Crystal structure of a new monoclinic polymorph of N-(4-methyl-phen-yl)-3-nitro-pyridin-2-amine.

Science.gov (United States)

Aznan, Aina Mardia Akhmad; Abdullah, Zanariah; Lee, Vannajan Sanghiran; Tiekink, Edward R T

2014-08-01

The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, with Z' = 4) of the previously reported monoclinic (P21/c, with Z' = 2) form [Akhmad Aznan et al. (2010 ▶). Acta Cryst. E66, o2400]. Four independent mol-ecules comprise the asymmetric unit, which have the common features of a syn disposition of the pyridine N atom and the toluene ring, and an intra-molecular amine-nitro N-H⋯O hydrogen bond. The differences between mol-ecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6-311 g+(d,p) basis set] has the same features except that the entire mol-ecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C-H⋯O, C-H⋯π, nitro-N-O⋯π and π-π inter-actions [inter-centroid distances = 3.649 (2)-3.916 (2) Å].

(E)-3-[4-(Pent-yloxy)phen-yl]-1-phenyl-prop-2-en-1-one.

Science.gov (United States)

Abbas, Asghar; Khawar Rauf, M; Bolte, Michael; Hasan, Aurangzeb

2009-05-14

The title compound, C(20)H(22)O(2), crystallizes with two independent mol-ecules in the asymmetric unit. In each mol-ecule, all the non-H atoms lie in a common plane (r.m.s. deviations of 0.098 and 0.079 Å). There is a π-π stacking inter-action in the crystal structure. The central aromatic rings of the two mol-ecules, which are stacked head-to-tail one above the other, are separated by centroid-to-centroid distances of 3.872 (13) and 3.999 (10) Å.

Crystal structure of 4-meth-oxy-N-(piperidine-1-carbono-thio-yl)benzamide.

Science.gov (United States)

Suhud, Khairi; Hasbullah, Siti Aishah; Ahmad, Musa; Heng, Lee Yook; Kassim, Mohammad B

2017-10-01

In the title compound, C 14 H 18 N 2 O 2 S, the piperidine ring has a chair conformation. Its mean plane is twisted with respect to the 4-meth-oxy-benzoyl ring, with a dihedral angle of 63.0 (3)°. The central N-C(=S)-N(H)-C(=O) bridge is twisted with an N-C-N-C torsion angle of 74.8 (6)°. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming chains along the c -axis direction. Adjacent chains are linked by C-H⋯π inter-actions, forming layers parallel to the ac plane. The layers are linked by offset π-π inter-actions [inter-centroid distance = 3.927 (3) Å], forming a supra-molecular three-dimensional structure.

Nonlinear spin wave coupling in adjacent magnonic crystals

Energy Technology Data Exchange (ETDEWEB)

Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

2016-07-25

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

Nonlinear spin wave coupling in adjacent magnonic crystals

International Nuclear Information System (INIS)

Sadovnikov, A. V.; Nikitov, S. A.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E.

2016-01-01

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

3-Nitro-phenol-1,3,5-triazine-2,4,6-tri-amine (2/1).

Science.gov (United States)

Sangeetha, V; Kanagathara, N; Chakkaravarthi, G; Marchewka, M K; Anbalagan, G

2013-06-01

The asymmetric unit of the title compound, C3H6N6·2C6H5NO3, contains one melamine and two 3-nitro-phenol mol-ecules. The mean planes of the 3-nitro-phenol mol-ecules are almost orthogonal to the plane of melamine, making dihedral angles of 82.77 (4) and 88.36 (5)°. In the crystal, mol-ecules are linked via O-H⋯N, N-H⋯N and N-H⋯O hydrogen bonds, forming a three-dimensional network. The crystal also features weak C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.9823 (9) Å].

Crystal structure of tri­chlorido­(4'-ferrocenyl-2,2':6',2''-terpyridine-[kappa]3N,N',N'')iridium(III) aceto­nitrile disolvate

KAUST Repository

Davaasuren, Bambar

2015-02-25

In the title compound, [FeIr(C5H5)(C20H14N3)Cl3]·2CH3CN, the central IrIII atom is sixfold coordinated by three chloride ligands and three terpyridine N atoms in a slightly distorted octa­hedral fashion. The terpyridine ligand is functionalized at the 4\\'-position with a ferrocenyl group, the latter being in an eclipsed conformation. In the crystal, mol­ecules are stacked in rows parallel to [001], with the aceto­nitrile solvent mol­ecules situated between the rows. An extensive network of intra- and inter­molecular C-H...Cl inter­actions is present, stabilizing the three-dimensional structure.

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

Science.gov (United States)

Decato, Daniel A; Berryman, Orion B

2015-09-01

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

1,5-Bis(1-phenyl-ethyl-idene)thio-carbono-hydrazide.

Science.gov (United States)

Feng, Lei; Ji, Haiwei; Wang, Renliang; Ge, Haiyan; Li, Li

2011-06-01

The title mol-ecule, C(17)H(18)N(4)S, is not planar, as indicated by the dihedral angle of 27.24 (9)° between the two benzene rings. In the crystal, inter-molecular N-H⋯S hydrogen bonds link pairs of mol-ecules into inversion dimers.

(R,S)-3-Carb-oxy-2-(isoquinolinium-2-yl)propanoate monohydrate.

Science.gov (United States)

Stilinović, Vladimir; Frkanec, Leo; Kaitner, Branko

2010-05-22

The title compound, C(13)H(11)NO(4)·H(2)O, is a monohydrate of a betaine exhibiting a positively charged N-substituted isoquino-line group and a deprotonated carboxyl group. In the crystal, mol-ecules are connected via short O-H⋯O hydrogen bonds between protonated and deprotonated carboxyl groups into chains of either R or S enanti-omers along [001]. These chains are additionally connected by hydrogen bonding between water mol-ecules and the deprotonated carb-oxy groups of neighbouring mol-ecules.

1-[1-(4-Chloro-phen-yl)ethyl-idene]carbono-hydrazide.

Science.gov (United States)

Du, Lingyun; Du, Lei; Wang, Shuhao

2009-08-12

The mol-ecular skeleton of the title mol-ecule, C(9)H(11)ClN(4)O, is essentially planar, the dihedral angle between the ring and the and N/N/C plane being 6.7 (3)°. In the crystal, inter-molecular N-H⋯O and N-H⋯N hydrogen bonds link the mol-ecules into ribbons propagated along [010].

Crystal structure of 4-meth­oxy-N-(piperidine-1-carbono­thio­yl)benzamide

Science.gov (United States)

Suhud, Khairi; Hasbullah, Siti Aishah; Ahmad, Musa; Heng, Lee Yook

2017-01-01

In the title compound, C14H18N2O2S, the piperidine ring has a chair conformation. Its mean plane is twisted with respect to the 4-meth­oxy­benzoyl ring, with a dihedral angle of 63.0 (3)°. The central N—C(=S)—N(H)—C(=O) bridge is twisted with an N—C—N—C torsion angle of 74.8 (6)°. In the crystal, mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds, forming chains along the c-axis direction. Adjacent chains are linked by C—H⋯π inter­actions, forming layers parallel to the ac plane. The layers are linked by offset π–π inter­actions [inter­centroid distance = 3.927 (3) Å], forming a supra­molecular three-dimensional structure. PMID:29250374

(R,S)-3-Carb­oxy-2-(isoquinolinium-2-yl)propanoate monohydrate

Science.gov (United States)

Stilinović, Vladimir; Frkanec, Leo; Kaitner, Branko

2010-01-01

The title compound, C13H11NO4·H2O, is a monohydrate of a betaine exhibiting a positively charged N-substituted isoquino­line group and a deprotonated carboxyl group. In the crystal, mol­ecules are connected via short O—H⋯O hydrogen bonds between protonated and deprotonated carboxyl groups into chains of either R or S enanti­omers along [001]. These chains are additionally connected by hydrogen bonding between water mol­ecules and the deprotonated carb­oxy groups of neighbouring mol­ecules. PMID:21579503

The crystal structures of two isomers of 5-(phenyl-iso-thia-zol-yl)-1,3,4-oxa-thia-zol-2-one.

Science.gov (United States)

Zhu, Shuguang; Schriver, Melbourne J; Hendsbee, Arthur D; Masuda, Jason D

2017-11-01

The syntheses and crystal structures of two isomers of phenyl iso-thia-zolyl oxa-thia-zolone, C 11 H 6 N 2 O 2 S 2 , are described [systematic names: 5-(3-phenyl-iso-thia-zol-5-yl)-1,3,4-oxa-thia-zol-2-one, (I), and 5-(3-phenyl-iso-thia-zol-4-yl)-1,3,4-oxa-thia-zol-2-one, (II)]. There are two almost planar (r.m.s. deviations = 0.032 and 0.063 Å) mol-ecules of isomer (I) in the asymmetric unit, which form centrosymmetric tetra-mers linked by strong S⋯N [3.072 (2) Å] and S⋯O contacts [3.089 (1) Å]. The tetra-mers are π-stacked parallel to the a -axis direction. The single mol-ecule in the asymmetric unit of isomer (II) is twisted into a non-planar conformation by steric repulsion [dihedral angles between the central iso-thia-zolyl ring and the pendant oxa-thia-zolone and phenyl rings are 13.27 (6) and 61.18 (7)°, respectively], which disrupts the π-conjugation between the heteroaromatic iso-thia-zoloyl ring and the non-aromatic oxa-thia-zolone heterocycle. In the crystal of isomer (II), the strong S⋯O [3.020 (1) Å] and S⋯C contacts [3.299 (2) Å] and the non-planar structure of the mol-ecule lead to a form of π-stacking not observed in isomer (I) or other oxa-thia-zolone derivatives.

1,5-Bis(1-phenyl­ethyl­idene)thio­carbono­hydrazide

Science.gov (United States)

Feng, Lei; Ji, Haiwei; Wang, Renliang; Ge, Haiyan; Li, Li

2011-01-01

The title mol­ecule, C17H18N4S, is not planar, as indicated by the dihedral angle of 27.24 (9)° between the two benzene rings. In the crystal, inter­molecular N—H⋯S hydrogen bonds link pairs of mol­ecules into inversion dimers. PMID:21754879

1-[1-(4-Chloro­phen­yl)ethyl­idene]carbono­hydrazide

Science.gov (United States)

Du, Lingyun; Du, Lei; Wang, Shuhao

2009-01-01

The mol­ecular skeleton of the title mol­ecule, C9H11ClN4O, is essentially planar, the dihedral angle between the ring and the and N/N/C plane being 6.7 (3)°. In the crystal, inter­molecular N—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules into ribbons propagated along [010]. PMID:21577542

4-Bromo-N-(di-n-propyl-carbamothioyl)-benzamide.

Science.gov (United States)

Binzet, Gün; Flörke, Ulrich; Külcü, Nevzat; Arslan, Hakan

2009-02-04

The synthesis of the title compound, C(14)H(19)BrN(2)OS, involves the reaction of 4-bromo-benzoyl chloride with potassium thio-cyanate in acetone followed by condensation of the resulting 4-bromo-benzoyl isothio-cyanate with di-n-propyl-amine. Typical thio-urea carbonyl and thio-carbonyl double bonds, as well as shortened C-N bonds, are observed in the title compound. The short C-N bond lengths in the centre of the mol-ecule reveal the effects of resonance in this part of the mol-ecule. The asymmetric unit of the title compound contains two crystallographically independent mol-ecules, A and B. There is very little difference between the bond lengths and angles of these mol-ecules. In mol-ecule B, one di-n-propyl group is twisted in a -anti-periplanar conformation with C-C-C-H = -179.1 (3)° and the other adopts a -synclinal conformation with C-C-C-H = -56.7 (4)°; in mol-ecule A the two di-n-propyl groups are twisted in + and -anti-periplanar conformations, with C-C-C-H = -179.9 (3) and 178.2 (3)°, respectively. In the crystal, the mol-ecules are linked into dimeric pairs via pairs of N-H⋯S hydrogen bonds.

Diallyl 5-[(4-hexyl-oxyphen-yl)imino-meth-yl]-m-phenyl-ene dicarbonate.

Science.gov (United States)

Herrera-González, Ana María; López-Velázquez, Delia; Bernès, Sylvain

2009-10-23

The title mol-ecule, C(27)H(31)NO(7), an imine derivative bearing both carbonate and allyl functionalities, was synthesized in the hope of obtaining a mesogenic polymerizable material. The allyl-carbonate arms are fully disordered over two sets of sites, reflecting a large degree of rotational freedom about σ bonds [occupancies: 0.665 (9)/0.335 (9) for one substituent, 0.564 (9)/0.436 (9) for the other]. In contrast, the hexyl chain is ordered, and presents the common all-trans extended conformation. The benzene rings connected via the imine group make a dihedral angle of 9.64 (11)°. In the crystal, the Y-shaped mol-ecules are weakly associated into centrosymmetric dimers through pairs of C-H⋯O(hex-yl) contacts. The resulting layers of dimers, approximately parallel to (25), are closely packed in the crystal, allowing π⋯π inter-actions between benzene rings of neighboring layers: the separation between the centroid of the benzene ring substituted by allyl-carbonate and the centroid of the benzene ring bearing the hex-yloxy group in the adjacent layer is 3.895 (1) Å.

Crystal structures and Hirshfeld surface analyses of bis-[N,N-bis-(2-meth-oxy-eth-yl)di-thio-carbamato-κ2S,S']di-n-butyl-tin(IV) and [N-(2-meth-oxy-eth-yl)-N-methyl-dithio-carbamato-κ2S,S']tri-phenyl-tin(IV).

Science.gov (United States)

Mohamad, Rapidah; Awang, Normah; Kamaludin, Nurul Farahana; Jotani, Mukesh M; Tiekink, Edward R T

2018-03-01

The crystal and mol-ecular structures of the two title organotin di-thio-carbamate compounds, [Sn(C 4 H 9 ) 2 (C 7 H 14 NO 2 S 2 ) 2 ], (I), and [Sn(C 6 H 5 ) 3 (C 5 H 10 NOS 2 )], (II), are described. Both structures feature asymmetrically bound di-thio-carbamate ligands leading to a skew-trapezoidal bipyramidal geometry for the metal atom in (I) and a distorted tetra-hedral geometry in (II). The complete mol-ecule of (I) is generated by a crystallographic twofold axis (Sn site symmetry 2). In the crystal of (I), mol-ecules self-assemble into a supra-molecular array parallel to (10-1) via methyl-ene-C-H⋯O(meth-oxy) inter-actions. In the crystal of (II), supra-molecular dimers are formed via pairs of weak phenyl-C-H⋯π(phen-yl) contacts. In each of (I) and (II), the specified assemblies connect into a three-dimensional architecture without directional inter-actions between them. Hirshfeld surface analyses confirm the importance of H⋯H contacts in the mol-ecular packing of each of (I) and (II), and in the case of (I), highlight the importance of short meth-oxy-H⋯H(but-yl) contacts between layers.

Diaqua­bis­(pyridine-2-carboxyl­ato-κ2 N,O)manganese(II) dimethyl­formamide hemisolvate

Science.gov (United States)

Golenya, Irina A.; Boyko, Alexander N.; Kalibabchuk, Valentina A.; Haukka, Matti; Tomyn, Stefania V.

2011-01-01

There are two crystallographically independent complex mol­ecules with very similar geometries in the unit cell of the title compound, [Mn(C6H4NO2)2(H2O)2]·0.5C3H7NO. The central ion is situated in a distorted octa­hedral environment of two N- and four O-donor atoms from two pyridine-2-carboxyl­ate ligands and two cis-disposed water mol­ecules. The carboxyl­ate ligands are coordinated in a chelate fashion with the formation of two five-membered rings. In the crystal, the complex mol­ecules are connected by O—H⋯O hydrogen bonds between the coordinated water mol­ecules and the uncoordinated carboxyl­ate O atoms, thus forming hydrogen-bonded walls disposed perpendicularly to the bc plane. PMID:22219799

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

Science.gov (United States)

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M; Yusoff, Siti Fairus M

2014-09-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro-benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro-benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl-thio-amide group and its attached ring is 12.98 (10)°. The major twists in the mol-ecule occur about the C-N-N-C bonds [torsion angle = -138.7 (2)°] and the Car-Car-C-N (ar = aromatic) bonds [-132.0 (2)°]. An intra-molecular N-H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯S hydrogen bonds, generating (001) sheets. Weak C-H⋯O and C-H⋯F inter-actions are also observed.

Crystal structure of bis-(3-bromo-pyridine-κN)bis-(O-ethyl di-thio-carbonato-κ(2) S,S')nickel(II).

Science.gov (United States)

Kant, Rajni; Kour, Gurvinder; Anthal, Sumati; Neerupama; Sachar, Renu

2015-01-01

In the title mol-ecular complex, [Ni(C3H5OS2)2(C5H4BrN)2], the Ni(2+) cation is located on a centre of inversion and has a distorted octa-hedral N2S4 environment defined by two chelating xanthate ligands and two monodentate pyridine ligands. The C-S bond lengths of the thio-carboxyl-ate group are indicative of a delocalized bond and the O-Csp (2) bond is considerably shorter than the O-Csp (3) bond, consistent with a significant contribution of one resonance form of the xanthate anion that features a formal C=O+ unit and a negative charge on each of the S atoms. The packing of the mol-ecules is stabilized by C-H⋯S and C-H⋯π inter-actions. In addition, π-π inter-actions between the pyridine rings [centroid-to-centroid distance = 3.797 (3) Å] are also present. In the crystal structure, mol-ecules are arranged in rows along [100], forming layers parallel to (010) and (001).

Crystal structure of di-bromo-meth-oxy-seselin (DBMS), a photobiologically active pyran-ocoumarin.

Science.gov (United States)

Bauri, A K; Foro, Sabine; Rahman, A F M M

2017-05-01

The title compound, C 15 H 14 Br 2 O 4 [systematic name: rac -(9 S ,10 R )-3,9-dibromo-10-methoxy-8,8-dimethyl-9,10-dihydropyrano[2,3- h ]chromen-2(8 H )-one], is a pyran-ocoumarin derivative formed by the bromination of seselin, which is a naturally occurring angular pyran-ocoumarin isolated from the Indian herb Trachyspermum stictocarpum . In the mol-ecule, the benzo-pyran ring system is essentially planar, with a maximum deviation of 0.044 (2) Å for the O atom. The di-hydro-pyran ring is in a half-chair conformation and the four essentially planar atoms of this ring form a dihedral angle of 4.6 (2)° with the benzo-pyran ring system. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming chains propagating along [010]. In addition, π-π stacking inter-actions, with centroid-centroid distances of 3.902 (2) and 3.908 (2) Å, link the hydrogen-bonded chains into layers parallel to (001).

Tetra­kis(aceto­nitrile)copper(I) hydrogen oxalate–oxalic acid–aceto­nitrile (1/0.5/0.5)

Science.gov (United States)

Royappa, A. Timothy; Stepherson, Jacob R.; Vu, Oliver D.; Royappa, Andrew D.; Stern, Charlotte L.; Müller, Peter

2013-01-01

In the title compound, [Cu(CH3CN)4](C2HO4)·0.5C2H2O4·0.5CH3CN, the CuI ion is coordinated by the N atoms of four aceto­nitrile ligands in a slightly distorted tetra­hedral environment. The oxalic acid mol­ecule lies across an inversion center. The aceto­nitrile solvent mol­ecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid mol­ecules are linked via O—H⋯O hydrogen bonds, forming chains along [010]. PMID:24098175

N,N′-Bis(3β-acet­oxy-5α-cholest-6-yl­idene)hydrazine

Science.gov (United States)

Tabassum, Zishan; Sulaiman, Othman; Ibrahim, M. N. Mohamad; Quah, Ching Kheng; Fun, Hoong-Kun

2011-01-01

The asymmetric unit of the title compound, C58H96N2O4, contains two crystallographically independent mol­ecules. All cyclohexane rings are in chair conformations, while the furan ring is in an envelope conformation in one mol­ecule and a twist conformation in the other. Two acetaldehyde and one isobutane groups are disordered over two orientations with refined site occupancies of 0.940 (4):0.060 (4) and 0.791 (7):0.209 (7), respectively. In the crystal, mol­ecules are stacked along the a axis through van der Waals inter­actions. PMID:21523172

Crystal structure of 1-meth-oxy-2,2,2-tris-(pyrazol-1-yl)ethane.

Science.gov (United States)

Lyubartseva, Ganna; Parkin, Sean; Coleman, Morgan D; Mallik, Uma Prasad

2014-09-01

The title compound, C12H14N6O, consists of three pyrazole rings bound via nitro-gen to the distal ethane carbon of meth-oxy ethane. The dihedral angles between the three pyrazole rings are 67.62 (14), 73.74 (14), and 78.92 (12)°. In the crystal, mol-ecules are linked by bifurcated C-H,H⋯N hydrogen bonds, forming double-stranded chains along [001]. The chains are linked via C-H⋯O hydrogen bonds, forming a three-dimensional framework structure. The crystal was refined as a perfect (0.5:0.5) inversion twin.

Structure and spectroscopic properties of N,S-coordinating 2-methyl-sulfanyl-N-[(1H-pyrrol-2-yl)methyl-idene]aniline methanol monosolvate.

Science.gov (United States)

Richards, D Douglas; Ang, M Trisha C; McDonald, Robert; Bierenstiel, Matthias

2015-10-01

The reaction of pyrrole-2-carboxaldehyde and 2-(methyl-sulfan-yl)aniline in refluxing methanol gave an olive-green residue in which yellow crystals of the title compound, C12H12N2S·CH3OH, were grown from slow evaporation of methanol at 263 K. In the crystal, hydrogen-bonding inter-actions link the aniline mol-ecule and a nearby methanol solvent mol-ecule. These units are linked by a pair of weak C-H⋯Omethanol interactions, forming inversion dimers consisting of two main molecules and two solvent molecules.

[1,2-Bis(diisopropyl-phosphan-yl)ethane-κ(2) P,P'](carbonato-κ(2) O,O')nickel(II).

Science.gov (United States)

Morales-Becerril, Illan; Flores-Alamo, Marcos; Garcia, Juventino J

2013-04-01

In the crystal of the title compound, [Ni(CO3)(C14H32P2)], the metal center in each of three independent mol-ecules shows slight tetra-hedral distortion from ideal square-planar coordination geometry, with angles between the normals to the planes defined by the cis-P-Ni-P and cis-O-Ni-O fragments of 3.92 (17), 0.70 (16) and 2.17 (14)° in the three mol-ecules. In the crystal, there are inter-molecular C-H⋯O hydrogen bonds that show a laminar growth in the ab plane.

(Z)-N-[1-(Aziridin-1-yl)-2,2,2-tri­fluoro­ethyl­idene]-4-bromo­aniline

OpenAIRE

Bunev, Alexander S.; Vasiliev, Maksim A.; Ostapenko, Gennady I.; Peregudov, Alexander S.; Khrustalev, Victor N.

2014-01-01

The title compound, C10H8BrF3N2, crystallizes with two independent mol­ecules in the asymmetric unit, which can be considered as being related by a pseudo-inversion center, so their conformations are different; the corresponding N=C—N—C torsion angles are 54.6 (5) and −50.5 (5)°. In the crystal, mol­ecules related by translation in [001] inter­act through short inter­molecular Br⋯F contacts [3.276 (2) and 3.284 (2) Å], thus forming two types of crystallographically independent chains....

1,5-Bis[(E)-cyclo-pentyl-idene]thio-carbono-hydrazide.

Science.gov (United States)

Guo, Qingliang; Sun, Junshan; Li, Jikun; Wu, Rentao; Duan, Wenzeng

2009-03-25

In the title mol-ecule, C(11)H(18)N(4)S, an intra-molecular N-H⋯N hydrogen bond [N⋯N = 2.558 (3)Å] is observed. The two cyclo-pentyl rings are disordered between two conformations in 1:1 and 2:1 ratios. In the crystal structure, weak inter-molecular N-H⋯S hydrogen bonds [N⋯S = 3.547 (3) Å] link pairs of mol-ecules into centrosymmetric dimers.

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

Science.gov (United States)

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

2010-01-01

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

[1,2-Bis(diisopropyl­phosphan­yl)ethane-κ2 P,P′](carbonato-κ2 O,O′)nickel(II)

Science.gov (United States)

Morales-Becerril, Illan; Flores-Alamo, Marcos; Garcia, Juventino J.

2013-01-01

In the crystal of the title compound, [Ni(CO3)(C14H32P2)], the metal center in each of three independent mol­ecules shows slight tetra­hedral distortion from ideal square-planar coordination geometry, with angles between the normals to the planes defined by the cis-P—Ni—P and cis-O—Ni—O fragments of 3.92 (17), 0.70 (16) and 2.17 (14)° in the three mol­ecules. In the crystal, there are inter­molecular C—H⋯O hydrogen bonds that show a laminar growth in the ab plane. PMID:23633999

Stress-induced martensitic transformation and ferroelastic deformation adjacent microhardness indents in tetragonal zirconia single crystals

International Nuclear Information System (INIS)

Chien, F.R.; Ubic, F.J.; Prakash, V.; Heuer, A.H.

1998-01-01

The stress-induced tetragonal to monoclinic (t → m) martensitic transformation, stress-induced ferroelastic domain switching, and dislocation slip were induced by Vickers microindentation at elevated temperatures in polydomain single crystals of 3 mol%-Y 2 O 3 -stabilized tetragonal ZrO 2 single crystals (3Y-TZS). Chemical etching revealed traces along t directions adjacent to indentations, and Raman spectroscopy and TEM have shown that these traces are caused by products of the martensitic transformation, i.e. the monoclinic product phase forms primarily as thin, long plates with a habit plane approximately on (bar 301) m . This habit plane and the associated shear strain arising from the transformation, visible in TEM micrographs at the intersection of crystallographically equivalent martensite plates, were successfully predicted using the observed lattice correspondence and the phenomenological invariant plane strain theory of martensitic transformations. The extent of the martensitic transformation increased with increasing temperature from room temperature up to 300 C, but then decreased at higher temperatures. Ferroelastic deformation of tetragonal ZrO 2 has been observed at all temperatures up to 1,000 C. At the highest temperature, only ferroelastic domain switching and dislocation slip occurred during indentation-induced deformation

Crystal structure of bis­(3-bromo­pyridine-κN)bis­(O-ethyl di­thio­carbonato-κ2 S,S′)nickel(II)

Science.gov (United States)

Kant, Rajni; Kour, Gurvinder; Anthal, Sumati; Neerupama; Sachar, Renu

2015-01-01

In the title mol­ecular complex, [Ni(C3H5OS2)2(C5H4BrN)2], the Ni2+ cation is located on a centre of inversion and has a distorted octa­hedral N2S4 environment defined by two chelating xanthate ligands and two monodentate pyridine ligands. The C—S bond lengths of the thio­carboxyl­ate group are indicative of a delocalized bond and the O—Csp 2 bond is considerably shorter than the O—Csp 3 bond, consistent with a significant contribution of one resonance form of the xanthate anion that features a formal C=O+ unit and a negative charge on each of the S atoms. The packing of the mol­ecules is stabilized by C—H⋯S and C—H⋯π inter­actions. In addition, π–π inter­actions between the pyridine rings [centroid-to-centroid distance = 3.797 (3) Å] are also present. In the crystal structure, mol­ecules are arranged in rows along [100], forming layers parallel to (010) and (001). PMID:25705471

1,5-Bis[(E)-cyclo­pentyl­idene]thio­carbono­hydrazide

Science.gov (United States)

Guo, Qingliang; Sun, Junshan; Li, Jikun; Wu, Rentao; Duan, Wenzeng

2009-01-01

In the title mol­ecule, C11H18N4S, an intra­molecular N—H⋯N hydrogen bond [N⋯N = 2.558 (3)Å] is observed. The two cyclo­pentyl rings are disordered between two conformations in 1:1 and 2:1 ratios. In the crystal structure, weak inter­molecular N—H⋯S hydrogen bonds [N⋯S = 3.547 (3) Å] link pairs of mol­ecules into centrosymmetric dimers. PMID:21582539

A second monoclinic polymorph of 2-(3,5-dimethyl-1H-pyrazol-1-yl)-2-hy­droxy­imino-N′-[1-(pyridin-2-yl)ethyl­idene]acetohydrazide

Science.gov (United States)

Plutenko, Maxym O.; Lampeka, Rostislav D.; Haukka, Matti; Nordlander, Ebbe

2013-01-01

The title compound, C14H16N6O2, is a second monoclinic polymorph of 2-[1-(3,5-dimeth­yl)pyrazol­yl]-2-hy­droxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene] acetohydrazide, with two crystallographically independent mol­ecules per asymmetric unit. The non-planar mol­ecules are chemically equal having similar geometric parameters. The previously reported polymorph [Plutenko et al. (2012 ▶). Acta Cryst. E68, o3281] was described in space group Cc (Z = 4). The oxime group and the O atom of the amide group are anti with respect to the C—C bond. In the crystal, mol­ecules are connected by N—H⋯N hydrogen bonds into zigzag chains extending along the b axis. PMID:23723911

Crystal structure of 4-fluoro-N-[2-(4-fluoro­benzo­yl)hydra­zine-1-carbono­thio­yl]benzamide

Science.gov (United States)

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M.; Yusoff, Siti Fairus M.

2014-01-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro­benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro­benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl­thio­amide group and its attached ring is 12.98 (10)°. The major twists in the mol­ecule occur about the C—N—N—C bonds [torsion angle = −138.7 (2)°] and the Car—Car—C—N (ar = aromatic) bonds [−132.0 (2)°]. An intra­molecular N—H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol­ecules are linked by N—H⋯O and N—H⋯S hydrogen bonds, generating (001) sheets. Weak C—H⋯O and C—H⋯F inter­actions are also observed. PMID:25309250

The bent crystal diffraction spectrometer at the BR2 reactor in Mol

Science.gov (United States)

Kaerts, E.; Jacobs, L.; Vandenput, G.; Van Assche, P. H. M.

1988-05-01

The DuMond-type bent crystal diffraction spectrometer installed at the BR2 reactor in Mol is presented. The spectrometer is mainly designed to study nuclear γ-transitions following thermal neutron capture. It covers the energy interval 25 ≦ Eγ ≦ 1500 keV. Instead of the traditionally used quartz crystals, a highly perfect silicium crystal is chosen as analysing crystal. Diffraction occurs from the (220) plane. The "quasi-mosaic" width, introduced by bending the crystal, is as small as 0.2″. The integrated reflecting power R of the bent crystal stays constant up to 1.5 MeV in first, 680 keV in second and 300 keV in third diffraction order. For higher photon energies, only an E-1 energy dependence is observed in second and third diffraction order. Consequently, besides improving the energy resolution, the use of these silicium crystals substantially increases the spectrometer efficiency and extends the high energy limit of bent crystal diffraction spectrometers. The diffraction angles are measured with a symmetrical interferometer system which covers an angular range of -6° to +6° with a precision of about 0.01″. Minimum diffraction line widths of 0.9″ have been measured, corresponding to an energy resolution ΔE = 1.35 × 10 -6E2n-1 keV -1. The dominant contribution to the observed line widths arises from the finite extent of the source.

Poly[[diaqua-μ(6)-succinato-di-μ(5)-succinato-didysprosium(III)] mono-hydrate].

Science.gov (United States)

Xu, Wei; Chang, Hai-Sheng; Guo, Xia-Xia

2011-07-01

The title compound, {[Dy(2)(C(4)H(4)O(4))(3)(H(2)O)(2)]·H(2)O}(n), is isostructural with other lanthanide succinates of the same formula. The Dy(III) atom is nine-coordinated in a tricapped trigonal-prismatic environment by eight O atoms, derived from six carboxyl-ate groups and a water mol-ecule. One of the independent succinate anions is located about a crystallographic inversion center and the uncoordinated water mol-ecule lies on a twofold axis. The crystal structure comprises edge-shared DyO(9) polyhedra linked by succinate bridges, forming a three-dimensional network architecture. Intra- and inter-molecular O-H⋯O hydrogen bonds are present in the crystal structure.

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

Science.gov (United States)

Decato, Daniel A.; Berryman, Orion B.

2015-01-01

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

Crystal structure of μ-oxalodi-hydroxamato-bis-[(2,2'-bipyrid-yl)(di-methyl sulfoxide-κO)copper(II)] bis-(perchlorate).

Science.gov (United States)

Odarich, Irina A; Pavlishchuk, Anna V; Kalibabchuk, Valentina A; Haukka, Matti

2016-02-01

The centrosymmetric binuclear complex, [Cu2(C2H2N2O4)(C10H8N2)2(C2H6OS)2](ClO4)2, contains two copper(II) ions, connected through an N-deprotonated oxalodi-hydroxamic acid dianion, two terminal 2,2'-bi-pyridine ligands, and two apically coordinating dimethylsulfoxide mol-ecules. Two non-coordinating perchlorate anions assure electrical neutrality. The copper(II) ions in the complex dication [Cu2(C10H8N2)2(μ-C2H2N2O4)(C2H6SO)2](2+) are in an O2N3 square-pyramidal donor environment, the Cu-Cu separation being 5.2949 (4) Å. Two hydroxamate groups in the deprotonated oxalodi-hydroxamic acid are located trans to one each other. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds link the complex cations to the perchlorate anions. Further C-H⋯O hydrogen bonds combine with π-π contacts with a centroid-to-centroid separation of 3.6371 (12) Å to stack the mol-ecules along the a-axis direction.

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazo­cine-6,12-dione acetic acid hemisolvate

Science.gov (United States)

Abbassi, Najat; Bassou, Oulemda; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The mol­ecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11)°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12)°. In the crystal, the mol­ecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent mol­ecule by non-classical O—H⋯O and C—H⋯O hydrogen bonds. Two half-occupied acetic acid solvent mol­ecules are disordered at the same site and linked by a center of symmetry. PMID:23634138

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazo-cine-6,12-dione acetic acid hemisolvate.

Science.gov (United States)

Abbassi, Najat; Bassou, Oulemda; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-04-01

The mol-ecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11)°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12)°. In the crystal, the mol-ecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent mol-ecule by non-classical O-H⋯O and C-H⋯O hydrogen bonds. Two half-occupied acetic acid solvent mol-ecules are disordered at the same site and linked by a center of symmetry.

Poly[[diaqua-μ6-succinato-di-μ5-succinato-didysprosium(III)] mono­hydrate

Science.gov (United States)

Xu, Wei; Chang, Hai-Sheng; Guo, Xia-Xia

2011-01-01

The title compound, {[Dy2(C4H4O4)3(H2O)2]·H2O}n, is isostructural with other lanthanide succinates of the same formula. The DyIII atom is nine-coordinated in a tricapped trigonal–prismatic environment by eight O atoms, derived from six carboxyl­ate groups and a water mol­ecule. One of the independent succinate anions is located about a crystallographic inversion center and the uncoordinated water mol­ecule lies on a twofold axis. The crystal structure comprises edge-shared DyO9 polyhedra linked by succinate bridges, forming a three-dimensional network architecture. Intra- and inter­molecular O—H⋯O hydrogen bonds are present in the crystal structure. PMID:21836969

1-{3-[1-(Hydroxyimino)ethyl]-4-methyl-1H-pyrazol-5-yl}ethanone

Science.gov (United States)

Malinkin, Sergey; Penkova, Larysa; Pavlenko, Vadim A.; Haukka, Matti; Pavlova, Svetlana V.

2011-01-01

In the title compound, C8H11N3O2, the oxime and the acetyl groups adopt a transoid conformation, while the pyrazole H atom is localized in the proximity of the acetyl group and is cis with respect to the acetyl O atom. In the crystal, dimers are formed as the result of hydrogen-bonding inter­actions involving the pyrazole NH group of one mol­ecule and the carbonyl O atom of another. The dimers are associated into sheets via O—H⋯N hydrogen bonds involving the oxime hydroxyl and the unprotonated pyrazole N atom, generating a macrocyclic motif with six mol­ecules. PMID:22058770

Di-μ-cyanido-tetra-cyanido(5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate.

Science.gov (United States)

Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

2013-05-01

The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]·2.07H2O, contains one [Fe(qcq)(CN)3](-) anion, half a [Ni(teta)](2+) cation and two partially occupied inter-stitial water mol-ecules [qcq(-) is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne]. In the complex mol-ecule, two [Fe(qcq)(CN)3](-) anions additionally coordinate the central [Ni(teta)](2+) cation through cyanide groups in a trans mode, resulting in a trinuclear structure with the Ni(2+) cation lying on an inversion centre. The two inter-stitial water mol-ecules are partially occupied, with occupancy factors of 0.528 (10) and 0.506 (9). O-H⋯O and O-H⋯N hydrogen bonding involving the two lattice water molecules and the carbonyl function and a teta N atom in an adjacent cluster leads to the formation of layers extending parallel to (010).

Crystal structure of bis-[N-(2-hy-droxy-eth-yl)-N-methyl-dithio-carbamato-κ2S,S'](pyridine)-zinc(II) pyridine monosolvate and its N-ethyl analogue.

Science.gov (United States)

Poplaukhin, Pavel; Tiekink, Edward R T

2017-07-01

The common structural feature of the title compounds, [Zn(C 4 H 8 NOS 2 ) 2 (C 5 H 5 N)]·C 5 H 5 N (I) and [Zn(C 5 H 10 NOS 2 ) 2 (C 5 H 5 N)]·C 5 H 5 N (II), which differ by having di-thio-carbamate N-bound methyl (I) and ethyl (II) groups, is the coordination of each Zn II atom by two non-symmetrically chelating di-thio-carbamate ligands and by a pyridine ligand; in each case, the non-coordinating pyridine mol-ecule is connected to the Zn-containing mol-ecule via a (hy-droxy)O-H⋯N(pyridine) hydrogen bond. The resulting NS 4 coordination geometry is closer to a square-pyramid than a trigonal bipyramid in the case of (I), but almost inter-mediate between the two extremes in (II). The mol-ecular packing features (hy-droxy)O-H⋯O(hy-droxy) hydrogen bonds, leading to supra-molecular chains with a zigzag arrangement along [10-1] (I) or a helical arrangement along [010] (II). In (I), π-π [inter-centroid distances = 3.4738 (10) and 3.4848 (10) Å] between coordinating and non-coordinating pyridine mol-ecules lead to stacks comprising alternating rings along the a axis. In (II), weaker π-π contacts occur between centrosymmetrically related pairs of coordinating pyridine mol-ecules [inter-centroid separation = 3.9815 (14) Å]. Further inter-actions, including C-H⋯π(chelate) inter-actions in (I), lead to a three-dimensional architecture in each case.

Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

Science.gov (United States)

Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

2015-01-01

Single crystals of the title salt, Me2NH2 +·HC2O4 −·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di­methyl­ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 −), and half a mol­ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra­molecular point of view, the three components inter­act together via hydrogen bonding. The Me2NH2 + cations and the HC2O4 − anions are in close proximity through bifurcated N—H⋯(O,O) hydrogen bonds, while the HC2O4 − anions are organized into infinite chains via O—H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol­ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter­molecular inter­actions with two Me2NH2 + and two HC2O4 − ions of four distinct polymeric chains, via two N—H⋯O and two O—H⋯O hydrogen bonds, respectively. The resulting mol­ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C—H⋯O hydrogen bond. PMID:25995858

Crystal structure, solvothermal synthesis, thermogravimetric studies and DFT calculations of a five-coordinate cobalt(II) compound based on the N,N-bis-(2-hy-droxy-eth-yl)glycine anion.

Science.gov (United States)

Zhou, Yanling; Liu, Xianrong; Wang, Qijun; Wang, Lisheng; Song, Baoling

2016-10-01

The reaction of CoCl 2 ·6H 2 O, N , N -bis-(2-hy-droxy-eth-yl)glycine and tri-ethyl-amine (Et 3 N) in ethanol solution under solvothermal conditions produced crystals of [ N , N -bis-(2-hy-droxy-eth-yl)glycinato]chloridocobalt(II), [Co(C 6 H 12 NO 4 )Cl]. The Co II ion is coordinated in a slightly distorted trigonal-bipyramidal environment which is defined by three O atoms occupying the equatorial plane and the N and Cl atoms in the apical sites. In the crystal, two types of O-H⋯O hydrogen bonds connect the mol-ecules, forming a two-dimensional network parallel to (001). The mol-ecular structure of the title compound confirms the findings of FTIR, elemental analysis, ESI-MS analysis and TG analysis. By using the density functional theory (DFT) (B3LYP) method with 6-31G(d) basis set, the molecular structure has been calculated and optimized.

Crystal structure of bis-[(acetato-κO)(imidazolidine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-μ-imidazol-idine-2-thione-κ(4) S:S-bis-[(imidazol-id-ine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-acetate aceto-nitrile disolvate tetra-hydrate.

Science.gov (United States)

Nimthong-Roldán, Arunpatcha; Ratthiwan, Janejira; Lakmas, Sawanya; Wattanakanjana, Yupa

2016-04-01

In the title compound, [Ag2(C3H6N2S)4(C18H15P)2](C2H3O2)2·[Ag(C2H3O2)(C3H6N2S)(C18H15P)2]2·2C2H3N·4H2O, the Ag(I) ion in the mononuclear neutral complex exhibits a distorted tetra-hedral environment with coordination by two P atoms from tri-phenyl-phosphane (PPh3) ligands, one S atom of an imidazolidine-2-thione (etu) ligand and one O atom of an acetate anion. The binuclear cationic complex comprises two inversion-related [Ag(C3H6N2S)2(C18H15P)] units with Ag(I) ions bridged by two S atoms from etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag(I) ion is coordinated by a P atom of a PPh3 ligand, two S atoms of bridging etu ligands and the terminal S atom of an etu ligand in a distorted tetra-hedral environment. In the crystal, the mononuclear complex is linked to lattice water mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a chain along [100]. In addition, the binuclear complex mol-ecules are connected to acetate anions and lattice water mol-ecules via O-H⋯O, N-H⋯O and O-H⋯S hydrogen bonds, also along [100].

A monoclinic polymorph of (1E,5E)-1,5-bis-(2-hy-droxy-benzyl-idene)thio-carbono-hydrazide.

Science.gov (United States)

Schmitt, Bonell; Gerber, Thomas; Hosten, Eric; Betz, Richard

2011-08-01

The title compound, C(15)H(14)N(4)O(2)S, is a derivative of thio-ureadihydrazide. In contrast to the previously reported polymorph (ortho-rhom-bic, space group Pbca, Z = 8), the current study revealed monoclinic symmetry (space group P2(1)/n, Z = 4). The mol-ecule shows non-crystallographic C(2) as well as approximate C(s) symmetry. Intra-molecular bifurcated O-H⋯(N,S) hydrogen bonds, are present. In the crystal, inter-molecular N-H⋯S hydrogen bonds and C-H⋯π contacts connect the mol-ecules into undulating chains along the b axis. The shortest centroid-centroid distance between two aromatic systems is 4.5285 (12) Å.

Crystal structure of di?methyl?ammonium hydrogen oxalate hemi(oxalic acid)

OpenAIRE

Diallo, Waly; Gueye, Ndongo; Crochet, Aur?lien; Plasseraud, Laurent; Cattey, H?l?ne

2015-01-01

Single crystals of the title salt, Me2NH2 +?HC2O4 ??0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di?methyl?ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 ?), and half a mol?ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra?molecular point of view, the t...

4′,5-Dihy­droxy-7-meth­oxy­flavanone dihydrate

Science.gov (United States)

Brito, Iván; Bórquez, Jorge; Simirgiotis, Mario; Cárdenas, Alejandro; López-Rodríguez, Matías

2012-01-01

The title compound, C16H14O5·2H2O [systematic name: 5-hy­droxy-2-(4-hy­droxy­phen­yl)-7-meth­oxy­chroman-4-one dihydrate], is a natural phytoalexin flavone isolated from the native chilean species Heliotropium taltalense and crystallizes with an organic mol­ecule and two water mol­ecules in the asymmetric unit. The 5-hy­droxy group forms a strong intra­molecular hydrogen bond with the carbonyl group, resulting in a six-membered ring. In the crystal, the components are linked by O—H⋯O hydrogen bonds, forming a three-dimensional network. The 4-hy­droxy­phenyl benzene ring is bonded equatorially to the pyrone ring, which adopts a slightly distorted sofa conformation. The title compound is the hydrated form of a previously reported structure [Shoja (1990 ▶). Acta Cryst. C46, 1969–1971]. There are only slight variations in the mol­ecular geometry between the two compounds. PMID:22259537

Di-μ-cyanido-tetra­cyanido(5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate

Science.gov (United States)

Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

2013-01-01

The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]·2.07H2O, contains one [Fe(qcq)(CN)3]− anion, half a [Ni(teta)]2+ cation and two partially occupied inter­stitial water mol­ecules [qcq− is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­deca­ne]. In the complex mol­ecule, two [Fe(qcq)(CN)3]− anions additionally coordinate the central [Ni(teta)]2+ cation through cyanide groups in a trans mode, resulting in a trinuclear structure with the Ni2+ cation lying on an inversion centre. The two inter­stitial water mol­ecules are partially occupied, with occupancy factors of 0.528 (10) and 0.506 (9). O—H⋯O and O—H⋯N hydrogen bonding involving the two lattice water molecules and the carbonyl function and a teta N atom in an adjacent cluster leads to the formation of layers extending parallel to (010). PMID:23723777

Bis{2-hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propanohydrazidato}zinc(II) dihydrate

Science.gov (United States)

Moroz, Yurii S.; Znovjyak, Kateryna O; Golenya, Iryna O.; Pavlova, Svetlana V.; Haukka, Matti

2010-01-01

The title compound, [Zn(C10H11N4O2)2]·2H2O, was prepared by the reaction between Zn(CH3COO)2·2H2O and 2-hydroxy­imino-N′-[1-(2-pyrid­yl)ethyl­idene]propano­hydrazide (Hpop). The central ZnII atom has a distorted tetra­gonal-bipyramidal coordination geometry formed by two amide O atoms and four N atoms of two azomethine and two pyridine groups. In the crystal, complex mol­ecules form layers parallel to the crystallographic b direction. The layers are connected by O—H⋯N and O—H⋯O hydrogen bonds involving the solvent water mol­ecules. PMID:21579695

A monoclinic polymorph of (1E,5E)-1,5-bis­(2-hy­droxy­benzyl­idene)thio­carbono­hydrazide

Science.gov (United States)

Schmitt, Bonell; Gerber, Thomas; Hosten, Eric; Betz, Richard

2011-01-01

The title compound, C15H14N4O2S, is a derivative of thio­ureadihydrazide. In contrast to the previously reported polymorph (ortho­rhom­bic, space group Pbca, Z = 8), the current study revealed monoclinic symmetry (space group P21/n, Z = 4). The mol­ecule shows non-crystallographic C 2 as well as approximate C s symmetry. Intra­molecular bifurcated O—H⋯(N,S) hydrogen bonds, are present. In the crystal, inter­molecular N—H⋯S hydrogen bonds and C—H⋯π contacts connect the mol­ecules into undulating chains along the b axis. The shortest centroid–centroid distance between two aromatic systems is 4.5285 (12) Å. PMID:22091213

Pseudosymmetric fac-di-aqua-trichlorido[(di-methyl-phosphor-yl)methanaminium-κO]manganese(II).

