyridine-κ2N,O]cobalt(II dichloride

Directory of Open Access Journals (Sweden)

Hocine Merazig

2013-08-01

Full Text Available In the title salt, [Co(C7H9NO2(H2O2]Cl2, the CoII cation, located on an inversion center, is N,O-chelated by two hydroxyethylpyridine ligands and coordinated by two water molecules in a distorted O4N2 octahedral geometry. In the crystal, the Cl− anions link with the complex cations via O—H...Cl hydrogen bonds, forming a three-dimensional supramolecular architecture. π–π stacking is observed between the pyridine rings of adjacent molecules [centroid–centroid distance = 3.5810 (11 Å].

Geração de solicitação de serviço para inspeção e manutenção em máquinas industriais utilizando redes sem fio

OpenAIRE

Ornelas, Fernando César de

2004-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Ciência da Computação Nesta dissertação apresentamos um estudo de caso de aplicação real de rede sem fio, cujo objetivo é a melhoria nas atividades de inspeção e a identificação da necessidade de manutenção em máquinas e equipamentos na área industrial. Fazendo utilização de redes sem fios e de unidades móveis, que se conectam periodicamente a uma rede estruturada, permitimos a...

Reduzir-se a nada: articulações entre o masoquismo, o feminino e a máscara

Directory of Open Access Journals (Sweden)

Carolina Nassau Ribeiro

2012-01-01

Full Text Available O artigo demonstra que o feminino não possui uma característica masoquista que lhe seja inerente. O suposto masoquismo feminino seria uma das máscaras utilizadas pelo feminino tanto para localizar-se como mulher como para atrair o desejo de um homem. Concluímos, porém, que existem parcerias tão devastadoras que podem reduzir o sujeito a nada.

Consumo no ciberespaço: a explosão de aplicativos de dispositivos móveis que ajudam a controlar a vida na palma da mão

Directory of Open Access Journals (Sweden)

Arlete Eni Granero

2013-12-01

Full Text Available A valorização da troca de informações está na espontaneidade e no tempo real. As pessoas criam textos, vídeos, músicas e divulgam através de seus telefones celulares, pela internet etc. 13% dos usuários de smarthphones no Brasil realizaram compras por celular no Brasil, de acordo com Ibope Media (2013. Entre os itens mais comprados estão os jogos e aplicativos (37%. Este trabalho tem como objetivo analisar a mudança das ferramentas que viabilizam o consumo via mobile e como as ‘coisas’ estão ganhando movimento pelos dispositivos eletrônicos. Neste contexto, as coisas na pós web tomam vida ao serem integradas ao cotidiano das pessoas.  A metodologia utilizada apresenta a revisão bibliográfica traçando um panorama que aborda os conceitos de consumo, a evolução do marketing, o perfil psicográfico das gerações, geração digital (DOVER; MOFFIT, 2012 e portabilidade cultural (CANCLINI, 2008.  O corpus do estudo provoca uma reflexão acerca da aplicabilidade dos conceitos de rede de dispositivos inteligentes presentes nos smartphones, aqui exemplificados pelos aplicativos Nike Running, AliveCor e Tinder e os benefícios dos mesmos entregues à sociedade. Os resultados apresentam uma indústria de “coisas” que atendem especificamente um público jovem que busca a experiência da participação e do engajamento na internet. Concluímos que diante das inovações criadas a cada mês, percebe-se uma indústria de “coisas” que possam atender especificamente um público jovem que busca a experiência da participação e do engajamento na internet. Para atender a “geração digital” (DOVER; MOFFIT, 2012, são necessários cada vez mais dispositivos que possam oferecer diversas mídias. Neste sentido, percebe-se um consumo tecnológico, onde máquinas e programas configuram-se como mercadorias (BRETA, 2007, mas que também pessoas tornem-se produtos, ao propagar suas subjetividades na internet.

Monitoramento de informação em mídias sociais: o e-Monitor Dengue

Directory of Open Access Journals (Sweden)

Michele Nacif Antunes

Full Text Available Este artigo apresenta os resultados preliminares da pesquisa "Monitoramento de informação sobre doenças negligenciadas: o e-Monitor Dengue". O e-Monitor Dengue é um sistema de monitoramento de informação na Internet feito por meio de um mecanismo robô, software ou agente inteligente que vasculha os sites sobre dengue disponíveis na Internet. Resultados de pesquisas anteriores indicaram novas perspectivas para o monitoramento, principalmente, por meio das mídias sociais. Dentre as mídias sociais, considera-se que o Twitter pode desempenhar um papel na gestão da informação ao permitir identificar usuários que podem atuar como filtro de informação, sendo possível acessar diretamente a informação mais relevante para uma determinada área de interesse. Assim, a partir do monitoramento do Twitter, a primeira pergunta a ser respondida no âmbito da pesquisa em andamento foi "Quem fala sobre dengue?". Inicialmente, foi possível identificar a relação dos atores/perfis localizados na cidade do Rio de Janeiro e Niterói com maior ocorrência do termo "dengue" em suas mensagens. Os perfis foram cadastrados no sistema de monitoramento e são monitorados constantemente. Outra pergunta a ser respondida foi "Quando se fala de dengue?". Observa-se que o número de twetts acompanha o crescimento do número de casos de dengue. São indícios de que há uma relação entre os rumores sobre dengue e o aumento de número de casos notificados. Evidencia-se, desta forma, que realizar o monitoramento nas mídias sociais durante o período de epidemia e fazer sua relação com a situação epidemiológica da dengue pode ser uma estratégia importante para as autoridades em vigilância epidemiológica.