Science.gov (United States)

Reiss, Guido J

2013-05-01

In the title compound, [Mn(C3H11NOP)Cl3(H2O)2], the Mn(II) metal center has a distorted o-cta-hedral geometry, coordinated by the three chloride ligands showing a facial arrangement. Two water mol-ecules and the O-coordinated dpmaH cation [dpmaH = (di-methyl-phosphor-yl)methanaminium] complete the coordination sphere. Each complex mol-ecule is connected to its neighbours by O-H⋯Cl and N-H⋯Cl hydrogen bonds. Two of the chloride ligands and the two water ligands form a hydrogen-bonded polymeric sheet in the ab plane. Furthermore, these planes are connected to adjacent planes by hydrogen bonds from the aminium function of cationic dpmaH ligand. A pseudo-mirror plane perpendicular to the b axis in the chiral space group P21 is observed together with inversion twinning [ratio = 0.864 (5):0.136 (5)].

Crystallization kinetics and growth mechanism of 8 mol% yttria-stabilized zirconia (8YSZ) nano-powders prepared by a sol-gel process

International Nuclear Information System (INIS)

Kuo, C.-W.; Lee, Y.-H.; Hung, I-M.; Wang, M.-C.; Wen, S.-B.; Fung, K.-Z.; Shih, C.-J.

2008-01-01

Eight mol% yttria-stabilized zirconia (8YSZ) gel powders were synthesized at 348 K for 2 h using ZrOCl 2 .8H 2 O and Y(NO 3 ) 3 .6H 2 O as starting materials in an ethanol-water solution by a sol-gel process. The crystallization kinetics and growth mechanism of the 8YSZ gel powders have been investigated using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The XRD results and SAED pattern show that the 8YSZ gel powders calcined at 773 K for 2 h is a cubic ZrO 2 . The activation energy for the crystallization of the cubic ZrO 2 formation in the 8YSZ gel powders is determined as 231.76 kJ/mol by a non-isothermal DTA method. Both growth morphology parameter (n) and crystallization mechanism index (m) are close to 3.0, indicating that the bulk nucleation is dominant in the cubic ZrO 2 formation. The TEM examination shows that the cubic ZrO 2 has a spherical-like morphology with a size ranging from 10 to 20 nm

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae).

Science.gov (United States)

Zheoat, Ahmed M; Gray, Alexander I; Igoli, John O; Kennedy, Alan R; Ferro, Valerie A

2017-09-01

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carb-oxy-lic acid dimethyl sulfoxide monosolvate], C 6 H 6 O 7 ·C 2 H 6 OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carboxyl-ate], C 8 H 10 O 7 , (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent mol-ecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar mol-ecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.

N′-(2-Hy­droxy­benzyl­idene)-2-(hy­droxy­imino)­propano­hydrazide

Science.gov (United States)

Plutenko, Maxym O.; Lampeka, Rostyslav D.; Moroz, Yurii S.; Haukka, Matti; Pavlova, Svetlana V.

2011-01-01

The mol­ecule of the title compound, C10H11N3O3, adopts an all-trans conformation and is approxomately planar, the largest deviation from the least-squares plane through all non-H atoms being 0.261 (1) Å. An intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, the mol­ecules are packed into layers lying parallel to the ab plane by π-stacking inter­actions between the benzene ring of one molecule and the C—N bond of the oxime group of another molecule; the shortest inter­molecular C⋯C separation within the layer is 3.412 (1) Å. The layers are connected by O—H⋯O and N—H⋯O hydrogen bonds. PMID:22199788

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

Science.gov (United States)

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

2017-01-01

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

Crystallization kinetics and growth mechanism of 8 mol% yttria-stabilized zirconia (8YSZ) nano-powders prepared by a sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Kuo, C.-W. [Department of Resources Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Lee, Y.-H. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hung, I-M. [Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Far-East Road, Chung-Li, Taoyuan, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Wen, S.-B. [Department of Resources Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Fung, K.-Z. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Shih, C.-J. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: cjshih@kmu.edu.tw

2008-04-03

Eight mol% yttria-stabilized zirconia (8YSZ) gel powders were synthesized at 348 K for 2 h using ZrOCl{sub 2}.8H{sub 2}O and Y(NO{sub 3}){sub 3}.6H{sub 2}O as starting materials in an ethanol-water solution by a sol-gel process. The crystallization kinetics and growth mechanism of the 8YSZ gel powders have been investigated using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The XRD results and SAED pattern show that the 8YSZ gel powders calcined at 773 K for 2 h is a cubic ZrO{sub 2}. The activation energy for the crystallization of the cubic ZrO{sub 2} formation in the 8YSZ gel powders is determined as 231.76 kJ/mol by a non-isothermal DTA method. Both growth morphology parameter (n) and crystallization mechanism index (m) are close to 3.0, indicating that the bulk nucleation is dominant in the cubic ZrO{sub 2} formation. The TEM examination shows that the cubic ZrO{sub 2} has a spherical-like morphology with a size ranging from 10 to 20 nm.

2-[Anilino(phen-yl)meth-yl]cyclo-heptan-one.

Science.gov (United States)

Eftekhari-Sis, Bagher; Mohajer, Sahar; Zirak, Maryam; Mozaffarnia, Sakineh; Büyükgüngör, Orhan

2013-01-01

In the title compound, C20H23NO, the cyclo-hepta-none ring adopts a twist-chair conformation, with the amino-methyl substituent in an equatorial position. The relative configuration of the two stereocenters is R,R. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds into chains along [100].

Pseudosymmetric fac-di­aqua­trichlorido[(di­methyl­phosphor­yl)methanaminium-κO]manganese(II)

Science.gov (United States)

Reiss, Guido J.

2013-01-01

In the title compound, [Mn(C3H11NOP)Cl3(H2O)2], the MnII metal center has a distorted o­cta­hedral geometry, coordinated by the three chloride ligands showing a facial arrangement. Two water mol­ecules and the O-coordinated dpmaH cation [dpmaH = (di­methyl­phosphor­yl)methanaminium] complete the coordination sphere. Each complex mol­ecule is connected to its neighbours by O—H⋯Cl and N—H⋯Cl hydrogen bonds. Two of the chloride ligands and the two water ligands form a hydrogen-bonded polymeric sheet in the ab plane. Furthermore, these planes are connected to adjacent planes by hydrogen bonds from the aminium function of cationic dpmaH ligand. A pseudo-mirror plane perpendicular to the b axis in the chiral space group P21 is observed together with inversion twinning [ratio = 0.864 (5):0.136 (5)]. PMID:23723764

Tris[(6S)-6-hy-droxy-4-epi-shikimic acid] monohydrate: an enanti-omerically pure hy-droxy-lated shikimic acid derived from methyl shikimate.

Science.gov (United States)

Griesbeck, Axel G; Miara, Claus; Neudörfl, Jörg-M

2012-11-01

The title compound, 3C(7)H(10)O(6)·H(2)O, is the enanti-omerically pure product of a multi-step synthesis from the enanti-omerically pure natural shikimic acid. The asymmetric unit contains three mol-ecules of the acid and one mol-ecule of water. The cyclo-hexene rings of the acids have half-chair conformations. The carboxyl-ate, the four hydroxide groups and the additional water mol-ecule form a complex three-dimensional hydrogen-bonding network.

1,2-Diiodo-4,5-dimethyl­benzene

Science.gov (United States)

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

2009-01-01

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

(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.

Crystal structure of trans-di-chloridobis-[N-(5,5-di-methyl-4,5-di-hydro-3H-pyrrol-2-yl-κN)acetamide]palladium(II) dihydrate.

Science.gov (United States)

Lasri, Jamal; Eltayeb, Naser Eltaher; Haukka, Matti; Babgi, Bandar A

2017-04-01

The title complex, [PdCl 2 (C 8 H 14 N 2 O) 2 ]·2H 2 O, was obtained by N-O bond cleavage of the oxa-diazo-line rings of the trans -[di-chlorido-bis-(2,5,5-trimethyl-5,6,7,7a-tetra-hydro-pyrrolo-[1,2- b ][1,2,4]oxa-diazole- N 1 )]palladium(II) complex. The palladium(II) atom exhibits an almost square-planar coordination provided by two trans -arranged chloride anions and a nitro-gen atom from each of the two neutral organic ligands. In the crystal, N-H⋯O, O-H⋯O and O-H⋯Cl hydrogen bonds link complex mol-ecules into double layers parallel to the bc plane.

Crystal structure of obscurine: a natural product isolated from the stem bark of B. obscura.

Science.gov (United States)

Lenta, Bruno N; Chouna, Rodolphe J; Neumann, Beate; Stammler, Hans-Georg; Sewald, Norbert

2015-07-01

The title compound, C24H31NO3 {systematic name: (E)-3-[(1R*,2S*,4aS*,8aR*)-2-(benzo[d][1,3]dioxol-5-yl)-1,2,4a,5,6,7,8,8a-octa-hydro-naphthalen-1-yl]-N-iso-butyl-acryl-amide}, is a natural product isolated from the stem bark of B. obscura. It is composed of an octa-hydro-naphthalene ring system substituted with an essentially planar benzodioxole ring system [r.m.s. deviation = 0.012 Å] and an extended iso-butyl-acryl-amide group. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains propagating along [100]. The chains are linked by pairs of C-H⋯O hydrogen bonds, involving inversion-related benzodioxole ring systems, forming ribbons lying parallel to (010). There are also C-H⋯π inter-actions present within the ribbons.

2-[Anilino(phen­yl)meth­yl]cyclo­heptan­one

Science.gov (United States)

Eftekhari-Sis, Bagher; Mohajer, Sahar; Zirak, Maryam; Mozaffarnia, Sakineh; Büyükgüngör, Orhan

2013-01-01

In the title compound, C20H23NO, the cyclo­hepta­none ring adopts a twist-chair conformation, with the amino­methyl substituent in an equatorial position. The relative configuration of the two stereocenters is R,R. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds into chains along [100]. PMID:23476371

(2E)-3-[4-(Benz-yloxy)phen-yl]-1-(2,6-dichloro-3-fluoro-phen-yl)prop-2-en-1-one.

Science.gov (United States)

Praveen, Aletti S; Yathirajan, Hemmige S; Gerber, Thomas; van Brecht, Benjamin; Betz, Richard

2012-12-01

In the title compound, C22H15Cl2FO2, a chalcone derivative featuring a threefold-halogenated aromatic substituent, the conformation about the C=C bond is E. In the crystal C-H⋯F and C-H⋯Cl contacts connect the mol-ecules into undulating sheets parallel to (101). In addition, C-H⋯π inter-actions are also present.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Hsu, Yu-Wei [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yang, Ko-Ho, E-mail: yangkoho@cc.kuas.edu.tw [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Dental Materials Research Center, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yeh, Sung-Wei [Metal Industries Research and Development Centre, 1001 Kaohsiung Highway, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100, Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)

2011-06-16

Highlights: > The thermal behavior of 3Y-TZP precursor powders had been investigated. > The crystallization behavior of 3Y-TZP nanopowders had been investigated. > The activation energy for crystallization of tetragonal ZrO{sub 2} was obtained. > The growth morphology parameter n is approximated as 2.0. > The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO{sub 2} crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 {+-} 21.9 kJ mol{sup -1}, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO{sub 2} was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

International Nuclear Information System (INIS)

Hsu, Yu-Wei; Yang, Ko-Ho; Chang, Kuo-Ming; Yeh, Sung-Wei; Wang, Moo-Chin

2011-01-01

Highlights: → The thermal behavior of 3Y-TZP precursor powders had been investigated. → The crystallization behavior of 3Y-TZP nanopowders had been investigated. → The activation energy for crystallization of tetragonal ZrO 2 was obtained. → The growth morphology parameter n is approximated as 2.0. → The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO 2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol -1 , was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO 2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Tris[(6S)-6-hy­droxy-4-epi-shikimic acid] monohydrate: an enanti­omerically pure hy­droxy­lated shikimic acid derived from methyl shikimate

Science.gov (United States)

Griesbeck, Axel G.; Miara, Claus; Neudörfl, Jörg-M.

2012-01-01

The title compound, 3C7H10O6·H2O, is the enanti­omerically pure product of a multi-step synthesis from the enanti­omerically pure natural shikimic acid. The asymmetric unit contains three mol­ecules of the acid and one mol­ecule of water. The cyclo­hexene rings of the acids have half-chair conformations. The carboxyl­ate, the four hydroxide groups and the additional water mol­ecule form a complex three-dimensional hydrogen-bonding network. PMID:23284468

2'-Fluoro-3',5'-dimethoxy-acetanilide.

Science.gov (United States)

Xie, Kai; Lou, Yuan-Yuan; Zheng, Jin; Zhao, Qing-Jie; Wei, Ya-Bing

2008-12-24

Mol-ecules of the title compound, C(10)H(12)FNO(3), are nearly planar considering all non-H atoms with a mean deviation of 0.0288 Å. Mol-ecules are linked through inter-molecular N-H⋯O and N-H⋯F hydrogen bonds.

Structure and optical homogeneity of LiNbO3:Zn (0.03–4.5 mol.%) crystals

International Nuclear Information System (INIS)

Sidorov, Nikolay; Tepljakova, Natalja; Gabain, Aleksei; Yanichev, Aleksander; Palatnikov, Mikhail

2014-01-01

Structure and optical homogeneity of LiNbO 3 :Zn (0.03–4.5 mol.%) crystals were searched by photoinduced light scattering and by Raman spectroscopy. The photorefractive effect depends on Zn 2+ concentration nonmonotonically. Decrease of photorefractive effect is explained by decrease of structure defects with localized electrons. The Zn 2+ cations replace structure defects Nb Li and Li Nb , trapping levels appear near the bottom of the conduction band and photo electrons recombine with emission under laser radiation. By the Raman spectra the area of the high structure order is found. In this area the own alternation, the alternation of impurity cations and the vacancies along the polar axis is almost perfect

(Carbonato-κ2 O,O′)bis­(5,5′-dimethyl-2,2′-bipyridyl-κ2 N,N′)cobalt(III) bromide trihydrate

Science.gov (United States)

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

2012-01-01

In the title complex, [Co(CO3)(C12H12N2)2]Br·3H2O, the CoIII cation has a distorted octa­hedral 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 mol­ecules 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 inter­actions between adjacent pyridine rings of the dmbpy ligands, with centroid–centroid distances of 3.694 (3) and 3.7053 (3) Å. PMID:22589773

Mol 7C/6; Mol 7C/6

Energy Technology Data Exchange (ETDEWEB)

Aberle, J.; Schleisiek, K.; Schmuck, I.; Schmidt, L.; Romer, O.; Weih, G.

1995-08-01

The Mol 7C/6 coolant blockage experiment in the Belgian BR2 reactor yielded results different from Mol 7C experiments with low burnup pins: At 10% burnup local failure is not self-limiting, but requires active systems for detection and scram. The Mol 7C series was finished in 1991. In each of the test bundles Mol 7C/4, /5 and /6, 30 Mk I pins pre-irradiated in KNK II were used. The central blockage consisted of enriched UO{sub 2} covering 30 percent of the bundle cross-section, with a height of 40 mm. The most important system for timely detection of coolant blockages of the type studied in Mol 7C/6 is based on DND. (orig.)

cis-Tetra­chloridobis(1H-imidazole-κN 3)platinum(IV)

Science.gov (United States)

Bokach, Nadezhda A.; Kukushkin, Vadim Yu.; Izotova, Yulia A.; Usenko, Natalia I.; Haukka, Matti

2012-01-01

In the title complex, cis-[PtCl4(C3H4N2)2], the PtIV ion lies on a twofold rotation axis and is coordinated in a slightly distorted octa­hedral geometry. The dihedral angle between the imidazole rings is 69.9 (2)°. In the crystal, mol­ecules are linked by N—H⋯Cl hydrogen bonds, forming a three-dimensional network. PMID:22590070

Di-tert-butyl-bis(N-isopropyl-N-methyl-dithio-carbamato-κS,S')tin(IV).

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Samsudin, Mohd Wahid; Ng, Seik Weng

2010-03-03

The dithio-carbamate anions in the title compound, [Sn(C(4)H(9))(2)(C(5)H(10)NS(2))(2)], chelate to the Sn(IV) atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol-ecule lies across a twofold rotation axis. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.82 (1):0.18 (1).

cis-Aquabis(2,2'-bipyridine-κ2N,N')-fluoridochromium(III) bis(perchlorate) dihydrate

DEFF Research Database (Denmark)

Birk, Torben; Bendix, Jesper

2010-01-01

The title mixed aqua-fluoride complex, [CrF(C(10)H(8)N(2))(2)(H(2)O)](ClO(4))(2)·2H(2)O, has been synthesized by aqua-tion of the corresponding difluoride complex using lanthan-ide(III) ions as F(-) acceptors. The complex crystallizes with a Cr(III) ion at the center of a distorted octa-hedral co......-hedral coordination polyhedron with a cis arrangement of ligands. The crystal packing shows a hydrogen-bonding pattern involving water mol-ecules, the coordinated F atom and the perchlorate anions....

Crystal structures of 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(naphthalen-1-yl)acetamide and 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(4-fluoro-phen-yl)acetamide.

Science.gov (United States)

Subasri, S; Kumar, Timiri Ajay; Sinha, Barij Nayan; Jayaprakash, Venkatesan; Viswanathan, Vijayan; Velmurugan, Devadasan

2017-02-01

The title compounds, C 16 H 15 N 5 OS, (I), and C 12 H 12 FN 5 OS, (II), are [(di-amino-pyrimidine)-sulfan-yl]acetamide derivatives. In (I), the pyrimidine ring is inclined to the naphthalene ring system by 55.5 (1)°, while in (II), the pyrimidine ring is inclined to the benzene ring by 58.93 (8)°. In (II), there is an intra-molecular N-H⋯N hydrogen bond and a short C-H⋯O contact. In the crystals of (I) and (II), mol-ecules are linked by pairs of N-H⋯N hydrogen bonds, forming inversion dimers with R 2 2 (8) ring motifs. In the crystal of (I), the dimers are linked by bifurcated N-H⋯(O,O) and C-H⋯O hydrogen bonds, forming layers parallel to (100). In the crystal of (II), the dimers are linked by N-H⋯O hydrogen bonds, also forming layers parallel to (100). The layers are linked by C-H⋯F hydrogen bonds, forming a three-dimensional architecture.

Tris(2,2′-bipyridine-κ2 N,N′)cobalt(III) bis­[bis­(pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)cobaltate(III)] perchlorate dimethyl­formamide hemisolvate 1.3-hydrate

Science.gov (United States)

Golenya, Irina A.; Boyko, Alexander N.; Kotova, Natalia V.; Haukka, Matti; Iskenderov, Turganbay S.

2012-01-01

In the title compound, [Co(C10H8N2)3][Co(C7H3NO4)2]2(ClO4)·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudoocta­hedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxyl­ate O atoms of two doubly deprotonated pyridine-2,6-dicarboxyl­ate ligands in a distorted octa­hedral geometry. One dimethyl­formamide solvent mol­ecule and two water mol­ecules are half-occupied and one water mol­ecule is 0.3-occupied. O—H⋯O hydrogen bonds link the water mol­ecules, the perchlorate anions and the complex anions. π–π inter­actions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3) Å]. PMID:23125573

MolProbity: all-atom structure validation for macromolecular crystallography

International Nuclear Information System (INIS)

Chen, Vincent B.; Arendall, W. Bryan III; Headd, Jeffrey J.; Keedy, Daniel A.; Immormino, Robert M.; Kapral, Gary J.; Murray, Laura W.; Richardson, Jane S.; Richardson, David C.

2010-01-01

MolProbity structure validation will diagnose most local errors in macromolecular crystal structures and help to guide their correction. MolProbity is a structure-validation web service that provides broad-spectrum solidly based evaluation of model quality at both the global and local levels for both proteins and nucleic acids. It relies heavily on the power and sensitivity provided by optimized hydrogen placement and all-atom contact analysis, complemented by updated versions of covalent-geometry and torsion-angle criteria. Some of the local corrections can be performed automatically in MolProbity and all of the diagnostics are presented in chart and graphical forms that help guide manual rebuilding. X-ray crystallography provides a wealth of biologically important molecular data in the form of atomic three-dimensional structures of proteins, nucleic acids and increasingly large complexes in multiple forms and states. Advances in automation, in everything from crystallization to data collection to phasing to model building to refinement, have made solving a structure using crystallography easier than ever. However, despite these improvements, local errors that can affect biological interpretation are widespread at low resolution and even high-resolution structures nearly all contain at least a few local errors such as Ramachandran outliers, flipped branched protein side chains and incorrect sugar puckers. It is critical both for the crystallographer and for the end user that there are easy and reliable methods to diagnose and correct these sorts of errors in structures. MolProbity is the authors’ contribution to helping solve this problem and this article reviews its general capabilities, reports on recent enhancements and usage, and presents evidence that the resulting improvements are now beneficially affecting the global database

4-[(1E)-3-(2,6-Dichloro-3-fluoro-phen-yl)-3-oxoprop-1-en-1-yl]benzonitrile.

Science.gov (United States)

Praveen, Aletti S; Yathirajan, Hemmige S; Narayana, Badiadka; Gerber, Thomas; Hosten, Eric; Betz, Richard

2012-05-01

In the title mol-ecule, C(16)H(8)Cl(2)FNO, the benzene rings form a dihedral angle of 78.69 (8)°. The F atom is disordered over two positions in a 0.530 (3):0.470 (3) ratio. The crystal packing exhibits π-π inter-actions between dichloro-substituted rings [centroid-centroid distance = 3.6671 (10) Å] and weak inter-molecular C-H⋯F contacts.

Di-tert-butyl­bis(N-isopropyl-N-methyl­dithio­carbamato-κ2 S,S′)tin(IV)

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Samsudin, Mohd Wahid; Ng, Seik Weng

2010-01-01

The dithio­carbamate anions in the title compound, [Sn(C4H9)2(C5H10NS2)2], chelate to the SnIV atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol­ecule lies across a twofold rotation axis. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.82 (1):0.18 (1). PMID:21580471

Thio-phene-2-carbonyl azide.

Science.gov (United States)

Hsu, Gene C; Singer, Laci M; Cordes, David B; Findlater, Michael

2013-01-01

The title compound, C5H3N3OS, is almost planar (r.m.s. deviation for the ten non-H atoms = 0.018 Å) and forms an extended layer structure in the (100) plane, held together via hydrogen-bonding inter-actions between adjacent mol-ecules. Of particular note is the occurrence of RC-H⋯N(-)=N(+)=NR inter-actions between an aromatic C-H group and an azide moiety which, in conjunction with a complementary C-H⋯O=C inter-action, forms a nine-membered ring.

μ-Hexa-thio-metadiphosphato-bis-[(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ(6) O)rubidium] aceto-nitrile disolvate.

Science.gov (United States)

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-12-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto-nitrile solvent mol-ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb(+) ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6](2-) moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6](2-) anion. The hexa-thio-metadiphosphate anion is built up from two tetra-hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto-nitrile solvent mol-ecules stacked along [010].

Anatomia foliar de Maytenus Mol. emend Mol. (Celastraceae, ocorrente no Estado do Rio de Janeiro, Brasil Leaf anatomy of the Maytenus Mol. emend Mol. (Celastraceae in Rio de Janeiro State, Brazil

Directory of Open Access Journals (Sweden)

Ana Joffily

2005-09-01

Full Text Available Este trabalho aborda o estudo anatômico de cinco espécies do gênero Maytenus Mol. emend. Mol. (Celastraceae. O gênero é o maior da família, e está representado no Brasil por aproximadamente 80 espécies. Maytenus é um gênero polifilético, necessitando de trabalhos adicionais para nova circunscrição. Maytenus ardisiaefolia Reiss., M. brasiliensis Mart., M. cestrifolia Reiss., M. communis Reiss. e M. obtusifolia Mart. são de difícil identificação, devido à semelhança dos verticilos reprodutivos, e pela variação na forma e no tamanho das folhas. As estruturas anatômicas observadas nas diversas partes da folha mostraram-se muito semelhantes nas espécies estudadas, sendo de valor taxonômico e de provável importância filogenética para o gênero Maytenus. A organização da epiderme e estratos subepidérmicos em M. obtusifolia demonstrou ser caráter diagnóstico importante na comparação com M. ardisiaefolia, e a ocorrência de cristais aciculares nas células epidérmicas de M. communis e de M. ardisiaefolia, que as separam de M. cestrifolia, que não apresenta cristais, apontaram a anatomia como importante ferramenta a ser explorada nos estudos taxonômicos das demais espécies do gênero. A observação e descrição das verrugas suberosas na epiderme da lâmina foliar poderá contribuir para a taxonomia das Celastraceae.This paper describes anatomical approaches to study the Genus Maytenus Mol. Emnd. Mol. (Celastraceae. The genus is the largest in the family Celastraceae, and in Brazil is represented by approximately 80 species. Maytenus is a polyphyletic genus and additional research is required to better understand its taxonomy. Maytenus ardisiaefolia Reiss., M. brasiliensis Mart., M. cestrifolia Reiss., M. communis Reiss. and M. obtusifolia Mart. are difficult to identify because of similarities in their reproductive structures and variations in the size and shape of their leaves. The anatomical structures observed

1-(3-Cyano­phen­yl)-3-(2-furo­yl)thio­urea

Science.gov (United States)

Theodoro, Jahyr E.; Mascarenhas, Yvonne; Ellena, Javier; Estévez-Hernández, Osvaldo; Duque, Julio

2008-01-01

The title compound, C13H9N3O2S, was synthesized from furoyl isothio­cyanate and 3-amino­benzonitrile in dry acetone. The thio­urea group is in the thio­amide form. The thio­urea fragment makes dihedral angles of 3.91 (16) and 37.83 (12)° with the ketofuran group and the benzene ring, respectively. The mol­ecular geometry is stabilized by N—H⋯O hydrogen bonds. In the crystal structure, centrosymmetrically related mol­ecules are linked by two inter­molecular N—H⋯S hydrogen bonds to form dimers. PMID:21202835

1-(4-Methyl­phenyl­sulfon­yl)-5,6-di­nitro-1H-indazole

Science.gov (United States)

Oulemda, Bassou; Rakib, El Mostapha; Abbassi, Najat; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

In the title compound, C14H10N4O6S, the indazole ring system is almost perpendicular to the tosyl ring, as indicated by the dihedral angle of 89.40 (9)° between their planes. The dihedral angles between the indazole system and the nitro groups are 57.0 (3) and 31.9 (3)°. In the crystal, mol­ecules are linked by C—H⋯O inter­actions, forming chains running along [100]. PMID:24526962

Effect of ion nitriding on the crystal structure of 3 mol% Y2O3-doped ZrO2 thin-films prepared by the sol-gel method

International Nuclear Information System (INIS)

Ortiz, A.L.; Diaz-Parralejo, A.; Borrero-Lopez, O.; Guiberteau, F.

2006-01-01

We investigated the effect of ion nitriding on the crystal structure of 3 mol% Y 2 O 3 -doped ZrO 2 (3YSZ) thin-films prepared by the sol-gel method. For this purpose, we used X-ray diffractometry to determine the crystalline phases, the lattice parameters, the crystal sizes, and the lattice microstrains, and glow discharge-optical emission spectroscopy to obtain the depth profiles of the elemental chemical composition. We found that nitrogen atoms substitute oxygen atoms in the 3YSZ crystal, thus leading to the formation of unsaturated-substitutional solid solutions with reduced lattice parameters and Zr 0.94 Y 0.06 O 1.72 N 0.17 stoichiometric formula. We also found that ion nitriding does not affect the grain size, but does generate lattice microstrains due to the increase in point defects in the crystalline lattice

μ-Hexa­thio­metadiphosphato-bis­[(1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane-κ6 O)rubidium] aceto­nitrile disolvate

Science.gov (United States)

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-01-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto­nitrile solvent mol­ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb+ ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6]2− moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6]2− anion. The hexa­thio­metadiphosphate anion is built up from two tetra­hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto­nitrile solvent mol­ecules stacked along [010]. PMID:24860286

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

Science.gov (United States)

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

2014-07-01

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

1-(o-Tol­yl)thio­urea

Science.gov (United States)

Corrêa, Rodrigo S.; Ribeiro, Leandro; Ellena, Javier; Estévez-Hernández, Osvaldo; Duque, Julio

2008-01-01

In the title compound, C8H10N2S, the o-tolyl group and the thio­urea core are planar. The mean planes of the two groups are almost perpendicular [82.19 (8)°]. The thio­urea group is in the thio­amide form, in which resonance is present. In the crystal structure, mol­ecules are linked by inter­molecular N—H⋯S hydrogen bonds, forming two infinite chains parallel to the (110) and (10) planes. PMID:21201662

(2E)-1-(2,6-Dichloro-3-fluoro-phen-yl)-3-phenyl-prop-2-en-1-one.

Science.gov (United States)

Praveen, Aletti S; Yathirajan, Hemmige S; Narayana, Badiadka; Gerber, Thomas; Hosten, Eric; Betz, Richard

2012-04-01

In the title compound, C(15)H(9)Cl(2)FO, the F atom shows positional disorder over two positions, with site-occupancy factors of 0.747 (4) and 0.253 (4). The dihedral angle between the rings is 86.37 (10)°. In the crystal, C-H⋯O contacts connect the mol-ecules into chains along the c axis. The shortest inter-centroid distance between two aromatic systems is 3.6686 (12) Å and is apparent between the halogenated rings.

(E)-Methyl 3-(3,4-dimeth-oxy-phen-yl)-2-[(1,3-dioxoisoindolin-2-yl)meth-yl]acrylate.

Science.gov (United States)

Kannan, D; Bakthadoss, M; Lakshmanan, D; Murugavel, S

2012-04-01

In the title compound, C(21)H(19)NO(6), the isoindole ring system is essentially planar [maximum deviation = 0.019 (2) Å for the N atom] and is oriented at a dihedral angle of 51.3 (1)° with respect to the benzene ring. The two meth-oxy groups are almost coplanar with the attached benzene ring [C-O-C-C = 3.7 (4) and 4.3 (4)°]. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(9) ring motif. In the crystal, mol-ecules are linked through bifurcated C-H⋯(O,O) hydrogen bonds having R(1) (2)(5) ring motifs, forming chains along the b-axis direction. The crystal packing is further stabilzed by π-π inter-actions [centriod-centroid distance = 3.463 (1) Å].

Redetermination of 2-methyl-4-nitro­pyridine N-oxide

Science.gov (United States)

Peukert, Max; Seichter, Wilhelm; Weber, Edwin

2014-01-01

An improved crystal structure of the title compound, C6H6N2O3, is reported. The structure, previously solved [Li et al. (1987 ▶). Jiegou Huaxue (Chin. J. Struct. Chem.), 6, 20–24] in the ortho­rhom­bic space group Pca21 and refined to R = 0.067, has been solved in the ortho­rhom­bic space group Pbcm with data of enhanced quality, giving an improved structure (R = 0.0485). The mol­ecule adopts a planar conformation with all atoms lying on a mirror plane. The crystal structure is composed of mol­ecular sheets extending parallel to the ab plane and connected via C—H⋯O contacts involving ring H atoms and O atoms of the N-oxide and nitro groups, while van der Waals forces consolidate the stacking of the layers. PMID:24826136

Distinguishing tautomerism in the crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide using DFT-D calculations and {sup 13}C solid-state NMR

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaozhou; Bond, Andrew D.; Johansson, Kristoffer E.; Van de Streek, Jacco, E-mail: jacco.vandestreek@sund.ku.dk [Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100 (Denmark)

2014-08-01

The crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide contains an imine tautomer, rather than the previously reported amine tautomer. The tautomers can be distinguished using dispersion-corrected density functional theory calculations and by comparison of calculated and measured {sup 13}C solid-state NMR spectra. The crystal structure of the title compound, C{sub 11}H{sub 13}N{sub 3}O{sub 2}S{sub 2}, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated {sup 13}C solid-state NMR spectra [Hangan et al. (2010 ▶). Acta Cryst. B66, 615–621]. The mol@@ecule is tautomeric, and was reported as an amine tautomer [systematic name: N-(5-ethyl-1,3,4-thia@@diazol-2-yl)-p-toluene@@sulfonamide], rather than the correct imine tautomer. The protonation site on the mol@@ecule’s 1,3,4-thia@@diazole ring is indicated by the inter@@molecular contacts in the crystal structure: N—H⋯O hydrogen bonds are established at the correct site, while the alternative protonation site does not establish any notable inter molecular inter@@actions. The two tautomers provide essentially identical Rietveld fits to laboratory PXRD data, and therefore they cannot be directly distinguished in this way. However, the correct tautomer can be distinguished from the incorrect one by previously reported qu@@anti@@tative criteria based on the extent of structural distortion on optimization of the crystal structure using dispersion-corrected density functional theory (DFT-D) calculations. Calculation of the {sup 13}C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured {sup 13}C SS-NMR spectrum.

Mol 7C/6

International Nuclear Information System (INIS)

Aberle, J.; Schleisiek, K.; Schmuck, I.; Schmidt, L.; Romer, O.; Weih, G.

1995-01-01

The Mol 7C/6 coolant blockage experiment in the Belgian BR2 reactor yielded results different from Mol 7C experiments with low burnup pins: At 10% burnup local failure is not self-limiting, but requires active systems for detection and scram. The Mol 7C series was finished in 1991. In each of the test bundles Mol 7C/4, /5 and /6, 30 Mk I pins pre-irradiated in KNK II were used. The central blockage consisted of enriched UO 2 covering 30 percent of the bundle cross-section, with a height of 40 mm. The most important system for timely detection of coolant blockages of the type studied in Mol 7C/6 is based on DND. (orig.)

(Carbonato-κO,O')bis-(1,10-phenan-throline-κN,N')cobalt(III) nitrate monohydrate.

Science.gov (United States)

Andaç, Omer; Yolcu, Zuhal; Büyükgüngör, Orhan

2009-12-12

The crystal structure of the title compound, [Co(CO(3))(C(12)H(8)N(2))(2)]NO(3)·H(2)O, consists of Co(III) complex cations, nitrate anions and uncoordinated water mol-ecules. The Co(III) cation is chelated by a carbonate anion and two phenanthroline ligands in a distorted octa-hedral coordination geometry. A three-dimensional supra-molecular structure is formed by O-H⋯O and C-H⋯O hydrogen bonding, C-H⋯π and aromatic π-π stacking [centroid-centroid distance = 3.995 (1)Å] inter-actions.

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

Science.gov (United States)

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

2013-01-01

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

(N-Benzyl-N-ethyl­dithio­carbamato)di-tert-butyl­chloridotin(IV)

OpenAIRE

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

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2Cl(C10H12NS2)], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C—H⋯π contacts link centrosymmetrically related mol­ecules into dimeric aggregates...

(N-Benzyl-N-ethyl-dithio-carbamato)di-tert-butyl-chloridotin(IV).

Science.gov (United States)

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R T

2011-02-26

The Sn(IV) atom in the title diorganotin dithio-carbamate, [Sn(C(4)H(9))(2)Cl(C(10)H(12)NS(2))], is penta-coordinated by an asymmetrically coordinating dithio-carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C(2)ClS(2) donor set defines a coordination geometry inter-mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C-H⋯π contacts link centrosymmetrically related mol-ecules into dimeric aggregates.

Crystal structures of 5-amino-N-phenyl-3H-1,2,4-di-thia-zol-3-iminium chloride and 5-amino-N-(4-chloro-phen-yl)-3H-1,2,4-di-thia-zol-3-iminium chloride monohydrate.

Science.gov (United States)

Yeo, Chien Ing; Tan, Yee Seng; Tiekink, Edward R T

2015-10-01

The crystal and mol-ecular structures of the title salt, C8H8N3S2 (+)·Cl(-), (I), and salt hydrate, C8H7ClN3S2 (+)·Cl(-)·H2O, (II), are described. The heterocyclic ring in (I) is statistically planar and forms a dihedral angle of 9.05 (12)° with the pendant phenyl ring. The comparable angle in (II) is 15.60 (12)°, indicating a greater twist in this cation. An evaluation of the bond lengths in the H2N-C-N-C-N sequence of each cation indicates significant delocalization of π-electron density over these atoms. The common feature of the crystal packing in (I) and (II) is the formation of charge-assisted amino-N-H⋯Cl(-) hydrogen bonds, leading to helical chains in (I) and zigzag chains in (II). In (I), these are linked by chains mediated by charge-assisted iminium-N(+)-H⋯Cl(-) hydrogen bonds into a three-dimensional architecture. In (II), the chains are linked into a layer by charge-assisted water-O-H⋯Cl(-) and water-O-H⋯O(water) hydrogen bonds with charge-assisted iminium-N(+)-H⋯O(water) hydrogen bonds providing the connections between the layers to generate the three-dimensional packing. In (II), the chloride anion and water mol-ecules are resolved into two proximate sites with the major component being present with a site occupancy factor of 0.9327 (18).

(E)-Methyl 3-(3,4-dimeth­oxy­phen­yl)-2-[(1,3-dioxoisoindolin-2-yl)meth­yl]acrylate

Science.gov (United States)

Kannan, D.; Bakthadoss, M.; Lakshmanan, D.; Murugavel, S.

2012-01-01

In the title compound, C21H19NO6, the isoindole ring system is essentially planar [maximum deviation = 0.019 (2) Å for the N atom] and is oriented at a dihedral angle of 51.3 (1)° with respect to the benzene ring. The two meth­oxy groups are almost coplanar with the attached benzene ring [C—O—C—C = 3.7 (4) and 4.3 (4)°]. The mol­ecular conformation is stabilized by an intra­molecular C—H⋯O hydrogen bond, which generates an S(9) ring motif. In the crystal, mol­ecules are linked through bifurcated C—H⋯(O,O) hydrogen bonds having R 1 2(5) ring motifs, forming chains along the b-axis direction. The crystal packing is further stabilzed by π–π inter­actions [centriod–centroid distance = 3.463 (1) Å]. PMID:22589965

Effect of ion nitriding on the crystal structure of 3 mol% Y{sub 2}O{sub 3}-doped ZrO{sub 2} thin-films prepared by the sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Ortiz, A.L. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Badajoz 06071 (Spain)]. E-mail: alortiz@unex.es; Diaz-Parralejo, A. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Badajoz 06071 (Spain); Borrero-Lopez, O. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Badajoz 06071 (Spain); Guiberteau, F. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Badajoz 06071 (Spain)

2006-06-30

We investigated the effect of ion nitriding on the crystal structure of 3 mol% Y{sub 2}O{sub 3}-doped ZrO{sub 2} (3YSZ) thin-films prepared by the sol-gel method. For this purpose, we used X-ray diffractometry to determine the crystalline phases, the lattice parameters, the crystal sizes, and the lattice microstrains, and glow discharge-optical emission spectroscopy to obtain the depth profiles of the elemental chemical composition. We found that nitrogen atoms substitute oxygen atoms in the 3YSZ crystal, thus leading to the formation of unsaturated-substitutional solid solutions with reduced lattice parameters and Zr{sub 0.94}Y{sub 0.06}O{sub 1.72}N{sub 0.17} stoichiometric formula. We also found that ion nitriding does not affect the grain size, but does generate lattice microstrains due to the increase in point defects in the crystalline lattice.

2,4,6-Tri-amino-1,3,5-triazin-1-ium 3-(prop-2-eno-yloxy)propano-ate acrylic acid monosolvate monohydrate.

Science.gov (United States)

Sangeetha, V; Kanagathara, N; Chakkaravarthi, G; Marchewka, M K; Anbalagan, G

2013-05-01

The asymmetric unit of the title salt, C3H7N6 (+)·C6H7O4 (-)·C3H4O2·H2O, contains a 2,4,6-tri-amino-1,3,5-triazin-1-ium cation, a 3-(prop-2-eno-yloxy)propano-ate anion and acrylic acid and water solvent mol-ecules in a 1:1:1:1 ratio and with each species in a general position. In the crystal, the components are linked into a supra-molecular layer in the bc plane via a combination of O-H⋯O, N-H⋯N and N-H⋯O hydrogen bonding. The crystal studied was a non-merohedral twin, the minor component contribution being approximately 26%.

(Carbonato-κ2 O,O′)bis­(1,10-phenan­throline-κ2 N,N′)cobalt(III) nitrate monohydrate

Science.gov (United States)

Andaç, Ömer; Yolcu, Zuhal; Büyükgüngör, Orhan

2010-01-01

The crystal structure of the title compound, [Co(CO3)(C12H8N2)2]NO3·H2O, consists of CoIII complex cations, nitrate anions and uncoordinated water mol­ecules. The CoIII cation is chelated by a carbonate anion and two phenanthroline ligands in a distorted octa­hedral coordination geometry. A three-dimensional supra­molecular structure is formed by O—H⋯O and C—H⋯O hydrogen bonding, C—H⋯π and aromatic π–π stacking [centroid–centroid distance = 3.995 (1)Å] inter­actions. PMID:21579944

3,5-Dimethyl-4-nitroso-1H-pyrazole

Science.gov (United States)

Safyanova, Inna; Dudarenko, Nikolay M.; Pavlenko, Vadim A.; Iskenderov, Turganbay S.; Haukka, Matti

2011-01-01

In the unit cell of the title compound, C5H7N3O, there are two conformers (A and B) which differ in the position of the oxime group with respect to the protonated pyrazole nitro­gen (trans in the A conformer and cis in the B conformer) and in the geometric parameters. The oxime group exists in the nitroso form in both conformers. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O and N—H⋯N hydrogen bonds into zigzag-like chains along the b axis. PMID:22059058

(N-Benzyl-N-ethyl­dithio­carbamato)di-tert-butyl­chloridotin(IV)

Science.gov (United States)

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

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2Cl(C10H12NS2)], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C—H⋯π contacts link centrosymmetrically related mol­ecules into dimeric aggregates. PMID:21522295

Kinetics and enthalpy of crystallization of uric acid dihydrate

International Nuclear Information System (INIS)

Sádovská, Galina; Honcová, Pavla; Sádovský, Zdeněk

2013-01-01

Highlights: • The kinetic constant and growth order of crystallization of uric acid dihydrate was calculated. • The equation describing first-order crystal growth was derived. • The enthalpy of crystallization of uric acid dihydrate was determined. - Abstract: The kinetics of crystallization of uric acid dihydrate in aqueous solution with a constant ionic strength 0.3 mol dm −3 NaCl and at thermodynamic and physiological temperature (25 and 37 °C) was studied using isoperibolic reaction twin calorimeter. The enthalpy of crystallization Δ cr H = −47.3 ± 0.9 and −46.2 ± 1.4 kJ mol −1 and kinetic constant k g = 2.0 × 10 −8 and 9.6 × 10 −8 m 4 s −1 mol −1 were determined at 25 and 37 °C, respectively

Crystallic silver amalgam--a novel electrode material.

Science.gov (United States)

Danhel, Ales; Mansfeldova, Vera; Janda, Pavel; Vyskocil, Vlastimil; Barek, Jiri

2011-09-21

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

4-Bromo-N-(di-n-propyl­carbamothioyl)­benzamide

OpenAIRE

Binzet, Gün; Flörke, Ulrich; Külcü, Nevzat; Arslan, Hakan

2009-01-01

The synthesis of the title compound, C14H19BrN2OS, involves the reaction of 4-bromo­benzoyl chloride with potassium thio­cyanate in acetone followed by condensation of the resulting 4-bromo­benzoyl isothio­cyanate with di-n-propyl­amine. Typical thio­urea carbonyl and thio­carbonyl double bonds, as well as shortened C—N bonds, are observed in the title compound. The short C—N bond lengths in the centre of the mol­ecule reveal the effects of resonance in this part of the mol­ecule. The asymmet...

Kinetics and enthalpy of crystallization of uric acid dihydrate

Energy Technology Data Exchange (ETDEWEB)

Sádovská, Galina, E-mail: galina.sadovska@upce.cz; Honcová, Pavla; Sádovský, Zdeněk

2013-08-20

Highlights: • The kinetic constant and growth order of crystallization of uric acid dihydrate was calculated. • The equation describing first-order crystal growth was derived. • The enthalpy of crystallization of uric acid dihydrate was determined. - Abstract: The kinetics of crystallization of uric acid dihydrate in aqueous solution with a constant ionic strength 0.3 mol dm{sup −3} NaCl and at thermodynamic and physiological temperature (25 and 37 °C) was studied using isoperibolic reaction twin calorimeter. The enthalpy of crystallization Δ{sub cr}H = −47.3 ± 0.9 and −46.2 ± 1.4 kJ mol{sup −1}and kinetic constant k{sub g} = 2.0 × 10{sup −8} and 9.6 × 10{sup −8} m{sup 4} s{sup −1} mol{sup −1} were determined at 25 and 37 °C, respectively.