Hydrogen-bonding effects on film structure and photoelectrochemical properties of porphyrin and fullerene composites on nanostructured TiO 2 electrodes

NARCIS (Netherlands)

Kira, Aiko; Tanaka, Masanobu; Umeyama, Tomokazu; Matano, Yoshihiro; Yoshimoto, Naoki; Zhang, Yi; Ye, Shen; Lehtivuori, Heli; Tkachenko, Nikolai V.; Lemmetyinen, Helge; Imahori, Hiroshi

2007-01-01

Hydrogen-bonding effects on film structures and photophysical, photoelectrochemical, and photovoltaic properties have been examined in mixed films of porphyrin and fullerene composites with and without hydrogen bonding on nanostructured TiO2 electrodes. The nanostructured TiO2 electrodes modified

Silylene-Nickel Promoted Cleavage of B-O Bonds: From Catechol Borane to the Hydroborylene Ligand.

Science.gov (United States)

Hadlington, Terrance J; Szilvási, Tibor; Driess, Matthias

2017-06-19

The first 16 valence electron [bis(NHC)](silylene)Ni 0 complex 1, [( TMS L)ClSi:→Ni(NHC) 2 ], bearing the acyclic amido-chlorosilylene ( TMS L)ClSi: ( TMS L=N(SiMe 3 )Dipp; Dipp=2,6-Pr i 2 C 6 H 4 ) and two NHC ligands (N-heterocyclic carbene=:C[(Pr i )NC(Me)] 2 ) was synthesized in high yield and structurally characterized. Compound 1 is capable of facile dihydrogen activation under ambient conditions to give the corresponding HSi-NiH complex 2. Most notably, 1 reacts with catechol borane to afford the unprecedented hydroborylene-coordinated (chloro)(silyl)nickel(II) complex 3, {[cat( TMS L)Si](Cl)Ni←:BH(NHC) 2 }, via the cleavage of two B-O bonds and simultaneous formation of two Si-O bonds. The mechanism for the formation of 3 was rationalized by means of DFT calculations, which highlight the powerful synergistic effects of the Si:→Ni moiety in the breaking of incredibly strong B-O bonds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlling the Sn-C bonds content in SnO2@CNTs composite to form in situ pulverized structure for enhanced electrochemical kinetics.

Science.gov (United States)

Cheng, Yayi; Huang, Jianfeng; Qi, Hui; Cao, Liyun; Luo, Xiaomin; Li, Jiayin; Xu, Zhanwei; Yang, Jun

2017-12-07

The Sn-C bonding content between the SnO 2 and CNTs interface was controlled by the hydrothermal method and subsequent heat treatment. Electrochemical analysis found that the SnO 2 @CNTs with high Sn-C bonding content exhibited much higher capacity contribution from alloying and conversion reaction compared with the low content of Sn-C bonding even after 200 cycles. The high Sn-C bonding content enabled the SnO 2 nanoparticles to stabilize on the CNTs surface, realizing an in situ pulverization process of SnO 2 . The in situ pulverized structure was beneficial to maintain the close electrochemical contact of the working electrode during the long-term cycling and provide ultrafast transfer paths for lithium ions and electrons, which promoted the alloying and conversion reaction kinetics greatly. Therefore, the SnO 2 @CNTs composite with high Sn-C bonding content displayed highly reversible alloying and conversion reaction. It is believed that the composite could be used as a reference for design chemically bonded metal oxide/carbon composite anode materials in lithium-ion batteries.

Ensino superior privado: expansão das cooperativas de mão de obra docente

OpenAIRE

Calderón,Adolfo Ignacio; Lourenço,Henrique da Silva

2011-01-01

Este artigo aborda a terceirização de professores por meio de cooperativas de mão de obra no âmbito do ensino superior privado, fenômeno educacional que surgiu na metade da presente década, enquadrado como prática ilegal que fere os princípios do cooperativismo quando visa fraudar a legislação trabalhista brasileira. Tem por objetivo compreender a expansão desse fenômeno por meio da reconstrução da cronologia dos fatos, da identificação dos momentos históricos do seu entendimento legal e do m...

Avaliação médica: o consumo na medicina e a mercantilização da saúde

Directory of Open Access Journals (Sweden)

Júlio César Monteiro dos Santos Jr

2006-03-01

Full Text Available INTRODUÇÃO: A Saúde vem sendo ameaçada pela colonização empresarial do médico que, iniciada dentro da Universidade, prolonga-se no ambiente de trabalho. Essa ação tem origem no ensino defasado da realidade científica e na asserção de tendências individualistas que expressam opiniões isoladas e não abalizadas, em geral induzidas pelas propagandas e investigações encomendadas para agitar o mercado no uso de aparelhos e produtos médico-farmacêuticos. OBJETIVO: Usar o ponto de vista do Cirurgião Geral e do Coloproctologista para comentar a mercantilização da saúde e a maneira como a Instituição Industrial, usando a empresa médica, age e modifica a ação do médico, contribuindo para o alto custo da Medicina. MATERIAL E MÉTODO: As bases serão os exames laboratoriais e as avaliações cardiovasculares pré-operatórias de rotina, usados para operações não cardíacas em pacientes cardiopatas. O material e o conteúdo para discussão foram extraídos do livro de Ivan Illich¹, do artigo de atualização de Coelho e col. ², do modelo proposto na Cleveland Clinic³ sobre avaliação pré-operatória e das normas estabelecidas pelo American College of Cardiology e pela American Heart Association4 para a orientação de avaliação médica mínima, necessária e suficiente, de pacientes cardiopatas, quando candidatos a tratamento cirúrgico de doenças em outros órgãos.BACKGROUND: The Health has been threatened by the physician's managerial colonization that, begun inside of the University, continues in the work environment. That action has origin of the teaching in disagreement with the scientific reality and in the assertion of individualistic tendencies expressing isolated and not-distinguished opinions, in general induced by the investigations requested to give rise to the market of drugs and devices disposable for physician and pharmacists. PURPOSE: The aim of this report is to use the General Surgeon's point of view