A first interpretation of the Mol 7C/l and Mol 7C/2 experiments

International Nuclear Information System (INIS)

Berthier, J.; Carluec, B.; Fortunato, M.; Lemmet, L.

1983-01-01

The interpretation of the two experiments MOL 7C/1 and MOL 7C/2 that has been performed at the CEA of Cadarache is presented here: one will find first a recall of the experimental conditions of the MOL experiments, then a short description of the codes that enable the interpretation and finally the results of this interpretation compared to the experimental results

Kinetic study of α-BZN crystallization obtained from chemical method

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Ronaldo Rodrigues Pelá

2008-09-01

Full Text Available The crystallization kinetics of ceramics composed by Bi2O3-ZnO-Nb2O5 (BZN was studied using non-isothermal method. The BZN samples were prepared by the polymeric precursors method. Phase evolution was evaluated by X ray diffraction and the thermal events were evaluated by differential scanning calorimetry (DSC. The crystallization of BZN occurs from 500 to 700 °C, which corresponds to a secondary event in DSC curves. The principal exothermic event in these curves is related to the decomposition of organic material and was isolated from the crystallization peak by deconvolution into two Gaussian curves. Those related to crystallization processes were evaluated in terms of crystallized fraction. Kinetic parameters were determined from Ligero (E = 242 ± 7 kJ.mol-1 and Kissinger (E = 241 ± 24 kJ.mol-1 methodologies and they are very close. The activation energy Ea = (241 ± 24 kJ.mol-1 and (242 ± 7 kJ.mol-1 (by the Kissinger and Ligero methodology, respectively, frequency factor k0 =10(13.s-1 and exponent of Avrami n = (1.3 ± 0.1 were determined. The n value indicates that the crystallization is diffusion controlled, with decreasing nucleation rate. Scanning electronic microscopy showed the presence of nanoparticulated powder.

A one-dimensional ladder-like coordination polymer: poly[[hexa-aqua-bis(μ-5-nitro-benzene-1,3-dicarboxyl-ato-κO,O',O'')(μ-oxalato-κO,O':O'',O''')diyttrium(III)] trihydrate].

Science.gov (United States)

Fu, Zhong; Lin, Ying; Zhou, Yun-You; Zhang, Hong-Tao

2007-12-06

In the crystal structure of the title one-dimensional coordination polymer, [Y(2)(C(8)H(3)NO(6))(2)(C(2)O(4))(H(2)O)(6)]·3H(2)O, each Y(III) ion is bridged to its neighbours by two 5-nitro-benzene-1,3-dicarboxyl-ate (nbdc) dianions and one oxalate dianion (located on an inversion centre) to form a ladder-like polymeric structure. The two carboxylate groups of nbdc assume different modes of coordination, one is chelating whereas the other is monodentate. Three water mol-ecules coordinate to the Y(III) ion to complete an eight-coordinate distorted dodecahedral geometry. The ladder-like polymers are assembled together by hydrogen bonding and π-π stacking [centrio-centriod distance = 3.819 (9) Å] in the crystal structure.

2,4,6-Tri­amino-1,3,5-triazin-1-ium 3-(prop-2-eno­yloxy)propano­ate acrylic acid monosolvate monohydrate

Science.gov (United States)

Sangeetha, V.; Kanagathara, N.; Chakkaravarthi, G.; Marchewka, M. K.; Anbalagan, G.

2013-01-01

The asymmetric unit of the title salt, C3H7N6 +·C6H7O4 −·C3H4O2·H2O, contains a 2,4,6-tri­amino-1,3,5-triazin-1-ium cation, a 3-(prop-2-eno­yloxy)propano­ate anion and acrylic acid and water solvent mol­ecules in a 1:1:1:1 ratio and with each species in a general position. In the crystal, the components are linked into a supra­molecular layer in the bc plane via a combination of O—H⋯O, N—H⋯N and N—H⋯O hydrogen bonding. The crystal studied was a non-merohedral twin, the minor component contribution being approximately 26%. PMID:23723892

La esfera, el mol y la ciudad

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Hernán Neira

2010-06-01

Full Text Available Apoyándonos en la noción de "esfera" de Slotedijk, analizamos la protección constituida por los moles. La libertad de elegir en el mol no tiene relación con la libertad individual propuesta por John Stuart Mill; ni con la anarco-individualista propuesta por Henry David Thoreau o incluso por Aldo Leopold en el elogio que éste realiza de la autonomía del pionero estadounidense. En la libertad de elegir en el mol han caducado todas las aventuras y las relaciones humanas se convierten en lo que Sloterdijk denomina "relaciones cristalizadas", bajo el proyecto del aburrimiento normativo poshistórico. La expresión económico-filosófica del mundo poshistórico es la idea de libertad de elegir, enunciada por Milton Friedman. El mol, actual Palacio de Cristal, es como una enciclopedia ilustrada, que exhibe, en orden y sin peligros, el conjunto, ya no del saber, sino de los bienes disponibles. Con ello, se modifica la condición humana.Based on the Sloterdijk's concept of sphere, we analyse the protection provided by the malls. Nevertheless, the freedom of choosing in a mall does not have any relation to liberty as it was proposed by John Stuart Mill, neither to the anarcho-individualist one proposed by Henry David Thoreau, nor even to that one proposed by Aldo Leopold, when he praises the authonomy of American pioneer. In the freedom process of choosing in the mall, all adventures perish and human relations become what Sloterdijk denominated "crystalised relations", under a post-historic normative boring project. The economic-philosophical expression of post-historic world is the idea of freedom of choosing, conceived by Milton Friedman. The mall, the current Crystal Palace, is like an enlightened encyclopaedia, which shows, in order and without dangers, the totality, no longer of knowledge, but of available goods. In this way, human condition has modified.

Di-?-cyanido-tetra?cyanido(5,5,7,12,12,14-hexa?methyl-1,4,8,11-tetra?aza?cyclo?tetra?decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate

OpenAIRE

Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

2013-01-01

The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]?2.07H2O, contains one [Fe(qcq)(CN)3]? anion, half a [Ni(teta)]2+ cation and two partially occupied inter?stitial water mol?ecules [qcq? is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa?methyl-1,4,8,11-tetra?aza?cyclo?tetra?deca?ne]. In the complex mol?ecule, two [Fe(qcq)(CN)3]? anions additionally coordinate the central [Ni(teta)]2+ cation through cyanide groups in a trans mode,...

2-Acetyl-amino-1,3,4,6-tetra-O-(tri-methyl-silyl)-2-de-oxy-α-d-gluco-pyran-ose.

Science.gov (United States)

Cheng, Zhao-Dong; Cui, Yan-Li; Mao, Jian-Wei

2013-06-01

The title compound, C20H47NO6Si4, was synthesized by per-O-tri-methyl-silylation of N-acetyl-d-glucosa-mine using chloro-tri-methyl-silane in the presence of hexa-methyl-disiloxane. The tri-methyl-silyl group and acetamido group are located on the same side of the pyran ring, showing an α-configuration glycoside. One of the tri-methyl-silyl groups is disordered over two orientations, with site-occupancy factors of 0.625 (9) and 0.375 (9). In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains along the a-axis direction.

Bis(8-hy-droxy-1-methyl-quinolin-1-ium) bis-(1,2-dicyano-ethene-1,2-dithiol-ato)nickelate(II) dihydrate.

Science.gov (United States)

Guan, Zhi-Heng; Jiang, Zhang; Wang, Fang-Ming

2011-12-01

In the title ion-pair complex, (C(10)H(10)NO)(2)[Ni(C(4)N(2)S(2))(2)]·2H(2)O, the anion has crystallographically imposed centre of symmetry. The Ni(II) atom exhibits a slightly distorted square-planar coordination geometry. In the crystal, the water mol-ecule links anions and cations into a three-dimensional network via O-H⋯N, O-H⋯S and O-H⋯O hydrogen bonds. The structure is further stabilized by weak S⋯π contacts [S⋯centroid = 3.8047 (9) Å] and π-π stacking inter-actions [centriod-centroid distance = 3.8653 (7) Å].

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

Science.gov (United States)

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

2011-01-01

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

Crystal structure of 5-{4'-[(2-{2-[2-(2-ammonio-eth-oxy)eth-oxy]eth-oxy}eth-yl)carbamo-yl]-4-meth-oxy-[1,1'-biphen-yl]-3-yl}-3-oxo-1,2,5-thia-diazo-lidin-2-ide 1,1-dioxide: a potential inhibitor of the enzyme protein tyrosine phosphatase 1B (PTP1B).

Science.gov (United States)

Ruddraraju, Kasi Viswanatharaju; Hillebrand, Roman; Barnes, Charles L; Gates, Kent S

2015-04-01

The title compound, C24H32N4O8S, (I), crystallizes as a zwitterion. The terminal amine N atom of the [(2-{2-[2-(2-ammonio-eth-oxy)eth-oxy]eth-oxy}eth-yl)carbamo-yl] side chain is protonated, while the 1,2,5-thia-diazo-lidin-3-one 1,1-dioxide N atom is deprotonated. The side chain is turned over on itself with an intra-molecular N-H⋯O hydrogen bond. The 1,2,5-thia-diazo-lidin-3-one 1,1-dioxide ring has an envelope conformation with the aryl-substituted N atom as the flap. Its mean plane is inclined by 62.87 (8)° to the aryl ring to which it is attached, while the aryl rings of the biphenyl unit are inclined to one another by 20.81 (8)°. In the crystal, mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming slabs lying parallel to (010). Within the slabs there are C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π inter-actions present.

Refractive Indices in Undoped and MgO-Doped Near-Stoichiometric LiTaO3 Crystals

Science.gov (United States)

Nakamura, Masaru; Higuchi, Shinji; Takekawa, Shunji; Terabe, Kazuya; Furukawa, Yasunori; Kitamura, Kenji

2002-04-01

Undoped and MgO (0.5 and 1.0-mol%)-doped near-stoichiometric LiTaO3 (SLT) crystals were grown from off-congruent Li-rich solutions (Li˜ 60 mol%) by the double-crucible Czochralski method using a continuous SLT ceramic grain charging system. Curie temperatures of the undoped and MgO (0.5 and 1.0-mol%)-doped SLT crystals are 688, 694 and 695°C, respectively. The ordinary and extraordinary refractive indices (no, ne) of these crystals were measured by the prism coupling technique in the wavelength range from 0.440 to 1.050 μm at room temperature, and the temperature-independent Sellmeier equations for each crystal were derived from the measured refractive index data. no of the SLT crystal was almost the same as that of a congruent-melt LiTaO3 (CLT) crystal, while ne of the SLT crystal was lower than that of the CLT crystal. ne was lower than no for the SLT crystal, similar to as in the case of the LiNbO3 crystal. The refractive indices of the SLT crystal, no and ne, were found to be almost independent of MgO concentration at the doping level of 0.5 and 1.0 mol%.

MolProbity for the masses–of data

Energy Technology Data Exchange (ETDEWEB)

Chen, Vincent B. [University of Wisconsin-Madison, National Magnetic Resonance Facility at Madison, Biochemistry Department (United States); Wedell, Jonathan R.; Wenger, R. Kent; Ulrich, Eldon L. [University of Wisconsin-Madison, BioMagResBank, Biochemistry Department (United States); Markley, John L., E-mail: markley@nmrfam.wisc.edu [University of Wisconsin-Madison, National Magnetic Resonance Facility at Madison, Biochemistry Department (United States)

2015-09-15

MolProbity is a powerful software program for validating structures of proteins and nucleic acids. Although MolProbity includes scripts for batch analysis of structures, because these scripts analyze structures one at a time, they are not well suited for the validation of a large dataset of structures. We have created a version of MolProbity (MolProbity-HTC) that circumvents these limitations and takes advantage of a high-throughput computing cluster by using the HTCondor software. MolProbity-HTC enables the longitudinal analysis of large sets of structures, such as those deposited in the PDB or generated through theoretical computation—tasks that would have been extremely time-consuming using previous versions of MolProbity. We have used MolProbity-HTC to validate the entire PDB, and have developed a new visual chart for the BioMagResBank website that enables users to easily ascertain the quality of each model in an NMR ensemble and to compare the quality of those models to the rest of the PDB.

A novel stibacarbaborane cluster with adjacent antimony atoms exhibiting unique pnictogen bond formation that dominates its crystal packing.

Science.gov (United States)

Holub, Josef; Melichar, Petr; Růžičková, Zdeňka; Vrána, Jan; Wann, Derek A; Fanfrlík, Jindřich; Hnyk, Drahomír; Růžička, Aleš

2017-10-17

We have prepared nido-7,8,9,11-Sb 2 C 2 B 7 H 9 , the first cluster with simultaneous Sb-B, Sb-C and Sb-Sb atom pairs with interatomic separations with magnitudes that approach the respective sums of covalent radii. However, the length of the Sb-Sb separation in this cluster is slightly less than the sum of the covalent radii. Quantum chemical analysis has revealed that the crystal packing of nido-7,8,9,11-Sb 2 C 2 B 7 H 9 is predominantly dictated by pnictogen (Pn) bonding, an unconventional σ-hole interaction. Indeed, the interaction energy of a very strong Sb 2 H-B Pn-bond in the nido-7,8,9,11-Sb 2 C 2 B 7 H 9 dimer exceeds -6.0 kcal mol -1 . This is a very large value and is comparable to the strengths of known Pn-bonds in Cl 3 Pnπ complexes (Pn = As, Sb).

N-[5-Methyl-2-(2-nitro-phen-yl)-4-oxo-1,3-thia-zolidin-3-yl]pyridine-3-carboxamide monohydrate.

Science.gov (United States)

Akkurt, Mehmet; Celik, Ismail; Demir, Hale; Ozkırımlı, Sumru; Büyükgüngör, Orhan

2011-01-08

In the title compound, C(16)H(14)N(4)O(4)S·H(2)O, the benzene and pyridine rings make a dihedral angle of 85.8 (1)°. Both enanti-omers of the chiral title compound are statistically disordered over the same position in the unit cell. The methyl and carbonyl group attached to the stereogenic center (C(5) of the thia-zolidine ring) were therefore refined with common site-occupation factors of 0.531 (9) and 0.469 (9), respectively, for each stereoisomer. In the crystal, inter-molecular N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules, forming a three-dimensional supra-molecular network. The crystal structure further shows π-π stacking inter-actions [centroid-centroid distance = 3.5063 (13) Å] between the pyridine rings.

Pyroelectric properties of phosphoric acid-doped TGS single crystals

International Nuclear Information System (INIS)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K

2003-01-01

Pyroelectric properties of phosphoric acid (H 3 PO 4 )-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H 3 PO 4 have been studied. Incorporation of H 3 PO 4 into the crystal lattice is found to induce an internal bias field (E b ) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient (λ), dielectric constant (ε') and polarization (P). A high E b value in the range 9 x 10 3 -15.5 x 10 4 V m -1 is obtained for crystals grown with 0.1-0.5 mol of H 3 PO 4 in the solution, and a specific concentration of 0.2-0.25 mol of H 3 PO 4 in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F d = 428 μC m -2 K -1

CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

Directory of Open Access Journals (Sweden)

A. NOZAD

2011-06-01

Full Text Available The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was bulk crystallization for base glass and the sample with addition of Li2O. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of Li2O was changed to the range of 317-322 KJ/mol.

N,N-Dimethyl-N-propyl-propan-1-aminium chloride monohydrate.

Science.gov (United States)

Kärnä, Minna; Lahtinen, Manu; Valkonen, Jussi

2008-10-11

The title compound, C(8)H(20)N(+)·Cl(-)·H(2)O, has been prepared by a simple one-pot synthesis route followed by anion exchange using resin. In the crystal structure, the cations are packed in such a way that channels exist parallel to the b axis. These channels are filled by the anions and water mol-ecules, which inter-act via O-H⋯Cl hydrogen bonds [O⋯Cl = 3.285 (3) and 3.239 (3) Å] to form helical chains. The cations are involved in weak inter-molecular C-H⋯Cl and C-H⋯O hydrogen bonds. The title compound is not isomorphous with the bromo or iodo analogues.

Dehydration and crystallization kinetics of zirconia-yttria gels

International Nuclear Information System (INIS)

Ramanathan, S.; Muraleedharan, R.V.; Roy, S.K.; Nayar, P.K.K.

1995-01-01

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process. The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ''glow effect'' reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form

Quiralidade em moléculas e cristais Chirality at molecules and crystals

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Ayres Guimarães Dias

2009-01-01

Full Text Available The present contribution describes some concepts of stereochemistry and chirality in molecules and crystals. This paper also reports on the development of a simple and fast experiment to prepare and recognize conglomerate and true racemate of tartaric acid produced by mechanic mixture of commercial enantiomers and recristalization. Optical activity and melting point of mixtures are also used in the analysis.

Unique Crystal Orientation of Poly(ethylene oxide) Thin Films by Crystallization Using a Thermal Gradient

DEFF Research Database (Denmark)

Gbabode, Gabin; Delvaux, Maxime; Schweicher, Guillaume

2017-01-01

Poly(ethylene oxide), (PEO), thin films of different thicknesses (220, 450, and 1500 nm) and molecular masses (4000, 8000, and 20000 g/mol) have been fabricated by spin-coating of methanol solutions onto glass substrates. All these samples have been recrystallized from the melt using a directional......, to significantly decrease the distribution of crystal orientation obtained after crystallization using the thermal gradient technique....

Pyroelectric properties of phosphoric acid-doped TGS single crystals

Energy Technology Data Exchange (ETDEWEB)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2003-12-21

Pyroelectric properties of phosphoric acid (H{sub 3}PO{sub 4})-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H{sub 3}PO{sub 4} have been studied. Incorporation of H{sub 3}PO{sub 4} into the crystal lattice is found to induce an internal bias field (E{sub b}) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient ({lambda}), dielectric constant ({epsilon}') and polarization (P). A high E{sub b} value in the range 9 x 10{sup 3}-15.5 x 10{sup 4} V m{sup -1} is obtained for crystals grown with 0.1-0.5 mol of H{sub 3}PO{sub 4} in the solution, and a specific concentration of 0.2-0.25 mol of H{sub 3}PO{sub 4} in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F{sub d} = 428 {mu}C m{sup -2} K{sup -1}.

ANATOMIA DA MADEIRA E CASCA DO ESPINILHO, Acacia caven (Mol. Mol.

Directory of Open Access Journals (Sweden)

José Newton Cardoso Marchiori

1992-12-01

Full Text Available São descritos os aspectos anatômicos da madeira e casca de Acacia cavem (Mol. Mol. São apresentados dados quantitativos de 34 características do xilema secundário, bem como fotomicrografias das estruturas anatômicas da madeira e casca. A ausência de septos em fibras, a abundância de parênquima axial e a elevada percentagem de raios com 4 ou mais células de largura, são os caracteres mais importantes na estrutura do lenho. O arranjo das fibras floemáticas em feixes tangenciais regulares, rodeados por sériescristalíferas, é, por sua vez, o aspecto mais notável da casca. Este caráter ainda não havia sido reportado pela literatura anatômica das acácias sul-americanas, e pode ter valor taxonômico em nivel infra-genético.

Anatomia da madeira e casca de espinilho, Acacia caven Mol.Mol.

Directory of Open Access Journals (Sweden)

José Newton Cardoso Marchiori

2009-09-01

Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 São descritos os aspectos anatômicos da madeira e casca de Acácia caven (Mol. Mol. São apresentados dados quantitativos de 34 caracteres do xilema secundário, bem como fotomicrografias das estruturas anatômicas da madeira e casca. A ausência de septos em fibras, a abundância de parênquima axial e a elevada percentagem de raios com 4 ou mais células de largura, são os caracteres mais importantes na estrutura do lenho. O arranjo das fibras floemáticas em feixes tangenciais regulares, rodeados por séries cristalíferas, é, por sua vez, o aspecto mais notável da casca. Este caráter ainda não havia sido reportado pela literatura anatômica das acácias sul-americanas, e pode ter valor taxonômico em nível infra-genérico.

Pyridinium bis­(pyridine-κN)tetra­kis­(thio­cyanato-κN)ferrate(III)–pyrazine-2-carbo­nitrile–pyridine (1/4/1)

Science.gov (United States)

Shylin, Sergii I.; Gural’skiy, Il’ya A.; Haukka, Matti; Golenya, Irina A.

2013-01-01

In the title compound, (C5H6N)[Fe(NCS)4(C5H5N)2]·4C5H3N3·C5H5N, the FeIII ion is located on an inversion centre and is six-coordinated by four N atoms of the thio­cyanate ligands and two pyridine N atoms in a trans arrangement, forming a slightly distorted octa­hedral geometry. A half-occupied H atom attached to a pyridinium cation forms an N—H⋯N hydrogen bond with a centrosymmetrically-related pyridine unit. Four pyrazine-2-carbo­nitrile mol­ecules crystallize per complex anion. In the crystal, π–π stacking inter­actions are present [centroid–centroid distances = 3.6220 (9), 3.6930 (9), 3.5532 (9), 3.5803 (9) and 3.5458 (8) Å]. PMID:23723782

Conversion of broadband thermal radiation in lithium niobate crystals of various compositions

Science.gov (United States)

Syuy, A. V.; Litvinova, M. N.; Goncharova, P. S.; Sidorov, N. V.; Palatnikov, M. N.; Krishtop, V. V.; Likhtin, V. V.

2013-05-01

The conversion of the broadband thermal radiation in stoichiometric ( R = 1) lithium niobate single crystals that are grown from melt with 58.6 mol % of LiO2, congruent ( R = Li/Nb = 0.946) melt with the K2O flux admixture (4.5 and 6.0 wt %), and congruent melt and in congruent single crystals doped with the Zn2+, Gd3+, and Er3+ cations is studied. It is demonstrated that the conversion efficiency of the stoichiometric crystal that is grown from the melt with 58.6 mol % of LiO2 is less than the conversion efficiency of congruent crystal. In addition, the stoichiometric and almost stoichiometric crystals and the doped congruent crystals exhibit the blue shift of the peak conversion intensity in comparison with a nominally pure congruent crystal. For the congruent crystals, the conversion intensities peak at 520 and 495 nm, respectively.

Results of postirradiation examination of the in-pile blockage experiments MOL-7C/4 and MOL-7C/5

International Nuclear Information System (INIS)

Weimar, P.; Schleisiek, K.

1991-01-01

The Mol-7C in-pile local blockage experiments are performed in the BR-2 reactor at Mol, Belgium as a joint project of Kernforchungszentrum Karlsruhe (KfK) and Studiecentrum voor Kernenergie/Centre d'Etude de l'Energie Nuclearire-Mol. The main objective is to investigate the consequences of local cooling disturbances in liquid-metal-cooled reactor (LMR) fuel subassemblies. In the tests Mol-7C/4 and MOL-7C/5, fuel pins from KNK II are used with a burnup of 5 and 1.7%, respectively. An active central porous blockage is used to simulate the cooling disturbance. During irradiation, the blockage causes significant local damage, including melting of cladding and fuel. Extensive postirradiation examinations (PIE) are performed to investigate the extent of damage. In this paper a description and interpretation of results of the destructive PIE performed at the Hot Cells Laboratory at KfK is given, along with some conclusions related to LMR safety

Composition and crystallization kinetics of R2O-Al2O3-SiO2 glass-ceramics

International Nuclear Information System (INIS)

Xiong, Dehua; Cheng, Jinshu; Li, Hong

2010-01-01

The crystallization behavior and microstructure of R 2 O-Al 2 O 3 -SiO 2 (R means K, Na and Li) glass were investigated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization kinetic parameters including the crystallization apparent activation energy (E a ), the Avrami parameter (n), glass transition temperature (T g ) and the activity energy of glass transition (E t ) were also measured with different methods. The results have shown that: the DSC traces of composition A parent glass have two different precipitation crystallization peaks corresponding to E a1 (A) = 151.4 kJ/mol (Li 2 SiO 3 ) and E a2 (A) = 623.1 kJ/mol (Li 2 Si 2 O 5 ), the average value of n = 1.70 (Li 2 Si 2 O 5 ) for the surface crystallization and E t (A) = 202.8 kJ/mol. And E a (B) = 50.7 kJ/mol (Li 2 SiO 3 ), the average value of n = 3.89 (Li 2 SiO 3 ) for the bulk crystallization and E t (B) = 220.4 kJ/mol for the composition B parent glass. Because of the content of R 2 O is bigger than composition A, composition B parent glass has a lower E a , T g and a larger n, E t .

2-Acetyl­amino-1,3,4,6-tetra-O-(tri­methyl­silyl)-2-de­oxy-α-d-gluco­pyran­ose

Science.gov (United States)

Cheng, Zhao-Dong; Cui, Yan-Li; Mao, Jian-Wei

2013-01-01

The title compound, C20H47NO6Si4, was synthesized by per-O-tri­methyl­silylation of N-acetyl-d-glucosa­mine using chloro­tri­methyl­silane in the presence of hexa­methyl­disiloxane. The tri­methyl­silyl group and acetamido group are located on the same side of the pyran ring, showing an α-configuration glycoside. One of the tri­methyl­silyl groups is disordered over two orientations, with site-occupancy factors of 0.625 (9) and 0.375 (9). In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into supra­molecular chains along the a-axis direction. PMID:23795087

2,3-Di­phenyl­male­imide 1-methyl­pyrrol­idin-2-one monosolvate

Science.gov (United States)

Bulatov, Evgeny; Boyarskaya, Dina; Chulkova, Tatiana; Haukka, Matti

2014-01-01

In the title compound, C16H11NO2·C5H9NO, the dihedral angles between the male­imide and phenyl rings are 34.7 (2) and 64.8 (2)°. In the crystal, the 2,3-di­phenyl­male­imide and 1-methyl­pyrrolidin-2-one mol­ecules form centrosymmetrical dimers via pairs of strong N—H⋯O hydrogen bonds and π–π stacking inter­actions between the two neighboring male­imide rings [centroid–centroid distance = 3.495 (2) Å]. The dimers are further linked by weak C—H⋯O and C—H⋯π hydrogen bonds into a three-dimensional framework. PMID:24764976

Effect of L-Cysteine doping on growth and some characteristics of potassium dihydrogen phosphate single crystals

Science.gov (United States)

Mahadik, Ashwini; Soni, P. H.; Desai, C. F.

2017-12-01

Among quite a number of technologically important NLO materials, Potassium Dihydrogen Phosphate (KDP) is one of the most favourable ones for second harmonic generation applications, such as in electro-optic modulators, parametric oscillators and harmonic generators. The authors report here their studies on KDP crystals doped with L-Cysteine (1 mol% and 2 mol%). The dopant inclusion in the crystals was confirmed using Fourier transform infrared (FT-IR) spectroscopy and Powder X-Ray Diffraction (XRD). The XRD results also confirm the tetragonal structure with lattice parameters a = b = 7.45 Å and c = 6.98 Å. The presence of functional groups of crystals was analyzed using the FTIR spectra. For band gap evaluation, UV-Vis spectra were used and it was found to be 3.41 eV, 4.40eVand 4.50 eV, respectively in the cases of pure KDP, 1 mol% and 2 mol% L-Cysteine dopings. The spectra quality indicates good transparency of the doped crystals in the visible region, a feature quite desirable for applications in optoelectronics.

Luminescence of the SrCl2:Pr crystals under high-energy excitation

International Nuclear Information System (INIS)

Antonyak, O.T.; Voloshinovskii, A.S.; Vistovskyy, V.V.; Stryganyuk, G.B.; Kregel, O.P.

2014-01-01

The present research was carried out in order to elucidate the mechanisms of energy transfer from the crystal lattice to Pr 3+ ions in SrCl 2 . The luminescence excitation and emission spectra as well as luminescence kinetics of the SrCl 2 :Pr single crystals containing 0.2 mol% Pr were investigated at 300 and 10 K using the vacuum ultraviolet (VUV) synchrotron radiation. The X-ray excited luminescence spectra of the SrCl 2 :Pr (C Pr =0.2 and 0.5 mol%) and SrCl 2 :Pr, K (C Pr =1.5 mol%; C K =1.5 mol%) crystals were studied at 294 and 80 K. Under optical excitation of the samples in the Pr 3+ absorption bands, there were observed five fast ultraviolet emissions assigned to the 4f 1 5d→4f 2 transitions, and two long-wave bands corresponding to the f–f transitions. Furthermore, the intrinsic emission bands of SrCl 2 were observed at 10 K. The X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal containing 0.2 mol% Pr, besides intrinsic emission band near 400 nm, has got a long-wave band at about 490 nm of the Pr 3+ centers. There were not observed any emission bands of the Pr 3+ centers corresponding to the 4f 1 5d–4f 2 transitions in the X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal. The possible mechanisms of energy transfer from the SrCl 2 matrix to the Pr 3+ centers are discussed. -- Highlights: • Spectral-luminescent properties of SrCl 2 :Pr have been investigated. • The identification of emission 4f–4f and 5d–4f bands of Pr 3+ ions was performed. • Adding of potassium prevents clustering of the Pr 3+ centers in the SrCl 2 :Pr, K crystals. • Under X-ray excitation at 80–300 K only Pr 3+ 4f–4f and intrinsic emission is observed

(Di­methyl­phosphor­yl)methanaminium hydrogen oxalate–oxalic acid (2/1)

Science.gov (United States)

Bialek, Sebastian; Clemens, Rebecca; Reiss, Guido J.

2014-01-01

The reaction of (di­methyl­phosphor­yl)methanamine (dpma) with oxalic acid in ethanol yielded the title solvated salt, C3H11NOP+·C2HO4 −·0.5C2H2O4. Its asymmetric unit consists of one dpmaH+ cation, one hydrogen oxalate anion and a half-mol­ecule of oxalic acid located around a twofold rotation axis. The H atom of the hydrogen oxalate anion is statistically disordered over two positions that are trans to each other. The hydrogen oxalate monoanion is not planar (bend angle ∼16°) whereas the oxalic acid molecule shows a significantly smaller bend angle (∼7°). In the crystal, the components are connected by strong O—H⋯O and much weaker N—H⋯O hydrogen bonds, leading to the formation of layers extending parallel to (001). The structure was refined from a racemically twinned crystal with twin components in an approximate 1:1 ratio. PMID:24765013

Co3(PO4)2·4H2O

Science.gov (United States)

Lee, Young Hoon; Clegg, Jack K.; Lindoy, Leonard F.; Lu, G. Q. Max; Park, Yu-Chul; Kim, Yang

2008-01-01

Single crystals of Co3(PO4)2·4H2O, tricobalt(II) bis­[ortho­phosphate(V)] tetra­hydrate, were obtained under hydro­thermal conditions. The title compound is isotypic with its zinc analogue Zn3(PO4)2·4H2O (mineral name hopeite) and contains two independent Co2+ cations. One Co2+ cation exhibits a slightly distorted tetra­hedral coordination, while the second, located on a mirror plane, has a distorted octa­hedral coordination environment. The tetra­hedrally coordinated Co2+ is bonded to four O atoms of four PO4 3− anions, whereas the six-coordinate Co2+ is cis-bonded to two phosphate groups and to four O atoms of four water mol­ecules (two of which are located on mirror planes), forming a framework structure. In addition, hydrogen bonds of the type O—H⋯O are present throughout the crystal structure. PMID:21200978

Gamma ray detecting device using dislocation-free crystal

International Nuclear Information System (INIS)

Vali, V.; Chang, D.B.

1991-01-01

This patent describes a γ-ray detector. It comprises: a dislocation-free single crystal having an input surface and a transmission surface at opposite ends thereof; an active shield surrounding the crystal and functioning as an anticoincidence counter; and γ-ray detector means disposed adjacent the transmission surface of the crystal for receiving and detecting γ-rays of a predetermined wavelength incident on the input surface of the crystal at a specific Bragg angle and transmitted through the crystal

Effect of oxalic acid on the optical, thermal, dielectric and mechanical behaviour of ADP crystals

International Nuclear Information System (INIS)

Rajesh, P.; Ramasamy, P.

2009-01-01

The effect of the addition, over a concentration range from 1 to 5 mol%, of oxalic acid on the growth rate, optical transparency, hardness, dielectric behaviour, and SHG efficiency of ammonium dihydrogen phosphate single crystals grown by slow evaporation method has been investigated. UV-Vis studies show that the transparency of the oxalic acid added crystals decreased gradually. Thermal studies indicate that the decomposition temperatures of the crystal are decreased in oxalic acid added ADP crystals. It is observed from the dielectric measurements that the dielectric constant and dielectric loss increase with increase in temperature for all the crystals. Vicker's microhardness study reveals that the addition of higher concentration of oxalic acid decreases the hardness of the crystal. SHG efficiency of 1 mol% of oxalic acid is higher than the pure ADP.

Sources of optical distortion in rapidly grown crystals of KH2PO4

International Nuclear Information System (INIS)

De Yoreo, J.J.; Zaitseva, N.P.; Woods, B.W.; Land, T.A.; Rek, Z.U.

1995-01-01

We report results of x-ray topographic and optical measurements on KH 2 PO 4 crystals grown at rates of 5 to 30mm/day. We show that optical distortion in these crystals is caused primarily by 3 sources: dislocations, differences in composition between adjacent growth sectors of the crystal, and differences in composition between adjacent sectors of vicinal growth hillocks within a single growth sector of the crystal. We find that the compositional heterogeneities cause spatial variations in the refractive index and induced distortion of the transmitted wave front while large groups of dislocations are responsible for strain induced birefringence which leads to beam depolarization

The phase transformation and crystallization kinetics of (1 - x)Li2O-xNa2O-Al2O3-4SiO2 glasses

International Nuclear Information System (INIS)

Wang, Moo-Chin; Li, Wang-Long; Cheng, Chih-Wei; Chang, Kuo-Ming; Chen, Yong-Feng; Hsi, Chi-Shiung

2010-01-01

The phase transformation and crystallization kinetics of (1 - x)Li 2 O-xNa 2 O-Al 2 O 3 -4SiO 2 glasses have been studied by using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) analysis. The crystallization temperature at the exothermic peak increases from 1171 to 1212 K when the Na 2 O content increases from 0 to 0.6 mol. The crystalline phase is composed of spodumene crystallization when the Na 2 O content increases from 0 to 0.6 mol. The activation energy of spodumene crystallization decreases from 444.0 ± 22.2 to 284.0 ± 10.8 kJ mol -1 when the Na 2 O content increases from 0 to 0.4 mol. Moreover, the activation energy increases from 284.0 ± 10.8 to 446.0 ± 23.2 kJ mol -1 when the Na 2 O content increases from 0.4 to 0.6 mol. The crystallization parameters m and n approach 2, indicating that the surface nucleation and two-dimensional growth are dominant in (1 - x)Li 2 O-xNa 2 O-Al 2 O 3 -4SiO 2 glasses.

(E)-6-Amino-1,3-dimethyl-5-[(pyridin-2-yl-methyl-idene)amino]-pyrimidine-2,4(1H,3H)-dione.

Science.gov (United States)

Booysen, Irvin; Hlela, Thulani; Ismail, Muhammed; Gerber, Thomas; Hosten, Eric; Betz, Richard

2011-09-01

In the title compound, C(12)H(13)N(5)O(2), a Schiff-base-derived chelate ligand, the non-aromatic heterocycle and its substituents essentially occupy one common plane (r.m.s. of fitted non-H atoms = 0.0503 Å). The N=C bond is E-configured. Intra-cyclic angles in the pyridine moiety cover the range 117.6 (2)-124.1 (2)°. Intra- and inter-molecular N-H⋯N and N-H⋯O hydrogen bonds are observed in the crystal structure, as are intra- and inter-molecular C-H⋯O contacts which, in total, connect the mol-ecules into a three-dimensional network. The shortest ring-centroid-to-ring-centroid distance of 3.5831 (14) Å is between the two different types of six-membered rings.

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.

Photorefractive effect at 775 nm in doped lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Nava, G.; Minzioni, P.; Cristiani, I.; Degiorgio, V. [Department of Electrical, Computer, and Biomedical Engineering, and CNISM, University of Pavia, 27100 Pavia (Italy); Argiolas, N.; Bazzan, M.; Ciampolillo, M. V.; Pozza, G.; Sada, C. [Physics and Astronomy Departement, University of Padova, 35131 Padova (Italy)

2013-07-15

The photorefractive effect induced by 775-nm laser light on doped lithium niobate crystals is investigated by the direct observation in the far field of the transmitted-beam distortion as a function of time. Measurements performed at various Zr-doping concentrations and different light intensities show that the 775-nm light beam induces a steady-state photorefractive effect comparable to that of 532-nm light, but the observed build-up time of the photovoltaic field is longer by three-orders of magnitude. The 775-nm photorefractivity of lithium niobate crystals doped with 3 mol. % ZrO{sub 2} or with 5.5 mol. % MgO is found to be negligible.

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

Science.gov (United States)

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

2008-12-10

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

(μ-3-Acetyl-5-carboxyl­ato-4-methyl­pyrazolido-1:2κ4 N 2,O 3:N 1,O 5)-μ-chlorido-tetra­pyridine-1κ2 N,2κ2 N-chlorido-1κCl-dicopper(II) propan-2-ol solvate

Science.gov (United States)

Malinkin, Sergey; Penkova, Larisa; Pavlenko, Vadim A.; Haukka, Matti; Fritsky, Igor O.

2009-01-01

The title compound, [Cu2(C7H6N2O3)Cl2(C5H5N)4]·C3H8O, is a binuclear pyrazolate complex, in which the two CuII atoms have different coordination numbers and are connected by a bridging Cl atom. One CuII atom has a distorted square-pyramidal coordination environment formed by two pyridine N atoms, one bridging Cl atom and an N,O-chelating pyrazolate ligand. The other CuII atom adopts an octa­hedral geometry defined by two pyridine N atoms at the axial positions, two Cl atoms and the coordinated pyrazolate ligand in the equatorial plane. An O—H⋯O hydrogen bond connects the complex mol­ecules and propan-2-ol solvent mol­ecules into pairs. These pairs form columns along the a axis. PMID:21577764

Effect of γ-radiation on crystallization of polycaprolactone

International Nuclear Information System (INIS)

Zhu Guangming; Xu, Qianyong; Qin Ruifeng; Yan Hongxia; Liang Guozheng

2005-01-01

The crystallization behavior of radiation cross-linked poly(ε-caprolactone) (PCL) was studied by DSC at different cooling rates. The crystallization process was analyzed by the Ozawa equation and the Mo-Zhishen method that is developed from combining the Avrami equation and the Ozawa equation. It was concluded that the crystallization of radiation crosslinked PCL is governed by heterogeneous nucleation and single-dimension growth; the crystal fraction and rates of crystallization are related to the radiation dose and degree of cross-linking; the relationship between relative crystallinity and time follows the Ozawa equation: The higher the degree of crosslinking, the less the crystal velocity constant. The activation energy of crystallization for irradiated PCL is between 65 and 54kJ/mol

eMolTox: prediction of molecular toxicity with confidence.

Science.gov (United States)

Ji, Changge; Svensson, Fredrik; Zoufir, Azedine; Bender, Andreas

2018-03-07

In this work we present eMolTox, a web server for the prediction of potential toxicity associated with a given molecule. 174 toxicology-related in vitro/vivo experimental datasets were used for model construction and Mondrian conformal prediction was used to estimate the confidence of the resulting predictions. Toxic substructure analysis is also implemented in eMolTox. eMolTox predicts and displays a wealth of information of potential molecular toxicities for safety analysis in drug development. The eMolTox Server is freely available for use on the web at http://xundrug.cn/moltox. chicago.ji@gmail.com or ab454@cam.ac.uk. Supplementary data are available at Bioinformatics online.

Crystal structure and magnetism of UOsAl

Energy Technology Data Exchange (ETDEWEB)

Andreev, A.V., E-mail: andreev@fzu.cz [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Daniš, S. [Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Šebek, J.; Henriques, M.S.; Vejpravová, J. [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Gorbunov, D.I. [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum, Dresden-Rossendorf, D-01314 Dresden (Germany); Havela, L. [Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic)

2017-04-15

Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn{sub 2} type, space group P6{sub 3}/mmc, with lattice parameters a=536.4 pm, c=845.3 pm. Shortest inter-uranium distance 313 pm (along the c-axis) is considerably smaller than the Hill limit (340 pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10{sup −8} m{sup 3} mol{sup −1} (at T=2 K), which is slightly higher with magnetic field along the a-axis compared to the c-axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ=36 mJ mol{sup −1} K{sup −2}. - Highlights: • Crystal structure and magnetic properties were studied on single crystal of UOsAl with hexagonal structure of MgZn{sub 2} type. • Shortest inter-uranium distance 313 pm (along the c-axis) is considerably smaller than the Hill limit (340 pm). • UOsAl has paramagnetic ground state as the compounds with T=Fe and Ru, i.e. 3d and 4d analogues of Os.

Chimie des interactions moléculaires

OpenAIRE

Lehn, Jean-Marie

2010-01-01

Le cours de l’année 2008-2009 a porté sur « Autoorganisation et dynamique moléculaires ». Des cours ont été donnés à l’Université de Strasbourg (3 h), à l’Université Charles de Prague (3 h) et à la City University de Hong Kong (3 h). Cours au Collège de France : Autoorganisation et dynamique moléculaires Introduction Le cours a porté sur l’évolution de la chimie supramoléculaire vers la chimie dynamique constitutionnelle (CDC) et la chimie adaptative. Du fait de la labilité des interactions n...

Spectrophotometric determination of boron by solvent extraction with hydrobenzoin and crystal violet

International Nuclear Information System (INIS)

Sato, Shigeya; Uchikawa, Sumio

1982-01-01

A highly sensitive and simple method for the spectrophotometric determination of boron was developed. Boron was found to react with hydrobenzoin in weak alkaline medium to form a complex anion extractable into benzene with crystal violet, and the measurement of the absorbance of crystal violet in the extract at 600 nm enabled the determination of boron indirectly. The recommended procedure is as follows: Take an aliquot of the boron solution (2.0 x 10 - 4 mol l - 1 ) into a 10-ml test tube. Add 1 ml of carbonate buffer solution (pH 9.4) and 0.25 ml of crystal violet solution (1.0 x 10 - 2 mol l - 1 ), and dilute the mixed solution to 4 ml with deionized water. Shake the solution with 4 ml of benzene solution containing hydrobenzoin (2.0 x 10 - 2 mol l - 1 ) for 2 min. Measure the absorbance of the organic phase at 600 nm using a 10-mm glass cell against benzene. The calibration curve obeyed Beer's law on the concentration range from 2.5 x 10 - 6 mol l - 1 to 2.5 x 10 - 5 mol l - 1 of boron, and the apparent molar absorptivity was 3.0 x 10 4 l mol - 1 cm - 1 at 20 0 C. It was found that many kinds of co-existing ions interfered with the determination. However, this method was applicable to the determination of boron in sea water when chloride ion and cations such as Ca(II) and Mg(II) were previously eliminated by treating the sample solution with Ag 2 O and cation exchanger resin. The proposed method is a very simple and rapid one, because this method does not require apparatus other than common laboratories and the evaporation to dryness of sample or removal of the excess of reagent. (author)

Development of a standard reference material containing 22 chlorinated hydrocarbon gases at 1 μmol/mol in nitrogen.

Science.gov (United States)

Li, Ning; Du, Jian; Yang, Jing; Fan, Qiang; Tian, Wen

2017-11-01

A gas standard mixture containing 22 chlorinated hydrocarbons in high purity nitrogen was prepared using a two-step weighing method and a gasifying apparatus developed in-house. The concentration of each component was determined using a gas chromatograph with flame ionization detection (GC/FID). Linear regression analysis of every component was performed using the gas standard mixture with concentrations ranging from 1 to 10 μmol/mol, showing the complete gasification of volatile organic compound (VOCs) species in a selected cylinder. Repeatability was also examined to ensure the reliability of the preparation method. In addition, no significant difference was observed between domestic treated and imported treated cylinders, which were conducive to reduction of the cost of raw materials. Moreover, the results of stability testing at different pressures and long-term stability tests indicated that the gas standard at 1 μmol/mol level with relative expanded uncertainties of 5% was stable above 2 MPa for a minimum of 12 months. Finally, a quantity comparison was conducted between the gas standard and a commercial gas standard from Scott Specialty Gases (now Air Liquide America Specialty Gases). The excellent agreement of every species suggested the favorable accuracy of our gas standard. Therefore, this reference material can be applied to routine observation of VOCs and for other purposes.

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

Science.gov (United States)

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

2009-01-01

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

Bis(N-ethyl-N-methyl?dithio?carbamato-?2 S,S?)diphenyl?tin(IV)

OpenAIRE

Muthalib, Amirah Faizah; Baba, Ibrahim; Ng, Seik Weng

2010-01-01

The dithio?carbamate anions in the title compound, [Sn(C6H5)2(C4H8NS2)2], chelate to the SnIV atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol?ecule lies across a twofold rotation axis.

Bis(N-isopropyl-N-methyl-dithio-carbamato-κS,S')diphenyl-tin(IV).

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Farina, Yang; Ng, Seik Weng

2010-03-03

The dithio-carbamate anions in the title compound, [Sn(C(6)H(5))(2)(C(5)H(10)NS(2))(2)], chelate to the Sn(IV) atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol-ecule lies across a twofold rotation axis.

Bis(N-isopropyl-N-methyl?dithio?carbamato-?2 S,S?)diphenyl?tin(IV)

OpenAIRE

Muthalib, Amirah Faizah; Baba, Ibrahim; Farina, Yang; Ng, Seik Weng

2010-01-01

The dithio?carbamate anions in the title compound, [Sn(C6H5)2(C5H10NS2)2], chelate to the SnIV atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol?ecule lies across a twofold rotation axis.

Bis(N-ethyl-N-methyl-dithio-carbamato-κS,S')diphenyl-tin(IV).

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Ng, Seik Weng

2010-03-03

The dithio-carbamate anions in the title compound, [Sn(C(6)H(5))(2)(C(4)H(8)NS(2))(2)], chelate to the Sn(IV) atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol-ecule lies across a twofold rotation axis.