Weighted density approximation for bonding in molecules: ring and cage polymers

CERN Document Server

Sweatman, M B

2003-01-01

The focus of this work is the bonded contribution to the intrinsic Helmholtz free energy of molecules. A weighted density approximation (WDA) for this contribution is presented within the interaction site model (ISM) for ring and cage polymers. The resulting density functional theory (ISM/WDA) for these systems is no more complex than theories for a pure simple fluid, and much less complex than density functional approaches that treat the bonding functional exactly. The ISM/WDA bonding functional is much more accurate than either the ISM/HNC or ISM/PY bonding functionals, which are related to the reference interaction-site model (RISM)/HNC and RISM/PY integral equations respectively, for ideal ring polymers. This means that the ISM/WDA functional should generally be more accurate for most 'real' ring or cage polymer systems when any reasonable approximation for the 'excess' contribution to the intrinsic Helmholtz free energy is employed.

Weighted density approximation for bonding in molecules: ring and cage polymers

International Nuclear Information System (INIS)

Sweatman, M B

2003-01-01

The focus of this work is the bonded contribution to the intrinsic Helmholtz free energy of molecules. A weighted density approximation (WDA) for this contribution is presented within the interaction site model (ISM) for ring and cage polymers. The resulting density functional theory (ISM/WDA) for these systems is no more complex than theories for a pure simple fluid, and much less complex than density functional approaches that treat the bonding functional exactly. The ISM/WDA bonding functional is much more accurate than either the ISM/HNC or ISM/PY bonding functionals, which are related to the reference interaction-site model (RISM)/HNC and RISM/PY integral equations respectively, for ideal ring polymers. This means that the ISM/WDA functional should generally be more accurate for most 'real' ring or cage polymer systems when any reasonable approximation for the 'excess' contribution to the intrinsic Helmholtz free energy is employed

Performance of a C4F8O gas radiator ring imaging Cherenkov detector using multi-anode photomultiplier tubes

International Nuclear Information System (INIS)

Artuso, M.; Boulahouache, C.; Blusk, S.; Butt, J.; Dorjkhaidav, O.; Menaa, N.; Mountain, R.; Muramatsu, H.; Nandakumar, R.; Randrianarivony, K.; Sia, R.; Skwarnicki, T.; Stone, S.; Wang, J.C.; Zhang, K.

2006-01-01

We report on tests of a novel ring imaging Cherenkov (RICH) detection system consisting of a 3-m-long gaseous C 4 F 8 O radiator, a focusing mirror, and a photon detector array based on Hamamatsu multi-anode photomultiplier tubes. This system was developed to identify charged particles in the momentum range from 3 to 70GeV/c for the BTeV experiment

Understanding of chemical bonding towards the enhancement of catalytic of Co(III)-doped ZrO2 catalyst material using x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Nor Aziah Buang; Wan Azelee Wan Abu Bakar; Harrison, P.G.

2000-01-01

The x-ray photoelectron spectroscopy (XPS) analysis has demonstrated the formation metal ions in different oxidation states or similar oxidation state with different bonding character in the ZrO 2 based catalyst material. Interaction of cobalt oxide with ZrO 2 matrixes shows the formation of surface species of Zr-O-Co with Co in the +2 oxidation state and Co 3 O 4 -CoO in a mixture of +2 and +3 oxidation states. The formation of Zr-O-Co species in sample calcined at 400 degree C results in the more ionic character of Co-O bond and more covalent character of Zr-0 bond compared to their ordinary oxides. These behaviour cause the shifting of Co(2p) XPS peaks position towards higher binding energy and the Zr(3d) XPS peaks position towards lower binding energy. Meanwhile, the formation Of Co 3 0 4 -CoO in sample calcined at temperature of 600 degree C exhibits Co(2p) XPS peaks in the region correspond to the Co in the +2 and +3 oxidation states, which is more covalent in bonding character. The catalytic activity measurement of the catalyst material calcined at 600 o C showed that the existence of Co-O species with more covalent in bonding character gave the best catalytic performance towards 100 % conversion of carbon monoxide and propane. (Author)

A novel metal-to-metal bonding process through in-situ formation of Ag nanoparticles using Ag2O microparticles

International Nuclear Information System (INIS)

Hirose, Akio; Tatsumi, Hiroaki; Takeda, Naoya; Akada, Yusuke; Ogura, Tomo; Ide, Eiichi; Morita, Toshiaki

2009-01-01

The metal-to-metal bonding has been successfully achieved via the bonding process using Ag metallo-organic nanoparticles at a bonding temperature of around 300-, which can be alternative to the current microsoldering in electronics assembly using high-temperature solders. However, further reduction of bonding temperature and/or bonding pressure is needed. In the present research, a novel bonding process through in-situ formation of Ag nanoparticles instead of the filler material of the Ag metallo-organic nanoparticles has been developed. The Ag nanoparticles can form by the reduction of Ag 2 O particles. In this study, the Ag 2 O particles were mixed with triethylene glycol as a reducing agent to form a paste for bonding. The Au coated cylindrical specimens were bonded using the paste. The Ag nanoparticles formed at around 130 to 160 through the reduction process of Ag2O particles with triethylene glycol. The Ag nanoparticles were immediately sintered each other due to a great surface energy per volume. A transmission electron microscope observation revealed that the sintered Ag metallurgically bonded to the Au substrate at around 160 and a dense Ag layer formed after further heating. The tensile strength of the joint bonded at 250 under a bonding pressure of 5MPa was around 60MPa