Nucleation and crystallization behaviors of nano-crystalline lithium–mica glass–ceramic prepared via sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Tohidifar, M.R. [Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Alizadeh, P., E-mail: p-alizadeh@modares.ac.ir [Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Riello, P. [Department of Molecular Sciences and Nanosystems, University of Ca’Foscari, Venice (Italy)

2012-06-15

Graphical abstract: The effects of nucleation and crystallization treatments on nano-crystalline lithium–mica glass–ceramic, synthesized by sol–gel technique, were investigated. It was found that MgF{sub 2} crystals act as nuclei centers for the mica crystallization so that a large quantity of mica crystallites was obtained following nucleation process. The crystallization activation energy for both the un-nucleated and nucleated samples was measured as 400.2 and 229.6 kJ mol{sup −1}, respectively. The calculated Avrami exponents demonstrated that the growth mechanism of mica crystallites changes from the needle-like to three-dimensional growth with applying the appropriate nucleation treatment ▪. Highlights: ► Crystallization temperature shifts to 625 from 680 °C following nucleation process. ► Activation energy of crystallization for the nucleated specimen is 229.6 kJ mol{sup −1}. ► Crystallization activation energy for the un-nucleated specimen is 400.2 kJ mol{sup −1}. ► Needle-like growth is predominant growth mechanism for un-nucleated sample. ► Three-dimensional growth is predominant growth mechanism for nucleated sample. -- Abstract: The paper investigates the effects of nucleation and crystallization treatments on nano-crystalline lithium–mica glass–ceramics, taking the composition LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} (x = 0.5) and 8 mass% MgF{sub 2} synthesized by sol–gel technique. Here, X-ray diffraction, thermal analysis and transmission electron microscopy were used to assess the structural evolutions of as-synthesized nano-crystalline lithium–mica glass–ceramics. It was found that MgF{sub 2} crystals perform as nuclei centers for the mica crystallization hence; a large quantity of mica crystallites obtained following the nucleation process at 400 °C for 12 h. For both the un-nucleated and nucleated samples, the crystallization activation energy was measured as 400.2 and 229.6 kJ mol{sup −1

A new polymer electrolyte based on a discotic liquid crystal triblock copolymer

International Nuclear Information System (INIS)

Stoeva, Zlatka; Lu, Zhibao; Ingram, Malcolm D.; Imrie, Corrie T.

2013-01-01

A discotic liquid crystal triblock copolymer consisting of a central main chain triphenylene-based liquid crystal block capped at both ends by blocks of poly(ethylene oxide) (PEO) (M W = 2000 g mol −1 ) has been doped with lithium perchlorate in an EO:Li 6:1 ratio. The polymer electrolyte exhibits a phase separated morphology consisting of a columnar hexagonal liquid crystal phase and PEO-rich regions. The polymer electrolyte forms self-supporting, solid-like films. The ionic conductivity on initial heating of the sample is very low below ca. 60 °C but increases rapidly above this temperature. This is attributed to the melting of crystalline PEO-rich regions. Crystallisation is suppressed on cooling, and subsequent heating cycles exhibit higher conductivities but still less than those measured for the corresponding lithium perchlorate complex in poly(ethylene glycol) (M W = 2000 g mol −1 ). Instead the triblock copolymer mimics the behaviour of high molecular weight poly(ethylene oxide) (M W = 300,000 g mol −1 ). This is attributed, in part, to the anchoring of the short PEG chains to the liquid crystal block which prevents their diffusion through the sample. Temperature and pressure variations in ion mobility indicate that the ion transport mechanism in the new material is closely related to that in the conventional PEO-based electrolyte, opening up the possibility of engineering enhanced conductivities in future

Mol - Research Division Report 1986 - 2

International Nuclear Information System (INIS)

Delbarre, J.

1987-03-01

This report covers the research activities carried out at the SCK-CEN, Mol during the second semester of 1986. It deals with chemistry, chemical engineering, biology, nuclear metrology, analytical chemistry. (MCB)

INTERACTION OF LASER RADIATION WITH MATTER: Influence of Ca and Pb impurities on the bulk optical strength of ultrapure NaCl and KCl crystals

Science.gov (United States)

Vinogradov, An V.; Voszka, R.; Kovalev, Valerii I.; Faĭzullov, F. S.; Janszky, J.

1987-06-01

A significant increase (by a factor of about 3) of the bulk damage threshold in the case of interaction of CO2 laser radiation pulses with ultrapure NaCl and KCl crystals grown in a reactive atmosphere was observed on introduction of divalent metal ions Ca and Pb in concentrations of 10-5-10-6 mol/mol. Impurities were introduced in concentrations of 10-8-10-3 and 2×10-7-10-4 mol/mol into the melts of KCl and NaCl, respectively. The concentration of other impurities (including OH) did not exceed ~10-6 mol/mol. A physical model was developed to account for the observed dependence on the basis of an analogy between a system of colloidal particles and F centers in a crystal and a liquid-vapor system.

catena-Poly[bis-(sulfamethoxazolium) [[trichloridocadmate(II)]-μ-chlorido] monohydrate].

Science.gov (United States)

Subashini, Annamalai; Muthiah, Packianathan Thomas; Bocelli, Gabriele; Cantoni, Andrea

2007-12-21

In the title compound, {(C(10)H(12)N(3)O(3)S)(2)[CdCl(4)]·H(2)O}(n), the Cd(II) atom is five-coordinate with a distorted trigonal-bipyramidal geometry formed by chloride ions. The Cd atom and two of the Cl atoms lie on a mirror plane. The cation is protonated on the amino group N atom; it is not coordinated to cadmium, but is hydrogen bonded to the chlorido ligands. Each water mol-ecule bridges two chlorido ligands, generating ring motifs along the -Cd-Cl-Cd- chains. The isoxazole unit and the amide groups are linked through a pair of N-H⋯N hydrogen bonds. The crystal structure is stabilized by N-H⋯O, O-H⋯Cl, C-H⋯N, N-H⋯Cl and C-H⋯O hydrogen bonds.

catena-Poly[bis­(sulfamethoxazolium) [[trichloridocadmate(II)]-μ-chlorido] monohydrate

Science.gov (United States)

Subashini, Annamalai; Muthiah, Packianathan Thomas; Bocelli, Gabriele; Cantoni, Andrea

2008-01-01

In the title compound, {(C10H12N3O3S)2[CdCl4]·H2O}n, the CdII atom is five-coordinate with a distorted trigonal–bipyramidal geometry formed by chloride ions. The Cd atom and two of the Cl atoms lie on a mirror plane. The cation is protonated on the amino group N atom; it is not coordinated to cadmium, but is hydrogen bonded to the chlorido ligands. Each water mol­ecule bridges two chlorido ligands, generating ring motifs along the –Cd—Cl—Cd– chains. The isoxazole unit and the amide groups are linked through a pair of N—H⋯N hydrogen bonds. The crystal structure is stabilized by N—H⋯O, O—H⋯Cl, C—H⋯N, N—H⋯Cl and C—H⋯O hydrogen bonds. PMID:21200590

Crystallization of poly(ethyleneterephthalate) modified with codiols

NARCIS (Netherlands)

Bouma, K.; Regelink, Marc; Gaymans, R.J.

2001-01-01

The nucleation of poly(ethylene terephthalate) (PET) by codiols and olefinic segments was studied. The codiols 1,5-pentanediol, 1,8-octanediol, 2,5-hexanediol, and 1,3-dihydroxymethyl benzene were copolymerized into PET in a concentration range of 0-10 mol %. The melting (Tm), crystallization (Tc),

Hydrothermal growth of PbSO4 (Anglesite) single crystal

International Nuclear Information System (INIS)

Kikuta, Ko-ichi; Yoneta, Yasuhito; Yogo, Toshinobu; Hirano, Shin-ichi

1994-01-01

Hydrothermal growth of single crystals of PbSO 4 , which is known as a natural mineral called anglesite, was investigated. Lead nitrate and nitric acid solutions were found to be useful for the growth of angle-site on the basis of the experimental results on the dissolution behavior. Relatively large euhedral single crystals bound by {210} and {101} planes were successfully grown in 1.5 mol/kg Pb(NO 3 ) 2 at 400degC and 100 MPa. Optical characterization revealed that the grown anglesite crystals can be useful for scintillators material. (author)

Ionic conductivity ageing behaviour of 10 mol.% Sc2O3–1 mol.% CeO2–ZrO2 ceramics

DEFF Research Database (Denmark)

Omar, Shobit; Bonanos, Nikolaos

2010-01-01

The long-term ionic conductivity behaviour of samples of zirconia co-doped with 10 mol.% of Sc2O3 and 1 mol.% CeO2 is evaluated in oxidizing and reducing atmospheres at 600 °C. After 3,000 h, the sample kept in reducing atmospheres exhibits 20% loss in the ionic conductivity, while the sample kep...

Preparation of TiO2 Nanocrystallite Powders Coated with 9 mol% ZnO for Cosmetic Applications in Sunscreens

Directory of Open Access Journals (Sweden)

Moo-Chin Wang

2012-02-01

Full Text Available The preparation of TiO2 nanocrystallite powders coated with and without 9 mol% ZnO has been studied for cosmetic applications in sunscreens by a co-precipitation process using TiCl4 and Zn(NO32·6H2O as starting materials. XRD results show that the phases of anatase TiO2 and rutile TiO2 coexist for precursor powders without added ZnO (T-0Z and calcined at 523 to 973 K for 2 h. When the T-0Z precursor powders are calcined at 1273 K for 2 h, only the rutile TiO2 appears. In addition, when the TiO2 precursor powders contain 9 mol% ZnO (T-9Z are calcined at 873 to 973 K for 2 h, the crystallized samples are composed of the major phase of rutile TiO2 and the minor phases of anatase TiO2 and Zn2Ti3O8. The analyses of UV/VIS/NIR spectra reveal that the absorption of the T-9Z precursor powders after being calcined has a red-shift effect in the UV range with increasing calcination temperature. Therefore, the TiO2 nanocrystallite powders coated with 9 mol% ZnO can be used as the attenuate agent in the UV-A region for cosmetic applications in sunscreens.

Bis(N-ethyl-N-methyl­dithio­carbamato-κ2 S,S′)diphenyl­tin(IV)

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Ng, Seik Weng

2010-01-01

The dithio­carbamate anions in the title compound, [Sn(C6H5)2(C4H8NS2)2], chelate to the SnIV atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol­ecule lies across a twofold rotation axis. PMID:21580470

Bis(N-isopropyl-N-methyl­dithio­carbamato-κ2 S,S′)diphenyl­tin(IV)

Science.gov (United States)

Muthalib, Amirah Faizah; Baba, Ibrahim; Farina, Yang; Ng, Seik Weng

2010-01-01

The dithio­carbamate anions in the title compound, [Sn(C6H5)2(C5H10NS2)2], chelate to the SnIV atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol­ecule lies across a twofold rotation axis. PMID:21580469

Mol - Research Division report 1987 - 2

International Nuclear Information System (INIS)

Delbarre, J.

1988-03-01

This report covers the research activities at the SCK-CEN, MOl, during the second semester of 1987. It deals with materials physics, nuclear physics, metallurgy, ceramics, nuclear chemistry, chemical engineering, biology, nuclear metrology and analytical chemistry. (MCB)

Mol - Research Division report 1987 - 1

International Nuclear Information System (INIS)

Delbarre, J.

1987-10-01

This report covers the research activities at the SCK-CEN, Mol, during the first semester of 1987. It deals with material physics, nuclear physics, metallurgy, ceramics, nuclear chemistry, chemical engineering, biology, nuclear metrology and analytical chemistry. (MCB)

The phase transformation and crystallization kinetics of (1 - x)Li{sub 2}O-xNa{sub 2}O-Al{sub 2}O{sub 3}-4SiO{sub 2} glasses

Energy Technology Data Exchange (ETDEWEB)

Wang, Moo-Chin [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Li, Wang-Long [Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Cheng, Chih-Wei [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming; Chen, Yong-Feng [Department of Electrical Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hsi, Chi-Shiung, E-mail: chsi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miaoli 36003, Taiwan (China)

2010-09-01

The phase transformation and crystallization kinetics of (1 - x)Li{sub 2}O-xNa{sub 2}O-Al{sub 2}O{sub 3}-4SiO{sub 2} glasses have been studied by using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) analysis. The crystallization temperature at the exothermic peak increases from 1171 to 1212 K when the Na{sub 2}O content increases from 0 to 0.6 mol. The crystalline phase is composed of spodumene crystallization when the Na{sub 2}O content increases from 0 to 0.6 mol. The activation energy of spodumene crystallization decreases from 444.0 {+-} 22.2 to 284.0 {+-} 10.8 kJ mol{sup -1} when the Na{sub 2}O content increases from 0 to 0.4 mol. Moreover, the activation energy increases from 284.0 {+-} 10.8 to 446.0 {+-} 23.2 kJ mol{sup -1} when the Na{sub 2}O content increases from 0.4 to 0.6 mol. The crystallization parameters m and n approach 2, indicating that the surface nucleation and two-dimensional growth are dominant in (1 - x)Li{sub 2}O-xNa{sub 2}O-Al{sub 2}O{sub 3}-4SiO{sub 2} glasses.

Crystal structure of N′-hydroxypyrimidine-2-carboximidamide

Directory of Open Access Journals (Sweden)

Nithianantham Jeeva Jasmine

2014-10-01

Full Text Available The title compound, C5H6N4O, is approximately planar, with an angle of 11.04 (15° between the planes of the pyrimidine ring and the non-H atoms of the carboximidamide unit. The molecule adopts an E configuration about the C=N double bond. In the crystal, adjacent molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers with an R22(10 ring motif. The dimers are further linked via N—H...N and O—H...N hydrogen bonds into a sheet structure parallel to the ac plane. The crystal structure also features N—H...O and weak C—H...O hydrogen bonds and offset π–π stacking interactions between adjacent pyrimidine rings [centroid–centroid distance = 3.622 (1 Å].

Non-isothermal crystallization kinetics and phase transformation of Bi2O3-SiO2 glass-ceramics

Directory of Open Access Journals (Sweden)

Guo H.W.

2011-01-01

Full Text Available The Bi2O3-SiO2 (BS glass-ceramics were prepared by melt-quench technique, and the crystallization kinetics and phase transformation behavior were investigated in accordance with Kissinger and Johson-Mehl-Avrami equation, DSC, XRD and SEM. The results show that in the heat treatment process (or termed as re-crystallizing process Bi2SiO5 and Bi4Si3O12 crystals were found consequently. Respectively, the crystallization activation energies of the two crystals are Ep1=14.8kJ/mol and Ep2=34.1kJ/mol. And the average crystallization index of n1=1.73 and n2=1.38 suggested volume nucleation, one-dimensional growth and surface nucleation, one-dimensional growth from surface to the inside respectively. The meta-stable needle-like Bi2SiO5 crystals are easily to be transformed into stable prismatic Bi4Si3O12 crystals. By quenching the melt and hold in 850°C for 1h, the homogenous single Bi4Si3O12 crystals were found in the polycrystalline phase of the BS glassceramics system.

Mol - Research Division Report 1986 - 1

International Nuclear Information System (INIS)

Delbarre, J.; Assche, P. van

1986-11-01

This report covers the research activities carried out at the SCK-CEN, Mol from the middle of 1985 till mid 1986. It deals with materials science, metallurgy, ceramics, nuclear chemistry, chemical engineering, biology, nuclear meteorology and analytical chemistry. (MCB)

Crystallization Kinetics of Barium and Strontium Aluminosilicate Glasses of Feldspar Composition

Science.gov (United States)

Hyatt, Mark J.; Bansal, Narottam P.

1994-01-01

Crystallization kinetics of BaO.Al2O3.2SiO2 (BAS) and SrO.Al2O3.2SiO2 (SAS) glasses in bulk and powder forms have been studied by non-isothermal differential scanning calorimetry (DSC). The crystal growth activation energies were evaluated to be 473 and 451 kJ/mol for bulk samples and 560 and 534 kJ/mol for powder specimens in BAS and SAS glasses, respectively. Development of crystalline phases on thermal treatments of glasses at various temperatures has been followed by powder x-ray diffraction. Powder samples crystallized at lower temperatures than the bulk and the crystallization temperature was lower for SAS glass than BAS. Crystallization in both glasses appeared to be surface nucleated. The high temperature phase hexacelsian, MAl2Si2O8 (M = Ba or Sr), crystallized first by nucleating preferentially on the glass surface. Also, monoclinic celsian does not nucleate directly in the glass, but is formed at higher temperatures from the transformation of the metastable hexagonal phase. In SAS the transformation to monoclinic celsian occurred rapidly after 1 h at 1100 C. In contrast, in BAS this transformation is sluggish and difficult and did not go to completion even after 10 h heat treatment at 1400 C. The crystal growth morphologies in the glasses have been observed by optical microscopy. Some of the physical properties of the two glasses are also reported.

Comparison of measurement capability with 100 μmol/mol of carbon monoxide in nitrogen

Science.gov (United States)

Lee, Jeongsoon; Lee, JinBok; Lim, Jeongsik; Tarhan, Tanıl; Liu, Hsin-Wang; Aggarwal, Shankar G.

2018-01-01

Carbon monoxide (CO) in nitrogen was one of the first types of gas mixtures used in an international key comparison. The comparison dates back to 1998 (CCQMK1a) [1]. Since then, many National Metrology Institutes (NMIs) have developed calibration and measurement capabilities (CMCs) for these mixtures. Recently, NMIs in the APMP region have actively participated in international comparisons to provide domestic services. At the 2013 APMP meeting, several NMIs requested a CO comparison to establish CO/N2 certification for industrial applications, which was to be coordinated by KRISS. Consequently, this comparison provides an opportunity for APMP regional NMIs to develop CO/N2 CMC claims. The goal of this supplementary comparison is to support CMC claim for carbon monoxide in the N2 range of 50–2000 μmol/mol. An extended range may be supported as described in the GAWG strategy for comparisons and CMC claims. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Crystallization behavior of (1 - x)Li2O.xNa2O.Al2O3.4SiO2 glasses

International Nuclear Information System (INIS)

Wang, Moo-Chin; Cheng, Chih-Wei; Chang, Kuo-Ming; Hsi, Chi-Shiung

2010-01-01

The crystallization behavior of the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and energy dispersive spectroscopy (EDS). The crystalline phase was composed of β-spodumene. The isothermal crystallization kinetics of β-spodumene from the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses has also been studied by a quantitative X-ray diffraction method. The activation energy of β-spodumene formation decreases from 359.2 to 317.8 kJ/mol when the Na 2 O content increases from 0 to 0.4 mol and it increases from 317.8 to 376.9 kJ/mol when the Na 2 O content increases from 0.4 to 0.6 mol. The surface nucleation and plate-like growth were dominant in the crystallization of the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses.

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

Directory of Open Access Journals (Sweden)

Hani Albetran

2018-02-01

Full Text Available The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10 kJ/mol for the titanium-to-anatase transformation, and 207 (17 kJ/mol for the anatase-to-rutile transformation were estimated.

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes.

Science.gov (United States)

Albetran, Hani; Vega, Victor; Prida, Victor M; Low, It-Meng

2018-02-23

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10) kJ/mol for the titanium-to-anatase transformation, and 207 (17) kJ/mol for the anatase-to-rutile transformation were estimated.

Improvements of uniformity and stoichiometry for zone-leveling Czochralski growth of MgO-doped LiNbO3 crystals

International Nuclear Information System (INIS)

Tsai, C.B.; Hsu, W.T.; Shih, M.D.; Tai, C.Y.; Hsieh, C.K.; Hsu, W.C.; Hsu, R.T.; Lan, C.W.

2006-01-01

The zone-leveling Czochralski (ZLCz) technique is a continuous feeding process and can be used for the growth of near-stoichiometric lithium niobate (SLN) single crystals. However, the finite crucible length can cause the variation of the zone length and thus the composition and stoichiometry, especially in the growth of a large diameter crystal. To solve the problems, several approaches were proposed for the growth of 4 cm-diameter 1 mol% MgO-doped SLN. The modification of the hot zone to minimize the zone variation was found useful for the uniformity, but the stoichiometry was inadequate even with the zone composition up to 60 mol% Li 2 O. A Li-excess feed was further used and a good Li/Nb ratio was obtained. Adding K 2 O (16 mol%) into the solution zone was useful as well, but it was inferior to using the Li-excess feed. In addition, a much lower growth rate was needed for getting an inclusion-free crystal

Review of Cytoskeleton Research in Cell Differentiation and Development.

Science.gov (United States)

1987-09-10

tetrameric mol- molecule and the corresponding site on ecule of dumbbell-like structure. Plec - ,MAP’s underwent molecular coevolution and tin’s globular...coworkers as plectin’s interaction by dlffe~ent MAP’s. Limited proteolysis partners. Thus, Wiche suggests that plec - of tubulin and MAP’s to analyze the

Octa-akis(4-amino-pyridine)-1κN,2κN-aqua-2κO-μ-carbonato-1:2κO,O':O''-dinickel(II) dichloride penta-hydrate.

Science.gov (United States)

Fun, Hoong-Kun; Sinthiya, A; Jebas, Samuel Robinson; Ravindran Durai Nayagam, B; Alfred Cecil Raj, S

2008-10-18

In the title compound, [Ni(2)(CO(3))(C(5)H(6)N(2))(8)(H(2)O)]Cl(2)·5H(2)O, one of the the Ni(II) ions is six-coordinated in a distorted octa-hedral geometry, with the equatorial plane defined by four pyridine N atoms from four amino-pyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other Ni(II) ion is also six-coordinated, by four other pyridine N atoms from four other amino-pyridine ligands and two carbonate O atoms to complete a distorted octa-hedral geometry. In the crystal structure, mol-ecules are linked into an infinite three-dimensional network by O-H⋯O, N-H⋯Cl, N-H⋯O, O-H⋯N, C-H⋯O, C-H⋯N and C/N-H⋯π inter-actions involving the pyridine rings.

Antibacterial Activity of Orthodontic Cement Containing Quaternary Ammonium Polyethylenimine Nanoparticles Adjacent to Orthodontic Brackets.

Science.gov (United States)

Sharon, Eldad; Sharabi, Revital; Eden, Adi; Zabrovsky, Asher; Ben-Gal, Gilad; Sharon, Esi; Pietrokovski, Yoav; Houri-Haddad, Yael; Beyth, Nurit

2018-03-27

Enamel demineralization is a common problem found in patients using orthodontic devices, such as orthodontic braces. It was found that Streptoccocus mutans growth increases adjacent to orthodontic devices, which may result in caries development. Incorporated antibacterial quaternary ammonium polyethylenimine (QPEI) nanoparticles were previously shown to be highly efficacious against various bacteria. Combining antibacterial materials in orthodontic cement may be advantageous to prevent bacterial outgrowth adjacent to orthodontic brackets. The aim was to evaluate the efficiency of orthodontic cement containing QPEI nanoparticles in reducing S. mutans and Lactobacillus casei outgrowth adjacent to orthodontic brackets. Orthodontic brackets were bonded to the buccal surfaces of extracted lower incisors. The antibacterial effect on S. mutans and L. casei outgrowth of Neobond bracket adhesive orthodontic cement with and without QPEI nanoparticles was compared. The antibacterial effect was evaluated using crystal violet staining and bacterial count (CFU/mL). The teeth in the experimental group, with the QPEI nanoparticles cement, showed significantly lower optical density (OD) values and CFU counts of S. mutans and L. casei than the teeth in the control group ( p brackets.

Optical properties of Pb-based aggregated phases in CsBr crystal

Energy Technology Data Exchange (ETDEWEB)

Voloshinovskii, A. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Myagkota, S. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Garapyn, I. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Stryganyuk, G. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Rodnyi, P. [St. Petersburg State Polytechnical University, 29 Polyteknicheskaya Str., 195251 St. Petersburg (Russian Federation); Eijk, C.W.E. van [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail: vaneijk@iri.tudelft.nl

2005-01-01

The emission and excitation spectra as well as luminescence decay kinetics of a CsBr:Pb (1.0mol%) crystal have been measured under pulsed synchrotron radiation excitation. The heat-treated ({approx}200 deg. C) crystal shows evidence of single lead centres and aggregated phases such as CsPbBr3 nanocrystals. The latter have been identified from comparison of the spectral-kinetic characteristics of the CsPbBr3 aggregated phases and single crystals. The process of energy transfer from the host to the aggregates is considered.

Optical properties of Pb-based aggregated phases in CsBr crystal

International Nuclear Information System (INIS)

Voloshinovskii, A.; Myagkota, S.; Garapyn, I.; Stryganyuk, G.; Rodnyi, P.; Eijk, C.W.E. van

2005-01-01

The emission and excitation spectra as well as luminescence decay kinetics of a CsBr:Pb (1.0mol%) crystal have been measured under pulsed synchrotron radiation excitation. The heat-treated (∼200 deg. C) crystal shows evidence of single lead centres and aggregated phases such as CsPbBr3 nanocrystals. The latter have been identified from comparison of the spectral-kinetic characteristics of the CsPbBr3 aggregated phases and single crystals. The process of energy transfer from the host to the aggregates is considered

Crystallization and spectroscopic properties investigations of Er3+ doped transparent glass ceramics containing CaF2

International Nuclear Information System (INIS)

Hu Zhongjian; Wang Yuansheng; Ma En; Bao Feng; Yu Yunlong; Chen Daqin

2006-01-01

Transparent oxyfluoride glass ceramics with composition of 45SiO 2 -25Al 2 O 3 -5CaCO 3 -10NaF-15CaF 2 -0.5ErF 3 (in mol%) were developed through controlled crystallization of melt-quenched glass. Non-isothermal crystallization kinetics investigation showed that the average apparent activation energy E a and Avrami exponent n are about 283 kJ/mol and 2.22, respectively, indicating the crystallization a three dimensional crystal growth process controlled by the diffusion with a decreasing nucleation rate. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) observation revealed the precipitation of CaF 2 crystallites sized about 15 nm among the glass matrix after heat-treatment at 650 deg. C for 2 h. For as-made glass, no upconversion signals were detected when excited with a 30 mW diode laser at 980 nm, while strong upconversion emissions at 545, 660 and 800 nm were obtained for transparent glass ceramic under similar excitation condition

Skew-adjacency matrices of graphs

NARCIS (Netherlands)

Cavers, M.; Cioaba, S.M.; Fallat, S.; Gregory, D.A.; Haemers, W.H.; Kirkland, S.J.; McDonald, J.J.; Tsatsomeros, M.

2012-01-01

The spectra of the skew-adjacency matrices of a graph are considered as a possible way to distinguish adjacency cospectral graphs. This leads to the following topics: graphs whose skew-adjacency matrices are all cospectral; relations between the matchings polynomial of a graph and the characteristic

Improved ferroelectric and pyroelectric parameters in iminodiacetic acid doped TGS crystal

Science.gov (United States)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2010-01-01

Single crystals of Iminodiacetic acid (HN(CH 2COOH) 2) doped Triglycine sulphate (IDATGS) has been grown from aqueous solution at constant temperature by slow evaporation technique. The concentration of the dopant in the TGS solution was 2 mol%. The X-ray diffraction analysis indicates that there is significant change in the lattice parameters compared to pure TGS crystal. The IDATGS crystal has larger transition temperature and observed higher and uniform figure of merit over most part of the ferroelectric phase. These crystals also exhibit higher internal bias field and micro-hardness number compared to pure TGS. Therefore IDATGS may be a potential material for IR detectors.

Crystal structure of poly[N,N-diethyl-2-hy-droxy-ethan-1-aminium [μ3-cyanido-κ(3) C:C:N-di-μ-cyanido-κ(4) C:N-dicuprate(I)

Science.gov (United States)

Corfield, Peter W R; Cleary, Emma; Michalski, Joseph F

2016-07-01

In the title compound, {(C6H16NO)[Cu2(CN)3]} n , the cyanide groups link the Cu(I) atoms into an open three-dimensional anionic network, with the mol-ecular formula Cu2(CN)3 (-). One Cu(I) atom is tetra-hedrally bound to four CN groups, and the other Cu(I) atom is bonded to three CN groups in an approximate trigonal-planar coordination. The tetra-hedrally coordinated Cu(I) atoms are linked into centrosymmetric dimers by the C atoms of two end-on bridging CN groups which bring the Cu(I) atoms into close contact at 2.5171 (7) Å. Two of the cyanide groups bonded to the Cu(I) atoms with trigonal-planar surrounding link the dimeric units into columns along the a axis, and the third links the columns together to form the network. The N,N-di-ethyl-ethano-lamine mol-ecules used in the synthesis have become protonated at the N atoms and are situated in cavities in the network, providing charge neutrality, with no covalent inter-actions between the cations and the anionic network.

MolTalk--a programming library for protein structures and structure analysis.

Science.gov (United States)

Diemand, Alexander V; Scheib, Holger

2004-04-19

Two of the mostly unsolved but increasingly urgent problems for modern biologists are a) to quickly and easily analyse protein structures and b) to comprehensively mine the wealth of information, which is distributed along with the 3D co-ordinates by the Protein Data Bank (PDB). Tools which address this issue need to be highly flexible and powerful but at the same time must be freely available and easy to learn. We present MolTalk, an elaborate programming language, which consists of the programming library libmoltalk implemented in Objective-C and the Smalltalk-based interpreter MolTalk. MolTalk combines the advantages of an easy to learn and programmable procedural scripting with the flexibility and power of a full programming language. An overview of currently available applications of MolTalk is given and with PDBChainSaw one such application is described in more detail. PDBChainSaw is a MolTalk-based parser and information extraction utility of PDB files. Weekly updates of the PDB are synchronised with PDBChainSaw and are available for free download from the MolTalk project page http://www.moltalk.org following the link to PDBChainSaw. For each chain in a protein structure, PDBChainSaw extracts the sequence from its co-ordinates and provides additional information from the PDB-file header section, such as scientific organism, compound name, and EC code. MolTalk provides a rich set of methods to analyse and even modify experimentally determined or modelled protein structures. These methods vary in complexity and are thus suitable for beginners and advanced programmers alike. We envision MolTalk to be most valuable in the following applications:1) To analyse protein structures repetitively in large-scale, i.e. to benchmark protein structure prediction methods or to evaluate structural models. The quality of the resulting 3D-models can be assessed by e.g. calculating a Ramachandran-Sasisekharan plot.2) To quickly retrieve information for (a limited number of

Optical properties and crystallization kinetics of (TeO{sub 2})(ZnO)(TiO{sub 2}) glasses

Energy Technology Data Exchange (ETDEWEB)

Kabalci, Idris [Department of Physics Education, Education Faculty, Harran University, Sanliurfa (Turkey); Koerpe, Nese Oeztuerk [Department of Materials Science, Eskisehir, Osmangazi University, Eskisehir (Turkey); Duran, Tugba; Oezdemir, Mustafa [Department of Physics, Science and Arts Faculty, Marmara University, Istanbul (Turkey)

2011-09-15

Ternary tellurite based glasses in the (TeO{sub 2})(ZnO)(TiO{sub 2}) system were prepared and its optical properties and crystallization kinetics investigated by using UV-VIS spectrophotometer and differential thermal analyzer (DTA). All the glasses were transparent from visible to near infrared region for different ZnO glass compositions (x=0.05, 0.10, 0.20, and 0.30 mol). In the experiment, optical band gap and Urbach energies were estimated from the optical absorption spectra between 400 and 800 nm wavelength region. The observed results confirm that the addition of ZnO glass composition from 0.05 to 0.30 mol increases the optical band gap energy from 2.94 to 3.0 eV. In addition, glass transition (T{sub g}), crystallization (T{sub p}) and melting temperature (T{sub m}) were determined by using the DTA plots. Finally, DTA results obtained with a heating rate of 20 C/min show that the peak crystallization temperature increases from 463 to 533 C as the ZnO content increases from 0.05 to 0.30 mol (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The Effect of Filler-Polymer Interactions on Cold-Crystallization Kinetics in Crosslinked, Silica Filled PDMS/PDPS Copolymer Melts

International Nuclear Information System (INIS)

Chien, A; DeTeresa, S; Thompson, L; Cohenour, R; Balazs, B; Maxwell, R S

2006-01-01

Crystallization in a series of variable crosslink density poly(dimethyl-diphenyl) siloxanes random block copolymers reinforced through a mixture of precipitated and fumed silica fillers has been studied by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and X-ray Diffraction (XRD). The silicone composite studied was composed of 94.6 mol% Dimethoylsiloxane, 5.1 mol% diphenylsiloxane, and 0.3 mol% methyl-vinyl siloxane (which formed crosslinking after a peroxide cure). The polymer was filled with a mixture of 21.6 wt. % fumed silica and 4.0 wt. % precipitated silica previously treated with 6.8 wt. % ethoxy-endblocked siloxane processing aid. The base composite was characterized by a molecular weight between crosslinks in the polymer network of ∼24 kDa and an overall molecular weight (including the influence of the silica fillers) between crosslinks of ∼11 kDa. Molecular weight between crosslinks and filler-polymer interaction strength were then modified by exposure to γ-irradiation in either air or vacuum. The unirradiated material exhibited crystallization at -80 C as measured by DSC with a 16% crystallization as measured by XRD. Isothermal DMA experiments illustrated that crystallization at -85 C occurred over a 1.8 hour period in silica-filled systems and 2.2-2.6 hours in unfilled systems. The onset of crystallization typically occurred after a 30-minute incubation/nucleation period. The crystallization kinetics were dependent on crosslink density. Changes in molecular weight of a factor of two did not, however, change the amount of crystallization. Irradiation in vacuum resulted in faster overall crystallization rates compared to air irradiation for the same crosslink density, likely due to a reduction in the interaction between the polymer chains and the silica filler surface. Modulated differential scanning calorimetry contrasted the crystallization and melting behavior of pure PDMS versus the PDMS/PDPS base copolymer and helped

Investigating the nucleation of protein crystals with hydrostatic pressure

Energy Technology Data Exchange (ETDEWEB)

Kadri, A [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France); Damak, M [Laboratoire de Chimie des Substances Naturelles, Faculte des Sciences de Sfax, BP 802, 3018 Sfax (Tunisia); Jenner, G [Laboratoire de Piezochimie Organique, UMR 7123, Faculte de Chimie, Universite Louis Pasteur, 1 rue Blaise Pascal, F-67008 Strasbourg Cedex (France); Lorber, B [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France); Giege, R [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France)

2003-12-17

Hydrostatic pressure in the 0.1-75 MPa range has been used as a non-invasive tool to study the crystallization process of the tetragonal crystal form of the protein thaumatin (M{sub r} 22 200). Crystals were prepared within agarose gel and at temperatures in the range from 283 to 303 K. The solubility, i.e. the concentration of soluble macromolecules remaining in equilibrium with the crystals, decreases when the pressure increases and when the temperature decreases. High pressure was used to probe the nucleation behaviour of thaumatin. The pressure dependence of the nucleation rate leads to an activation volume of -46.5cm{sup 3} mol{sup -1}. It is shown that an increase in pressure decreases the enthalpy, the entropy and the free energy of crystallization of thaumatin. The data are discussed in the light of the results of crystallographic analyses and of the structure of the protein.

Investigating the nucleation of protein crystals with hydrostatic pressure

International Nuclear Information System (INIS)

Kadri, A; Damak, M; Jenner, G; Lorber, B; Giege, R

2003-01-01

Hydrostatic pressure in the 0.1-75 MPa range has been used as a non-invasive tool to study the crystallization process of the tetragonal crystal form of the protein thaumatin (M r 22 200). Crystals were prepared within agarose gel and at temperatures in the range from 283 to 303 K. The solubility, i.e. the concentration of soluble macromolecules remaining in equilibrium with the crystals, decreases when the pressure increases and when the temperature decreases. High pressure was used to probe the nucleation behaviour of thaumatin. The pressure dependence of the nucleation rate leads to an activation volume of -46.5cm 3 mol -1 . It is shown that an increase in pressure decreases the enthalpy, the entropy and the free energy of crystallization of thaumatin. The data are discussed in the light of the results of crystallographic analyses and of the structure of the protein

Enhancement of struvite pellets crystallization in a full-scale plant using an industrial grade magnesium product.

Science.gov (United States)

Crutchik, D; Morales, N; Vázquez-Padín, J R; Garrido, J M

2017-02-01

A full-scale struvite crystallization system was operated for the treatment of the centrate obtained from the sludge anaerobic digester in a municipal wastewater treatment plant. Additionally, the feasibility of an industrial grade Mg(OH) 2 as a cheap magnesium and alkali source was also investigated. The struvite crystallization plant was operated for two different periods: period I, in which an influent with low phosphate concentration (34.0 mg P·L -1 ) was fed to the crystallization plant; and period II, in which an influent with higher phosphate concentration (68.0 mg P·L -1 ) was used. A high efficiency of phosphorus recovery by struvite crystallization was obtained, even when the effluent treated had a high level of alkalinity. Phosphorus recovery percentage was around 77%, with a phosphate concentration in the effluent between 10.0 and 30.0 mg P·L -1 . The experiments gained struvite pellets of 0.5-5.0 mm size. Moreover, the consumption of Mg(OH) 2 was estimated at 1.5 mol Mg added·mol P recovered -1 . Thus, industrial grade Mg(OH) 2 can be an economical alternative as magnesium and alkali sources for struvite crystallization at industrial scale.

Nuclear matter as an MIT bag crystal

International Nuclear Information System (INIS)

Zhang, Q.; Derreth, C.; Schaefer, A.; Greiner, W.

1986-01-01

An MIT bag crystal model of nuclear matter is formulated. The energy bands of the quarks are calculated as a function of the overlap between adjacent bags. A clear indication of substantial overlap is found. Accordingly, infinite nuclear matter is more similar to a quark gas than to a nucleonic structure. (author)

Laboratory hydro-mechanical characterisation of Boom Clay at Essen and Mol

International Nuclear Information System (INIS)

Deng, Y. F.; Tang, A. M.; Cui, Y. J.; Nguyen, X. P.; Li, X. L.; Wouters, L.

2011-01-01

Boom Clay has been selected as a potential host rock formation for the geological disposal of radioactive waste in Belgium. In the present work, the hydro-mechanical behaviour of Boom Clay samples from the borehole Essen-1 at a depth of 220-260 m and from HADES that is the underground rock laboratory at Mol in Belgium, at 223-m depth was investigated in the laboratory by performing low pressure odometer tests (vertical effective stress ranging from 0.05 to 3.2 MPa), high pressure odometer tests (vertical effective stress ranging from 0.125 to 32 MPa), isotropic consolidation tests (confining effective stress ranging from the in situ stress to 20 MPa) and triaxial shear tests. It has been observed that the mineralogy, geotechnical properties and hydro-mechanical behaviour of Boom Clay from Essen at 227-m, 240-m and 248-m depths are similar to that of Boom Clay from Mol. As in the case of Boom Clay at Mol, the failure envelope of Boom Clay at Essen in the p'- q plane is not linear. The slope of the portion beyond the pre-consolidation stress of Boom Clay from Essen is almost the same as that from Mol, suggesting a similar internal friction angle of about 13 deg. The compression curves (void index I v versus logarithm of vertical stress) beyond the pre-consolidation stress are the same for both samples from Mol and Essen, and situated between the intrinsic compression line (ICL) and the sedimentation compression line (SCL). The yield stress determined from odometer tests seems to be stress-path dependent and lower than the pre-consolidation stress. Thus determining the over-consolidation ratio (OCR) using the yield stress value would lead to an incorrect estimate. From a practical point view, the laboratory test results from Essen and their comparison with those from Mol provide important information regarding the transferability of knowledge on Boom Clay at different sites, taking into account the fact that most investigations have been carried out on Boom Clay at

Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

KAUST Repository

Kelarakis, Antonios; Giannelis, Emmanuel P.

2011-01-01

We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay

Trichlorido[(meth­yl{2-[meth­yl(2-pyridyl­meth­yl)amino]eth­yl}amino)acetonitrile]iron(III) methanol hemisolvate

Science.gov (United States)

Nielsen, Anne; McKenzie, Christine J.; Bond, Andrew D.

2009-01-01

The title compound, [FeCl3(C12H18N4)]·0.5CH3OH, contains an FeIII ion in a distorted octa­hedral coordination environment. The neutral N,N′,N′′-tridentate ligand adopts a fac coordination mode, and chloride ligands lie trans to each of the three coordinated N atoms. In the crystal, the complexes form columns extending parallel to the approximate local threefold axes of the FeN3Cl3 octa­hedra, and the columns are arranged so that the uncoordinated nitrile groups align in an anti­parallel manner and the pyridyl rings form offset face-to-face arrangements [inter­planar separations = 2.95 (1) and 3.11 (1) Å; centroid–centroid distances = 5.31 (1) and 4.92 (1) Å]. The methanol solvent mol­ecule is disordered about a twofold rotation axis. PMID:21578169

Octa­akis(4-amino­pyridine)-1κ4 N 1,2κ4 N 1-aqua-2κO-μ-carbonato-1:2κ3 O,O′:O′′-dinickel(II) dichloride penta­hydrate

Science.gov (United States)

Fun, Hoong-Kun; Sinthiya, A; Jebas, Samuel Robinson; Ravindran Durai Nayagam, B.; Alfred Cecil Raj, S.

2008-01-01

In the title compound, [Ni2(CO3)(C5H6N2)8(H2O)]Cl2·5H2O, one of the the NiII ions is six-coordinated in a distorted octa­hedral geometry, with the equatorial plane defined by four pyridine N atoms from four amino­pyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other NiII ion is also six-coordinated, by four other pyridine N atoms from four other amino­pyridine ligands and two carbonate O atoms to complete a distorted octa­hedral geometry. In the crystal structure, mol­ecules are linked into an infinite three-dimensional network by O—H⋯O, N—H⋯Cl, N—H⋯O, O—H⋯N, C—H⋯O, C—H⋯N and C/N—H⋯π inter­actions involving the pyridine rings. PMID:21580879

Incorporation of μ3-CO3 into an MnIII/MnIV Mn12 cluster: {[(cyclam)MnIV(μ-O)2MnIII(H2O)(μ-OH)]6(μ3-CO3)2}Cl8·24H2O

Science.gov (United States)

Levaton, Ben B.; Olmstead, Marilyn M.

2010-01-01

The centrosymmetric title cluster, hexa­aquadi-μ3-carbonato-hexa­cyclamhexa-μ2-hydroxido-dodeca-μ2-oxido-hexa­mang­an­ese(IV)hexa­manganese(III) octa­chloride tetra­cosa­hydrate, [Mn12(CO3)2O12(OH)6(C10H24N4)6(H2O)6]Cl8·24H2O, has two μ3-CO3 groups that not only bridge octahedrally coordinated MnIII ions but also act as acceptors to two different kinds of hydrogen bonds. The carbonate anion is planar within experimental error and has an average C—O distance of 1.294 (4) Å. The crystal packing is stabilized by O—H⋯Cl, O—H⋯O, N—H⋯Cl and N—H⋯O hydrogen bonds. Two of the four independent chloride ions are disordered over five positions, and eight of the 12 independent water mol­ecules are disordered over 21 positions. PMID:21587382

A second polymorph with composition Co3(PO4)2·H2O

Science.gov (United States)

Lee, Young Hoon; Clegg, Jack K.; Lindoy, Leonard F.; Lu, G. Q. Max; Park, Yu-Chul; Kim, Yang

2008-01-01

Single crystals of Co3(PO4)2·H2O, tricobalt(II) bis­[ortho­phosphate(V)] monohydrate, were obtained under hydro­thermal conditions. The compound is the second polymorph of this composition and is isotypic with its zinc analogue, Zn3(PO4)2·H2O. Three independent Co2+ cations are bridged by two independent orthophosphate anions. Two of the metal cations exhibit a distorted tetra­hedral coordination while the third exhibits a considerably distorted [5 + 1] octa­hedral coordination environment with one very long Co—O distance of 2.416 (3) Å. The former cations are bonded to four different phosphate anions, and the latter cation is bonded to four anions (one of which is bidentate) and one water mol­ecule, leading to a framework structure. Additional hydrogen bonds of the type O—H⋯O stabilize this arrangement. PMID:21200979

Lanthanite-(Nd), Nd2(CO3)3·8H2O

Science.gov (United States)

Morrison, Shaunna M.; Andrade, Marcelo B.; Wenz, Michelle D.; Domanik, Kenneth J.; Downs, Robert T.

2013-01-01

Lanthanite-(Nd), ideally Nd2(CO3)3·8H2O [dineodymium(III) tricarbonate octa­hydrate], is a member of the lanthanite mineral group characterized by the general formula REE 2(CO3)3·8H2O, where REE is a 10-coordinated rare earth element. Based on single-crystal X-ray diffraction of a natural sample from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan, this study presents the first structure determination of lanthanite-(Nd). Its structure is very similar to that of other members of the lanthanite group. It is composed of infinite sheets made up of corner- and edge-sharing of two NdO10-polyhedra (both with site symmetry ..2) and two carbonate triangles (site symmetries ..2 and 1) parallel to the ab plane, and stacked perpendicular to c. These layers are linked to one another only through hydrogen bonding involving the water mol­ecules. PMID:23476479

Glass transition and crystallization kinetics of a barium borosilicate glass by a non-isothermal method

International Nuclear Information System (INIS)

Lopes, Andreia A. S.; Soares, Roque S.; Lima, Maria M. A.; Monteiro, Regina C. C.

2014-01-01

The glass transition and crystallization kinetics of a glass with a molar composition 60BaO-30B 2 O 3 -10SiO 2 were investigated by differential scanning calorimetry (DSC) under non-isothermal conditions. DSC curves exhibited an endothermic peak associated with the glass transition and two partially overlapped exothermic peaks associated with the crystallization of the glass. The dependence of the glass transition temperature (T g ) and of the maximum crystallization temperature (T p ) on the heating rate was used to determine the activation energy associated with the glass transition (E g ), the activation energy for crystallization (E c ), and the Avrami exponent (n). X-ray diffraction (XRD) revealed that barium borate (β-BaB 2 O 4 ) was the first crystalline phase to be formed followed by the formation of barium silicate (Ba 5 Si 8 O 21 ). The variations of activation energy for crystallization and of Avrami exponent with the fraction of crystallization (χ) were also examined. When the crystallization fraction (χ) increased from 0.1 to 0.9, the value of local activation energy (E c (χ)) decreased from 554 to 458 kJ/mol for the first exothermic peak and from 1104 to 831 kJ/mol for the second exothermic peak. The value determined for the Avrami exponent was near 2 indicating a similar one-dimensional crystallization mechanism for both crystalline phases. This was confirmed by the morphological studies performed by scanning electron microscopy (SEM) on glass samples heat-treated at the first and at the second crystallization temperatures

Isostructurality and non-isostructurality in the series of halogenated organic crystal substances. The structure of Hal-aggregates

International Nuclear Information System (INIS)

Grineva, O.V.; Zorkij, P.M.

2001-01-01

Local characteristics and the type of intermolecular Hal-aggregates (ensembles of contacting halogen atoms of adjacent molecules) present in chemically similar halogenated crystal substances, differing only in the nature of Hal atoms, are compared. 23 series of halogenated hydrocarbons, including 57 crystal structures were considered. A clearly pronounced specificity of Hal-aggregates for compounds with a low and intermediate content of halogen was revealed. It was found that, as a rule, coordination number of Hal atom by Hal adjacent atoms increases in the series F-Cl-Br-I [ru

Mass Spectrometric Investigation of Silicon Extremely Enriched in (28)Si: From (28)SiF4 (Gas Phase IRMS) to (28)Si Crystals (MC-ICP-MS).

Science.gov (United States)

Pramann, Axel; Rienitz, Olaf

2016-06-07

A new generation of silicon crystals even further enriched in (28)Si (x((28)Si) > 0.999 98 mol/mol), recently produced by companies and institutes in Russia within the framework of a project initiated by PTB, were investigated with respect to their isotopic composition and molar mass M(Si). A modified isotope dilution mass spectrometric (IDMS) method treating the silicon as the matrix containing a so-called virtual element (VE) existing of the isotopes (29)Si and (30)Si solely and high resolution multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) were applied in combination. This method succeeds also when examining the new materials holding merely trace amounts of (29)Si (x((29)Si) ≈ 5 × 10(-6) mol/mol) and (30)Si (x((30)Si) ≈ 7 × 10(-7) mol/mol) extremely difficult to detect with lowest uncertainty. However, there is a need for validating the enrichment in (28)Si already in the precursor material of the final crystals, silicon tetrafluoride (SiF4) gas prior to crystal production. For that purpose, the isotopic composition of selected SiF4 samples was determined using a multicollector magnetic sector field gas-phase isotope ratio mass spectrometer. Contaminations of SiF4 by natural silicon due to storing and during the isotope ratio mass spectrometry (IRMS) measurements were observed and quantified. The respective MC-ICP-MS measurements of the corresponding crystal samples show-in contrast-several advantages compared to gas phase IRMS. M(Si) of the new crystals were determined to some extent with uncertainties urel(M) < 1 × 10(-9). This study presents a clear dependence of the uncertainty urel(M(Si)) on the degree of enrichment in (28)Si. This leads to a reduction of urel(M(Si)) during the past decade by almost 3 orders of magnitude and thus further reduces the uncertainty of the Avogadro constant NA which is one of the preconditions for the redefinition of the SI unit kilogram.

Crystal structure of cafenstrole

Directory of Open Access Journals (Sweden)

Gihaeng Kang

2015-08-01

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

Crystal orientation of PEO confined within the nanorod templated by AAO nanochannels.

Science.gov (United States)

Liu, Chien-Liang; Chen, Hsin-Lung

2018-06-18

The orientation of poly(ethylene oxide) (PEO) crystallites developed in the nanochannels of anodic aluminum oxide (AAO) membrane has been investigated. PEO was filled homogeneously into the nanochannels in the melt state, and the crystallization confined within the PEO nanorod thus formed was allowed to take place subsequently at different temperatures. The effects of PEO molecular weight (MPEO), crystallization temperature (Tc) and AAO channel diameter (DAAO) on the crystal orientation attained in the nanorod were revealed by 2-D wide angle X-ray scattering (WAXS) patterns. In the nanochannels with DAAO = 23 nm, the crystallites formed from PEO with the lowest MPEO (= 3400 g mol-1) were found to adopt a predominantly perpendicular orientation with the crystalline stems aligning normal to the channel axis irrespective of Tc (ranging from -40 to 20 °C). Increasing MPEO or decreasing Tc tended to induce the development of the tilt orientation characterized by the tilt of the (120) plane by 45° from the channel axis. In the case of the highest MPEO (= 95 000 g mol-1) studied, both perpendicular and tilt orientations coexisted irrespective of Tc. Coexistent orientation was always observed in the channels with a larger diameter (DAAO = 89 nm) irrespective of MPEO and Tc. Compared with the previous results of the crystal orientation attained in nanotubes templated by the preferential wetting of the channel walls by PEO, the window of the perpendicular crystal orientation in the nanorod was much narrower due to its weaker confinement effect imposed on the crystal growth than that set by the nanotube.

Deformation, Stress Relaxation, and Crystallization of Lithium Silicate Glass Fibers Below the Glass Transition Temperature

Science.gov (United States)

Ray, Chandra S.; Brow, Richard K.; Kim, Cheol W.; Reis, Signo T.

2004-01-01

The deformation and crystallization of Li(sub 2)O (center dot) 2SiO2 and Li(sub 2)O (center dot) 1.6SiO2 glass fibers subjected to a bending stress were measured as a function of time over the temperature range -50 to -150 C below the glass transition temperature (Tg). The glass fibers can be permanently deformed at temperatures about 100 C below T (sub)g, and they crystallize significantly at temperatures close to, but below T,, about 150 C lower than the onset temperature for crystallization for these glasses in the no-stress condition. The crystallization was found to occur only on the surface of the glass fibers with no detectable difference in the extent of crystallization in tensile and compressive stress regions. The relaxation mechanism for fiber deformation can be best described by a stretched exponential (Kohlrausch-Williams-Watt (KWW) approximation), rather than a single exponential model.The activation energy for stress relaxation, Es, for the glass fibers ranges between 175 and 195 kJ/mol, which is considerably smaller than the activation energy for viscous flow, E, (about 400 kJ/mol) near T, for these glasses at normal, stress-free condition. It is suspected that a viscosity relaxation mechanism could be responsible for permanent deformation and crystallization of the glass fibers below T,

Energetic aspects of diclofenac acid in crystal modifications and in solutions--mechanism of solvation, partitioning and distribution.

Science.gov (United States)

Perlovich, German L; Surov, Artem O; Hansen, Lars Kr; Bauer-Brandl, Annette

2007-05-01

Temperature dependency of saturated vapor pressure and heat capacity for the diclofenac acid (Form II) were measured and thermodynamic functions of sublimation calculated (DeltaG(sub)(298) = 49.3 kJ x mol(-1); DeltaH(sub)(298) = 115.6 +/- 1.3 kJ x mol(-1); DeltaS(sub)(298) = 222 +/- 4 J x mol(-1) x K(-1)). Crystal polymorphic Forms I (P2(1)/c) and II (C2/c) of diclofenac acid have been prepared and characterized by X-ray diffraction experiments. The difference between crystal lattice energies of the two forms were obtained by solution calorimetry: DeltaDeltaH(sol)(I --> II) = 1.6 +/- 0.4 kJ x mol(-1). Temperature dependencies of the solubility in buffers with pH 2.0 and 7.4, n-octanol and n-hexane were measured. The thermodynamic functions of solubility, solvation, and transfer processes were deduced. Specific and non-specific solvation terms were distinguished using the transfer from the "inert" n-hexane to the other solvents. The transfer of diclofenac acid molecules from the buffers to n-octanol (partitioning and distribution) is an entropy driven process. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Thermal, dielectric studies on pure and amino acid ( L-glutamic acid, L-histidine, L-valine) doped KDP single crystals

Science.gov (United States)

Kumaresan, P.; Moorthy Babu, S.; Anbarasan, P. M.

2008-05-01

Amino acids ( L-glutamic acid, L-histidine, L-valine) doped potassium dihydrogen phospate crystals are grown by solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV-VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV-Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm -1 for metal ion doped crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

MolTalk – a programming library for protein structures and structure analysis

Science.gov (United States)

Diemand, Alexander V; Scheib, Holger

2004-01-01

Background Two of the mostly unsolved but increasingly urgent problems for modern biologists are a) to quickly and easily analyse protein structures and b) to comprehensively mine the wealth of information, which is distributed along with the 3D co-ordinates by the Protein Data Bank (PDB). Tools which address this issue need to be highly flexible and powerful but at the same time must be freely available and easy to learn. Results We present MolTalk, an elaborate programming language, which consists of the programming library libmoltalk implemented in Objective-C and the Smalltalk-based interpreter MolTalk. MolTalk combines the advantages of an easy to learn and programmable procedural scripting with the flexibility and power of a full programming language. An overview of currently available applications of MolTalk is given and with PDBChainSaw one such application is described in more detail. PDBChainSaw is a MolTalk-based parser and information extraction utility of PDB files. Weekly updates of the PDB are synchronised with PDBChainSaw and are available for free download from the MolTalk project page following the link to PDBChainSaw. For each chain in a protein structure, PDBChainSaw extracts the sequence from its co-ordinates and provides additional information from the PDB-file header section, such as scientific organism, compound name, and EC code. Conclusion MolTalk provides a rich set of methods to analyse and even modify experimentally determined or modelled protein structures. These methods vary in complexity and are thus suitable for beginners and advanced programmers alike. We envision MolTalk to be most valuable in the following applications: 1) To analyse protein structures repetitively in large-scale, i.e. to benchmark protein structure prediction methods or to evaluate structural models. The quality of the resulting 3D-models can be assessed by e.g. calculating a Ramachandran-Sasisekharan plot. 2) To quickly retrieve information for (a limited

MolTalk – a programming library for protein structures and structure analysis

Directory of Open Access Journals (Sweden)

Diemand Alexander V

2004-04-01

Full Text Available Abstract Background Two of the mostly unsolved but increasingly urgent problems for modern biologists are a to quickly and easily analyse protein structures and b to comprehensively mine the wealth of information, which is distributed along with the 3D co-ordinates by the Protein Data Bank (PDB. Tools which address this issue need to be highly flexible and powerful but at the same time must be freely available and easy to learn. Results We present MolTalk, an elaborate programming language, which consists of the programming library libmoltalk implemented in Objective-C and the Smalltalk-based interpreter MolTalk. MolTalk combines the advantages of an easy to learn and programmable procedural scripting with the flexibility and power of a full programming language. An overview of currently available applications of MolTalk is given and with PDBChainSaw one such application is described in more detail. PDBChainSaw is a MolTalk-based parser and information extraction utility of PDB files. Weekly updates of the PDB are synchronised with PDBChainSaw and are available for free download from the MolTalk project page http://www.moltalk.org following the link to PDBChainSaw. For each chain in a protein structure, PDBChainSaw extracts the sequence from its co-ordinates and provides additional information from the PDB-file header section, such as scientific organism, compound name, and EC code. Conclusion MolTalk provides a rich set of methods to analyse and even modify experimentally determined or modelled protein structures. These methods vary in complexity and are thus suitable for beginners and advanced programmers alike. We envision MolTalk to be most valuable in the following applications: 1 To analyse protein structures repetitively in large-scale, i.e. to benchmark protein structure prediction methods or to evaluate structural models. The quality of the resulting 3D-models can be assessed by e.g. calculating a Ramachandran-Sasisekharan plot. 2 To

Time-constrained project scheduling with adjacent resources

NARCIS (Netherlands)

Hurink, Johann L.; Kok, A.L.; Paulus, J.J.; Schutten, Johannes M.J.

We develop a decomposition method for the Time-Constrained Project Scheduling Problem (TCPSP) with adjacent resources. For adjacent resources the resource units are ordered and the units assigned to a job have to be adjacent. On top of that, adjacent resources are not required by single jobs, but by

Time-constrained project scheduling with adjacent resources

NARCIS (Netherlands)

Hurink, Johann L.; Kok, A.L.; Paulus, J.J.; Schutten, Johannes M.J.

2008-01-01

We develop a decomposition method for the Time-Constrained Project Scheduling Problem (TCPSP) with Adjacent Resources. For adjacent resources the resource units are ordered and the units assigned to a job have to be adjacent. On top of that, adjacent resources are not required by single jobs, but by

Crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders synthesized by a coprecipitation process

Energy Technology Data Exchange (ETDEWEB)

Chu, Hsueh-Liang [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Du, Je-Kang [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); Chen, Ker-Kong, E-mail: enamel@kmu.edu.tw [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China)

2016-09-05

Crystallization behaviors of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders were studied with zirconium nitrate (Zr(NO{sub 3}){sub 4}·xH{sub 2}O), yttrium nitrate (Y(NO{sub 3}){sub 3}·6H{sub 2}O) and strontium nitrate (Sr(NO{sub 3}){sub 2}) constituting the initial materials. Differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED) and high-resolution TEM (HRTEM) were utilized to characterize the crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders. The activation energies of tetragonal ZrO{sub 2} (t-ZrO{sub 2}) crystallization were 389.1, 327.6, and 315.1 kJ/mol with SrO content for 1, 2, and 3 mol%, respectively, obtained with a non-isothermal method. The growth morphology parameter and growth mechanism index were close to 2.0 and 1.0, respectively, showing that t-ZrO{sub 2} had a plate-like morphology. - Highlights: • The single phase of tetragonal ZrO{sub 2} formed when calcined at 923 K for 2 h. • ZrO{sub 2}−3Y{sub 2}O{sub 3}−2SrO precursor powders crystallization is at 765.6 K. • The activation energy of t-ZrO{sub 2} crystallization was 389.1 kJ/mol with 1 mol% SrO. • The growth morphology and index of crystallization were close to 2.0 and 1.0.

Crystallization kinetic of clear burning kaolinitic clay; Cinetica de cristalizacao de argila caulinitica de queima clara

Energy Technology Data Exchange (ETDEWEB)

Silva, R.A.; Medeiros, J.; Teixeira, S.R. [Universidade Estadual Paulista (DFQB/FCT/UNESP), Presidente Prudente, SP (Brazil). Fac. de Ciencias e Tecnologia. Dept. de Fisica, Quimica e Biologia

2009-07-01

It was studied the crystallization kinetics of one caulinitic clay of clear burning, from Teodoro Sampaio (SP) region. Differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF) had been used in the development of the work. Non-isothermal methods had been used for attainment of the kinetic data and in the determination of the crystallization mechanisms. The exothermic peak associate to the crystallization is located between 900 and 1000 deg C, varying in accordance with the heating rate of the sample. The activation energies were taken using the data of thermal analysis (DTA) and the methods of Kissinger (700 kJ/mol) and Ligero (721 kJ/mol). The Avrami constant n was calculated using Ligero and the m parameter was obtained using Matusita method and the n and E of Ligero. Both values (1.17) are close to 1, indicating growth in two dimensions with morphology of plates and nucleation of surface as dominant mechanism. (author)

Computational study on potassium picrate crystal

Energy Technology Data Exchange (ETDEWEB)

Ju, Xue-Hai; Lu, Ya-Lin; Ma, Xiu-Fang; Xiao, He-Ming [Department of Chemistry, Nanjing University of Science and Technology, Nanjing, 210094 (China)

2006-08-15

DFT calculation at the B3LYP level was performed on crystalline potassium picrate. The frontier bands are slightly fluctuant. The energy gap between the highest occupied crystal orbital (HOCO) and the lowest unoccupied crystal orbital (LUCO) is 0.121 a.u. (3.29 eV). The carbon atoms that are connected with the nitro groups make up the narrow lower energy bands, with small contributions from nitro oxygen and phenol oxygen. The higher energy bands consist of orbitals from the nitro groups and carbon atom. The potassium bears almost 1 a.u. positive charge. The potassium forms ionic bonding with the phenol oxygen and the nitro oxygen at the same time. The crystal lattice energy is predicted to be -574.40 kJ/mol at the B3LYP level determined with the effective core pseudopotential HAYWSC-31G basis set for potassium and 6-31G** basis set for other atoms. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Rate constants and mechanisms for the crystallization of Al nano-goethite under environmentally relevant conditions

Science.gov (United States)

Bazilevskaya, Ekaterina; Archibald, Douglas D.; Martínez, Carmen Enid

2012-07-01

Mobile inorganic and organic nanocolloidal particles originate-from and interact-with bulk solid phases in soil and sediment environments, and as such, they contribute to the dynamic properties of environmental systems. In particular, ferrihydrite and (nano)goethite are the most abundant of nanocolloidal Fe oxy(hydr)oxides in these environments. We therefore investigated the ferrihydrite to goethite phase transformation using experimental reaction conditions that mimicked environmental conditions where the formation of nanocolloidal Fe oxy(hydr)oxides may occur: slow titration of dilute solutions to pH 5 at 25 °C with and without 2 mol% Al. Subsequently, the rate constants from 54-d nano-goethite aging/crystallization experiments at 50 °C were determined using aliquots pulled for vibrational spectroscopy (including multivariate curve resolution, MCR, analyses of infrared spectra) and synchrotron-based X-ray diffraction (XRD). We also present a mechanistic model that accounts for the nano-goethite crystallization observed by the aforementioned techniques, and particle structural characteristics observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In contrast to the common assumption that metastable ferrihydrite precipitates first, before it transforms to goethite, the presence of characteristic infrared bands in freshly synthesized nanoparticle suspensions indicate goethite can precipitate directly from solution under environmentally relevant conditions: low Fe concentration, ambient temperature, and pH maintained at 5. However, the presence of 2 mol% Al prevented direct goethite precipitation. Rate constants obtained by fitting the contributions from the MCR-derived goethite-like component to the OH-stretching region were (7.4 ± 1.1) × 10-7 s-1 for 0% Al and (4.2 ± 0.4) × 10-7 s-1 for 2 mol% Al suspensions. Rate constants derived from intensities of OH-bending infrared vibrations (795 and 895 cm-1) showed similar values

Digested livestock wastewater treatment using gamma-ray irradiation and struvite crystallization

International Nuclear Information System (INIS)

Kim, Tak Hyun; Lee, Sang Ryul; Nam, Youn Ku; Lee, Myun Joo

2009-01-01

Livestock wastewater generally contains high strength of organics (COD), ammonia nitrogen (NH 4 + -N), phosphate phosphorus (PO 4 3- -P) and suspended solids. It is very difficult to treat by conventional wastewater treatment techniques. In this study, struvite crystallization was carried out to treat the digested livestock wastewater. 1.0 :1.2 :1.2 was determined as an optimal NH 4 + :Mg 2+ : PO 4 3- mol ratio of struvite crystallization. For the digested livestock wastewater, COD, NH 4 + -N and PO 4 3- -P removal efficiencies by struvite crystallization were 72.4%, 98.9%, and 74.8%, respectively. Gamma-ray irradiation was carried out prior to struvite crystallization of livestock wastewater. The enhancement of struvite crystallization efficiency could be obtained by the pretreatment of gamma-ray irradiation due to the decrease of COD, NH 4 + -N and PO 4 3- -P concentration

Magma crust interaction at Merapi volcano, Java Indonesia: insights from crystal isotope stratigraphy

NARCIS (Netherlands)

Chadwick, J.P.; Troll, V.R.; Ginibre, C.; Morgan, D.; Gertisser, R.; Waight, T.; Davidson, J.P.

2007-01-01

Recent basaltic andesite lavas from Merapi volcano contain abundant, complexly zoned, plagioclase phenocrysts, analysed here for their petrographic textures, major element composition and Sr isotope composition. Anorthite (An) content in individual crystals can vary by as much as 55 mol% (An

The effect of magnetic field on the shape of etch pits of paracetamol crystals

Energy Technology Data Exchange (ETDEWEB)

Ivashchenko, V.E. [Kemerovo State University, Novosibirsk (Russian Federation); Research and Educational Center, Novosibirsk State University (Russian Federation); Boldyrev, V.V.; Shakhtshneider, T.P. [Institute of Solid State Chemistry and Mechanochemistry, RAS, Novosibirsk (Russian Federation); Zakharov, Yu.A.; Krasheninin, V.I. [Kemerovo State University, Novosibirsk (Russian Federation); Ermakov, A.E. [Institute of Physics of Metals, Ural Branch of RAS, Ekaterinburg (Russian Federation)

2002-04-01

In the present study we investigate the effect of magnetic field on the shape of etch pits of the crystals of p-hydroxyacetanilide (paracetamol), which is widely used in pharmacy as antipyretic, antiphlogistic medicine. It was discovered that the magnetic field (H=0.5 T, {tau}=15 min) changes the morphology of etch pits and shifts dislocations in paracetamol crystal. Activation energy of the changes induced by the action of the magnetic field was determined to be 63 kJ/mol, which is comparable with the energy of hydrogen bonds in crystal lattice. (orig.)

Crystallization and preliminary X-ray crystallographic analysis of a new crystal form of hydroxylamine oxidoreductase from Nitrosomonas europaea

International Nuclear Information System (INIS)

Cedervall, Peder E.; Hooper, Alan B.; Wilmot, Carrie M.

2009-01-01

A new crystal form of N. europaea hydroxylamine oxidoreductase (space group P2 1 2 1 2) diffracted to 2.25 Å resolution at a third-generation synchrotron X-ray source. Hydroxylamine oxidoreductase (HAO) from Nitrosomonas europaea is a homotrimeric protein that catalyzes the oxidation of hydroxylamine to nitrite. Each monomer, with a molecular weight of 67.1 kDa, contains seven c-type hemes and one heme P460, the porphyrin ring of which is covalently linked to a tyrosine residue from an adjacent subunit. HAO was first crystallized and structurally characterized at a resolution of 2.8 Å in 1997. The structure was solved in space group P6 3 and suffered from merohedral twinning. Here, a crystallization procedure is presented that yielded untwinned crystals belonging to space group P2 1 2 1 2, which diffracted to 2.25 Å resolution and contained one trimer in the asymmetric unit. The unit-cell parameters were a = 140.7, b = 142.6, c = 107.4 Å

Crystallization behavior of tetragonal ZrO{sub 2} prepared in a silica bath

Energy Technology Data Exchange (ETDEWEB)

Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Huang, Hung-Jui [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China)

2013-09-10

Highlights: ► The activation energy of t-ZrO{sub 2} crystallization calculated by the JMA equation is 643.0 ± 13.9 kJ·mol{sup −1}. ► The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0. ► Bulk nucleation is dominant in the t-ZrO{sub 2} crystallization process, and has a spherical-like morphology. ► The TEM microstructure reveals that the t-ZrO{sub 2} crystallites have a spherical-like morphology. - Abstract: The synthesis of zirconia (ZrO{sub 2}) precursor powders by a co-precipitation process is studied in this work, using a silica bath prepared at 348 K and pH = 7, with 10 min mixing using zirconium (IV) nitrate and tetraethylorthosilicate (TEOS, Si(OC{sub 2}H{sub 5}){sub 4}) as the starting materials. The XRD result show that only a single phase of tetragonal ZrO{sub 2} (t-ZrO{sub 2}) appears when the freeze dried precursor powders are calcined between 1173 and 1473 K for 120 min. The activation energy of t-ZrO{sub 2} crystallization, as calculated by the Johnson–Mehl–Avrami (JMA) equation, is 643.0 ± 13.9 kJ/mol. The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0, which indicates that bulk nucleation is dominant in the t-ZrO{sub 2} crystallization process, and that the material has a plate-like morphology.

Crystallization behavior of (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses

Energy Technology Data Exchange (ETDEWEB)

Wang, Moo-Chin [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Cheng, Chih-Wei; Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Hsi, Chi-Shiung, E-mail: chsi@nuu.edu.t [Department of Materials Science and Engineering, National United University, 1 Lien-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China)

2010-07-02

The crystallization behavior of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and energy dispersive spectroscopy (EDS). The crystalline phase was composed of {beta}-spodumene. The isothermal crystallization kinetics of {beta}-spodumene from the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has also been studied by a quantitative X-ray diffraction method. The activation energy of {beta}-spodumene formation decreases from 359.2 to 317.8 kJ/mol when the Na{sub 2}O content increases from 0 to 0.4 mol and it increases from 317.8 to 376.9 kJ/mol when the Na{sub 2}O content increases from 0.4 to 0.6 mol. The surface nucleation and plate-like growth were dominant in the crystallization of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses.

Thermal stability of radiation-induced free radicals in γ-irradiated l-alanine single crystals

International Nuclear Information System (INIS)

Maltar-Strmecki, N.; Rakvin, B.

2005-01-01

Decay of the radiation-induced stable free radicals in l-alanine single crystals and powders at the temperatures from 379 to 476K was examined by electron paramagnetic resonance. For single crystals, the calculated activation energy of the radical decay is 104.3±1.7kJ/mol (i.e. 12 538+/-202K) and the frequency factor lnν 0 is 24.1±0.4min -1 . The lifetime of the radical in single crystals at 296K is 162 years. The results confirm the long-term stability of the radicals, but the decay was found to be faster in large crystals than in powders

Non-isothermal crystallization kinetics and fragility of (Cu46Zr47Al7)97Ti3 bulk metallic glass investigated by differential scanning calorimetry

International Nuclear Information System (INIS)

Zhu, Man; Li, Junjie; Yao, Lijuan; Jian, Zengyun; Chang, Fang’e; Yang, Gencang

2013-01-01

Highlights: • Non-isothermal crystallization kinetics of (Cu 46 Zr 47 Al 7 ) 97 Ti 3 BMGs was studied. • Two-stage of crystallization process is confirmed by DSC. • The nucleation process is difficult than growth process during crystallization. • The second crystallization process is the most sensitive to heating rate. • Kinetic fragility index is evaluated suggesting it is an intermediate glass. - Abstract: In this paper, bulk metallic glasses with the composition of (Cu 46 Zr 47 Al 7 ) 97 Ti 3 were prepared by copper mold casting technique. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate its structure and non-isothermal crystallization kinetics. DSC traces revealed that it undergoes two-stage crystallization. The activation energies corresponding to the characteristic temperatures have been calculated, and the results reveal that the as-cast alloys have a good thermal stability in thermodynamics. Based on Kissinger equation, the activation energies for glass transition, the first and second crystallization processes were obtained as 485 ± 16 kJ/mol, 331 ± 7 kJ/mol and 210 ± 3 kJ/mol, respectively, suggesting that the nucleation process is more difficult than the grain growth process. The fitting curves using Lasocka's empirical relation show that the influence of the heating rate for crystallization is larger than glass transition. Furthermore, the kinetic fragility for (Cu 46 Zr 47 Al 7 ) 97 Ti 3 bulk metallic glasses is evaluated. Depending on the fragility index, (Cu 46 Zr 47 Al 7 ) 97 Ti 3 bulk metallic glasses should be considered as “intermediate glasses”

Effect of amaranth dye on the growth and properties of conventional and SR method grown KAP single crystals

Science.gov (United States)

Babu Rao, G.; P., Rajesh; Ramasamy, P.

2018-04-01

The 0.1 mol% amaranth added KAP single crystals were grown from aqueous solutions by both slow evaporation solution technique and Sankaranarayanan-Ramasamy method. The single crystal having dimension of 45 mm length and 12 mm diameter was grown with growth rate of 1.5 mm/day using SR method. 87 % transmittance is obtained for SR method grown amaranth added KAP single crystal. The high intense luminescence at 661 nm is obtained from amaranth added conventional and SR method grown KAP single crystal. The amaranth added KAP single crystal possesses good mechanical and laser damage threshold stability.

Studies on the crystallization of a metal glass by ferromagnetic resonance

International Nuclear Information System (INIS)

Rodrigues, R.W.D.

1983-01-01

The crystallization of the metal glass METGLAS 2826A has been studied with the ferromagnetic resonance technique. The first-derivative linewidth of the absorption curve was measured for several times and temperatures of isothermal treatments, in the range 350 0 C - 375 0 C. After an initial decrease, attributed to stress relaxation, the linewidth increases linearly with the transformed fraction of the first crystallization phase. The measured apparent activation energy for this first phase is 306 KJ/mol. The experimental results for larger aging times show that, for all aging temperature, the second crystallization phase starts to form when the transformed fraction of the first phase is of the order of 50%. (Author) [pt

HackaMol: An Object-Oriented Modern Perl Library for Molecular Hacking on Multiple Scales.

Science.gov (United States)

Riccardi, Demian; Parks, Jerry M; Johs, Alexander; Smith, Jeremy C

2015-04-27

HackaMol is an open source, object-oriented toolkit written in Modern Perl that organizes atoms within molecules and provides chemically intuitive attributes and methods. The library consists of two components: HackaMol, the core that contains classes for storing and manipulating molecular information, and HackaMol::X, the extensions that use the core. The core is well-tested, well-documented, and easy to install across computational platforms. The goal of the extensions is to provide a more flexible space for researchers to develop and share new methods. In this application note, we provide a description of the core classes and two extensions: HackaMol::X::Calculator, an abstract calculator that uses code references to generalize interfaces with external programs, and HackaMol::X::Vina, a structured class that provides an interface with the AutoDock Vina docking program.

The role of the Mg2+ ions in Cr3+ spectroscopy for near-stoichiometric LiNbO3 crystals

International Nuclear Information System (INIS)

Han, T P J; Jaque, F; Bermudez, V; Dieguez, E

2003-01-01

The optical spectroscopy of Cr 3+ ions doped into near-stoichiometric LiNbO 3 crystals, pure and co-doped with MgO, has been investigated. In the near-stoichiometric LiNbO 3 :Cr(0.2 mol%):Mg(2 mol%) crystal, the optical spectra resemble those previously observed for congruent LiNbO 3 :Cr:MgO samples when the total MgO content exceeds the 4.6 mol% threshold. The coexistence of two types of Cr 3+ centre ([Cr] Li and [Cr] Nb ) characterized the optical and luminescence spectra of this sample. The concentration equilibrium between the two types of centre is strongly displaced towards the [Cr 3+ ] Nb centre, permitting us to obtain with accuracy the parameters of the broad bands. The R-line associated with the [Cr] Nb centre is only observable in the low-temperature emission spectrum. The Fano anti-resonance lines present have been observed to be more pronounced for the near-stoichiometric samples than for congruent ones

Structural evolution of plasma-sprayed nanoscale 3 mol% and 5 mol% yttria-stabilized zirconia coatings during sintering

Science.gov (United States)

Zhao, Yan; Gao, Yang

2017-12-01

The microstructure of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings may change during high-temperature exposure, which would influence the coating performance and service lifetime. In this study, the phase structure and the microstructural evolution of 3YSZ (zirconia-3 mol% yttria) and 5YSZ (zirconia-5 mol% yttria) nanostructured coatings were investigated by means of sintering at 1400 °C for 50-100 h. The microhardness, elastic moduli, and thermal shock cycles of the 3YSZ and 5YSZ nanostructured coatings were also investigated. The results showed that the redistribution of yttrium ions at 1400 °C caused the continuous increase of monoclinic-phase zirconia, but no obvious inter-splat cracking formed at the cross-sections, even after 100 h. Large voids appeared around the nanoporous zone because of the sintering of nanoscale granules upon high-temperature exposure. The microhardness and elastic moduli of the nanostructured coatings first increased and then decreased with increasing sintering times. The growth rate of the nanograins in the 3YSZ coating was lower than that in 5YSZ, which slowed the changes in 3YSZ coating porosity during sintering. Although the 3YSZ coating was prone to monoclinic phase transition, the experimental results showed that the thermal shock resistance of the 3YSZ coating was better than that of the 5YSZ coating.

Bis(2,2'-bipyridyl-κN,N')(carbonato-κO,O')cobalt(III) bromide trihydrate.

Science.gov (United States)

Ma, Peng-Tao; Wang, Yu-Xia; Zhang, Guo-Qian; Li, Ming-Xue

2007-12-06

The title complex, [Co(CO(3))(C(10)H(8)N(2))(2)]Br·3H(2)O, is isostructural with the chloride analogue. The six-coordinated octahedral [Co(2,2'-bipy)(2)CO(3)](+) cation (2,2'-bipy is 2,2'-bipyrid-yl), bromide ion and water mol-ecules are linked together via O-H⋯Br and O-H⋯O hydrogen bonds, generating a one-dimensional chain.

Crystal structure of pseudoguainolide

Directory of Open Access Journals (Sweden)

Noureddine Beghidja

2015-03-01

Full Text Available The lactone ring in the title molecule, C15H22O3 (systematic name: 3,4a,8-trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione, assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methylene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific interactions are noted in the the crystal packing.

Crystallization Behavior of A Bulk Amorphous Mg62Cu26Y12 Alloy

Science.gov (United States)

Wu, Shyue-Sheng; Chin, Tsung-Shune; Su, Kuo-Chang

1994-07-01

The crystallization temperature, the associated activation energy and the crystallized structure of a bulk amorphous Mg62Cu26Y12 alloy with a diameter of 2.5 mm were studied. It possesses a one-step crystallization behavior. The crystallization reaction was found to be represented by: AM(MG62Cu26Y12)→Mg2Cu+MgY+CuY+Mg, ( Tx=188°C, Eac=134 kJ/mol) where AM represents the amorphous state, T x the crystallization temperature at an infinitesimal heating rate, and E ac the associated activation energy. The amount of crystalline phases were found to be Mg2Cu:MgY:CuY=76:17:7. The Mg phase is identifiable only by high resolution electron microscopy, not by X-ray diffraction. The crystallization leads to a sharp rise in electrical resistivity which is reversed to those of iron-based amorphous alloys.

Luminescence and scintillation properties of Ce-doped Cs2ZnCl4 crystals

Science.gov (United States)

Sugawara, K.; Koshimizu, M.; Yanagida, T.; Fujimoto, Y.; Haruki, R.; Nishikido, F.; Kishimoto, S.; Asai, K.

2015-03-01

In this study, we have synthesized scintillation materials based on Ce-doped Cs2ZnCl4 crystals. The light yield was enhanced by up to 20% by doping Cs2ZnCl4 with Ce3+ ions. In the scintillation time profiles, fast components exhibited decay time constants on the order of nanoseconds, which was ascribed to Auger-free luminescence (AFL). The light yield of the AFL component decreased at 10 mol% Ce3+ concentration, which is mainly attributed to the reabsorption of AFL photons inside the crystals by Ce3+ ions, as seen in the scintillation spectra. Long components had decay time constants of approximately 30 ns. In addition, at 10 mol% Ce3+ concentration, a prominent band appeared at approximately 500 nm in the scintillation spectrum, which was not observed in the photoluminescence spectra. The long components in the scintillation time profiles and the 500 nm band in the scintillation spectra were tentatively attributed to self-trapped excitons perturbed by Ce3+ ions.

The effects of moisture on LiD single crystals studied by temperature-programmed decomposition

International Nuclear Information System (INIS)

Dinh, L.N.; Cecala, C.M.; Leckey, J.H.; Balooch, M.

2001-01-01

Temperature-programmed decomposition (TPD) technique was performed on LiOH powders and LiD single crystals previously exposed to different moisture levels. Our results show that the LiOH decomposition process is rate-limited by an inward moving reaction front mechanism with an activation energy barrier of ∼122-149 kJ/mol. The LiOH structure is stable even if kept at 320 K. However, LiOH structures formed on the surface of LiD single crystals during moisture exposure at low dosages may have multiple activation energy barriers, some of which may be much lower than 122 kJ/mol. The rate-limiting mechanism for the decomposition of LiOH structures with reduced activation energy barriers is consistent with a unimolecular nucleation model. We attribute the lowering of the activation energy barrier for the LiOH decomposition to the existence of sub-stoichiometric Li(OH) x with x 2 O formation is observed. The release of H 2 O molecules from LiOH · H 2 O structure has small activation energy barriers in the range of 48-69 kJ/mol and follows a unimolecular nucleation process. The loosely bonded H 2 O molecules in the LiOH · H 2 O structure can be easily pumped away at room temperature in a reasonable amount of time. Our experiments also suggest that handling LiD single crystals at an elevated temperature of 340 K or more reduces the growth rate of LiOH and LiOH · H 2 O significantly

Laboratory studies on the uptake of aromatic hydrocarbons by ice crystals during vapor depositional crystal growth

Science.gov (United States)

Fries, Elke; Starokozhev, Elena; Haunold, Werner; Jaeschke, Wolfgang; Mitra, Subir K.; Borrmann, Stephan; Schmidt, Martin U.

Uptake of aromatic hydrocarbons (AH) by ice crystals during vapor deposit growth was investigated in a walk-in cold chamber at temperatures of 242, 251, and 260 K, respectively. Ice crystals were grown from ambient air in the presence of gaseous AH namely: benzene (C 6H 6), toluene (methylbenzene, C 7H 8), the C 8H 10 isomers ethylbenzene, o-, m-, p-xylene (dimethylbenzenes), the C 9H 12 isomers n-propylbenzene, 4-ethyltoluene, 1,3,5-trimethylbenzene (1,3,5-TMB), 1,2,4-trimethylbenzene (1,2,4-TMB), 1,2,3-trimethylbenzene (1,2,3-TMB), and the C 10H 14 compound tert.-butylbenzene. Gas-phase concentrations calculated at 295 K were 10.3-20.8 μg m -3. Uptake of AH was detected by analyzing vapor deposited ice with a very sensitive method composed of solid-phase micro-extraction (SPME), followed by gas chromatography/mass spectrometry (GC/MS). Ice crystal size was lower than 1 cm. At water vapor extents of 5.8, 6.0 and 8.1 g m -3, ice crystal shape changed with decreasing temperatures from a column at a temperature of 260 K, to a plate at 251 K, and to a dendrite at 242 K. Experimentally observed ice growth rates were between 3.3 and 13.3×10 -3 g s -1 m -2 and decreased at lower temperatures and lower value of water vapor concentration. Predicted growth rates were mostly slightly higher. Benzene, toluene, ethylbenzene, and xylenes (BTEX) were not detected in ice above their detection limits (DLs) of 25 pg g ice-1 (toluene, ethylbenzene, xylenes) and 125 pg g ice-1 (benzene) over the entire temperature range. Median concentrations of n-propylbenzene, 4-ethyltoluene, 1,3,5-TMB, tert.-butylbenzene, 1,2,4-TMB, and 1,2,3-TMB were between 4 and 176 pg g ice-1 at gas concentrations of 10.3-10.7 μg m -3 calculated at 295 K. Uptake coefficients ( K) defined as the product of concentration of AH in ice and density of ice related to the product of their concentration in the gas phase and ice mass varied between 0.40 and 10.23. K increased with decreasing temperatures. Values of

Multi criteria decision analysis on a waste repository in Mol

International Nuclear Information System (INIS)

Carle, B.

2005-01-01

In Belgium, the management of radioactive waste is taken care of by ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials. Local partnerships with stakeholders from municipalities in existing nuclear zones were setup to facilitate the dialogue between the repository designers and the local community. Since the establishment of the partnership in Mol, MONA in February 2000, all aspects of a possible near-surface or a deep geological repository are discussed in 4 working groups by around 50 volunteer members. The outcome of the discussions in the partnership can be a shared project, supported by both local stakeholders and ONDRAF/NIRAS, in which the specifications and the conditions needed for establishing a repository in Mol are elaborated. MONA asked the Decision Strategy Research Department of SCK-CEN to organise a Multi Criteria Analysis (MCA) in the context of the deciding between a surface and a deep repository for low level radioactive waste. The objective of the multi criteria analysis is to support a number of representatives of the various working groups within MONA in their selection between two acceptable options for a repository of low level radioactive waste on the territory of Mol. The options are the surface repository developed by the working groups of MONA, and a deep repository in the clay layers underneath the nuclear site of Mol. This study should facilitate the selection between both options, or in case this appears to be difficult, at least to get a well-structured overview of all factors (criteria) of importance to the judgement, and to get insight into the degree in which the various criteria contribute to the selection

1.8 μm luminescent properties and energy transfer of Yb{sup 3+}/Tm{sup 3+} co-doped α-NaYF{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhigang [Key Laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang, 315211 (China); Xia, Haiping, E-mail: hpxcm@nbu.edu.cn [Key Laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang, 315211 (China); Wang, Cheng; Zhang, Zhixiong; Jiang, Dongsheng; Zhang, Jian; He, Shinan; Tang, Qingyang; Sheng, Qiguo; Gu, Xuemei; Zhang, Yuepin [Key Laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang, 315211 (China); Chen, Baojiu [Department of Physics, Dalian Maritime University, Dalian, Liaoning Province, 116026 (China); Jiang, Haochuan, E-mail: jianghaochuan@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, The Chinese Academy of Sciences, Ningbo, Zhejiang, 315211 (China)

2016-09-25

This paper reports on successful preparation of α-NaYF{sub 4} single crystals co-doped with ∼1.9 mol% Tm{sup 3+} and various concentrations (3.85 mol%, 7.69 mol%, 11.54 mol%, 15.38 mol%) of Yb{sup 3+} by using a flux-Bridgman method. The fluorescence decay curve was measured to investigate the luminescent properties of the Yb{sup 3+}/Tm{sup 3+} co-doped α-NaYF{sub 4}, and the energy transfer process from Yb{sup 3+} to Tm{sup 3+}; the J-O intensity parameters of Tm{sup 3+} were further calculated and analyzed according to the absorption spectra. Results show that, an intense 1.8 μm emission was achieved with Yb{sup 3+} as sensitizer for Tm{sup 3+} in the α-NaYF{sub 4} single crystal under the excitation of 980 nm LD (Laser Diode) because of the strong energy transfer from Yb{sup 3+} to Tm{sup 3+}. The maximum emission intensity at 1.8 μm is obtained at about 15.38 mol% doping concentration of Yb{sup 3+} when the concentration of Tm{sup 3+} ions is fixed at ∼1.90 mol% in the current research. Moreover, the calculated maximum value of emission cross section at 1.8 μm is 1.63 × 10{sup −20} cm{sup 2} for 3.85 mol% Yb{sup 3+}/1.9 mol% Tm{sup 3+} sample, and the obtained energy transfer rate (W{sub ET}) and energy transfer efficiency (η) are 1543 s{sup −1} and 83.8%, respectively. Our analysis of the fluorescence dynamics indicates that electric dipole-dipole interaction is dominant for the energy transfer from Yb{sup 3+} ions to Tm{sup 3+} ions by using Inokuti-Hirayama’s model. - Highlights: • The Tm{sup 3+}/Yb{sup 3+} co-doped α-NaYF{sub 4} single crystals were grown by Bridgman method. • The 1.8 μm emission intensity is obtained at 15.38 mol% Yb{sup 3+}/1.90 mol% Tm{sup 3+} sample. • The maximum value of emission cross section at 1.8 μm is 1.63 × 10{sup −20} cm{sup 2}. • The energy transfer rate is 1543 s{sup −1} and energy transfer efficiency is 83.8%. • The physical mechanism for energy transfer from Yb{sup 3+} to Tm{sup 3+} ions

Structure and crystallization kinetics of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses

Energy Technology Data Exchange (ETDEWEB)

Cheng Yin [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Xiao Hanning [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China)]. E-mail: zjbcy@126.com; Guo Wenming [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Guo Weiming [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China)

2006-05-15

The experimental IR (infrared spectra) and differential scanning calorimetry (DSC) curves of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses, containing 30-60 mol% Bi{sub 2}O{sub 3}, have been investigated in the article. The composition dependence of IR absorption suggests that addition of Bi{sub 2}O{sub 3} results in a change in the short-range order structure of the borate matrix. The increase of Bi{sub 2}O{sub 3} content causes a progressive conversion of [BO{sub 3}] to [BO{sub 4}] units. Bi{sub 2}O{sub 3}, in the form of [BiO{sub 6}] octahedral units, plays the role of glass former. The crystallization kinetics of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses were described by thermal stability indexes (k {sub gl}, {delta}T), activation energy (E) for crystallization and numerical factors(n, m) depending on the nucleation process and growth morphology, which were calculated by Satava method and the modified Ozawa-Chen method. When Bi{sub 2}O{sub 3} {<=} 45 mol%, the increase of Bi{sub 2}O{sub 3} tends to improve the thermal stabilities of the glasses. In this case, k {sub gl} may be more suitable for estimating the glass thermal stability in above composition range than {delta}T. A further increase of Bi{sub 2}O{sub 3} content will increase the crystallization trends of investigated glasses. Two possible kinds of growth mechanisms were involved in Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses: one-dimensional growth and two-dimensional growth. Moreover, structures of crystallized glasses were observed by X-ray diffraction (XRD). BiBO{sub 3} crystal with special non-linear optical properties can be obtained when Bi{sub 2}O{sub 3} {>=} 50 mol%.

Effects of electric fields on the photonic crystal formation from block copolymers

Science.gov (United States)

Lee, Taekun; Ju, Jin-wook; Ryoo, Won

2012-03-01

Effects of electric fields on the self-assembly of block copolymers have been investigated for thin films of polystyrene-bpoly( 2-vinyl pyridine); PS-b-P2VP, 52 kg/mol-b-57 kg/mol and 133 kg/mol-b-132 kg/mol. Block copolymers of polystyrene and poly(2-vinyl pyridine) have been demonstrated to form photonic crystals of 1D lamellar structure with optical band gaps that correspond to UV-to-visible light. The formation of lamellar structure toward minimum freeenergy state needs increasing polymer chain mobility, and the self-assembly process is accelerated usually by annealing, that is exposing the thin film to solvent vapor such as chloroform and dichloromethane. In this study, thin films of block copolymers were spin-coated on substrates and placed between electrode arrays of various patterns including pin-points, crossing and parallel lines. As direct or alternating currents were applied to electrode arrays during annealing process, the final structure of thin films was altered from the typical 1D lamellae in the absence of electric fields. The formation of lamellar structure was spatially controlled depending on the shape of electrode arrays, and the photonic band gap also could be modulated by electric field strength. The spatial formation of lamellar structure was examined with simulated distribution of electrical potentials by finite difference method (FDM). P2VP layers in self-assembled film were quaternized with methyl iodide vapor, and the remaining lamellar structure was investigated by field emission scanning electron microscope (FESEM). The result of this work is expected to provide ways of fabricating functional structures for display devices utilizing photonic crystal array.