Programa mais médicos: uma revisão integrativa

Directory of Open Access Journals (Sweden)

Ana Caroline Pereira Martins

2017-12-01

Full Text Available Objetivo: Descrever o conhecimento produzido na literatura acerca da criação do Programa Mais Médicos e sua repercussão no Brasil. Métodos: Revisão integrativa, realizada no período de 2013 a 2016, nas bases de dados: Scientific Electronic Library Online (SciELO, Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS, Biblioteca Virtual em Saúde (BVS e na Coleciona SUS, utilizando-se os descritores: programa, médicos, atenção primária, atenção básica, saúde. Resultados: Foram selecionadas 21 publicações que atenderam aos critérios de inclusão, mas encontravam-se em periódicos com estratos intermediários e apresentaram baixo nível de evidência. Os principais resultados se referem à criação do Programa Mais Médicos (PMM e sua repercussão na classe médica, na população e na mídia. O PMM foi criado tendo como objetivo ampliar o acesso e atenuar as desigualdades em saúde através da distribuição de médicos em municípios considerados prioritários, ocasionou grande repercussão no Brasil, com posicionamentos diversos entre os órgãos governamentais, usuários, mídia e, em especial, entre a classe médica brasileira. Conclusão: Diminuir as desigualdades de alocação de médicos, no entanto, é uma ação difícil e que exige ações em longo prazo. Soma-se a necessidade de implantar estratégias como melhoraria de infraestrutura, melhor distribuição de insumos e equipamentos, apoio logístico e rede de atenção à saúde resolutiva, eficiente e eficaz em todos os níveis de atenção.

Top Operations and Maintenance (O&M) Efficiency Opportunities at DoD/Army Sites - A Guide for O&M/Energy Managers and Practitioners

Energy Technology Data Exchange (ETDEWEB)

Sullivan, Gregory P.; Dean, Jesse D.; Dixon, Douglas R.

2007-05-25

This report, sponsored the Army's Energy Engineering Analysis Program, provides the Operations and Maintenance (O&M) Energy manager and practitioner with useful information about the top O&M opportunities consistently found across the DoD/Army sector. The target is to help the DoD/Army sector develop a well-structured and organized O&M program.

Nb 3d and O 1s core levels and chemical bonding in niobates

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation)]. E-mail: atuchin@thermo.isp.nsc.ru; Kalabin, I.E. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Technical Center, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Pervukhina, N.V. [Laboratory of Crystal Chemistry, Institute of Inorganic Chemistry, SB RAS, Novosibirsk 630090 (Russian Federation)

2005-02-01

A set of available experimental data on binding energies of Nb 3d{sub 5/2} and O 1s core levels in niobates has been observed with using energy difference (O 1s-Nb 3d{sub 5/2}) as a robust parameter for compound characterization. An empirical relationship between (O 1s-Nb 3d{sub 5/2}) values measured with XPS for Nb{sup 5+}-niobates and mean chemical bond length L(Nb-O) has been discussed. A range of (O 1s-Nb 3d{sub 5/2}) values possible in Nb{sup 5+}-niobates has been defined. An energy gap {approx}1.4-1.8 eV is found between (O 1s-Nb 3d{sub 5/2}) values reasonable for Nb{sup 5+} and Nb{sup 4+} states in niobates.

Synthesis and structure of bis(β-dibenzoyl methanato -O,O') (aquo-O ...

Indian Academy of Sciences (India)

Synthesis and structure of bis(β-dibenzoyl methanato -O,O') (aquo-O) dioxouranium (VI) compound ... Keywords. β-diketonates; uranyl ion; adduct compound; crystal structure; hydrogen bonding. 1. Introduction. Structural studies on uranyl ... crystalline product obtained was filtered, washed with ether and dried. The crystal ...

Ab initio computational study of –N-C and –O-C bonding formation : functional group modification reaction based chitosan

Science.gov (United States)

Siahaan, P.; Salimah, S. N. M.; Sipangkar, M. J.; Hudiyanti, D.; Djunaidi, M. C.; Laksitorini, M. D.

2018-04-01

Chitosan application in pharmaceutics and cosmeceutics industries is limited by its solubility issue. Modification of -NH2 and -OH fuctional groups of chitosan by adding carboxyl group has been shown to improve its solubility and application. Attempt to synthesize carboxymethyl chitosan (CMC) from monocloroacetic acid (MCAA) has been done prior this report. However no information is available wether –OH (-O-C bonding formation) or -NH2 (-N-C bonding formation) is the preference for - CH2COOH to attach. In the current study, the reaction mechanism between chitosan and MCAA reactants into carboxymethyl chitosan (CMC) was examined by computational approach. Dimer from of chitosan used as a molecular model in calculation All the molecular structure involved in the reaction mechanism was optimized by ab initio computational on the theory and basis set HF/6-31G(d,p). The results showed that the - N-C bonding formation via SN2 than the -O-C bonding formation via SN2 which have activation energy 469.437 kJ/mol and 533.219 kJ/mol respectively. However, the -O-C bonding formation more spontaneous than the -N-C bonding formation because ΔG the formation of O-CMC-2 reaction is more negative than ΔG of formation N-CMC-2 reaction is -4.353 kJ/mol and -1.095 kJ/mol respectively. The synthesis of N,O-CMC first forms -O-CH2COOH, then continues to form -NH-CH2COOH. This information is valuable to further optimize the reaction codition for CMC synthesis.