Growth of Bi 12SiO 20 single crystals by the pulling-down method with continuous feeding

Science.gov (United States)

Maida, Shigeru; Higuchi, Mikio; Kodaira, Kohei

1999-09-01

Bi 12SiO 20 single crystals were successfully grown by the pulling-down method with continuous feeding. As-grown crystals were amber in color and transparent, and had no cracks or inclusions. A crystal with homogeneous composition was obtained from Bi-rich feed powder having a composition of 14.1 mol% SiO 2, whereas precipitates of Bi 4Si 3O 12 were observed on the surface of a crystal grown with stoichiometric powder. The shape of the solid-liquid interface during the crystal growth was estimated to be almost flat, which was favorable to avoid core formation. Average dislocation density was 4×10 3/cm 2, which was comparable to that of Bi 12SiO 20 crystals grown by the Czochralski method.

Synthesis and characterization of KY3F10 and KY3F10:Yb:Nd:Tm crystals for optical applications

International Nuclear Information System (INIS)

Linhares, Horacio Marconi da Silva Dantas

2009-01-01

In this work, crystals of KY 3 F 10 pure and doped with Yb, Nd and Tm were grown aiming at the attainment of blue emission via Tm 3+ ions up conversion. It was established the best conditions to synthesis and purification of KY 3 F 10 . Crystals doped with 1.3 mol% Nd, 0.5 mol% Tm and some concentrations of Yb (5, 10, 20, 30 and 40 mol%) were obtained by slow cooling of the charge from the melt, using an usual conventional synthesis system and in a reactive HF atmosphere. It was taken into account parameters as cooling rate and different configurations of boats to conditioning the materials. The limit of Yb concentration to obtain a unique cubic phase was determined as 30mol%, for the cooling rates used in this work. The physical and chemical characterizations of the samples were performed by X-ray diffraction, differential thermal analysis, inductively coupled plasma-optical emission spectroscopy (ICP-OES), scanning electron microscopy, optical absorption and emission. An initial spectroscopic study was performed to verify the effect of the Yb 3+ concentration regarding the blue emission efficiency in the KY 3 F 10 :Yb:Nd:Tm. When the Nd 3+ is pumped at 797 nm, it was determined that the suitable Yb concentrations are between 10 and 20 mol% to obtain blue emission at 480 nm, and between 20 and 30 mol% to obtain emission at 450 nm. It was observed that two emissions bands in the UV (350 and 360nm) enhanced proportionally with the Yb 3+ concentration. (author)

Étude des matrices sol-gel en film mince par détection de molécule unique en champ large : diffusion moléculaire et agrégation photo-induite

Science.gov (United States)

Nutarelli, D.; Débarre, A.; Jaffiol, R.; Julien, C.; Richard, A.; Tchénio, P.; Chaput, F.; Boilot, J. P.

2004-11-01

La fluorescence de molécules de colorant dans des matrices sol-gel en film mince a été étudiée par détection de molécule unique. Outre les phénomènes de photo-blanchiment et de clignotement, un processus de photo-agrégation a été observé. Ce phénomène, dont la dynamique dépend de la présence d'oxygène, de l'intensité du laser d'excitation et de la température, montre l'existence de deux classes de molécules dans l'échantillon. Des molécules immobiles et d'autres qui diffusent. L'analyse de la dynamique d'agrégation permettra de dégager certaines caractéristiques du mécanisme de photo-agrégation et d'appréhender le rôle joué par la matrice sol-gel dans ce processus.

Prediction of molecular crystal structures

International Nuclear Information System (INIS)

Beyer, Theresa

2001-01-01

The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol -1 of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

Prediction of molecular crystal structures

Energy Technology Data Exchange (ETDEWEB)

Beyer, Theresa

2001-07-01

The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol{sup -1} of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

Electron paramagnetic resonance study of Ce doped partially stabilized ZrO2 crystals

Directory of Open Access Journals (Sweden)

Mikhail А. Borik

2017-09-01

Full Text Available ZrO2 (PSZ solid solutions crystals stabilized with yttrium and cerium oxides have been studied using electron paramagnetic resonance (EPR in the X and Q ranges. Zr3+ have been observed centers in the as-annealed ZrO2 crystals stabilized only by yttrium oxide (2.8 mol% Y2O3. Another type of paramagnetic-O-centers appear as a result of CeO2 addition to ZrO2 crystals along with yttrium oxide. To estimate the concentration of Ce3+ ions in PZS crystals, we recorded the EPR spectra in the presence of a reference at 7 K. Paramagnetic Ce3+ ions have been identified and their relative amount in the PSZ crystals before and after high-temperature heat treatment has been assessed. Annealing in air leads decreases the concentration of Ce3+ ions for all the test compositions and changes the color of the crystals from red to white. After annealing of the sample 2.0Y0.8Ce3Zr, the amount of paramagnetic Ce3+ ions decreased approximately twofold. Paramagnetic centers from Ce3+ have not been detected in the specimen with a low cerium content of 0.1 mol% after annealing which indicates the complete transition of Ce3+ to the Ce4+ state. We show that the forming cerium paramagnetic centers are bound by strong exchange interactions. No angular dependence of the EPR lines of the paramagnetic Ce3+ cations on the applied external magnetic field has been observed. Probable origin of the absence of angular dependence is that the impurity rare-earth ions are located close to one another, forming impurity clusters with an effective spin of Seff=1/2.

(2RS)-2-(2,4-Difluoro-phen-yl)-1-[(4-iodo-benz-yl)(meth-yl)amino]-3-(1H-1,2,4-tri-azol-1-yl)propan-2-ol.

Science.gov (United States)

Xiong, Hui-Ping; Gao, Shou-Hong; Li, Chun-Tong; Wu, Zhi-Jun

2012-08-01

IN THE TITLE COMPOUND (COMMON NAME: iodiconazole), C(19)H(19)F(2)IN(4)O, there is an intra-molecular O-H⋯N hydrogen bond and mol-ecules are linked by weak inter-actions only, namely C-H⋯N, C-H⋯O and C-H⋯F hydrogen bonds, and π-electron ring-π-electron ring inter-actions between the triazole rings with centroid-centroid distances of 3.725 (3) Å.

Spondylolisthesis adjacent to a cervical disc arthroplasty does not increase the risk of adjacent level degeneration.

Science.gov (United States)

Kieser, David Christopher; Cawley, Derek Thomas; Roscop, Cecile; Mazas, Simon; Coudert, Pierre; Boissiere, Louis; Obeid, Ibrahim; Vital, Jean-Marc; Pointillart, Vincent; Gille, Olivier

2018-03-31

To understand whether a spondylolisthesis in the sub-axial spine cranial to a cervical disc arthroplasty (CDA) construes a risk of adjacent level disease (ALD). A retrospective review of 164 patients with a minimum 5-year follow-up of a cervical disc arthroplasty was performed. Multi-level surgeries, including hybrid procedures, were included. Multiple implant types were included. The two inter-vertebral discs (IVD) cranial of the CDA were monitored for evidence of radiologic degeneration using the Kettler criteria. The rate of ALD in CDA found in this series was 17.8%, with most affecting the immediately adjacent IVD (27.4 and 7.6%, respectively p = 0.000). Pre-operative mild spondylolisthesis adjacent to a planned CDA was not found to be a risk factor for ALD within 5 years. Those with a degenerative spondylolisthesis are at higher risk of ALD (33%) than those with a non-degenerative cause for their spondylolisthesis (11%). Post-operative CDA alignment, ROM or induced spondylolisthesis do not affect the rate of ALD in those with an adjacent spondylolisthesis. Patients with ALD experience significantly worse 5-year pain and functional outcomes than those unaffected by ALD. A pre-operatively identified mild spondylolisthesis in the sub-axial spine cranially adjacent to a planned CDA is not a risk factor for ALD within 5 years. These slides can be retrieved under Electronic Supplementary Material.

Crystallization kinetics of bioactive glasses in the ZnO-Na2O-CaO-SiO2 system.

Science.gov (United States)

Malavasi, Gianluca; Lusvardi, Gigliola; Pedone, Alfonso; Menziani, Maria Cristina; Dappiaggi, Monica; Gualtieri, Alessandro; Menabue, Ledi

2007-08-30

The crystallization kinetics of Na(2)O.CaO.2SiO(2) (x = 0) and 0.68ZnO.Na(2)O.CaO.2SiO(2) (x = 0.68, where x is the ZnO stoichiometric coefficient in the glass formula) bioactive glasses have been studied using both nonisothermal and isothermal methods. The results obtained from isothermal XRPD analyses have showed that the first glass crystallizes into the isochemical Na(2)CaSi(2)O(6) phase, whereas the Na(2)ZnSiO(4) crystalline phase is obtained from the Zn-rich glass, in addition to Na(2)CaSi(2)O(6). The activation energy (Ea) for the crystallization of the Na(2)O.CaO.2SiO(2) glass is 193 +/- 10 and 203 +/- 5 kJ/mol from the isothermal in situ XRPD and nonisothermal DSC experiments, respectively. The Avrami exponent n determined from the isothermal method is 1 at low temperature (530 degrees C), and its value increases linearly with temperature increase up to 2 at 607 degrees C. For the crystallization of Na(2)CaSi(2)O(6) from the Zn-containing glass, higher values of both the crystallization temperature (667 and 661 degrees C) and Ea (223 +/- 10 and 211 +/- 5 kJ/mol) have been found from the isothermal and nonisothermal methods, respectively. The Na(2)ZnSiO(4) crystalline phase crystallizes at lower temperature with respect to Na(2)CaSi(2)O(6), and the Ea value is 266 +/- 20 and 245 +/- 15 kJ/mol from the isothermal and nonisothermal methods, respectively. The results of this work show that the addition of Zn favors the crystallization from the glass at lower temperature with respect to the Zn-free glass. In fact, it causes an increase of Ea for the Na diffusion process, determined using MD simulations, and consequently an overall increase of Ea for the crystallization process of Na(2)CaSi(2)O(6). Our results show good agreement between the Ea and n values obtained with the two different methods and confirm the reliability of the nonisothermal method applied to kinetic crystallization of glassy systems. This study allows the determination of the temperature

Synthesis and Crystal Structure of 1-Chloro-2-methyl-4-nitrobenzene

Directory of Open Access Journals (Sweden)

Jim Simpson

2012-03-01

Full Text Available The title compound (3 was prepared from 4-chloroaniline in good yield on successive oxidation and methylation and its crystal and molecular structure is reported. The compound crystallizes in the monoclinic space group P 21/n with unit cell dimensions a = 13.5698(8, b = 3.7195 (3, c = 13.5967 (8 Å, ß = 91.703(3 °, V = 685.96 (10 Å3. The molecule is essentially planar with a dihedral angle of 6.2(3 ° between the nitro group and the phenyl ring. The crystal structure is stabilised by π...π contacts between adjacent benzene rings together with C–H...O hydrogen bonds and close Cl...O contacts.

Inulin crystal initiation via a glucose-fructose cross-link of adjacent polymer chains: atomic force microscopy and static molecular modelling.

Science.gov (United States)

Cooper, Peter D; Rajapaksha, K Harinda; Barclay, Thomas G; Ginic-Markovic, Milena; Gerson, Andrea R; Petrovsky, Nikolai

2015-03-06

Semi-crystalline microparticles of inulin (MPI) have clinical utility as potent human vaccine adjuvants but their relevant surface structure and crystal assembly remain undefined. We show inulin crystal surfaces to resemble multi-layered, discoid radial spherulites resulting from very rapid formation of complex tertiary structures, implying directed crystal initiation. Physical and in silico molecular modelling of unit cells confirm steric feasibility of initiation by hydrogen-bonded cross-linking of terminal glucose to a fructose of another chain, mimicking bonding in sucrose crystals. A strong, chelate-like dual H-bond is proposed to compel the known antiparallel alignment of inulin chains. Such cross-linking would require one extra fructose per chain in the native inulin crystal, as observed. Completion of five H-bonded internal ring-domains would 'lock in' each new 6-fructose structural unit of each antiparallel helix pair to create a new isoform. All known properties of inulin isoforms follow readily from these concepts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Crystal structure of 1-(2,4-dihydroxy-6-methylphenylethanone

Directory of Open Access Journals (Sweden)

Samran Prabpai

2015-08-01

Full Text Available The title compound, C9H10O3, is a bioactive secondary metabolite, isolated from the endophytic fungus Nodulisporium sp. The compound exhibits an intramolecular O—H...O hydrogen bond between the phenolic H atom and the carbonyl O atom of the adjacent acetyl group. In the crystal, molecules are linked by hydrogen bonds involving the 4-phenolic H atom and a symmetry-related carbonyl O atom of a neighboring molecule, resulting in extended supramolecular chains along the a-axis direction. Aromatic π–π stacking interactions between the nearly parallel benzene rings of adjacent chains [centroid–centroid distance = 3.7478 (8 Å] further stabilize the three-dimensional supramolecular framework.

Single-crystal study of the charge density wave metal LuNiC2

Science.gov (United States)

Steiner, S.; Michor, H.; Sologub, O.; Hinterleitner, B.; Höfenstock, F.; Waas, M.; Bauer, E.; Stöger, B.; Babizhetskyy, V.; Levytskyy, V.; Kotur, B.

2018-05-01

We report on single-crystal growth, single-crystal x-ray diffraction, physical properties, and density functional theory (DFT) electronic structure as well as Fermi surface calculations for two ternary carbides, LuCoC2 and LuNiC2. Electrical resistivity measurements reveal for LuNiC2 a charge density wave (CDW) transition at TCDW≃450 K and, for T >TCDW , a significant anisotropy of the electrical resistivity, which is lowest along the orthorhombic a axis. The analysis of x-ray superstructure reflections suggest a commensurate CDW state with a Peierls-type distortion of the Ni atom periodicity along the orthorhombic a axis. DFT calculations based on the CDW modulated monoclinic structure model of LuNiC2 as compared to results of the orthorhombic parent type reveal the formation of a partial CDW gap at the Fermi level which reduces the electronic density of states from N (EF)=1.03 states/eV f.u. without CDW to N (EF)=0.46 states/eV f.u. in the CDW state. The corresponding bare DFT Sommerfeld value of the latter, γDFTCDW=0.90 mJ/mol K2, reaches reasonable agreement with the experimental value γ =0.83 (5 ) mJ/mol K2 of LuNiC2. LuCoC2 displays a simple metallic behavior with neither CDW ordering nor superconductivity above 0.4 K. Its experimental Sommerfeld coefficient, γ =5.9 (1) mJ/mol K2, is in realistic correspondence with the calculated, bare Sommerfeld coefficient, γDFT=3.82 mJ/mol K2, of orthorhombic LuCoC2.

Copper oxide content dependence of crystallization behavior, glass forming ability, glass stability and fragility of lithium borate glasses

International Nuclear Information System (INIS)

Soliman, A.A.; Kashif, I.

2010-01-01

Differential thermal analysis (DTA) and X-ray diffraction (XRD) have been employed to investigate the copper oxide content dependence of the glass transition temperatures data, activation energy for the glass transition E t , glass stability GS, fragility index Fi, the glass-forming ability (GFA) and crystallization behavior of {(100-x) mol% Li 2 B 4 O 7 -x mol% CuO} glass samples, where x=0-40 mol% CuO. From the dependence of the glass transition temperature T g on the heating rate β, the fragility, F i , and the activation energy, E t , have been calculated. It is seen that F i and E t are attained their minimum values at 0 x -T g , SCL region and the GS. The GFA has been investigated on the basis of Hruby parameter K H , which is a strong indicator of GFA, and the relaxation time. Results of GFA are in good agreement with the fragility index, F i , calculations indicating that {90Li 2 B 4 O 7 .10CuO} is the best glass former. The stronger glass forming ability has decreasing the fragility index. XRD result indicates that no fully amorphous samples but a mixture of crystalline and amorphous phases are formed in the samples containing x>25 mol% CuO and below it composed of glassy phase. Increasing the CuO content above 25 mol% helps the crystallization process, and thus promotes a distinct SCL region. XRD suggests the presence of micro-crystallites of remaining residual amorphous matrix by increasing the CuO content.

Intracomplex {pi}-{pi} stacking interaction between adjacent phenanthroline molecules in complexes with rare-earth nitrates: Crystal and molecular structures of bis(1,10-Phenanthroline)trinitratoytterbium and bis(1,10-Phenanthroline)trinitratolanthanum

Energy Technology Data Exchange (ETDEWEB)

Sadikov, G. G., E-mail: sadgg@igic.ras.ru; Antsyshkina, A. S.; Rodnikova, M. N.; Solonina, I. A. [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation)

2009-01-15

Crystals of the compounds Yb(NO{sub 3}){sub 3}(Phen){sub 2} and La(NO{sub 3}){sub 3}(Phen){sub 2} (Phen = 1,10-phenanthroline) are investigated using X-ray diffraction. It is established that there exist two different crystalline modifications: the main modification (phase 1) is characteristic of all members of the isostructural series, and the second modification (phase 2) is observed only for the Eu, Er, and Yb elements. It is assumed that the stability and universality of main phase 1 are associated with the occurrence of the nonbonded {pi}-{pi} stacking interactions between the adjacent phenanthroline ligands in the complexes. The indication of the interactions is a distortion of the planar shape of the Phen molecule (the folding of the metallocycle along the N-N line with a folding angle of 11{sup o}-13{sup o} and its 'boomerang' distortion). The assumption regarding the {pi}-{pi} stacking interaction is very consistent with the shape of the ellipsoids of atomic thermal vibrations, as well as with the data obtained from thermography and IR spectroscopy. An analysis of the structures of a number of rare-earth compounds has demonstrated that the intracomplex {pi}-{pi} stacking interactions directly contribute to the formation of supramolecular associates in the crystals, such as molecular dimers, supramolecules, chain and layered ensembles, and framework systems.

Scintillation properties of pure and Ca-doped ZnWO4 crystals

International Nuclear Information System (INIS)

Danevich, F.A.; Shkulkova, O.G.; Henry, S.; Kraus, H.; McGowan, R.; Mikhailik, V.B.; Telfer, J.

2008-01-01

Following the investigations of the structure and scintillation properties of Ca-doped zinc tungstate powder [phys. stat. sol. (a) 204, 730 (2007)] a single-crystal of ZnWO 4 -Ca (0.5 mol%) was grown and characterised. The relative light output, energy resolution and decay characteristics were measured for pure and Ca-doped ZnWO 4 scintillators. An increase in the light yield of ∝40% compared with the undoped crystal, and an energy resolution 9.6% ( 137 Cs) were obtained for Ca-doped ZnWO 4 . The observed improvement is attributed to the reduction of self-absorption (bleaching) of the crystal. The cause of bleaching as well as the possible contribution of scattering is discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Design, irradiation, and post-irradiation examination of the UC and (U,Pu)C fuel rods of the test groups Mol-11/K1 and Mol-11/K2

International Nuclear Information System (INIS)

Freund, D.; Elbel, H.; Steiner, H.

1976-06-01

The test groups K1 and K2 of the irradiation experiment Mol-11 are reported. Design, irradiation, and post-irradiation examination of the fuel rods irradiated are described. Mol-11/K1 consisted of one fuel rod with UC of 94% T.D. and helium bonding. This test group was intended to prove the high power irradiation capsule in pile. Mol-11/K2 consists of three fuel rods in total. One of these is presently still in the reactor. In this test group mixed carbide fuel of 83% T.D. and 15% Pu content under helium bonding is irradiated. The fuel rod K2-2 was provided with a capillary tube for the continuous measurement of fission gas pressure built up. 1.4988 stainless steel was chosen as cladding material. The final burnup lies between 35 and 70 MWd/kg M. Post-irradiation examination of the two test groups covers a theoretical analysis of the irradiation behaviour. (orig./GSCH) [de

Permanent Electric Dipole-Dipole Interactions in Lyotropic Polypeptide Liquid Crystals

OpenAIRE

MORI, Norio; Norio, MORI; Research Associate, Department of Industrial Chemistry

1981-01-01

The interaction energy between two adjacent α-helical molecules was calculated taking into account for permanent electric dipoles locating orl the helical core of a polymer mainchain in order to explain the cholesteric structure of lyotropic polypeptide liquid crystals. It was concluded that the dipole-dipole interactions were responsible for the formation of the cholesteric structure.

Crystallization kinetic study of the lithium-disilicate bioceramic obtained from rice-husk silica starting powder

International Nuclear Information System (INIS)

Santos, F.A.; Santos, C.; Pinatti, D.G.; Davim, E.; Fernandes, M.H.F.V.

2011-01-01

In this work, the study of crystallization of the lithium disilicate glass-ceramic produced for alternative source (rice husk silica), and comparatively by commercial source (commercial silica) it was carried through. The stoichiometry 66%.mol SiO_2: 33%.mol LiO_2 was used. The kinetic studies of crystallization and calculations had been carried through thermal analysis (DTA), and were possible to study the behavior of the curves in accordance with the variation of taxes (5; 10; 15; e 20°C/min), of the granulometries 63 μm, 250μm and 1mm), and for the influence of the substitution commercial SiO_2 by rice husk. The structural characterization was carried through by X-Ray diffractometry (DRX) and scanning electron microscopy (MEV), for chemical characterization used X-Ray fluorescence (FRX). The preliminary results show that the substitution of the silica source is sufficiently promising, since the gotten properties are similar. (author)

Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

Science.gov (United States)

Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

2016-02-01

We present here a novel experimental set-up that is able to measure the enthalpy of sublimation of a given compound by means of piezoelectric crystal microbalances (PCMs). The PCM sensors have already been used for space measurements, such as for the detection of organic and non-organic volatile species and refractory materials in planetary environments. In Earth atmospherics applications, PCMs can be also used to obtain some physical-chemical processes concerning the volatile organic compounds (VOCs) present in atmospheric environments. The experimental set-up has been developed and tested on dicarboxylic acids. In this work, a temperature-controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC recondensed onto the PCM quartz crystal, allowing the determination of the deposition rate. From the measurements of deposition rates, it has been possible to infer the enthalpy of sublimation of adipic acid, i.e. ΔHsub : 141.6 ± 0.8 kJ mol-1, succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1, and azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1. The results obtained show an accuracy of 1 % for succinic, adipic, and azelaic acid and within 5 % for oxalic acid and are in very good agreement with previous works (within 6 % for adipic, succinic, and oxalic acid and within 11 % or larger for azelaic acid).

Optical properties of Mg2+, Yb3+, and Ho3+ tri-doped LiNbO3 crystals

Science.gov (United States)

Dai, Li; Liu, Chun-Rui; Tan, Chao; Yan, Zhe-Hua; Xu, Yu-Heng

2017-04-01

A series of LiNbO3 crystals tri-doped with Mg{}2+, Yb{}3+, and Ho{}3+ are grown by the conventional Czochraski technique. The concentrations of Mg{}2+, Yb{}3+, and Ho{}3+ ions in Mg:Yb:Ho:LiNbO3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO3 crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy ({E}{{r}}) is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm2, approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO3 crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices. Project supported by the National Natural Science Foundation of China (Grant No. 51301055), the Youth Science Fund of Heilongjiang Province, China (Grant No. QC2015061), the Special Funds of Harbin Innovation Talents in Science and Technology Research, China (Grant No. 2015RQQXJ045 ), and the Science Funds for the Young Innovative Talents of Harbin University of Science and Technology, China (Grant No. 201501).

Dielectric Losses and Charge Transfer in Antimony-Doped TlGaS2 Single Crystal

Science.gov (United States)

Asadov, S. M.; Mustafaeva, S. N.

2018-03-01

Effect of semimetallic antimony (0.5 mol % Sb) on the dielectric properties and ac-conductivity of TlGaS2-based single crystals grown by the Bridgman-Stockbarger method has been studied. The experimental results on the frequency dispersion of dielectric coefficients and the conductivity of TlGa0.995Sb0.005S2 single crystals allowed the revealing of the dielectric loss nature, the charge transfer mechanism, and the estimation of the parameters of the states localized in the energy gap. The antimony-doping of the TlGaS2 single crystal leads to an increase in the density of states near the Fermi level and a decrease in the average time and average distance of hopes.

Competition of the connectivity with the local and the global order in polymer melts and crystals

Energy Technology Data Exchange (ETDEWEB)

Bernini, S.; Puosi, F.; Barucco, M.; Leporini, D., E-mail: dino.leporini@df.unipi.it [Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B.Pontecorvo 3, I-56127 Pisa (Italy)

2013-11-14

The competition between the connectivity and the local or global order in model fully flexible chain molecules is investigated by molecular-dynamics simulations. States with both missing (melts) and high (crystal) global order are considered. Local order is characterized within the first coordination shell (FCS) of a tagged monomer and found to be lower than in atomic systems in both melt and crystal. The role played by the bonds linking the tagged monomer to FCS monomers (radial bonds), and the bonds linking two FCS monomers (shell bonds) is investigated. The detailed analysis in terms of Steinhardt's orientation order parameters Q{sub l} (l = 2 − 10) reveals that increasing the number of shell bonds decreases the FCS order in both melt and crystal. Differently, the FCS arrangements organize the radial bonds. Even if the molecular chains are fully flexible, the distribution of the angle formed by adjacent radial bonds exhibits sharp contributions at the characteristic angles θ ≈ 70°, 122°, 180°. The fractions of adjacent radial bonds with θ ≈ 122°, 180° are enhanced by the global order of the crystal, whereas the fraction with 70° ≲ θ ≲ 110° is nearly unaffected by the crystallization. Kink defects, i.e., large lateral displacements of the chains, are evidenced in the crystalline state.

Simulation of iron impurity in BaTiO3 crystals

International Nuclear Information System (INIS)

Stashans, Arvids; Castillo, Darwin

2009-01-01

Iron-doped barium titanate (BaTiO 3 ) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO 3 crystal has been discussed too.

Bis(2,2′-bipyridyl-κ2 N,N′)(carbonato-κ2 O,O′)cobalt(III) bromide trihydrate

Science.gov (United States)

Ma, Peng-Tao; Wang, Yu-Xia; Zhang, Guo-Qian; Li, Ming-Xue

2008-01-01

The title complex, [Co(CO3)(C10H8N2)2]Br·3H2O, is isostructural with the chloride analogue. The six-coordinated octahedral [Co(2,2′-bipy)2CO3]+ cation (2,2′-bipy is 2,2′-bipyrid­yl), bromide ion and water mol­ecules are linked together via O—H⋯Br and O—H⋯O hydrogen bonds, generating a one-dimensional chain. PMID:21200495

Ferroelectric lead magnesium niobate-lead titanate single crystals for ultrasonic hydrophone applications

International Nuclear Information System (INIS)

Lau, S.T.; Lam, K.H.; Chan, H.L.W.; Choy, C.L.; Luo, H.S.; Yin, Q.R.; Yin, Z.W.

2004-01-01

Ferroelectric lead magnesium niobate-lead titanate (PMN-PT) single crystals with a composition around the rhombohedral-tetragonal morphotropic phase boundary (65 mol% of PMN) were used to fabricate single-element needle-type hydrophones for measuring the spatial and temporal characteristics of medical ultrasonic transducers. PMN-PT single crystal was grown by a modified Bridgman method. Discs (0.5 mm thick) with normal along the direction were cut and then poled by a dc field in the thickness direction. The single crystal has a high relative permittivity (ε r ∼4000) making it appropriate for small area hydrophone applications. Single-element needle-type hydrophones with this material as the sensing element have been fabricated and characterized. The hydrophones have flat frequency response and good receiving sensitivity over certain frequency range in the megahertz region

Rapid rate sintering of nanocrystalline ZrO2-3 mol% Y2O3

International Nuclear Information System (INIS)

Chen, D.J.; Mayo, M.J.

1996-01-01

Conventional ramp-and-hold sintering with a wide range of heating rates was conducted on submicrometer and nanocrystalline ZrO 2 -3 mol% Y 2 O 3 powder compacts. Although rapid heating rates have been reported to produce high density/fine grain size products for many submicrometer and smaller starting powders, the application of this technique to ZrO 2 -3 mol% Y 2 O 3 produced mixed results. In the case of submicrometer ZrO 2 -3 mol% Y 2 O 3 , neither densification nor grain growth was affected by the heating rate used. In the case of nanocrystalline ZrO 2 -3 mol% Y 2 O 3 , fast heating rates severely retarded densification and had a minimal effect on grain growth. The large adverse effect of fast heating rates on the densification of the nanocrystalline powder was traced to a thermal gradient/differential densification effect. Microstructural evidence suggests that the rate of densification greatly exceeded the rate of heat transfer in this material; consequently, the sample interior was not able to densify before being geometrically constrained by a fully dense shell which formed at the sample exterior. This finding implies that rapid rate sintering will meet severe practical constraints in the manufacture of bulk nanocrystalline ZrO 2 -3 mol% Y 2 O 3 specimens

Sintering and crystallization behavior of CaMgSi2O6-NaFeSi2O6 based glass-ceramics

International Nuclear Information System (INIS)

Goel, Ashutosh; Kansal, Ishu; Ferrari, Anna Maria; Pascual, Maria J.; Barbieri, Luisa; Bondioli, Federica; Lancellotti, Isabella; Ribeiro, Manuel J.; Ferreira, Jose M. F.

2009-01-01

We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi 2 O 6 -10 mol % NaFeSi 2 O 6 . The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850-950 deg. C in both air and N 2 atmosphere. X-ray diffraction studies adjoined with the Rietveld-reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions.

Spin-coupled charge dynamics in layered manganite crystals

CERN Document Server

Tokura, Y; Ishikawa, T

1998-01-01

Anisotropic charge dynamics has been investigated for single crystals of layered manganites, La sub 2 sub - sub 2 sub x Sr sub 1 sub + sub 2 sub x Mn sub 2 O sub 7 (0.3<=X<=0.5). Remarkable variations in the magnetic structure and in the charge-transport properties are observed by changing the doping level x . A crystal with x = 0.3 behaves like a 2-dimensional ferromagnetic metal in the temperature region between approx 90 K and approx 270 K and shows an interplane tunneling magnetoresistance at lower temperatures which is sensitive to the interplane magnetic coupling between the adjacent MnO sub 2 bilayers. Optical probing of these layered manganites has also clarified the highly anisotropic and incoherent charge dynamics.

Theoretical modeling of zircon's crystal morphology according to data of atomistic calculations

Science.gov (United States)

Gromalova, Natalia; Nikishaeva, Nadezhda; Eremin, Nikolay

2017-04-01

potential. The other sets of interatomic potentials («Zircon 2, Zircon 3») differed from the first in that parameters was found with the help of quantum-chemical calculations of the structure «ab initio».The surface energies for different faces of zircon were calculated using Metadise code (Watson et al., 1996) at P4-3000 personal computer with Windows XP operating system. The computation time for one simple form was from 30 minutes to 12 hours. Calculations have shown that depending on the chosen model the surface energy of zircons faces several changes. For example, Esurf of face (331) obtained using models of potentials «Zircon 2», «Zircon 3» sufficiently similar (2.82 and 3.01 J/mol2 respectively). Meaning of Esurf of this face, calculated on the basis of set «Zircon 1» significantly lower (1,54 J/mol2). With regard to the face (100), it has low surface energies when selecting all three models, with a minimum value (1,14 J/mol2) in the model «Zircon 1». References: Gromalova N.A., Eremin N.N., Urusov V.S. Atomistic computer modeling of the crystal-morpology of corundum group minerals // Zapiski RMO. V. 144. №4. 2015. p. 84-92. Watson G.W., Kelsey E.T., de Leeuw N.H., Harris D.J, Parker S.C. Atomistic simulation of dislocations, surfaces and interfaces in MgO. Journal of the Chemical Society Faraday Transactions. 1996. V.92 P. 433-438.

Combined ion beam and hyperfine interaction studies of LiNbO3 single crystals

International Nuclear Information System (INIS)

Marques, J.G.; Kling, A.; Soares, J.C.; Rebouta, L.

1999-01-01

A review of recent studies of LiNbO 3 crystals doped with Hf and Mg,Hf combining high precision RBS/channelling, PIXE/channelling and hyperfine interaction techniques is presented. The lattice location of Hf was found to depend strongly on the dopant concentration, crystal stoichiometry and Mg co-doping level. At low concentrations Hf occupies Li sites in congruent crystals, while it occupies both Li and Nb sites for higher doping levels or in near-stoichiometric crystals. Co-doping with Mg also forces a split location of Hf in Li and Nb sites and when the MgO amount exceeds 4.5 mol% Hf occupies only Nb sites. Neutron irradiation of these crystals displaces Hf from its initial lattice site and leads to a strong decrease of the Nb site fraction. The results are discussed in the framework of the Li and Nb vacancy models currently proposed in the literature for the defect structure of LiNbO 3 . (author)

The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite.

Science.gov (United States)

Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Benning, Liane G

2011-01-01

The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray diffraction and infrared spectroscopy. The crystallization process occurs in two stages; firstly, the particles of ACC rapidly dehydrate and crystallize to form individual particles of vaterite; secondly, the vaterite transforms to calcite via a dissolution and reprecipitation mechanism with the reaction rate controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower than the first. Activation energies of calcite nucleation and crystallization are 73±10 and 66±2 kJ mol(-1), respectively. A model to calculate the degree of calcite crystallization from ACC at environmentally relevant temperatures (7.5-40 °C) is also presented.

Gibbs Energy Modeling of Digenite and Adjacent Solid-State Phases

Science.gov (United States)

Waldner, Peter

2017-08-01

All sulfur potential and phase diagram data available in the literature for solid-state equilibria related to digenite have been assessed. Thorough thermodynamic analysis at 1 bar total pressure has been performed. A three-sublattice approach has been developed to model the Gibbs energy of digenite as a function of composition and temperature using the compound energy formalism. The Gibbs energies of the adjacent solid-state phases covelitte and high-temperature chalcocite are also modeled treating both sulfides as stoichiometric compounds. The novel model for digenite offers new interpretation of experimental data, may contribute from a thermodynamic point of view to the elucidation of the role of copper species within the crystal structure and allows extrapolation to composition regimes richer in copper than stoichiometric digenite Cu2S. Preliminary predictions into the ternary Cu-Fe-S system at 1273 K (1000 °C) using the Gibbs energy model of digenite for calculating its iron solubility are promising.

Investigation of grain competitive growth during directional solidification of single-crystal nickel-based superalloys

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xinbao [National Energy R and D Center of Clean and High-Efficiency Fossil-Fired Power Generation Technology, Xi' an Thermal Power Research Institute Co. Ltd., Xi' an (China); Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an (China); Liu, Lin; Zhang, Jun [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, Xi' an (China)

2015-08-15

Grain competitive growth of nickel-based single-crystal superalloys during directional solidification was investigated. A detailed characterization of bi-crystals' competitive growth was performed to explore the competitive grain evolution. It was found that high withdrawal rate improved the efficiency of grain competitive growth. The overgrowth rate was increased when the misorientation increased. Four patterns of grain competitive growth with differently oriented dispositions were characterized. The results indicated that the positive branching of the dendrites played a significant role in the competitive growth process. The effect of crystal orientation and heat flow on the competitive growth can be attributed to the blocking mechanism between the adjacent grains. (orig.)

A New CCD Camera at the Molėtai Observatory

Directory of Open Access Journals (Sweden)

Zdanavičius J.

2003-12-01

Full Text Available The results of the first testing of a new CCD camera of the Molėtai Observatory are given. The linearity and the flat field corrections of good accuracy are determined by using shifted star field exposures.

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

Directory of Open Access Journals (Sweden)

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.

Energy transfer and 2.0 μm emission in Tm{sup 3+}/Ho{sup 3+} co-doped α-NaYF{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhigang; Yang, Shuo [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Xia, Haiping, E-mail: hpxcm@nbu.edu.cn [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Wang, Cheng; Jiang, Dongsheng; Zhang, Jian; Gu, Xuemei; Zhang, Yuepin [Key laboratory of Photo-electronic Materials, Ningbo University, Ningbo, Zhejiang 315211 (China); Chen, Baojiu, E-mail: bjchen@dlmu.edu.cn [Department of Physics, Dalian Maritime University, Dalian, Liaoning Province 116026 (China); Jiang, Haochuan [Ningbo Institute of Materials Technology and Engineering, the Chinese Academy of Sciences, Ningbo, Zhejiang 315211 (China)

2016-04-15

Highlights: • Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. • The maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+} (1.90 mol%)/Ho{sup 3+} (3.89 mol%) co-doped α-NaYF{sub 4}. • The obtained energy transfer rate (W{sub ET}) and energy transfer efficiency (η) of Tm{sup 3+}:{sup 3}F{sub 4} are 1077 s{sup −1} and 95.0%, respectively. • The maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2}. - Abstract: Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. The energy transfer from Tm{sup 3+} to Ho{sup 3+} and the optimum fluorescence emission around 2.04 μm of Ho{sup 3+} ion were investigated based on the measured absorption spectra, emission spectra, emission cross section and decay curves under excitation of 800 nm LD. The emission intensity at 2.04 μm increased with the increase of Ho{sup 3+} concentration from 0.96 mol% to 3.89 mol% when the concentration of Tm{sup 3+} was held constantly at ∼1.90 mol%. Moreover, the maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2} and the maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+}(1.90 mol%)/Ho{sup 3+}(3.89 mol%) co-doped one. According to the measured lifetime of Tm{sup 3+} single-doped and Tm{sup 3+}/Ho{sup 3+} co-doped samples, the maximum energy transfer efficiency of Tm{sup 3+}:{sup 3}F{sub 4} level was 95.0%. Analysis on the fluorescence dynamics indicated that electric dipole–dipole is dominant for the energy transfer from Tm{sup 3+} to Ho{sup 3+}.

Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

Science.gov (United States)

Maxwell, Eric J; Tong, William G

2016-05-01

An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2. Copyright © 2016. Published by Elsevier B.V.

Simulation of iron impurity in BaTiO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids, E-mail: arvids@utpl.edu.e [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Castillo, Darwin [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

2009-05-01

Iron-doped barium titanate (BaTiO{sub 3}) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO{sub 3} crystal has been discussed too.

Crystal structure of natural phaeosphaeride A

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Victoria V. Abzianidze

2015-08-01

Full Text Available The asymmetric unit of the title compound, C15H23NO5, contains two independent molecules. Phaeosphaeride A contains two primary sections, an alkyl chain consisting of five C atoms and a cyclic system consisting of fused five- and six-membered rings with attached substituents. In the crystal, the molecules form layered structures. Nearly planar sheets, parallel to the (001 plane, form bilayers of two-dimensional hydrogen-bonded networks with the hydroxy groups located on the interior of the bilayer sheets. The network is constructed primarily of four O—H...O hydrogen bonds, which form a zigzag pattern in the (001 plane. The butyl chains interdigitate with the butyl chains on adjacent sheets. The crystal was twinned by a twofold rotation about the c axis, with refined major–minor occupancy fractions of 0.718 (6:0.282 (6.

Calcific tendinitis of the shoulder in basic calcium phosphate crystal deposition disease

International Nuclear Information System (INIS)

Scutellari, P.N.; Mazzilli, M.P.; Orzincolo, C.

1986-01-01

Basic calcium phosphate (BCP) crystal deposition can lead to periarticular collections associated with typical radiographic findings, most frequently observed in the shoulder. Moreover, these deposits may be revealed in other articular sites (i.e.,wrist, hand, foot, elbow, hip, etc.). Initially, the calcium deposits may appear poorly defined (cloudlike); sequently, they may reveal different patterns (linear, triangular or circular areas), changing in size, configuration and site. Adjacent bone may be normal, altough osteoporosis, cystic lesions and reactive sclerosis are reported. The radiographic appearance of calcifications will depend upon the exact location of the deposits in the specific tendon of the rotator cuff, the adjacent bursae and the soft tissues

Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

International Nuclear Information System (INIS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S.M.

2009-01-01

Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 deg. C/min. An increase in the Curie temperature T c =51 deg. C (for pure TGS, T c =48.5 deg. C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

Science.gov (United States)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2009-11-01

Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 °C/min. An increase in the Curie temperature Tc=51 °C (for pure TGS, Tc=48.5 °C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

Lithium manganese(II) diaqua-boro-phosphate monohydrate.

Science.gov (United States)

Zhuang, Rong-Chuan; Chen, Xue-Yun; Mi, Jin-Xiao

2008-07-05

The title compound, LiMn(H(2)O)(2)[BP(2)O(8)]·H(2)O, is built up of an open framework of helical borophosphate ribbons inter-connected by MnO(4)(H(2)O)(2) octa-hedra, forming one-dimensional channels along [001] occupied by Li(+) cations and disordered H(2)O mol-ecules (site occupancy 0.5). The Li cations reside in two partially occupied sites [occupancies = 0.42 (3) and 0.289 (13)] near the helices.

Thermoluminescence mechanisms in CaSO4:Dy single crystals

International Nuclear Information System (INIS)

Morgan, M.D.; Stoebe, T.G.

1986-01-01

ESR studies of gamma-irradiated CaSO 4 :Dy have shown, in addition to the usual intrinsic defects, four new paramagnetic centres. An analysis of the g values and the g tensors in conjunction with the anhydrite crystal structure indicate that these centres are related to sulphate ions. Two of these centres (denoted 1a and 3a) are proposed as holes trapped and shared between two adjacent sulphate ions, this structure being stabilised by a neighbouring Ca vacancy. Centre 3b is suggested as a hole associated with one sulphate ion, again stabilised by an adjacent Ca vacancy. Because of the two distinct crystallographic directions in the anhydrite structure, centre 3b was found to consist of two distinguishable defects with slightly differing decay temperatures. The fourth centre appears to be an electron trapping site with structure similar to centre 3b. Decay temperatures of these ESR defects are correlated with the observance of TL peaks in CaSO 4 :Dy. Thermoluminescence studies as a function of impurity content confirmed the presence of calcium vacancies, which are formed during crystal growth, and that they play an important role in the TL process. TL models are proposed to account for the observed properties of CaSO 4 :Dy. (author)

NavMol 3.0: enabling the representation of metabolic reactions by blind users.

Science.gov (United States)

Binev, Yuri; Peixoto, Daniela; Pereira, Florbela; Rodrigues, Ian; Cavaco, Sofia; Lobo, Ana M; Aires-de-Sousa, João

2018-01-01

The representation of metabolic reactions strongly relies on visualization, which is a major barrier for blind users. The NavMol software renders the communication and interpretation of molecular structures and reactions accessible by integrating chemoinformatics and assistive technology. NavMol 3.0 provides a molecular editor for metabolic reactions. The user can start with templates of reactions and build from such cores. Atom-to-atom mapping enables changes in the reactants to be reflected in the products (and vice-versa) and the reaction centres to be automatically identified. Blind users can easily interact with the software using the keyboard and text-to-speech technology. NavMol 3.0 is free and open source under the GNU general public license (GPLv3), and can be downloaded at http://sourceforge.net/projects/navmol as a JAR file. joao@airesdesousa.com. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

The effect of UV exposure and heat treatment on crystallization behavior of photosensitive glasses

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Kıbrıslı, Orhan; Ersundu, Ali Erçin

2018-05-01

In this study, photosensitive glasses in the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, silver, tin, antimony) and halogenides (NaF and KBr) were synthesized through a conventional melt-quenching technique. The crystallization mechanism was investigated for solely heat-treated and UV-exposed + heat-treated samples using differential thermal analysis (DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques to understand the effect of UV exposure on crystallization behavior of photosensitive glasses. Accordingly, non-isothermal DTA measurements were performed at different heating rates to determine crystallization peak, T p, and onset, T c, temperatures. For solely heat-treated samples, the kinetic parameters such as the Avrami constant, n, and morphology index, m, were calculated as 1 from the Ozawa method indicating surface crystallization and the value of crystallization activation energy was calculated as 944 kJ/mol using modified Kissinger method. On the contrary, bulk crystallization was found to be predominant for UV exposed + heat-treated samples revealing that UV exposure is the primary cause of bulk crystallization in photosensitive glasses.

Cryopreserved embryo transfer: adjacent or non-adjacent to failed fresh long GnRH-agonist protocol IVF cycle.

Science.gov (United States)

Volodarsky-Perel, Alexander; Eldar-Geva, Talia; Holzer, Hananel E G; Schonberger, Oshrat; Reichman, Orna; Gal, Michael

2017-03-01

The optimal time to perform cryopreserved embryo transfer (CET) after a failed oocyte retrieval-embryo transfer (OR-ET) cycle is unknown. Similar clinical pregnancy rates were recently reported in immediate and delayed CET, performed after failed fresh OR-ET, in cycles with the gonadotrophin-releasing hormone (GnRH) antagonist protocol. This study compared outcomes of CET performed adjacently (<50 days, n = 67) and non-adjacently (≥50 to 120 days, n = 62) to the last OR-day of cycles with the GnRH agonist down-regulation protocol. Additional inclusion criteria were patients' age 20-38 years, the transfer of only 1-2 cryopreserved embryos, one treatment cycle per patient and artificial preparation for CET. Significantly higher implantation, clinical pregnancy and live birth rates were found in the non-adjacent group than in the adjacent group: 30.5% versus 11.3% (P = 0.001), 41.9% versus 17.9% (P = 0.003) and 32.3% versus 13.4% (P = 0.01), respectively. These results support the postponement of CET after a failed OR-ET for at least one menstrual cycle, when a preceding long GnRH-agonist protocol is used. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

[Distributions and air-sea fluxes of dissolved nitrous oxide in the Yangtze River estuary and its adjacent marine area in spring and summer].

Science.gov (United States)

Wang, Lan; Zhang, Gui-ling; Sun, Ming-shuang; Ren, Jing-ling

2014-12-01

Distributions and air-sea fluxes of nitrous oxide (N2O) in the seawaters of the Yangtze River estuary and its adjacent marine area were investigated during two cruises in March and July 2012. Dissolved N2O concentrations in surface waters ranged from 9.34 to 49.08 nmol x L(-1) with an average of (13.27 ± 6.40) nmol x L(-1) in spring and ranged from 7.27 to 27.81 nmol x L(-1) with an average of (10.62 ± 5.03) nmol x L(-1) in summer. There was no obvious difference between surface and bottom N2O concentrations. N2O concentrations in both surface and bottom waters decreased along the freshwater plume from the river mouth to the open sea. High values of dissolved N2O were found in turbidity maximum zone, which suggests that maximal turbidity enhances nitrification. Temperature had dual effects on dissolved N2O concentrations. N2O saturations in surface waters ranged from 86.9% to 351.3% with an average of (111.5 ± 41.4)% in spring and ranged from 111.7% to 396.0% with an average of (155.9 ± 68.4)% in summer. N2O were over-saturated at most stations. The sea-to-air fluxes of N2O were estimated to be (3.2 ± 10.9), (5.5 ± 19.3) and (12.2 ±52.3) μmol x (m2 x d)(-1) in spring and (7.3 ± 12.4), (12.7 ± 20.4) and (20.4 ± 35.9) μmol x (m2 x d)(-1) in summer using the LM86, W92 and RC01 relationships, respectively. The annual emissions of N2O from the Yangtze River estuary and its adjacent marine area were estimated to be 0.6 x 10(-2) Tg x a(-1) (LM86), 1.1 x 10(-2) Tg x a(-1) (W92) and 2.0 x 10(-2) Tg x a(-1) (RC01). Although the area of the Yangtze River estuary and its adjacent marine area only accounts for 0.02% of the total area of the world's oceans, their emission of N2O accounts for 0.06% of global oceanic N2O emission, indicating that the Yangtze River estuary and its adjacent marine area is an active area to produce and emit N2O.

Reconnaissance de formes moléculaires dans les relations structure-activité

OpenAIRE

Mathis , Hervé

1992-01-01

Non disponible / Not available; Cette thèse présente un logiciel qui a pour but de mieux comprendre les relations entre caractéristiques structurales et propriétés thérapeutiques de molécules envisagées comme médicaments. L'idée majeure est de soumettre une famille de composés, d'une part à des calculs de chimie quantique, d'autre part à des méthodes de reconnaissance de formes, afin d'observer si certaines propriétés moléculaires sont discriminantes vis-à-vis d'une activité pharmacologique m...

Corrosion inhibition of iron in 0.5 mol L-1 H2SO4 by halide ions

Directory of Open Access Journals (Sweden)

Jeyaprabha C.

2006-01-01

Full Text Available The inhibition effect of halide ions such as iodide, bromide and chloride ions on the corrosion of iron in 0.5 mol L-1 H2SO4 and the adsorption behaviour of these ions on the electrode surface have been studied by polarization and impedance methods. It has been found that the inhibition of nearly 90% has been observed for iodide ions at 2.5 10-3 mol L-1, for bromide ions at 10 10-3 mol L-1 and 80% for chloride ions at 2.5 10-3 mol L-1. The inhibition effect is increased with increase of halide ions concentration in the case of I- and Br- ions, whereas it has decreased in the case of Cl- ion at concentrations higher than 5 10-3 mol L-1. The double layer capacitance values have decreased considerably in the presence of halide ions which indicate that these anions are adsorbed on iron at the corrosion potential.

CCQM-K90, formaldehyde in nitrogen, 2 μmol mol-1 Final report

Science.gov (United States)

Viallon, Joële; Flores, Edgar; Idrees, Faraz; Moussay, Philippe; Wielgosz, Robert Ian; Kim, D.; Kim, Y. D.; Lee, S.; Persijn, S.; Konopelko, L. A.; Kustikov, Y. A.; Malginov, A. V.; Chubchenko, I. K.; Klimov, A. Y.; Efremova, O. V.; Zhou, Z.; Possolo, A.; Shimosaka, T.; Brewer, P.; Macé, T.; Ferracci, Valerio; Brown, Richard J. C.; Aoki, Nobuyuki

2017-01-01

The CCQM-K90 comparison is designed to evaluate the level of comparability of national metrology institutes (NMI) or designated institutes (DI) measurement capabilities for formaldehyde in nitrogen at a nominal mole fraction of 2 μmol mol-1. The comparison was organised by the BIPM using a suite of gas mixtures prepared by a producer of specialty calibration gases. The BIPM assigned the formaldehyde mole fraction in the mixtures by comparison with primary mixtures generated dynamically by permeation coupled with continuous weighing in a magnetic suspension balance. The BIPM developed two dynamic sources of formaldehyde in nitrogen that provide two independent values of the formaldehyde mole fraction: the first one based on diffusion of trioxane followed by thermal conversion to formaldehyde, the second one based on permeation of formaldehyde from paraformaldehyde contained in a permeation tube. Two independent analytical methods, based on cavity ring down spectroscopy (CRDS) and Fourier transform infrared spectroscopy (FTIR) were used for the assignment procedure. Each participating institute was provided with one transfer standard and value assigned the formaldehyde mole fraction in the standard based on its own measurement capabilities. The stability of the formaldehyde mole fraction in transfer standards was deduced from repeated measurements performed at the BIPM before and after measurements performed at participating institutes. In addition, 5 control standards were kept at the BIPM for regular measurements during the course of the comparison. Temporal trends that approximately describe the linear decrease of the amount-of-substance fraction of formaldehyde in nitrogen in the transfer standards over time were estimated by two different mathematical treatments, the outcomes of which were proposed to participants. The two treatments also differed in the way measurement uncertainties arising from measurements performed at the BIPM were propagated to the

Smarandachely Adjacent-Vertex-Distinguishing Proper Edge Chromatic Number of Cm∨Kn

OpenAIRE

Shunqin Liu

2016-01-01

According to different conditions, researchers have defined a great deal of coloring problems and the corresponding chromatic numbers. Such as, adjacent-vertex-distinguishing total chromatic number, adjacent-vertex-distinguishing proper edge chromatic number, smarandachely-adjacent-vertex-distinguishing proper edge chromatic number, smarandachely-adjacent-vertex-distinguishing proper total chromatic number. And we focus on the smarandachely adjacent-vertex-distinguishing proper edge chromatic...

Luminescence and scintillation properties of Rb2HfCl6 crystals

International Nuclear Information System (INIS)

Saeki, Keiichiro; Wakai, Yuki; Fujimoto, Yutaka; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki; Nakauchi, Daisuke

2016-01-01

We developed a scintillator based on a Rb 2 HfCl 6 crystal as a ternary halide crystal with intrinsic luminescence. In the photoluminescence spectra, two emission bands are observed at 383 and 434 nm. The 434 nm emission band for Rb 2 HfCl 6 may be attributed to [HfCl 6 ] 2- complex ion or [ZrCl 6 ] 2- impurity, since the Rb 2 HfCl 6 contained Zr as impurity at 0.62 mol %. The radioluminescence band is observed at 420 nm and can be attributed to the same origin as the photoluminescence band at 434 nm. The scintillation decay-time constants were 0.84 and 5.4 μs. The light yield was estimated to be 24,100 photons/MeV. (author)

Loading effects of anterior cervical spine fusion on adjacent segments

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Chien-Shiung Wang

2012-11-01

Full Text Available Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3–C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1; and C5–C6 segments that were fused via cage-instrumented plate fixation (group 2. Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3–C4 adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress-shielding effects

Ionic Liquid Crystals Modifier for Selective Determination of Terazosin Antihypertensive Drug in Presence of Common Interference Compounds

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Nada F. Atta

2017-01-01

Full Text Available Electrochemical sensor was fabricated based on carbon paste electrode modified with an ionic liquid crystal ILC (2-chloro-1,3-dimethyl-imidazolidinium hexafluorophosphate in presence of sodium dodecyl sulfate for the selective electrochemical determination of Terazosin (TZ in presence of common interference compounds. The electrode performance was compared in presence of other ionic liquids ILs (1-Butyl-4-methyl pyridinium tetrafluoroborate and (1-n-Hexyl-3-methyl imidazolium tetrafluoroborate. Ultrasensitive determination of Terazosin HCl at the ILC modified electrode in the linear dynamic ranges of 0.002 to 0.09 μmol·L−1 and 0.2 to 30 μmol·L−1 with correlation coefficients 0.996 and 0.995 and LODs 1.69 × 10−11 mol·L−1 and 6.43 × 10−9 mol·L−1, respectively, were obtained. Selective determination of TZ in presence of uric acid and ascorbic acid and simultaneous determination of binary mixtures of TZ/dopamine, TZ/paracetamol and TZ/Morphine were also determined successfully using the modified sensor.

Change in the electrical conductivity of SnO2 crystal from n-type to p-type conductivity

International Nuclear Information System (INIS)

Villamagua, Luis; Stashans, Arvids; Lee, Po-Ming; Liu, Yen-Shuo; Liu, Cheng-Yi; Carini, Manuela

2015-01-01

Highlights: • Switch from n-type to p-type conductivity in SnO 2 has been studied. • Computational DFT + U method where used. • X-ray diffraction and X-ray photoelectron spectroscopy where used. • Al- and N-codoped SnO 2 compound shows stable p-type conductivity. • Low resistivity (3.657 × 10 −1 Ω cm) has been obtained. • High carrier concentration (4.858 × 10 19 cm −3 ) has been obtained. - Abstract: The long-sought fully transparent technology will not come true if the n region of the p–n junction does not get as well developed as its p counterpart. Both experimental and theoretical efforts have to be used to study and discover phenomena occurring at the microscopic level in SnO 2 systems. In the present paper, using the DFT + U approach as a main tool and the Vienna ab initio Simulation Package (VASP) we reproduce both intrinsic n-type as well as p-type conductivity in concordance to results observed in real samples of SnO 2 material. Initially, an oxygen vacancy (1.56 mol% concentration) combined with a tin-interstitial (1.56 mol% concentration) scheme was used to achieve the n-type electrical conductivity. Later, to attain the p-type conductivity, crystal already possessing n-type conductivity, was codoped with nitrogen (1.56 mol% concentration) and aluminium (12.48 mol% concentration) impurities. Detailed explanation of structural changes endured by the geometry of the crystal as well as the changes in its electrical properties has been obtained. Our experimental data to a very good extent matches with the results found in the DFT + U modelling

1,4a-Dimethyl-6-methyl-ene-5-(5,5,6,6-tetra-cyano-2-methyl-cyclo-hex-2-enylmeth-yl)deca-hydro-naphthalene-1-carboxylic acid: a trans-communic acid derivative.

Science.gov (United States)

Rejouani, Nezha; Auhmani, Aziz; Ait Itto, My Youssef; Benharref, Ahmed; Daran, Jean-Claude

2008-01-18

In the search for cancer chemopreventive agents, we have studied the Diels-Alder reaction of trans-communic acid with tetra-cyano-ethyl-ene in the presence of SiO(2) as catalyst. The title cycloadduct, C(26)H(30)N(4)O(2), was obtained in 75% yield. The mol-ecules are arranged in pairs through O-H⋯O hydrogen bonds, forming an R(2) (2)(8) ring motif. Both the fused cyclohexyl rings adopt a chair conformation, whereas the nonfused ring adopts a half-chair conformation.

Thermogravimetric investigation into some crystals of rare earth ultraphosphates and glasses on their base

Energy Technology Data Exchange (ETDEWEB)

Dudko, G D; Musiyachenko, V D; Shevelevich, R S; Gut' ko, A D

1986-01-01

Thermal properties of crystal and glass-like ulraphosphates (UP) rare earth and bismuth: LnP/sub 5/O/sub 14/, where Ln-La, Nd, Eu, Gd, and (R, Nd)P/sub 5/O/sub 14/, where R=La, Gd, Bi, depending on their thermal prehistory are studied. The ratio R/sub 2/O/sub 3/:Nd/sub 2/O/sub 3/ equals 1:2. The glasses were produced by initial UP melt cooling from 1200 deg C to room temperature. It is shown, that the reaction of continuous decomposition with the maximum rate at 1000-1080 deg C and the loss of P/sub 2/O/sub 5/ at 1200 deg C not exceeding 4.5 weight % precedes the melting of LnP/sub 5/O/sub 14/ type crystal, where Ln=La, Nd, Eu, Gd, and (R, Nd)P/sub 5/O/sub 14/, where R=La, Gd, Bi (at the temperatures 1035-1100 deg C). The decomposition activation energy E/sub a/, as well as melting enthalpy ..delta..H/sub melting/ and melting temperature t/sub melting/ of LnP/sub 5/O/sub 14/ crystals, decrease in the series from La to Gd with the increase in the rare earth atomic number E/sub a/:580+-34-464+-32 kJ/mol, ..delta..H/sub melting/:37+-3-32+-2 kJ/mol, t/sub melting/:1100+-10-1035+-10 deg C.

Mineralization Process of Biocemented Sand and Impact of Bacteria and Calcium Ions Concentrations on Crystal Morphology

Directory of Open Access Journals (Sweden)

Guobin Xu

2017-01-01

Full Text Available Microbial-induced calcite precipitation (MICP is a sustainable technique used to improve sandy soil. Analysis of the mineralization process, as well as different bacterial suspensions and calcium concentrations on the crystal morphology, revealed that the mineralization process included four stages: self-organised hydrolysis of microorganisms, molecular recognition and interface interaction, growth modulation, and epitaxial growth. By increasing bacterial suspensions and calcium concentrations, the crystal morphology changed from hexahedron to oblique polyhedron to ellipsoid; the best crystal structure occurs at OD600 = 1.0 and [Ca2+] = 0.75 mol/l. It should be noted that interfacial hydrogen bonding is the main force that binds the loose sand particles. These results will help in understanding the mechanism of MICP.

Dispersion corrected hartree-fock and density functional theory for organic crystal structure prediction.

Science.gov (United States)

Brandenburg, Jan Gerit; Grimme, Stefan

2014-01-01

We present and evaluate dispersion corrected Hartree-Fock (HF) and Density Functional Theory (DFT) based quantum chemical methods for organic crystal structure prediction. The necessity of correcting for missing long-range electron correlation, also known as van der Waals (vdW) interaction, is pointed out and some methodological issues such as inclusion of three-body dispersion terms are discussed. One of the most efficient and widely used methods is the semi-classical dispersion correction D3. Its applicability for the calculation of sublimation energies is investigated for the benchmark set X23 consisting of 23 small organic crystals. For PBE-D3 the mean absolute deviation (MAD) is below the estimated experimental uncertainty of 1.3 kcal/mol. For two larger π-systems, the equilibrium crystal geometry is investigated and very good agreement with experimental data is found. Since these calculations are carried out with huge plane-wave basis sets they are rather time consuming and routinely applicable only to systems with less than about 200 atoms in the unit cell. Aiming at crystal structure prediction, which involves screening of many structures, a pre-sorting with faster methods is mandatory. Small, atom-centered basis sets can speed up the computation significantly but they suffer greatly from basis set errors. We present the recently developed geometrical counterpoise correction gCP. It is a fast semi-empirical method which corrects for most of the inter- and intramolecular basis set superposition error. For HF calculations with nearly minimal basis sets, we additionally correct for short-range basis incompleteness. We combine all three terms in the HF-3c denoted scheme which performs very well for the X23 sublimation energies with an MAD of only 1.5 kcal/mol, which is close to the huge basis set DFT-D3 result.

Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

Energy Technology Data Exchange (ETDEWEB)

Rai, Chitharanjan, E-mail: raichitharanjan@gmail.co [Department of Physics, Mangalore University, Mangalagangotri 574 199 (India); Kalpataru First Grade Science College, Tiptur 572 202 (India); Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Dharmaprakash, S.M., E-mail: smdharma@yahoo.co [Department of Physics, Mangalore University, Mangalagangotri 574 199 (India)

2009-11-15

Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 deg. C/min. An increase in the Curie temperature T{sub c}=51 deg. C (for pure TGS, T{sub c}=48.5 deg. C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

Physicochemical Properties of α-Form Hydrated Crystalline Phase of 3-(10-Carboxydecyl)-1,1,1,3,5,5,5-heptamethyl Trisiloxane/Higher alcohol/Polyoxyethylene (5 mol) Glyceryl monostearate/Water System.

Science.gov (United States)

Uyama, Makoto; Araki, Hidefumi; Fukuhara, Tadao; Watanabe, Kei

2018-06-07

The α-form hydrated crystalline phase (often called as an α-gel) is one of the hydrated crystalline phases which can be exhibited by surfactants and lipids. In this study, a novel system of an α-form hydrated crystal was developed, composed of 3-(10-carboxydecyl)-1,1,1,3,5,5,5-heptamethyl trisiloxane (CDTS), polyoxyethylene (5 mol) glyceryl monostearate (GMS-5), higher alcohol. This is the first report to indicate that a silicone surfactant can form an α-form hydrated crystal. The physicochemical properties of this system were characterized by small and wide angle X-ray scattering (SWAXS), differential scanning calorimetry (DSC), and diffusion-ordered NMR spectroscopy (DOSY) experiments. SWAXS and DSC measurements revealed that a plurality of crystalline phases coexist in the CDTS/higher alcohol/water ternary system. By adding GMS-5 to the ternary system, however, a wide region of a single α-form hydrated crystalline phase was obtained. The self-diffusion coefficients (D sel ) from the NMR measurements suggested that all of the CDTS, GMS-5, and higher alcohol molecules were incorporated into the same α-form hydrated crystals.

The influence of ion hydration on nucleation and growth of LiF crystals in aqueous solution.

Science.gov (United States)

Lanaro, G; Patey, G N

2018-01-14

Molecular dynamics (MD) simulations are employed to investigate crystal nucleation and growth in oversaturated aqueous LiF solutions. Results obtained for a range of temperatures provide evidence that the rate of crystal growth is determined by a substantial energy barrier (∼49 kJ mol -1 ) related to the loss of water from the ion hydration shells. Employing direct MD simulations, we do not observe spontaneous nucleation of LiF crystals at 300 K, but nucleation is easily observable in NVT simulations at 500 K. This contrasts with the NaCl case, where crystal nucleation is directly observed in similar simulations at 300 K. Based on these observations, together with a detailed analysis of ion clustering in metastable LiF solutions, we argue that the ion dehydration barrier also plays a key role in crystal nucleation. The hydration of the relatively small Li + and F - ions strongly influences the probability of forming large, crystal-like ion clusters, which are a necessary precursor to nucleation. This important factor is not accounted for in classical nucleation theory.

Crystal nucleus formation on the cathode under conditions of supersaturation of melt by lower valent forms

International Nuclear Information System (INIS)

Kaliev, K.A.; Aksent'ev, A.G.; Baraboshkin, A.N.

1979-01-01

Nucleation on the cathode of sodium-tungsten bronzes forom the Na 2 WO 4 -WO 3 melt, containing 40 mol.% WO 3 is studied. It has been found that in the initial period the cathode deposition of sodium-tungsten bronze is preceeded by the formation of tungsten soluble lower reduced forms, the concentration of which can considerably exceed the equilibrium one because of excessive overstress of oxide bronze crystal nucleation. The polarization of cathode and change of its potential at the crystal nucleation of sodium-tungsten bronze and switching-off of the electrolysis current has been studied

N-(N-[2-(3,5-Difluorophenyl)acetyl]-(S)-alanyl)-(S)-phenylglycine tert-butyl ester (DAPT): an inhibitor of γ-secretase, revealing fine electronic and hydrogen-bonding features

Energy Technology Data Exchange (ETDEWEB)

Czerwinski, Andrzej; Valenzuela, Francisco [Peptides International Inc., 11621 Electron Drive, Louisville, KY 40299 (United States); Afonine, Pavel [Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 64R0121, Berkeley, CA 94720 (United States); Dauter, Miroslawa, E-mail: dauter@anl.gov [Basic Research Program, SAIC-Frederick Inc., Synchrotron Radiation Research Section, MCL, NCI, Argonne National Laboratory, Biosciences Division, Building 202, Argonne, IL 60439 (United States); Dauter, Zbigniew [Synchrotron Radiation Research Section, MCL, NCI, Argonne National Laboratory, Biosciences Division, Building 202, Argonne, IL 60439 (United States); Peptides International Inc., 11621 Electron Drive, Louisville, KY 40299 (United States)

2010-12-01

The title compound, C{sub 23}H{sub 26}F{sub 2}N{sub 2}O{sub 4}, is a dipeptidic inhibitor of γ-secretase, one of the enzymes involved in Alzheimer’s dis@@ease. The mol@@ecule adopts a compact conformation, without intra@@molecular hydrogen bonds. In the crystal structure, one of the amide N atoms forms the only inter@@molecular N—H⋯O hydrogen bond; the second amide N atom does not form hydrogen bonds. High-resolution synchrotron diffraction data permitted the unequivocal location and refinement without restraints of all H atoms, and the identification of the characteristic shift of the amide H atom engaged in the hydrogen bond from its ideal position, resulting in a more linear hydrogen bond. Significant residual densities for bonding electrons were revealed after the usual SHELXL refinement, and modeling of these features as additional inter@@atomic scatterers (IAS) using the program PHENIX led to a significant decrease in the R factor from 0.0411 to 0.0325 and diminished the r.m.s. deviation level of noise in the final difference Fourier map from 0.063 to 0.037 e Å{sup −3}.

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

Science.gov (United States)

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

2013-02-01

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

catena-Poly[bis(1,3-benzo-thia-zol-3-ium) [[di-chlorido-anti-monate(III)]-di-μ-chlorido-μ-oxido-[chlorido-anti-monate(III)]-μ-chlorido

Science.gov (United States)

Chebout, Oussama; Boudraa, Mhamed; Bouacida, Sofiane; Merazig, Hocine; Boudaren, Chaouki

2016-02-01

The title compound, {(C7H6NS)2[Sb2Cl6O]} n , contains two benzo-thia-zolidium cations and one tri-μ-chlorido-tri-chlorido-μ-oxido-di-anti-monate(III) anion. The structure of the inorganic cation may be described as as being built up from two polyhedra, i.e. a square-pyramidal SbCl4O and a distorted octa-hedral SbOCl5 unit, sharing a common face (comprising the O atom and two Cl atoms). The two benzo-thia-zole cations are quasi-planar and subtend a dihedral angle of 19.93 (5)°. The crystal packing can be described by alternating (100) layers and [001] chains of the organic cations and inorganic anions connected through an extensive three-dimensional network of N-H⋯Cl, C-H⋯O and C-H⋯Cl hydrogen bonds. This is consolidated by slipped π-π stacking, with centroid-to-centroid distances between the benzo-thia-zole rings of 3.7111 (18)-3.8452 (16) Å. These inter-actions link the mol-ecules within the layers and also link the layers together and reinforce the cohesion of the ionic structure.

Towards an understanding of the molecular mechanism of solvation of drug molecules: a thermodynamic approach by crystal lattice energy, sublimation, and solubility exemplified by paracetamol, acetanilide, and phenacetin.

Science.gov (United States)

Perlovich, German L; Volkova, Tatyana V; Bauer-Brandl, Annette

2006-10-01

Temperature dependencies of saturated vapor pressure for the monoclinic modification of paracetamol (acetaminophen), acetanilide, and phenacetin (acetophenetidin) were measured and thermodynamic functions of sublimation calculated (paracetamol: DeltaGsub298=60.0 kJ/mol; DeltaHsub298=117.9+/-0.7 kJ/mol; DeltaSsub298=190+/-2 J/mol.K; acetanilide: DeltaGsub298=40.5 kJ/mol; DeltaHsub298=99.8+/-0.8 kJ/mol; DeltaSsub298=197+/-2 J/mol.K; phenacetin: DeltaGsub298=52.3 kJ/mol; DeltaHsub298=121.8+/-0.7 kJ/mol; DeltaSsub298=226+/-2 J/mol.K). Analysis of packing energies based on geometry optimization of molecules in the crystal lattices using diffraction data and the program Dmol3 was carried out. Parameters analyzed were: (a) energetic contribution of van der Waals forces and hydrogen bonding to the total packing energy; (b) contributions of fragments of the molecules to the packing energy. The fraction of hydrogen bond energy in the packing energy increases as: phenacetin (17.5%)acetanilide (20.4%)acetanilide and phenacetin, entropy driven. Copyright (c) 2006 Wiley-Liss, Inc. and the American Pharmacists Association

Resonant spin wave excitations in a magnonic crystal cavity

Science.gov (United States)

Kumar, N.; Prabhakar, A.

2018-03-01

Spin polarized electric current, injected into permalloy (Py) through a nano contact, exerts a torque on the magnetization. The spin waves (SWs) thus excited propagate radially outward. We propose an antidot magnonic crystal (MC) with a three-hole defect (L3) around the nano contact, designed so that the frequency of the excited SWs, lies in the band gap of the MC. L3 thus acts as a resonant SW cavity. The energy in this magnonic crystal cavity can be tapped by an adjacent MC waveguide (MCW). An analysis of the simulated micromagnetic power spectrum, at the output port of the MCW reveals stable SW oscillations. The quality factor of the device, calculated using the decay method, was estimated as Q > 105 for an injected spin current density of 7 ×1012 A/m2.

A new 28Si single crystal: counting the atoms for the new kilogram definition

Science.gov (United States)

Bartl, G.; Becker, P.; Beckhoff, B.; Bettin, H.; Beyer, E.; Borys, M.; Busch, I.; Cibik, L.; D'Agostino, G.; Darlatt, E.; Di Luzio, M.; Fujii, K.; Fujimoto, H.; Fujita, K.; Kolbe, M.; Krumrey, M.; Kuramoto, N.; Massa, E.; Mecke, M.; Mizushima, S.; Müller, M.; Narukawa, T.; Nicolaus, A.; Pramann, A.; Rauch, D.; Rienitz, O.; Sasso, C. P.; Stopic, A.; Stosch, R.; Waseda, A.; Wundrack, S.; Zhang, L.; Zhang, X. W.

2017-10-01

A new single crystal from isotopically enriched silicon was used to determine the Avogadro constant N A by the x-ray-crystal density method. The new crystal, named Si28-23Pr11, has a higher enrichment than the former ‘AVO28’ crystal allowing a smaller uncertainty of the molar mass determination. Again, two 1 kg spheres were manufactured from this crystal. The crystal and the spheres were measured with improved and new methods. One sphere, Si28kg01a, was measured at NMIJ and PTB with very consistent results. The other sphere, Si28kg01b, was measured only at PTB and yielded nearly the same Avogadro constant value. The mean result for both 1 kg spheres is N A  =  6.022 140 526(70)  ×  1023 mol-1 with a relative standard uncertainty of 1.2  ×  10-8. This value deviates from the Avogadro value published in 2015 for the AVO28 crystal by about 3.9(2.1)  ×  10-8. Possible reasons for this difference are discussed and additional measurements are proposed.

Concepciones de los profesores acerca del concepto mol

Directory of Open Access Journals (Sweden)

Saida Matute

2015-08-01

Full Text Available ResumenEste estudio analiza las concepciones del concepto de mol que tienen los docentes que administran la asignatura de química a nivel de bachillerato del municipio Bruzual-Yaracuy (periodo escolar 2012-2013. La muestra está representada por sesenta docentes que respondieron la encuesta. Los resultados indican que la mayoría de ellos tienen buena información en relación con el átomo y masa atómica de un elemento. En lo que se refiere al mol, como se atribuye su significado a la unidad individual de masa, de porción de sustancia y de número de partículas (número de Avogadro, se detecta que no tienen conocimiento de la definición que le dio la Iupac, lo que induce a pensar su desconocimiento acerca de dicha definición. AbstractThis study analyzes the conceptions of the term “mole” according to Chemistry teachers in Secondary school in the municipality of Yaracuy Bruzual (School year 2012-2013. The sample is represented by sixty teachers who responded to the survey. The results indicate that most of them have good information regarding atom and atomic weight of an element. With regard to the term “mol”, it was determined that they lack of knowledge on the definition given by Iupac, since its meaning is related to the individual unit of mass, portion of substance and number of particles (Avogadro’s number.

The role of the Mg sup 2 sup + ions in Cr sup 3 sup + spectroscopy for near-stoichiometric LiNbO sub 3 crystals

CERN Document Server

Han, T P J; Bermudez, V; Diéguez, E

2003-01-01

The optical spectroscopy of Cr sup 3 sup + ions doped into near-stoichiometric LiNbO sub 3 crystals, pure and co-doped with MgO, has been investigated. In the near-stoichiometric LiNbO sub 3 :Cr(0.2 mol%):Mg(2 mol%) crystal, the optical spectra resemble those previously observed for congruent LiNbO sub 3 :Cr:MgO samples when the total MgO content exceeds the 4.6 mol% threshold. The coexistence of two types of Cr sup 3 sup + centre ([Cr] sub L sub i and [Cr] sub N sub b) characterized the optical and luminescence spectra of this sample. The concentration equilibrium between the two types of centre is strongly displaced towards the [Cr sup 3 sup + ] sub N sub b centre, permitting us to obtain with accuracy the parameters of the broad bands. The R-line associated with the [Cr] sub N sub b centre is only observable in the low-temperature emission spectrum. The Fano anti-resonance lines present have been observed to be more pronounced for the near-stoichiometric samples than for congruent ones.

Controlled parallel crystallization of lithium disilicate and diopside using a combination of internal and surface nucleation

Directory of Open Access Journals (Sweden)

Markus Rampf

2016-10-01

Full Text Available In the mid-19th century, Dr. Donald Stookey identified the importance and usability of nucleating agents and mechanisms for the development of glass-ceramic materials. Today, a number of various internal and surface mechanisms as well as combinations thereof have been established in the production of glass-ceramic materials. In order to create new innovative material properties the present study focuses on the precipitation of CaMgSiO6 as a minor phase in Li2Si2O5 based glass-ceramics. In the base glass of the SiO2-Li2O-P2O5-Al2O3-K2O-MgO-CaO system P2O5 serves as nucleating agent for the internal precipitation of Li2Si2O5 crystals while a mechanical activation of the glass surface by means of ball milling is necessary to nucleate the minor CaMgSi2O6 crystal phase. For a successful precipitation of CaMgSi2O6 a minimum ratio of MgO and CaO in the range between 1.4 mol% and 2.9 mol% in the base glasses was determined. The nucleation and crystallization of both crystal phases takes place during sintering a powder compact. Dependent on the quality of the sintering process the dense Li2Si2O5-CaMgSi2O6 glass-ceramics show a mean biaxial strength of up to 392 ± 98 MPa. The microstructure of the glass-ceramics is formed by large (5-10 µm bar like CaMgSi2O6 crystals randomly embedded in a matrix of small (≤ 0.5 µm plate like Li2Si2O5 crystals arranged in an interlocking manner. While there is no significant influence of the minor CaMgSi2O6 phase on the strength of the material, the translucency of the material decreases upon precipitation of the minor phase.

Crystallization kinetics of magnetic glass-ceramics prepared by the processing of waste materials

International Nuclear Information System (INIS)

Francis, A.A.

2006-01-01

The objective of the present investigation was to study the feasibility of conversion of an intimate mixture of blast furnace slag and blast furnace flue dust generated by a single industrial company into magnetic glass-ceramic product. Blast furnace slag (BFS) and blast furnace flue dust (BFD) are generated at a rate of 300,000 and 30,000 tons/year, respectively, from iron and steel factory. The crystallization mechanisms of a composition containing BFS and BFD in a 50/50 proportion were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization temperature was found to vary from 900 to 1100 deg. C and two phases appeared in the crystallized samples: pyroxene Ca(Mg, Fe, Al)(Si, Al) 2 O 6 and magnetite/maghemite. Heating rate and particle sizes effects on crystal growth of powdered samples were studied by DTA. The apparent activation energy of crystal growth using the particle size 180-315 μm was determined to be 355 and 329 kJ/mol for the first and second peak, respectively. The presence of sharp and broad crystallization peaks indicate simultaneous surface and internal crystallization mechanism. Good wear resistance and chemical durability particularly in alkaline environment, combine with good hardness and magnetic properties make this glass-ceramic material potentially useful for various industrial applications

Classification of a Haemophilus influenzae ABC Transporter HI1470/71 through Its Cognate Molybdate Periplasmic Binding Protein, MolA

Energy Technology Data Exchange (ETDEWEB)

Tirado-Lee, Leidamarie; Lee, Allen; Rees, Douglas C.; Pinkett, Heather W. (CIT); (NWU)

2014-10-02

molA (HI1472) from H. influenzae encodes a periplasmic binding protein (PBP) that delivers substrate to the ABC transporter MolB{sub 2}C{sub 2} (formerly HI1470/71). The structures of MolA with molybdate and tungstate in the binding pocket were solved to 1.6 and 1.7 {angstrom} resolution, respectively. The MolA-binding protein binds molybdate and tungstate, but not other oxyanions such as sulfate and phosphate, making it the first class III molybdate-binding protein structurally solved. The {approx}100 {mu}M binding affinity for tungstate and molybdate is significantly lower than observed for the class II ModA molybdate-binding proteins that have nanomolar to low micromolar affinity for molybdate. The presence of two molybdate loci in H. influenzae suggests multiple transport systems for one substrate, with molABC constituting a low-affinity molybdate locus.

On improvement of scintillation characteristics of Gd2SiO5:Ce crystals by thermal treatment

International Nuclear Information System (INIS)

Bondar, Valery G.; Grinyov, Boris V.; Katrunov, Konstantin A.; Lisetski, Longin N.; Nagornaya, Lyudmila L.; Ryzhikov, Vladimir D.; Spasov, Vladimir G.; Starzhinskiy, Nikolai; Tamulaitis, Gintautas

2005-01-01

Effects of thermal treatment of Gd 2 SiO 5 :Ce crystals at T∼0.7T m under low pressure on their optical and scintillation properties were studied. It is shown that thermal treatment in the atmosphere with the chemical potential of ∼40 J mol -1 decreases the absorption in the UV region and substantially improves the crystal transparency in the region of intrinsic emission peaked at 427 nm.Narrowing of the emission band due to suppression of the long-wave component in the range of 520-560 nm, light output increase by 7-10%, decrease of the emission decay time, and improvement of thermal stability of the luminescence yield were also observed. Transformations of the ensemble of structural defects in cerium-activated gadolinium oxyorthosilicate crystals are under discussion

Scintillation and optical properties of Pb-doped YCa{sub 4}O(BO{sub 3}){sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Yutaka, E-mail: fuji-you@tagen.tohoku.ac.jp [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); JSPS, 8 Ichibanmachi, Chiyoda-ku, Tokyo 102-8472 (Japan); Yanagida, Takayuki; Yokota, Yuui [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, 3 Shibuya Shibuya-ku, Tokyo 150-8383 (Japan); Fukuda, Kentaro [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tokuyama Corporation, 3 Shibuya Shibuya-ku, Tokyo 150-8383 (Japan); Totsuka, Daisuke [Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho Tatebayashi Gunma (Japan); Watanabe, Kenichi; Yamazaki, Atsushi [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Chani, Valery [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); NICHe, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2011-10-01

This communication reports optical properties and radiation responses of Pb{sup 2+} 0.5 and 1.0 mol%-doped YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB) single crystals grown by the micro-pulling-down ({mu}-PD) method for neutron scintillator applications. The crystals had no impurity phases according to the results of X-ray powder diffraction. These Pb{sup 2+}-doped crystals demonstrated blue-light luminescence at 330 nm because of Pb{sup 2+1}S{sub 0}-{sup 3}P{sub 0,1} transition in the photoluminescence spectra. The main emission decay component was determined to be about 250-260 ns under 260 nm excitation wavelength. When irradiated by a {sup 252}Cf source, the relative light yield of 0.5% Pb{sup 2+}-doped crystal was about 300 ph/n that was determined using the light yield of a reference Li-glass scintillator.

Effect of Si and Co on the crystallization of Al-Ni-RE amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Wang, S.H. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China); Bian, X.F. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China)], E-mail: xfbian@sdu.edu.cn

2008-04-03

Crystallization of Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 7}Nd{sub 6} and Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} amorphous alloys has been studied by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The multiple transition metal (TM) (containing metalloid element) have significant effect on the crystallization behavior. A small addition of Si transforms a eutectic crystallization (Al{sub 85}Ni{sub 10}Ce{sub 5}) to a primary crystallization (Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}); while a small addition of Co transforms a primary crystallization (Al{sub 87}Ni{sub 7}Nd{sub 6}) to a eutectic crystallization (Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6}). In addition, the activation energies for crystallization (E{sub a}) are obtained to be 191, 290, 221 and 166 kJ/mol for the Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} and Al{sub 87}Ni{sub 7}Nd{sub 6} amorphous alloys based on the Kissinger method, respectively. It is found that the primary crystallization of fcc-Al is characteristic of a lower E{sub a}, as compared with eutectic crystallization.

A systematic review of definitions and classification systems of adjacent segment pathology.

Science.gov (United States)

Kraemer, Paul; Fehlings, Michael G; Hashimoto, Robin; Lee, Michael J; Anderson, Paul A; Chapman, Jens R; Raich, Annie; Norvell, Daniel C

2012-10-15

Systematic review. To undertake a systematic review to determine how "adjacent segment degeneration," "adjacent segment disease," or clinical pathological processes that serve as surrogates for adjacent segment pathology are classified and defined in the peer-reviewed literature. Adjacent segment degeneration and adjacent segment disease are terms referring to degenerative changes known to occur after reconstructive spine surgery, most commonly at an immediately adjacent functional spinal unit. These can include disc degeneration, instability, spinal stenosis, facet degeneration, and deformity. The true incidence and clinical impact of degenerative changes at the adjacent segment is unclear because there is lack of a universally accepted classification system that rigorously addresses clinical and radiological issues. A systematic review of the English language literature was undertaken and articles were classified using the Grades of Recommendation Assessment, Development, and Evaluation criteria. RESULTS.: Seven classification systems of spinal degeneration, including degeneration at the adjacent segment, were identified. None have been evaluated for reliability or validity specific to patients with degeneration at the adjacent segment. The ways in which terms related to adjacent segment "degeneration" or "disease" are defined in the peer-reviewed literature are highly variable. On the basis of the systematic review presented in this article, no formal classification system for either cervical or thoracolumbar adjacent segment disorders currently exists. No recommendations regarding the use of current classification of degeneration at any segments can be made based on the available literature. A new comprehensive definition for adjacent segment pathology (ASP, the now preferred terminology) has been proposed in this Focus Issue, which reflects the diverse pathology observed at functional spinal units adjacent to previous spinal reconstruction and balances

Synthesis, Crystal Structure, and Nonlinear Optical Properties of a New Alkali and Alkaline Earth Metal Carbonate RbNa5Ca5(CO3)8

OpenAIRE

Qiaoling Chen; Min Luo

2016-01-01

A new nonlinear optical (NLO) material, RbNa5Ca5(CO3)8, has been synthesized by the hydrothermal method. The crystal structure is established by single-crystal X-ray diffraction. RbNa5Ca5(CO3)8 crystallizes in the hexagonal crystal system with space group P63mc (No. 186). The structure of RbNa5Ca5(CO3)8 can be described as the adjacent infinite [CaCO3]∞ layers lying in the a-b plane bridged through standing-on-edge [CO3] groups by sharing O atoms (two-fold coordinated) to build a framework wi...

Electron paramagnetic resonance study of neutral Mg acceptors in β-Ga2O3 crystals

Science.gov (United States)

Kananen, B. E.; Halliburton, L. E.; Scherrer, E. M.; Stevens, K. T.; Foundos, G. K.; Chang, K. B.; Giles, N. C.

2017-08-01

Electron paramagnetic resonance (EPR) is used to directly observe and characterize neutral Mg acceptors ( M gGa0 ) in a β-Ga2O3 crystal. These acceptors, best considered as small polarons, are produced when the Mg-doped crystal is irradiated at or near 77 K with x rays. During the irradiation, neutral acceptors are formed when holes are trapped at singly ionized Mg acceptors ( M gGa- ). Unintentionally present Fe3+ (3d5) and Cr3+ (3d3) transition-metal ions serve as the corresponding electron traps. The hole is localized in a nonbonding p orbital on a threefold-coordinated oxygen ion adjacent to an Mg ion at a sixfold-coordinated Ga site. These M gGa0 acceptors (S = 1/2) have a slightly anisotropic g matrix (principal values are 2.0038, 2.0153, and 2.0371). There is also partially resolved 69Ga and 71Ga hyperfine structure resulting from unequal interactions with the two Ga ions adjacent to the hole. With the magnetic field along the a direction, hyperfine parameters are 2.61 and 1.18 mT for the 69Ga nuclei at the two inequivalent neighboring Ga sites. The M gGa0 acceptors thermally convert back to their nonparamagnetic M gGa- charge state when the temperature of the crystal is raised above approximately 250 K.

Assessing Methane Fluxes in a Small Run-of-River Reservoir: The Importance of Adjacent Marshland

Science.gov (United States)

McGinnis, D. F.; Flury, S.; Fietzek, P.; Bilsley, N. A.; Bodmer, P.; Premke, K.; Maeck, A.; Lorke, A.; Schmidt, M.

2013-12-01

We investigate methane (CH4) emissions from a small run-of-river impoundment, the Schwentine River in Kiel, Germany. Small dammed rivers, while important regions for carbon transformation, are presently not considered in the terrestrial carbon budget and are under-represented in CH4 emission studies. Using state-of-the-art monitoring techniques, we determine that 1) the CH4 emissions well-exceed those reported for temperate reservoirs and 2) the hydrodynamic linkage to bordering marshland (consisting of reed belts, sidebays and creeks) is an important CH4 source for Schwentine River CH4. During our study, the Schwentine River discharged into the Kieler Fjord at 3 - 12 m3/s. CH4 measurements included 1) a moored sensor near the dam discharge, 2) discrete water sampling, and 3) real time surface flux measurements with floating chambers. We observed that the CH4 concentration increased nearly linearly from 2.5 km upstream towards the dam. The CH4 concentration near the dam discharge was logged and reported every 30 minutes nearly continuously from 11 July - 28 Sept 2011, and varied from 500 μmol/L to 2,200 μmol/L. Surprisingly, the CH4 mass discharge from the dam - ranging from 4 to 20 kg/day - increased with both temperature and flowrate, suggesting a flow-dependent CH4 source. We found that the bordering and numerous inundated reed belts, sidebays and small creeks, had significantly elevated CH4 concentrations. These marshland regions are relatively productive and quiescent compared to the main river, and trap organic and particulate matter, leading to enhanced CH4 production. As the river flowrate increases, the lateral exchange with these adjacent areas also increases. Using the CH4 concentration time series, measured surface diffusive and ebullition fluxes, and sediment CH4 porewater profiles, we estimate the relative contributions of CH4 in the main branch due to 1) sediment diffusion, 2) dissolution from sediment CH4 bubble release, and 3) lateral fluxes from

Orbits of the Asteroids Discovered at the Molėtai Observatory in 2000–2004

Directory of Open Access Journals (Sweden)

Černis K.

2014-12-01

Full Text Available The paper presents statistics of the asteroids observed and discovered at the Molėtai Observatory, Lithuania in 2000–2004 within the project for astrometric observations of the near-Earth objects (NEOs, the main belt asteroids and comets. CCD observations of asteroids were obtained with the 35/51 cm Maksutov-type meniscus telescope and the 1.65 m Ritchey-Chretien reflector. In the Minor Planet Circulars and the Minor Planet Electronic Circulars (2000–2004 we published 6629 astrometric positions of 1114 asteroids. Among them 78 were newly discovered asteroids at Molėtai, a few NEOs were found by our team independently. For the 67 asteroids discovered at Molėtai the precise orbits were calculated. Because of small number of observations, a few asteroids have low-precision orbits and some asteroids have been lost. For seven objects we present their ephemerides for 2015.

Efectos de la irradiación iónica en hielos de moléculas carbonadas

Science.gov (United States)

Satorre, M. A.

En Astrofísica podemos encontrar numerosos contextos en los cuales se observan moléculas en estado sólido que, en condiciones estándar de presión y temperatura, se encontrarían como gases o líquidos. Dichas moléculas se denominan hielos y han sido observadas en nubes densas del medio interestelar, en envolturas circumestelares, en satélites del Sistema Solar, en cometas, etc. Los hielos pueden ser alterados en su composición química debido a diversos factores como por ejemplo variaciones de temperatura o aportes energéticos por parte de la irradiación, ya sea tanto de fotones ultravioleta como de iones. Dependiendo del escenario astrofísico que analicemos, unos factores cobran más importancia que otros. Los experimentos de laboratorio muestran el efecto que produce sobre la composición de los hielos la irradiación iónica, en particular sobre los que contenían alguna molécula con átomos de carbono. Dicha composición se analiza con espectroscopía IR en el rango de 2 a ˜ 25μ m. La aplicabilidad de los resultados de los experimentos es distinta dependiendo de la composición química inicial de los hielos, del tipo de ion utilizado y de la dosis total de irradiación. Existen efectos generales de la irradiación sobre la materia en los experimentos de relevancia astrofísica como son: - la formación de nuevas moléculas, que pueden incluir o no el ion incidente; - la progresiva pérdida de hidrógeno (carbonización) cuando irradiamos muestras que originalmente contienen una determinada relación carbono/hidrógeno; - la variación de la temperatura de sublimación que presentan algunos hielos. Esto puede suceder tanto en hielos que estaban presentes antes de la irradiación como en hielos formados por ésta. Se presentará el papel del ion en la formación de nuevas moléculas a partir de las que originalmente se encontraban en el hielo. Al penetrar en él, el ion provoca distintos procesos como rotura de enlaces y excitaciones electr

The crystal structure and morphology of NiO-YSZ composite that prepared from local zircon concentrate of Bangka Island

Energy Technology Data Exchange (ETDEWEB)

Rahmawati, F., E-mail: fitria@mipa.uns.ac.id; Apriyani, K.; Heraldy, E. [Research Group of Solid State Chemistry & Catalysis, Department of Chemistry, Sebelas Maret University, Jl. Ir. Sutami 36A Kentingan Surakarta (Indonesia); Soepriyanto, S. [Department of Metallurgical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132 (Indonesia)

2016-03-29

In order to increase the economic value of local zircon concentrate from Bangka Island, NiO-YSZ was synthesized from Zirconia, ZrO{sub 2} that was prepared from local zircon concentrate. The NiO-YSZ composite was synthesized by solid state reaction method. XRD analysis equipped with Le Bail refinement was carried out to analyze the crystal structure and cell parameters of the prepared materials. The result showed that zirconia was crystallized in tetragonal structure with a space group of P42/NMC. Yttria-Stabilized-Zirconia (YSZ) was prepared by doping 8% mol yttrium oxide into zirconia and then sintered at 1250°C for 3 hours. Doping of 8% mol Yttria allowed phase transformation of zirconia from tetragonal into the cubic structure. Meanwhile, the composite of NiO-YSZ consists of two crystalline phases, i.e. the NiO with cubic structure and the YSZ with cubic structure. SEM analysis of the prepared materials shows that the addition of NiO into YSZ allows the morphology to become more roughness with larger grain size.