M-commerce e o comportamento de compra dos consumidores portugueses

OpenAIRE

Gonçalves, Ana Rute Antunes

2015-01-01

Mestrado em Ciências Empresariais O m-commerce tem vindo a ganhar atratividade no contexto internacional e nacional. Nesta investigação é analisado o impacto das crenças normativas, motivações de compra, experiência de compra, satisfação, benefício percebido, risco percebido, diversas etapas do processo de compra e a complementaridade entre canais, na intenção de utilização do m-commerce. Adicionalmente, pretende-se compreender qual o perfil de compra do utilizador de m-commerce português....

Site specific interaction between ZnO nanoparticles and tyrosine: A density functional theory study

Science.gov (United States)

Singh, Satvinder; Singh, Janpreet; Singh, Baljinder; Singh, Gurinder; Kaura, Aman; Tripathi, S. K.

2018-05-01

First Principles Calculations have been performed on ZnO/Tyrosine atomic complex to study site specific interaction of Tyrosine and ZnO nanoparticles. Calculated results shows that -COOH group present in Tyrosine is energetically more favorable than -NH2 group. Interactions show ionic bonding between ZnO and Tyrosine. All the calculations have been performed under the Density Functional Theory (DFT) framework. Structural and electronic properties of (ZnO)3/Tyrosine complex have been studied. Gaussian basis set approach has been adopted for the calculations. A ring type most stable (ZnO)3 atomic cluster has been modeled, analyzed and used for the calculations.

Revisão dos métodos empregados na avaliação da dimensão corporal em pacientes com transtornos alimentares

Directory of Open Access Journals (Sweden)

Bianca Elisabeth Thurm

2011-01-01

Full Text Available Objetivo: O presente artigo analisou os métodos de avaliação da percepção da dimensão corporal abordados na literatura científica. Método: Foram utilizadas a palavra-chave "body image" e a combinação desta com os termos "size perception" e "size estimation", nas bases de dados Medline, Bireme, EBSCO e SCOPUS, para o levantamento científico. O período considerado para essas buscas foi de 1975 a 2010. Resultados: Foram encontrados quatro métodos que avaliam e quantificam a percepção dimensional do corpo, aplicando-se um índice de percepção da dimensão corporal. Os métodos diferem em sua forma de execução, utilização de instrumentos, uso ou não de feedback visual por parte do avaliado, utilização de estímulo tátil ou não para gerar a resposta do avaliado. Conclusão: O Image Marking Procedure (IMP mostrou-se apropriado para a avaliação da dimensão corporal nos distúrbios alimentares, pela possibilidade de avaliar o grau de distorção corporal e dos segmentos corporais específicos sem a interferência visual, cognitiva e qualquer referencial externo comparado aos outros testes que mostraram limitações quanto a esses aspectos. Sugere-se que ele seja utilizado em futuras pesquisas que avaliem o aspecto dimensional da percepção corporal.

O consentimento informado: Qual o seu real valor na prática médica?

Directory of Open Access Journals (Sweden)

José Guilherme Minossi

Full Text Available Trata-se de um artigo que comenta sobre a real importância do Termo de Consentimento Informado na prática médica. Este documento tem sido cada vez mais usado como uma prática defensiva, a fim de constituir provas para defesa de um eventual processo judicial de responsabilidade médica, desvirtuando assim a idéia original, que seria a de respeitar a autonomia do paciente e delimitar a responsabilidade médica. O documento tem como objetivo mostrar que o médico cumpriu com seu dever de informar. Seu grande valor reside nos casos onde existam riscos de danos irreversíveis ao paciente. Conclui-se, porém, que um prontuário bem elaborado onde se inclui o registro das informações que foram transmitidas, bem como o grau de participação dos pacientes e seus familiares nas decisões terapêuticas, também deve ter valor ético e jurídico semelhante do TCI.

Tensile bond strength of adhesive systems: effects of primer and thermocycling Resistência à tração de sistemas adesivos: efeitos do “ primer” e dos ciclos térmicos

Directory of Open Access Journals (Sweden)

Luciana Tibiriçá AGUILAR

2002-03-01

Full Text Available The objective of this study was to evaluate the effects of primer and thermocycling on the bond strength of multi-purpose adhesive systems applied to enamel, under tensile stress. The following bonding systems were applied, according to the manufacturers' instructions, on unground enamel buccal surfaces of 96 premolars, with or without the application of primer: Scotchbond MP, OptiBond FL, Amalgambond Plus and OptiBond (dual-cure. A composite resin (Z100, 3M was applied and light-cured in a cast metal hollow cone, which was previously fixed to the enamel surfaces. Half of the sample was subjected to 3,000 thermocycles (5-37ºC; 37-55ºC, dwell time of 60 s, and the other half was stored in water at 37ºC for the same period. The data were treated by means of ANOVA and no significant effects were detected, which indicates that tensile bond strength was not affected by the adhesive systems, application of primer or thermocycling.O objetivo desta pesquisa foi o de verificar o efeito do "primer" e dos ciclos térmicos na resistência da união entre adesivos multiuso e esmalte dental, sob ensaios de tração. Os seguintes sistemas adesivos foram aplicados, de acordo com as instruções dos fabricantes, na superfície vestibular (sem desgaste de 96 pré-molares com ou sem a aplicação prévia do "primer": Scotchbond MP, OptiBond FL, Amalgambond Plus e OptiBond - "dual cure". Após a aplicação do sistema adesivo, foi confeccionado um cone de resina composta (Z100, 3M, e fotoativado dentro de um molde metálico. Metade do total de espécimes foi submetida a 3.000 ciclos térmicos (5-37ºC; 37-55ºC, 60 s de imersão; a outra metade permaneceu imersa em água a 37ºC pelo mesmo tempo dispensado no procedimento anterior. Os dados foram submetidos a uma análise de variância (p = 0,05 e nenhum efeito significante foi detectado, indicando que a resistência de união não foi afetada pelo sistema adesivo, pela aplicação do "primer" ou pelos ciclos térmicos.

Electrically detected magnetic resonance study of the Ge dangling bonds at the Ge(1 1 1)/GeO{sub 2} interface after capping with Al{sub 2}O{sub 3} layer

Energy Technology Data Exchange (ETDEWEB)

Paleari, S., E-mail: s.paleari6@campus.unimib.it [Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via Cozzi 53, I-20125 Milan (Italy); Molle, A. [Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy); Accetta, F. [Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via Cozzi 53, I-20125 Milan (Italy); Lamperti, A.; Cianci, E. [Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy); Fanciulli, M., E-mail: marco.fanciulli@unimib.it [Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via Cozzi 53, I-20125 Milan (Italy); Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy)

2014-02-01

The electrical activity of Ge dangling bonds is investigated at the interface between GeO{sub 2}-passivated Ge(1 1 1) substrate and Al{sub 2}O{sub 3} grown by atomic layer deposition, by means of electrically detected magnetic resonance spectroscopy (EDMR). The Al{sub 2}O{sub 3}/GeO{sub 2}/Ge stacked structure is promising as a mobility booster for the post-Si future electronic devices. EDMR proved to be useful in characterizing interface defects, even at the very low concentrations of state-of-the-art devices (<10{sup 10} cm{sup −2}). In particular, it is shown that capping the GeO{sub 2}-passivated Ge(1 1 1) with Al{sub 2}O{sub 3} has no impact on the microstructure of the Ge dangling bond.

Formação de mão-de-obra e desenvolvimento econômico : o caso da indústria de São Luís-MA

OpenAIRE

PEREIRA, Ilmar Polary

2003-01-01

Avanços da formação de mão-de-obra no desenvolvimento econômico mundial, são aqui examinados. De forma histórica cronológica evidenciou-se os diversos níveis de exigência do perfil da força de trabalho como pré-requisito de eficiência Industrial e seus reflexos na economia. O trabalho discute tendências no Brasil sobre o tema formação de mão-de-obra e desenvolvimento econômico, considerando-se uma perspectiva histórica do crescente impulso ao desenvolvimento das forças produtiv...

Effect of V2O5 on SrO-ZnO-B2O3-SiO2 glass-ceramics for high temperature sealant application

Science.gov (United States)

Tiwari, Babita; Bhatacharya, S.; Dixit, A.; Gadkari, S. C.; Kothiyal, G. P.

2012-06-01

Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with and without V2O5 were prepared by melt-quench method and transformed into glass-ceramics by controlled crystallization. Investigated glasses and glass-ceramics have thermal expansion coefficients (TEC) in the range of 95-120 × 10-7/°C (30-600 °C), which match closely with TEC of other components of solid oxide fuel cell (SOFC). Study of thermo-physical properties of SZBS glasses revealed the network modifying effect of V2O5. Addition of V2O5 increases the TEC and decreases the viscosity of the glass which is beneficial for making seal with Crofer-22-APU. Microstructural investigations have shown good bonding of SZBS glasses with Crofer-22-APU. Elemental line scans indicate that inter-diffusion of Fe, Cr and Si across interface, which is thought to be responsible for good bonding with Crofer-22-APU.

Effects of variation in background mixing ratios of N2, O2, and Ar on the measurement of δ18O–H2O and δ2H–H2O values by cavity ring-down spectroscopy

Directory of Open Access Journals (Sweden)

J. E. Johnson

2017-08-01

Full Text Available Cavity ring-down spectrometers have generally been designed to operate under conditions in which the background gas has a constant composition. However, there are a number of observational and experimental situations of interest in which the background gas has a variable composition. In this study, we examine the effect of background gas composition on a cavity ring-down spectrometer that measures δ18O–H2O and δ2H–H2O values based on the amplitude of water isotopologue absorption features around 7184 cm−1 (L2120-i, Picarro, Inc.. For background mixtures balanced with N2, the apparent δ18O values deviate from true values by −0.50 ± 0.001 ‰ O2 %−1 and −0.57 ± 0.001 ‰ Ar %−1, and apparent δ2H values deviate from true values by 0.26 ± 0.004 ‰ O2 %−1 and 0.42 ± 0.004 ‰ Ar  %−1. The artifacts are the result of broadening, narrowing, and shifting of both the target absorption lines and strong neighboring lines. While the background-induced isotopic artifacts can largely be corrected with simple empirical or semi-mechanistic models, neither type of model is capable of completely correcting the isotopic artifacts to within the inherent instrument precision. The development of strategies for dynamically detecting and accommodating background variation in N2, O2, and/or Ar would facilitate the application of cavity ring-down spectrometers to a new class of observations and experiments.

Origin of the Ability of α-Fe2 O3 Mesopores to Activate C-H Bonds in Methane.

Science.gov (United States)

Dong, Bing; Han, Zhen; Zhang, Yongbo; Yu, Youyi; Kong, Aiguo; Shan, Yongkui

2016-02-01

Methane is a most abundant and inexpensive hydrocarbon feedstock for the production of chemicals and fuels. However, it is extremely difficult to directly convert methane to higher hydrocarbons because the C-H bonds in methane are the most stable C-H bonds of all hydrocarbons. The activation of the C-H bonds in methane by using an efficient and mild route remains a daunting challenge. Here, we show that the inner surface structures of the pore walls in mesoporous α-Fe 2 O 3 possess excellent catalytic performance for methane activation and convert C-H bonds into the C-O bonds in an O 2 atmosphere at 140 °C. We found that such unusual structures are mainly comprised of turbostratic ribbons and K crystal faces and have higher catalytic activity than the (110) plane. These results are without precedent in the history of catalysis chemistry and will provide a new pathway for designing and preparing highly efficient catalytic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Avaliação do módulo da aceleração da gravidade com Arduino

Directory of Open Access Journals (Sweden)

Samir Lacerda da Silva

2016-09-01

Full Text Available http://dx.doi.org/10.5007/2175-7941.2016v33n2p619   Nesse trabalho, utilizamos a plataforma de hardware livre Arduino para automatizar o processo de coleta de dados no movimento de queda de um objeto, em experimento capaz de fornecer o módulo da aceleração da gravidade local com boa precisão. A partir de sensores posicionados em alturas conhecidas, coletamos os intervalos de tempo gastos por uma esfera para percorrer diferentes distâncias verticais, sendo sua aceleração determinada através da análise de ajuste linear da curva de variação de altura por intervalo de tempo versus intervalo de tempo, onde o dobro da inclinação da reta média corresponde ao módulo local g da aceleração da gravidade. Em virtude das condições de lançamento, os efeitos da resistência do ar não foram considerados na obtenção de g, de modo que consideramos ser esse um movimento de queda livre como boa aproximação. O instrumento desenvolvido nos permitiu obter o valor médio de g diferindo em apenas 1% do valor encontrado na literatura, mostrando que o Arduino é uma ferramenta interessante para aquisição de dados e automatização de experimentos de Física. Reforçamos nesse trabalho a importância da utilização das novas tecnologias no ensino de Ciências, em especial de Física.

Comunicação, espaço e tempo: Vilém Flusser e os processos de vinculação

Directory of Open Access Journals (Sweden)

José Eugenio de O. Menezes

2009-09-01

Full Text Available RESUMO Com o objetivo de reunir instrumentos para a compreensão dos processos comunicativos na contemporaneidade, o presente trabalho mapeia as concepções de comunicação, espaço e tempo nas obras de Vilém Flusser. Por meio de indícios presentes na vida e nas obras do autor, especialmente nos estudos a respeito da escalada da abstração, são apresentados os quatro processos de comunicação: comunicação tridimensional, comunicação bidimensional, comunicação unidimensional e comunicação nulodimensional. Nas formas como Flusser estudou a mudança dos códigos dominantes nos processos de comunicação (gestos do corpo, imagem, escrita, digitalização, observa-se o que homens e mulheres ganham e perdem no trânsito entre os diferentes processos de comunicação. Palavras-chave: Comunicação; cultura; Vilém Flusser; processos de vinculação; diálogo. Resumen Con el objetivo de reunir instrumentos para la comprensión de los procesos comunicativos en la contemporaneidad, el presente trabajo apunta las concepciones de comunicación, espacio y tiempo en las obras de Vilém Flusser. Por medio de elementos presentes en la vida y en las obras del autor, especialmente en los estudios respecto a la escalada de la abstracción, son presentados los cuatro procesos de comunicación: comunicación tridimensional, comunicación bidimensional, comunicación unidimensional y comunicación nulodimensional. En las maneras cómo Flusser estudió la modificación de los códigos dominantes en los procesos de comunicación (gestos del cuerpo, imagen, escritura, digitalización, se observa lo que los hombres y las mujeres ganan y pierden en el tránsito entre los diferentes procesos de comunicación. Palabras-clave: Comunicación; cultura; Vilém Flusser; procesos de vinculación; diálogo. Abstrac t With the goal of gathering means for the comprehension of the communicative processes nowadays, this present paper maps the conceptions of

Microstructural characterization in diffusion bonded TiC–Al 2 O 3 ...

Indian Academy of Sciences (India)

The diffusion bonded TiC–Al2O3/Cr18–Ni8 joint was investigated by a variety of characterization techniques such as scanning electron microscope (SEM) with energy dispersion ... Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University (South Campus), Jinan 250061, P.R. China ...

Avaliação de métodos indiretos de determinação da erodibilidade de Latossolos brasileiros

Directory of Open Access Journals (Sweden)

SILVA MARX LEANDRO NAVES

2000-01-01

Full Text Available Existem três maneiras de se determinar a erodibilidade do solo (Fator K. A primeira envolve a determinação do fator K em condições de campo, sob chuva natural, a qual é onerosa e muito demorada. O segundo método é semelhante ao primeiro, porém baseia-se na quantificação do fator K em razão das perdas de solo e do fator erosividade, sob condições de chuva simulada. O terceiro método baseia-se em regressões múltiplas que contenham, como variáveis independentes, atributos do solo correlacionados com o fator K obtido pelos dois métodos anteriores, tidos como padrões. A carência de dados básicos e a indefinição do melhor método para determinação da erodibilidade de maneira indireta, que possibilite enquadrar os solos em classes de resistência à erosão, constituem problemas na utilização destes métodos indiretos, particularmente nos Latossolos brasileiros. Portanto, objetivou-se com este estudo a determinação indireta da erodibilidade desses solos e avaliação da correlação com os métodos diretos. Nenhum dos métodos testados mostrou-se recomendável para a estimativa da erodibilidade para o conjunto de Latossolos do Brasil, sendo necessário, então, desenvolver modelos específicos para este grupamento de solos.

Análise da comunicação verbal e não verbal de uma mãe cega e com limitação motora durante a amamentação

Directory of Open Access Journals (Sweden)

Lorita Marlena Freitag Pagliuca

2011-06-01

Full Text Available Análise da comunicação verbal e não verbal de mãe cega e com limitação motora durante a amamentação. Coleta por entrevista e filmagem, com análise qualitativa dos dados. Na comunicação verbal a mãe atua como remetente durante amamentação e uso da mamadeira, predominando a mensagem dificuldade de amamentar. Na não verbal, na posição deitada há ausência de contato face a face e diminui o contato físico; sentada, o contato está aumentado, expressa afeto, mas a mãe não direciona a face para o filho; administrando mamadeira, mãe sentada, expressa afeto e interação, mantém cabeça baixa. Conclui-se que a comunicação verbal está centrada na mensagem alimentação e na não verbal há interferência da posição para alimentar a criança.

VALE QUANTO PESA: o que leva(m mulheres grávidas à prisão?

Directory of Open Access Journals (Sweden)

Heloisa Vieira Simões

2017-11-01

Full Text Available O exponencial crescimento do número de mulheres encarceradas no Brasil não mudou o contexto de invisibilidade em que vivem. Diante de tal silêncio, e tendo a percepção de que é em face do feminino e de seu corpo que o sistema de justiça criminal parece expressar sua mais perversa atuação, o Projeto Mulheres pelas Mulheres se propôs a dar voz e visibilidade a essas mulheres. A partir de uma série de entrevistas – com as próprias internas e com as mulheres que visitavam presos nas penitenciárias de Piraquara-PR – foi possível traçar um perfil da mulher encarcerada no Paraná. Entretanto, chamou a atenção a expressiva quantidade de mulheres grávidas e com bebês dentro do sistema. Assim, tendo como base uma epistemologia feminista, foi possível perceber, através dos relatos e de informações a respeito da visita, da revista e das circunstâncias da prisão de determinadas mulheres, um padrão, uma série de histórias repetidas. Mulheres grávidas que, nas filas para a visita, recebem ofertas razoáveis de dinheiro em troca de um serviço, cujo sucesso já estaria acertado com os responsáveis pela revista. Em um instante, porém, tornam-se, para o sistema de justiça criminal, traficantes. Mulheres-traficantes que trazem no ventre a paradoxal contradição de serem mulheres-traficantes-grávidas, subvertendo a ordem de gênero e os papeis naturalmente estabelecidos, caracterizando aquilo que, simbolicamente, não se admite: que uma criminosa seja, também, mãe.

PREPARATION,COMPLEX MECHANISM AND STRUCTURE MODEL OF METALLOPHTHALOC- YANINE-Fe3O4 NANOPARTICLES COMPOSITE

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

MPc-Fe3O4-nanoparticles composite(M=Co, Cu, Ni, Mn) have been prepared and the factors that influence their mean size have been studied. The mean size of the nanoparticles composite increase with the increase of complex temperature. The interaction of MPc with Fe3O4 nanoparticles has been studied. There are M-O covalent bonding and ionic bonding between MPc and Fe3O4 nanoparticles. The intensities of M-O bonding and ionic bonding are in vestigated .The complex mechanism of MPc with Fe3O4 nanoparticles have been studied. First, there are complex between MPc and all Fe3O4 nanoparticles. Then, Fe3O4 nanoparticles accumulate together to form the accumulators, MPc have the function of cohering Fe3O4 nanoparticles. A considerable number of MPc combine with Fe3O4 nanoparticles on the surface of the accumulators to form MPc-Fe3O4 nanoparticles composite. All the above proesses take place spontaneously. The structure model of MPc-Fe3O4 nanoparticles composite has also been investigated. Inside the MPc-Fe3O4 nanoparticles composite, Fe3O4 nanoparticles accumulate together without order, on the surface of the composite, MPc form molecular dispersion layer. The threshold of molecular dispersion layer are also investigated.

Chronos Mobi: uma aplicação móvel multiplataforma para o gerenciamento de projetos

Directory of Open Access Journals (Sweden)

Marcelo Kasperbauer

2013-05-01

Full Text Available Este trabalho propõe uma aplicação multiplataforma para dispositivos móveis voltada ao gerenciamento de projetos. O Chronos Mobi baseia-se no modelo Chronos, cujos componentes englobam mapas mentais, PMBoK e Scrum. A implementação baseou-se no uso do framework Phonegap que prove inúmeros recursos para o desenvolvimento móvel. Para a avaliação do Chronos Mobi realizou-se uma análise comparativa do desempenho da aplicação executando em tablets e smartphones nas plataformas Android, Windows Phone e Symbian.

Análise da correlação entre o protocolo Polar Fitness Test® para predição de VO2máx e ergoespirometria

Directory of Open Access Journals (Sweden)

Moacir Marocolo

2012-06-01

Full Text Available INTRODUÇÃO: A importância da mensuração do consumo máximo de oxigênio (O2máxé justificada por sua aceitação internacional como o melhor parâmetro fisiológico para avaliar a capacidade funcional do sistema cardiorrespiratório tanto em atletas como em não atletas que treinam fisicamente com objetivo de obter melhor saúde. OBJETIVO: Verificar a concordância entre os protocolos Polar Fitness Test® para a estimativa do O2máx e o teste de esforço máximo com medida direta de gases. MÉTODOS: Dezessete homens ativos (22,5 ± dois anos participaram. Em repouso, aplicou-se o protocolo Polar Fitness Test® e, em seguida, a coleta direta de gases sob o esforço máximo, em esteira, seguindo o protocolo de Bruce. RESULTADOS: Houve diferença significativa entre os valores médios dos métodos para estimativa do O2máx. O protocolo Polar Fitness Test® subestimou o O2máx, em média 15% (IC95%: 24; -53% comparado com a medida direta de gases. Os valores obtidos pelo Polar Fitness Test® não tiveram boa correlação com a medida direta em ergoespirômetro (r = 0,1. CONCLUSÃO: O protocolo Polar Fitness Test® não é válido para a estimativa do O2máx em homens jovens ativos fisicamente.