Change in the electrical conductivity of SnO{sub 2} crystal from n-type to p-type conductivity

Energy Technology Data Exchange (ETDEWEB)

Villamagua, Luis, E-mail: luis.villamagua@tyndall.ie [Grupo de Fisicoquímica de Materiales, Universidad Técnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Dipartimento di Ingegneria per l’Ambiente e il Territorio e Ingegneria Chimica, Università della Calabria, 87036 Rende (CS) (Italy); Stashans, Arvids [Grupo de Fisicoquímica de Materiales, Universidad Técnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Lee, Po-Ming; Liu, Yen-Shuo; Liu, Cheng-Yi [Department of Chemical and Materials Engineering, National Central University, Jhong-Li, Taiwan (China); Carini, Manuela [Dipartimento di Ingegneria per l’Ambiente e il Territorio e Ingegneria Chimica, Università della Calabria, 87036 Rende (CS) (Italy)

2015-05-01

Highlights: • Switch from n-type to p-type conductivity in SnO{sub 2} has been studied. • Computational DFT + U method where used. • X-ray diffraction and X-ray photoelectron spectroscopy where used. • Al- and N-codoped SnO{sub 2} compound shows stable p-type conductivity. • Low resistivity (3.657 × 10{sup −1} Ω cm) has been obtained. • High carrier concentration (4.858 × 10{sup 19} cm{sup −3}) has been obtained. - Abstract: The long-sought fully transparent technology will not come true if the n region of the p–n junction does not get as well developed as its p counterpart. Both experimental and theoretical efforts have to be used to study and discover phenomena occurring at the microscopic level in SnO{sub 2} systems. In the present paper, using the DFT + U approach as a main tool and the Vienna ab initio Simulation Package (VASP) we reproduce both intrinsic n-type as well as p-type conductivity in concordance to results observed in real samples of SnO{sub 2} material. Initially, an oxygen vacancy (1.56 mol% concentration) combined with a tin-interstitial (1.56 mol% concentration) scheme was used to achieve the n-type electrical conductivity. Later, to attain the p-type conductivity, crystal already possessing n-type conductivity, was codoped with nitrogen (1.56 mol% concentration) and aluminium (12.48 mol% concentration) impurities. Detailed explanation of structural changes endured by the geometry of the crystal as well as the changes in its electrical properties has been obtained. Our experimental data to a very good extent matches with the results found in the DFT + U modelling.

Change of electrical resistivity and Young's modulus during crystallization of amorphous Fe40Ni40B20

International Nuclear Information System (INIS)

Stel, J. van der; Veldhuizen, H.B. van; Koebrugge, G.W.; Sietsma, J.; Beukel, A. van den

1989-01-01

The kinetics of crystallization of amorphous Fe 40 Ni 40 B 20 is studied by measuring isothermal changes of the electrical resistivity and Young's modulus in the temperature range 600 to 700 K. The results satisfy very well the Johnson-Mehl-Avrami equation for phase transformations with a constant activation energy of 317 kJ/mol and a constant Avrami exponent n ∼ 2. This result is interpreted as two-dimensional growth of pre-existing nuclei which become as thick as the specimen in an early stage of crystallization. The relative change in electrical resistivity upon crystallization strongly depends on the measuring temperature T m , varying from 47% at T m = 77 K to 5% at T m = 600 K. It extrapolates to zero at T m ∼ 700 K. (author)

Effects of B{sub 2}O{sub 3} content and sintering temperature on crystallization and microstructure of CBS glass–ceramic coatings

Energy Technology Data Exchange (ETDEWEB)

Li, Pengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials and Engneering, Beihang University, Beijing 100191 (China); Liu, Jianggao; Feng, Mengjie; Yang, Xinwang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2015-11-30

Graphical abstract: (a) TEM photogram of CG3 sintered at 800 °C, crystals are obvious; (b) the XRD patterns of CG3 glass samples sintered at various temperatures; (c) SEM photogram of CG3 sintered at 800 °C; (d) Kissinger, Augis–Bennett and Ozawa kinetics plots of CG3 glass samples. - Highlights: • Combining sol–gel method with direct sintering method to reduce the temperature of coatings formation. • Characterizing CaO–SiO{sub 2}–B{sub 2}O{sub 3} glass–ceramic coatings on porous substrates. • Surface crystallization of CBS glass–ceramic coatings: nucleation and kinetics. • Activation energies for crystal growth in CBS glass–ceramics with different contents of B{sub 2}O{sub 3}. - Abstract: Borosilicate glass–ceramics precursors with varying compositional ratios in the CaO–SiO{sub 2}–B{sub 2}O{sub 3} (CBS) system were synthesized by sol–gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass–ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass–ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (E{sub c}) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass–ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The E{sub c} values of CBS glasses and glass–ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B{sub 2}O{sub 3} content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

PIRAMID 1: a prime European CEC experiment in BR2 at Mol, Belgium

International Nuclear Information System (INIS)

Joly, C.; Simoni, O.

1987-01-01

In the event of a core disruptive accident in a Liquid Metal Fast Breeder Reactor (LMFBR), molten core materials interacting with liquid sodium may form debris beds to settle on the retention structures or on the reactor vessel. The decay heat of retained fission products can induce high temperatures or high thermal loads on the retention structures or the reactor vessel with consequent fission product release. To assess the long-term coolability of core debris beds the Commission of the European Communities (CEC) decided to coordinate and fund the European PAHR (Post-Accident Heat Removal) program. The first work carried out for the program resulted in PIRAMID 1 (Pahr IRradiation According to a Mol Integrated Device), a unique irradiation device, designed, constructed and tested at Mol

Objectifying the adjacent and opposite angles: a cultural historical analysis

Science.gov (United States)

Daher, Wajeeh; Musallam, Nadera

2018-02-01

The angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles' concepts. We videoed the learning of a group of three high-achieving students who used technology, specifically GeoGebra, to explore geometric relations related to the adjacent and opposite angles' concepts. To analyze students' objectification of these concepts, we used the categories of objectification of knowledge (attention and awareness) and the categories of generalization (factual, contextual and symbolic), developed by Radford. The research results indicate that teacher's and students' verbal and visual signs, together with the software dynamic tools, mediated the students' objectification of the adjacent and opposite angles' concepts. Specifically, eye and gestures perceiving were part of the semiosis cycles in which the participating students were engaged and which related to the mathematical signs that signified the adjacent and the opposite angles. Moreover, the teacher's suggestions/requests/questions included/suggested semiotic signs/tools, including verbal signs that helped the students pay attention, be aware of and objectify the adjacent and opposite angles' concepts.

Single crystal NMR studies of high temperature superconductors

International Nuclear Information System (INIS)

Pennington, C.H.; Durand, D.J.; Zax, D.B.; Slichter, C.P.; Rice, J.P.; Bukowski, E.D.; Ginsberg, D.M.

1989-01-01

The authors report Cu NMR studies in the normal state of a single crystal of the T/sub c/ = 90 K superconductor YBa 2 Cu 3 O/sub 7/minus/δ/. The authors have measured the magnetic shift tensor, the electric field gradient tensor, the nuclear spin-lattice relaxation rate tensor, and the time dependence and functional form of the transverse decay. From these data they obtain information about the charge state and magnetic state of the Cu atoms, and the existence and size of the electronic exchange coupling between spins of adjacent Cu atoms. 18 refs., 3 figs., 2 tabs

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

Energy Technology Data Exchange (ETDEWEB)

Mercer, Brian Scott [Univ. of California, Berkeley, CA (United States)

2016-05-19

In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations. Two major topics are addressed: The rst is the general behavior of PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not a ected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the C N bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The e ect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not in uence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate

Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

International Nuclear Information System (INIS)

Ibraheem, Zeyid T.; Rahman, Md. Mijanur; Yaakob, S. N.; Razalli, Mohammad Shahrazel; Kadhim, Rasim A.

2015-01-01

Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction

Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

Energy Technology Data Exchange (ETDEWEB)

Ibraheem, Zeyid T.; Rahman, Md. Mijanur; Yaakob, S. N.; Razalli, Mohammad Shahrazel; Kadhim, Rasim A. [School of Computer and Communication Engineering, Universiti Malaysia Perlis, 02600 Arau, Perlis (Malaysia)

2015-05-15

Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction.

Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

KAUST Repository

Kelarakis, Antonios

2011-05-01

We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay surface modifier was synthesized and characterized. Incorporation of organoclays with polar (MMT-OH) or aromatic groups (MMT-Ar) suppresses the crystallization of polymer chains in low MW PEO, but does not significantly affect the crystallization of high MW matrices. In addition, the relative complex viscosity of the nanocomposites based on low MW PEO increases significantly, but the effect is less pronounced at higher MWs. The viscosity increases in the series MMT-Alk < MMT-OH < MMT-Ar. In contrast to the neat PEO which exhibits a monotonic decrease of viscosity with temperature, all nanocomposites show an increase after a certain temperature. This is the first report of such dramatic enhancements in the viscoelasticity of nanocomposites, which are reversible, are based on a simple polymer matrix and are true in a wide temperature range. © 2011 Elsevier Ltd. All rights reserved.

Preparation of Lead Magnesium Niobate-Lead Zirconate Titanate Films and Their Crystallization Behaviors

International Nuclear Information System (INIS)

Tursiloadi, Silvester

2002-01-01

The thin films with composition near morpotropic phase boundary (MPB) of the system xPb(Mg 1 /3, Nb 2 /3) O 3 -yPbTiO 3 -zPbZrO 3 (x = 0-0.35, y = 0.47 and z = 0.53), were prepared by sol-gel method. The starting materials were consisted of Pb(iso-OC 3 H 7 ) 2 , Zr(n-OC 4 H 9 ) 4 , Ti(iso-OC 3 H 7 ) 4 , Mg(CH 3 COO) 2 4H 2 O and Nb(OC 2 H 5 ) 5 . The l-propanol was used as solvent. The concentration of PMN-PT-PZ in coating solution was 0.7 M, and the pH of the solution was 4.5. The thin films were prepared by dip coating and spin coating. The crystallization behaviors of the PMN-PT-PZ thin films showed that the formation of perovskite phase at low temperature becomes difficult with increasing the content of PMN. The amounts of pyrochlore and perovskite phase in PMN-PT-PZ films depended on the heating temperatures, and PMN contents. Single-phase perovskite was found for the coated films containing 0 and 12.5 mol% after calculating at 600 o C, 21 mol% after calculating at 700 o C, and 30 mol% after calculating at 750 o C. Single-phase perovskite of coated films will never be found when the content of PMN was 35 mol%

Improved measurement results for the Avogadro constant using a 28Si-enriched crystal

Science.gov (United States)

Azuma, Y.; Barat, P.; Bartl, G.; Bettin, H.; Borys, M.; Busch, I.; Cibik, L.; D'Agostino, G.; Fujii, K.; Fujimoto, H.; Hioki, A.; Krumrey, M.; Kuetgens, U.; Kuramoto, N.; Mana, G.; Massa, E.; Meeß, R.; Mizushima, S.; Narukawa, T.; Nicolaus, A.; Pramann, A.; Rabb, S. A.; Rienitz, O.; Sasso, C.; Stock, M.; Vocke, R. D., Jr.; Waseda, A.; Wundrack, S.; Zakel, S.

2015-04-01

New results are reported from an ongoing international research effort to accurately determine the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal. The surfaces of two 28Si-enriched spheres were decontaminated and reworked in order to produce an outer surface without metal contamination and improved sphericity. New measurements were then made on these two reconditioned spheres using improved methods and apparatuses. When combined with other recently refined parameter measurements, the Avogadro constant derived from these new results has a value of NA = 6.022 140 76(12) × 1023 mol-1. The x-ray crystal density method has thus achieved the target relative standard uncertainty of 2.0  ×  10-8 necessary for the realization of the definition of the new kilogram.

Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

International Nuclear Information System (INIS)

Shih, C.J.; Chen, Y.J.; Hon, M.H.

2010-01-01

Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol -1 .

Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Chen, Y.J. [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hon, M.H. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

2010-05-15

Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol{sup -1}.

Anisotropy of laser emission in monoclinic, disordered crystal Nd:LYSO.

Science.gov (United States)

Zhao, Yongguang; Zhuang, Shidong; Xu, Xiaodong; Xu, Jun; Yu, Haohai; Wang, Zhengping; Xu, Xinguang

2014-02-10

Multi-wavelength emissions have been demonstrated in many disordered laser crystals. Improving the emission controllability is crucial for their practical applications. However, it is difficult because the closely adjacent laser components cannot be effectively adjusted by the traditional resonator design. In this paper, the anisotropy of laser emission in a monoclinic, disordered crystal Nd:LuYSiO(5) (Nd:LYSO) is reported for the first time. By selecting crystal orientation, high power laser emission with different wavelengths and polarizations were obtained. For X-cut sample, 1076 nm single-wavelength laser output reached 7.56 W, which will be a useful light source for detecting carbonyl-hemoglobin and nitrite after frequency doubling. For Y- and Z-cut samples, 1076, 1079 nm dual-wavelength laser output reached 10.3 W and 7.61 W, with parallel and orthogonal polarizations, respectively, which are convenient to be used as the generation sources of 0.78 THz wave by type-I or type-II difference frequency. The output characteristic is well explained by a theoretical analysis on the stimulated emission cross-section. The present work reveals that the intrinsic anisotropy in disordered laser crystal can be utilized to elevate the emission controllability. Accordantly, the material's application scopes can be extended.

33 CFR 80.1395 - Puget Sound and adjacent waters.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Puget Sound and adjacent waters. 80.1395 Section 80.1395 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake Union...

Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

International Nuclear Information System (INIS)

Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

2016-01-01

Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

Synthesis and crystal structure of nanocrystalline phase: Ca1-xMxZr4P6O24 (M = Sr, Ba and x = 0.0-1.0)

International Nuclear Information System (INIS)

Rashmi, Ch.; Shrivastava, O.P.

2011-01-01

The structure of strontium and barium substituted nano crystalline calcium zirconium phosphate (CZP) was determined on the basis of crystal data of solid solutions. It was found that up to 2.42 mol % of strontium and 1.62 mol % of barium could be loaded into CZP formulations without significant changes of the three-dimensional framework structure. The crystal chemistry of Ca 1-x M x Zr 4 P 6 O 24 (M = Sr, Ba and x = 0.0-1.0) phases has been investigated using General Structure Analysis System (GSAS) programming. The Sr and Ba substituted CZP phases crystallize in the space group R-3 and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The unit cell volume and polyhedral (ZrO 6 and PO 4 ) distortion increases with rise in the size and mole % of loaded cation in the CZP matrix. The PO 4 stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM, TEM and EDAX analysis provide evidence of Sr and Ba in the matrix. (authors)

Cryopreservation of in vitro shoot apices of Oxalis tuberosa Mol.

Science.gov (United States)

Gonzalez-Benito, M E; Mendoza-Condori, V H; Molina-Garcia, A D

2007-01-01

Oca (Oxalis tuberosa Mol.) is an under-utilized tuber crop from the Andean region. Cryopreservation would allow the safe and long-term preservation of the genetic resources of this crop. A protocol for the cryopreservation of in vitro grown shoots has been developed using the vitrification solution PVS2. Two genotypes were studied (G1 and G27). Nodal segments were cultured on MS medium and incubated at 10 degree C with 16 h photoperiod and 10 mol per square meter per second irradiance, for two weeks. Apices were then excised and cultured on MS+0.15 M sucrose for 3 days at 5 degree C in darkness. Subsequently, apices were immersed in a loading solution (liquid MS medium+2 M glycerol+0.4 M sucrose), and then treated with the vitrification solution PVS2 for 0 to 40 minutes. Cryovials were then immersed in liquid nitrogen. Four weeks after rewarming and culture on recovery medium, genotype G1 showed approximately 60 percent recovery (normal growth) with 20 min PVS2 treatment. Genotype G27 showed lower recovery (30 percent). Differential scanning calorimetry yielded a Tg midpoint for PSV2 solution of ca. -120 degree C. Calorimetric studies on apices at different stages of the cryopreservation protocol showed a change in calorimetric parameters consistent with a decrease in the amount of frozen water as the protocol advanced.

Characterization of crystallization kinetics of a Ni- (Cr, Fe, Si, B, C, P) based amorphous brazing alloy by non-isothermal differential scanning calorimetry

International Nuclear Information System (INIS)

Raju, S.; Kumar, N.S. Arun; Jeyaganesh, B.; Mohandas, E.; Mudali, U. Kamachi

2007-01-01

The thermal stability and crystallization kinetics of a Ni- (Cr, Si, Fe, B, C, P) based amorphous brazing foil have been investigated by non-isothermal differential scanning calorimetry. The glass transition temperature T g , is found to be 720 ± 2 K. The amorphous alloy showed three distinct, yet considerably overlapping crystallization transformations with peak crystallization temperatures centered around 739, 778 and 853 ± 2 K, respectively. The solidus and liquidus temperatures are estimated to be 1250 and 1300 ± 2 K, respectively. The apparent activation energies for the three crystallization reactions have been determined using model free isoconversional methods. The typical values for the three crystallization reactions are: 334, 433 and 468 kJ mol -1 , respectively. The X-ray diffraction of the crystallized foil revealed the presence of following compounds Ni 3 B (Ni 4 B 3 ), CrB, B 2 Fe 15 Si 3 , CrSi 2 , and Ni 4.5 Si 2 B

Radiation-induced defects in LiAlO{sub 2} crystals: Holes trapped by lithium vacancies and their role in thermoluminescence

Energy Technology Data Exchange (ETDEWEB)

Holston, M.S.; McClory, J.W.; Giles, N.C. [Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, OH 45433 (United States); Halliburton, L.E., E-mail: Larry.Halliburton@mail.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States)

2015-04-15

Electron paramagnetic resonance (EPR) is used to identify the primary hole trap in undoped lithium aluminate (LiAlO{sub 2}) crystals. Our interest in this material arises because it is a candidate for radiation detection applications involving either optically stimulated luminescence (OSL) or thermoluminescence (TL). During an x-ray irradiation at room temperature, holes are trapped at oxygen ions adjacent to lithium vacancies. Large concentrations of these lithium vacancies are introduced into the crystal during growth. With the magnetic field along the [001] direction, the EPR spectrum from these trapped-hole centers consists of eleven lines, evenly spaced but with varying intensities, caused by nearly equal hyperfine interactions with two {sup 27}Al nuclei (I=5/2, 100% abundant). The g matrix is determined from the angular dependence of the EPR spectrum and has principal values of 2.0130, 2.0675, and 2.0015. These g shifts strongly support the model of a hole in a p orbital on an oxygen ion. The adjacent lithium vacancy stabilizes the hole on the oxygen ion. A sequence of pulsed thermal anneals above room temperature shows that the EPR spectrum from the holes trapped adjacent to the lithium vacancies disappears in the 90–120 °C range. The thermal decay of these hole centers directly correlates with an intense TL peak near 105 °C. Signals at lower magnetic field in the 9.4 GHz EPR spectra suggest that the electron trap associated with this TL peak at 105 °C may be a transition-metal-ion impurity, most likely Fe, located at a cation site. Additional less intense TL peaks are observed near 138, 176, and 278 °C. - Highlights: • Undoped LiAlO{sub 2} crystals are irradiated at room temperature with x-rays. • EPR is used to identify holes trapped at oxygen ions adjacent to lithium vacancies. • Thermal decay of the EPR spectrum correlates with an intense TL peak at 105 °C.

Crystal structure determination and thermal behavior upon melting of p-synephrine

Energy Technology Data Exchange (ETDEWEB)

Rosa, Frédéric [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France); Négrier, Philippe [Laboratoire Ondes et Matière d' Aquitaine, Université de Bordeaux, UMR CNRS 5798, 351 cours de la Libération, 33 405 Talence Cedex (France); Corvis, Yohann [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France); Espeau, Philippe, E-mail: philippe.espeau@parisdescartes.fr [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France)

2016-05-20

Highlights: • The refinement of the crystal structure is achieved from X-ray powder diffraction. • P-Synephrine is revealed to be a racemic compound. • Degradation during melting can be bypassed using high DSC scan rates. • The temperature and enthalpy of melting are then proposed for this compound. - Abstract: The crystal structure of p-synephrine was solved from a high-resolution X-ray powder diffraction pattern optimized by energy-minimization calculations using the Dreiding force field. The title compound crystallizes in a monoclinic system (space group P2{sub 1}/c, Z = 4, with a = 8.8504(11) Å, b = 12.1166(15) Å, c = 9.7820(11) Å, β = 122.551(2)°, V = 884.21(19) Å{sup 3} and d = 1.256 g cm{sup −3}). Since p-synephrine degrades upon melting, its melting data were determined from DSC experiments carried out as a function of the heating rate. This method allowed determining a melting temperature and enthalpy equal to 199.8 ± 1.3 °C and 57 ± 3 kJ mol{sup −1}, respectively.

Ikaite crystal distribution in winter sea ice and implications for CO2 system dynamics

Science.gov (United States)

Rysgaard, S.; Søgaard, D. H.; Cooper, M.; Pućko, M.; Lennert, K.; Papakyriakou, T. N.; Wang, F.; Geilfus, N. X.; Glud, R. N.; Ehn, J.; McGinnis, D. F.; Attard, K.; Sievers, J.; Deming, J. W.; Barber, D.

2013-04-01

The precipitation of ikaite (CaCO3 ⋅ 6H2O) in polar sea ice is critical to the efficiency of the sea ice-driven carbon pump and potentially important to the global carbon cycle, yet the spatial and temporal occurrence of ikaite within the ice is poorly known. We report unique observations of ikaite in unmelted ice and vertical profiles of ikaite abundance and concentration in sea ice for the crucial season of winter. Ice was examined from two locations: a 1 m thick land-fast ice site and a 0.3 m thick polynya site, both in the Young Sound area (74° N, 20° W) of NE Greenland. Ikaite crystals, ranging in size from a few μm to 700 μm, were observed to concentrate in the interstices between the ice platelets in both granular and columnar sea ice. In vertical sea ice profiles from both locations, ikaite concentration determined from image analysis, decreased with depth from surface-ice values of 700-900 μmol kg-1 ice (~25 × 106 crystals kg-1) to values of 100-200 μmol kg-1 ice (1-7 × 106 crystals kg-1) near the sea ice-water interface, all of which are much higher (4-10 times) than those reported in the few previous studies. Direct measurements of total alkalinity (TA) in surface layers fell within the same range as ikaite concentration, whereas TA concentrations in the lower half of the sea ice were twice as high. This depth-related discrepancy suggests interior ice processes where ikaite crystals form in surface sea ice layers and partly dissolve in layers below. Melting of sea ice and dissolution of observed concentrations of ikaite would result in meltwater with a pCO2 of <15 μatm. This value is far below atmospheric values of 390 μatm and surface water concentrations of 315 μatm. Hence, the meltwater increases the potential for seawater uptake of CO2.

Optimization and applications of planar silicon-based photonic crystal devices

DEFF Research Database (Denmark)

Borel, Peter Ingo; Frandsen, Lars Hagedorn; Burgos Leon, Juan

2005-01-01

such as topology optimization. We have also investigated a new device concept for coarse wavelength division de-multiplexing based on planar photonic crystal waveguides. The filtering of the wavelength channels has been realized by shifting the cut-off frequency of the fundamental photonic band gap mode...... in consecutive sections of the waveguide. Preliminary investigations show that this concepts allows coarse de-multiplexing to take place, but that optimization is required in order to reduce cross talk between adjacent channels and to increase the overall transmission. In this work the design, fabrication...

A new uranyl phosphate sheet in the crystal structure of furongite

Energy Technology Data Exchange (ETDEWEB)

Dal Bo, Fabrice; Hatert, Frederic [Liege Univ. (Belgium). Lab. de Mineralogie; Philippo, Simon [Musee National d' Historie Naturelle, Luxembourg (Luxembourg). Section Mineralogie

2017-06-15

The crystal structure of furongite, Al{sub 4}[(UO{sub 2}){sub 4}(PO{sub 4}){sub 6}](OH){sub 2}(H{sub 2}O){sub 19.5}, from the Kobokobo pegmatite, Kivu, Democratic Republic of Congo, was solved for the first time. Furongite is triclinic, the space group P anti 1, Z=2, a = 12.1685(8), b = 14.1579(6), c = 17.7884(6) Aa, α = 79.822(3), β = 77.637(4), γ = 67.293(2) , and V = 2746.2(2)Aa{sup 3}. The crystal structure was refined from single crystal X-ray diffraction data to R{sub 1} = 0.0733 for 7716 unique observed reflections, and to wR{sub 2} = 0.2081 for all 12,538 unique reflections. The structure of furongite contains infinite uranyl phosphate sheets of composition [(UO{sub 2}){sub 4}(PO{sub 4}){sub 6}]{sup 10-} which are parallel to (1 0 1). The sheets are constituted by UrO{sub 5} pentagonal bipyramids and PO{sub 4} tetrahedra which share edges and vertices, and adjacent sheets are linked by a dense network of hydrogen bonds. Running through the sheets and connected mainly to the free apical oxygen atom of PO4 tetrahedra are Al octahedra connected together to form remarkable Al{sub 2}O{sub 5}(OH)(H{sub 2}O){sub 5} and Al{sub 4}O{sub 8}(OH){sub 2}(H{sub 2}O){sub 10} clusters. These Al clusters are only bonded to one sheet, and do not connect two adjacent sheets together. The topology of the uranyl phosphate sheets is related to the uranophane anion topology, and can be described as a new geometrical isomer of the uranophane group. Furongite is the first uranyl phosphate reported in nature with a U:P ratio of 2:3.

Interaction of light with impurities in lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Schwesyg, Judith Renate Marie-Luise

2011-06-06

Congruent lithium niobate (LiNbO{sub 3}) and 5-mol% MgO-doped LiNbO{sub 3} (MgO:LN) crystals are widely used as nonlinear-optical crystals in frequency-conversion devices due to their large nonlinear-optic coefficients. These devices usually require high optical pump powers, but absorption of photons by impurities limits their usability due to heat accumulation that leads to thermo-optic refractive index changes. These refractive index changes distort the beam shape and disturb the phase-matching condition. Furthermore pyroelectric fields can build up. In this thesis the residual optical absorption in congruent LiNbO{sub 3} (CLN) and MgO:LN crystals is studied. Absorption spectra of CLN and MgO:LN crystals between 400-2000 nm reveal a residual absorption up to 0.04 cm{sup -1}. This absorption is mainly caused by transition metal impurities. Between 2300-2800 nm unknown hydrogen absorption bands in CLN and MgO:LN are revealed on the order of 0.001 cm{sup -1}. High-temperature annealing is applied to the CLN and MgO:LN crystals, which decreases optical absorption by up to one order of magnitude. As an application, the operation of a 1550-nm pumped singly-resonant CW optical parametric oscillator, resonant around 2600 nm, using a low-loss, periodically-poled, annealed CLN crystal is demonstrated. Another issue that affects CLN is photorefractive damage (PRD), i.e. light-induced refractive index changes. In contrast, MgO:LN crystals do not suffer from PRD even at high optical intensities. However, it is shown in this thesis that PRD can occur within seconds in MgO:LN, using green laser light at light intensity levels as low as 100 mW/cm{sup 2}, if the crystal is heated by several degrees Celsius during or before illumination. Photorefractive damage does not occur in CLN crystals under the same conditions. We show that the pyroelectric effect together with an elevated photoconductivity compared to that of CLN causes this beam distortion and that this effect also

Interaction of light with impurities in lithium niobate crystals

International Nuclear Information System (INIS)

Schwesyg, Judith Renate Marie-Luise

2011-01-01

Congruent lithium niobate (LiNbO 3 ) and 5-mol% MgO-doped LiNbO 3 (MgO:LN) crystals are widely used as nonlinear-optical crystals in frequency-conversion devices due to their large nonlinear-optic coefficients. These devices usually require high optical pump powers, but absorption of photons by impurities limits their usability due to heat accumulation that leads to thermo-optic refractive index changes. These refractive index changes distort the beam shape and disturb the phase-matching condition. Furthermore pyroelectric fields can build up. In this thesis the residual optical absorption in congruent LiNbO 3 (CLN) and MgO:LN crystals is studied. Absorption spectra of CLN and MgO:LN crystals between 400-2000 nm reveal a residual absorption up to 0.04 cm -1 . This absorption is mainly caused by transition metal impurities. Between 2300-2800 nm unknown hydrogen absorption bands in CLN and MgO:LN are revealed on the order of 0.001 cm -1 . High-temperature annealing is applied to the CLN and MgO:LN crystals, which decreases optical absorption by up to one order of magnitude. As an application, the operation of a 1550-nm pumped singly-resonant CW optical parametric oscillator, resonant around 2600 nm, using a low-loss, periodically-poled, annealed CLN crystal is demonstrated. Another issue that affects CLN is photorefractive damage (PRD), i.e. light-induced refractive index changes. In contrast, MgO:LN crystals do not suffer from PRD even at high optical intensities. However, it is shown in this thesis that PRD can occur within seconds in MgO:LN, using green laser light at light intensity levels as low as 100 mW/cm 2 , if the crystal is heated by several degrees Celsius during or before illumination. Photorefractive damage does not occur in CLN crystals under the same conditions. We show that the pyroelectric effect together with an elevated photoconductivity compared to that of CLN causes this beam distortion and that this effect also influences frequency conversion

Effect of Y2O3 addition on the crystal growth and sintering behavior of YSZ nanopowders prepared by a sol-gel process

International Nuclear Information System (INIS)

Kuo, C.-W.; Shen, Y.-H.; Hung, I-M.; Wen, S.-B.; Lee, H.-E.; Wang, M.-C.

2009-01-01

The effect of Y 2 O 3 (8 mol% ≤ Y 2 O 3 ≤ 10 mol%) addition on the crystal growth and sintering behavior of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol-gel process with various mixtures of ZrOCl 2 .8H 2 O and Y(NO 3 ) 3 .6H 2 O ethanol-water solutions at low temperatures has been studied. X-ray diffraction (XRD), Brunauer-Emmett-Teller specific surface area analyses (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and dilatometric analysis (DA) have been utilized to characterize the YSZ nanocrystallites. Characterization reveals that the YSZ nanopowders are weakly agglomerated. When calcined at various temperatures for 2 h, the crystallite size increases and the surface area of the YSZ powders decreases when the calcination temperature increased from 673 to 1273 K. A nanocrystallite size distribution between 10 and 15 nm is obtained in the TEM examination, which is consistent with the XRD investigation. The activation energy for crystal growth were determined as 5.75 ± 0.68, 4.22 ± 0.51, and 5.24 ± 0.20 kJ/mol for 8, 9 and 10 YSZ precipitates, respectively. The morphology of the YSZ sintered at high temperature indicates the abnormal growth is due to the low activation energy for crystallite growth

Single crystal study of the heavy-fermion antiferromagnet CePt2In7

International Nuclear Information System (INIS)

Tobash, Paul H; Ronning, F; Thompson, J D; Scott, B L; Bauer, E D; Moll, P J W; Batlogg, B

2012-01-01

We report the synthesis, structure, and physical properties of single crystals of CePt 2 In 7 . Single crystal x-ray diffraction analysis confirms the tetragonal I4/mmm structure of CePt 2 In 7 with unit cell parameters a = 4.5886(6) Å, c = 21.530(6) Å and V = 453.32(14) Å 3 . The magnetic susceptibility, heat capacity, Hall effect and electrical resistivity measurements are all consistent with CePt 2 In 7 undergoing an antiferromagnetic order transition at T N = 5.5 K, which is field independent up to 9 T. Above T N , the Sommerfeld coefficient of specific heat is γ ≈ 300 mJ mol -1 K -2 , which is characteristic of an enhanced effective mass of itinerant charge carriers. The electrical resistivity is typical of heavy-fermion behavior and gives a residual resistivity ρ 0 ∼ 0.2 µΩ cm, indicating good crystal quality. CePt 2 In 7 also shows moderate anisotropy of the physical properties that is comparable to structurally related CeMIn 5 (M = Co, Rh, Ir) heavy-fermion superconductors. (paper)

Acoustic band gaps of the woodpile sonic crystal with the simple cubic lattice

Energy Technology Data Exchange (ETDEWEB)

Wu, Liang-Yu; Chen, Lien-Wen, E-mail: chenlw@mail.ncku.edu.t [Department of Mechanical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

2011-02-02

This study theoretically and experimentally investigates the acoustic band gap of a three-dimensional woodpile sonic crystal. Such crystals are built by blocks or rods that are orthogonally stacked together. The adjacent layers are perpendicular to each other. The woodpile structure is embedded in air background. Their band structures and transmission spectra are calculated using the finite element method with a periodic boundary condition. The dependence of the band gap on the width of the stacked rods is discussed. The deaf bands in the band structure are observed by comparing with the calculated transmission spectra. The experimental transmission spectra for the {Gamma}-X and {Gamma}-X' directions are also presented. The calculated results are compared with the experimental results.

Structure and crystallization behavior of La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} metaborate glasses doped with Nd{sup 3+} or Eu{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Pytalev, D.S., E-mail: pytalev@isan.troitsk.ru [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation); Caurant, D.; Majérus, O.; Trégouët, H. [Institut de Recherche de Chimie Paris, CNRS – Chimie ParisTech, 11 Rue Pierre et Marie Curie, 75005 Paris (France); Charpentier, T. [CEA, IRAMIS, NIMBE, CEA-CNRS UMR 3299, Laboratoire de Structure et Dynamique par Résonance Magnétique, 91191 Gif-sur-Yvette (France); Mavrin, B.N. [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation)

2015-08-25

Highlights: • The structure and crystallization behavior of the La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} glass are studied. • LaB{sub 3}O{sub 6} crystallizes congruently without intermediate but only from glass surface. • The structure of the amorphous and the crystalline phases differ significantly. • The activation energy of LaB{sub 3}O{sub 6} crystal growth is determined. - Abstract: The local structure and crystallization behavior of the stoichiometric La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} (LaMB) metaborate glass doped with Nd{sup 3+} or Eu{sup 3+} ions are studied using differential thermal analysis (DTA), X-ray diffraction (XRD), Raman scattering and {sup 11}B magic-angle spinning nuclear magnetic resonance (MAS NMR), optical absorbance and luminescence techniques. In the crystallized samples, XRD, NMR and Raman spectroscopy have detected the formation of only one crystalline phase (congruent crystallization of LaB{sub 3}O{sub 6}). No intermediate metastable crystalline phase has been detected before LaB{sub 3}O{sub 6} crystals formation (single stage crystallization process). The observation of heat treated glass samples by scanning electron microscopy (SEM) and optical microscopy coupled with the study of the effect of varying the glass particle size on the DTA curves have both revealed that LaB{sub 3}O{sub 6} crystallization only occurs by a heterogeneous nucleation mechanism (needle-shape crystals) from glass surface. The activation energy E{sub c} of crystal growth has been determined by performing DTA experiments at different heating rates with the Kissinger (784 kJ/mol) and Ozawa (801 kJ/mol) equations than can be used for surface crystallization processes. The heterogeneous crystallization behavior and the spectroscopic results obtained in this work by comparing the LaMB glass with the LaB{sub 3}O{sub 6} crystalline phase suggest the existence of significant structural differences between the amorphous and the crystalline phases contrary to what

Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In1 -xFex )2O3

Science.gov (United States)

Green, R. J.; Regier, T. Z.; Leedahl, B.; McLeod, J. A.; Xu, X. H.; Chang, G. S.; Kurmaev, E. Z.; Moewes, A.

2015-10-01

Dilute magnetic semiconductors (DMSs) show great promise for applications in spin-based electronics, but in most cases continue to elude explanations of their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and Anderson impurity model calculations to study ferromagnetic Fe-substituted In2 O3 films, and we identify a subset of Fe atoms adjacent to oxygen vacancies in the crystal lattice which are responsible for the observed room temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map out the near gap electronic structure and provide further support for this conclusion. Serving as a concrete verification of recent theoretical results and indirect experimental evidence, these results solidify the role of impurity-vacancy coupling in oxide-based DMSs.

Local adjacency metric dimension of sun graph and stacked book graph

Science.gov (United States)

Yulisda Badri, Alifiah; Darmaji

2018-03-01

A graph is a mathematical system consisting of a non-empty set of nodes and a set of empty sides. One of the topics to be studied in graph theory is the metric dimension. Application in the metric dimension is the navigation robot system on a path. Robot moves from one vertex to another vertex in the field by minimizing the errors that occur in translating the instructions (code) obtained from the vertices of that location. To move the robot must give different instructions (code). In order for the robot to move efficiently, the robot must be fast to translate the code of the nodes of the location it passes. so that the location vertex has a minimum distance. However, if the robot must move with the vertex location on a very large field, so the robot can not detect because the distance is too far.[6] In this case, the robot can determine its position by utilizing location vertices based on adjacency. The problem is to find the minimum cardinality of the required location vertex, and where to put, so that the robot can determine its location. The solution to this problem is the dimension of adjacency metric and adjacency metric bases. Rodrguez-Velzquez and Fernau combine the adjacency metric dimensions with local metric dimensions, thus becoming the local adjacency metric dimension. In the local adjacency metric dimension each vertex in the graph may have the same adjacency representation as the terms of the vertices. To obtain the local metric dimension of values in the graph of the Sun and the stacked book graph is used the construction method by considering the representation of each adjacent vertex of the graph.

On Mathematical Optimization for the Visualization of Frequencies and Adjacencies as Rectangular Maps

DEFF Research Database (Denmark)

Carrizosa, Emilio; Guerrero, Vanesa; Morales, Dolores Romero

2018-01-01

individuals as adjacent rectangular portions as possible and adding as few false adjacencies, i.e., adjacencies between rectangular portions corresponding to non-adjacent individuals, as possible. We formulate this visualization problem as a Mixed Integer Linear Programming (MILP) model. We propose......In this paper we address the problem of visualizing a frequency distribution and an adjacency relation attached to a set of individuals. We represent this information using a rectangular map, i.e., a subdivision of a rectangle into rectangular portions so that each portion is associated with one...

Pressure effect on ionic conductivity in yttrium-oxide-doped single-crystal zirconium oxide

International Nuclear Information System (INIS)

Park, E.T.; Park, J.H.

1998-06-01

In this study, the authors investigated the effect of pressure on the ionic conductivity of a 9.5 mol% yttria-stabilized zirconia (YSZ) single crystal. The experiment was conducted in the elastic region, and the oxygen ion transport number was unity (t ion > 0.99999). A conventional four-probe DC method was used to measure the ionic conductivity of the rectangular-shaped sample under uniaxial pressures up to 600 atm at 750 C in air. Measured ionic conductivity decreased as applied pressure increased. Based on henry Eyring's absolute reaction rate theory, which states that the calculated activation volume has a positive value (ΔV 2 = 2.08 cm 3 /mol of O -2 ) for oxygen ion transport in the fluoride cubic lattice, they concluded that the results they obtained could be explained by an oxygen ion transport mechanism. This mechanism can explain the fact that the interionic distance increases during oxygen ion transport from one unit cell to neighboring unit cells

On Pathos Adjacency Cut Vertex Jump Graph of a Tree

OpenAIRE

Nagesh.H.M; R.Chandrasekhar

2014-01-01

In this paper the concept of pathos adjacency cut vertex jump graph PJC(T) of a tree T is introduced. We also present a characterization of graphs whose pathos adjacency cut vertex jump graphs are planar, outerplanar, minimally non-outerplanar, Eulerian and Hamiltonian.

Crystallite growth kinetics of TiO2 surface modification with 9 mol% ZnO prepared by a coprecipitation process

International Nuclear Information System (INIS)

Ko, Horng-Huey; Hsi, Chi-Shiung; Wang, Moo-Chin; Zhao, Xiujian

2014-01-01

Highlights: • TiO 2 powder surface modification with 9 mol% ZnO was obtained. • Phase transformation from anatase to rutile was hindered by ZnO added. • Growth kinetic of anatase TiO 2 nanocrystallites in T-9Z powders was described as: D A,9 2 =2.42×10 5 ×exp(-39.9×10 3 /RT). • Growth kinetic of rutile TiO 2 nanocrystallites in T-9Z powders was described as: D R,9 2 =8.49×10 5 ×exp(-47.6×10 3 /RT) rutile TiO 2 . -- Abstract: The nanocrystallite growth of TiO 2 surface modification with 9 mol% ZnO prepared by a coprecipitation process has been studied. Thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–VIS–NIR spectrophotometry have been utilized to characterize the TiO 2 nanocrystallites surface modification with 9 mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO 2 first formed at 533 K and the completion of anatase TiO 2 crystallization occurred at 745 K for the T-9Z freeze-dried precursor powders. XRD results reveal that the anatase and rutile TiO 2 coexist when the T-9Z freeze-dried precursor powders were calcined at 523–973 K for 2 h. When the T-9Z freeze-dried precursor powders were calcined at 973 K for 2 h, rutile TiO 2 was the major phase, and the minor phases were anatase TiO 2 and Zn 2 Ti 3 O 8 . The phase was composed of the rutile TiO 2 and Zn 2 TiO 4 for the T-9Z freeze-dried precursor powders after calcination at 1273 K for 2 h. The growth kinetics of TiO 2 nanocrystallites in T-9Z powders were described as: D A,9 2 =2.42×10 5 ×exp(-39.9×10 3 /RT)and D R,9 2 =8.49×10 5 ×exp(-47.6×10 3 /RT) for anatase and rutile TiO 2 nanocrystallites respectively. The analysis results of UV/VIS/NIR spectra reveal that the T-9Z freeze-dried precursor powders after calcination have a red-shifted effect with increasing calcination temperature and can be used as a UVA-attenuating agent

Emission of pesticides during drilling and deposition in adjacent areas

Directory of Open Access Journals (Sweden)

Heimbach, Udo

2014-02-01

Full Text Available In seven experiments seeds of maize, oil seed rape and barley, treated with neonicotinoids, were sown using pneumatic drilling equipment with deflectors attached in case of pneumatic suction systems. Directly adjacent to the drilled area of usually about 50 m width were replicated areas with bare soil as well as with crops. During maize (Zea mays drilling flowering oil seed rape (Brassica napus and during drilling of barley (Hordeum vulgare and oil seed rape flowering white mustard (Sinapis alba was adjacent. The amount of residues in the adjacent non crop areas in Petri dishes being distributed on the bare soil declined only slowly from 1 to 20 m distance from the area drilled. Seed batches with more abrasion and higher content of active substances in the dust resulted in higher residues off crop. After drilling of maize in four experiments in Petri dishes in adjacent non crop areas in 1-5 m distance between 0.02 and 0.40 g a.s./ha of neonicotinoids and in the adjacent oil seed rape a total of 0.05–0.80 g a.s./ha were detected. After drilling oil seed rape or barley these values were only 0.02–0.06 g a.s./ha in Petri dishes in non crop areas and 0.03-0.08 g a.s./ha in total in adjacent white mustard. In gauze net samplers installed vertically in 3 m distance in non crop areas up to seven times higher values were detected compared to Petri dishes.

Laser stimulated third harmonic generation studies in ZnO-Ta2O5-B2O3 glass ceramics entrenched with Zn3Ta2O8 crystal phases

Science.gov (United States)

Siva Sesha Reddy, A.; Jedryka, J.; Ozga, K.; Ravi Kumar, V.; Purnachand, N.; Kityk, I. V.; Veeraiah, N.

2018-02-01

In this study zinc borate glasses doped with different concentrations Ta2O5 were synthesized and were crystallized by heat treatment for prolonged times. The samples were characterized by XRD, SEM, IR and Raman spectroscopy techniques. The SEM images of the crystallized samples have indicated that the samples contain randomly distributed crystal grains with size ∼1 μm entrenched in the residual amorphous phase. XRD studies have exhibited diffraction peaks identified as being due to the reflections from (1 1 1) planes of monoclinic Zn3Ta2O8 crystal phase that contains intertwined tetrahedral zinc and octahedral tantalate structural units. The concentration of such crystal phases in the bulk samples is observed to increase with increase of Ta2O5 up to 3.0 mol%. The IR and Raman spectroscopy studies have confirmed the presence of ZnO4 and TaO6 structural units in the glass network in addition to the conventional borate structural units. For measuring third harmonic generation (THG) in the samples, the samples were irradiated with 532 nm laser beam and the intensity of THG of probing beam (Nd:YAG λ = 1064 nm 20 ns pulsed laser (ω)) is measured as a function of fundamental beam power varying up to 200 J/m2. The intensity of THG is found to be increasing with increase of fundamental beam power and found to be the maximal for the glass crystallized with 3.0 mol% of Ta2O5. The intensity of THG of the ceramicized samples is found to be nearly 5 times higher with respect to that of pre-crystallized samples. The generation of 3ω is attributed to the perturbation/interaction between Zn3Ta2O8 anisotropic crystal grains and the incident probing beam.

Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

Energy Technology Data Exchange (ETDEWEB)

Noriega, David C., E-mail: dcnoriega1970@gmail.com [Valladolid University Hospital, Spine Department (Spain); Marcia, Stefano, E-mail: stemarcia@gmail.com [SS. Trinità Hospital ASL 8 Cagliari, Department of Radiology (Italy); Ardura, Francisco, E-mail: fardura@ono.com [Valladolid University Hospital, Spine Department (Spain); Lite, Israel Sanchez, E-mail: israelslite@hotmail.com [Valladolid University Hospital, Radiology Department (Spain); Marras, Mariangela, E-mail: mariangela.marrasmd@gmail.com [Azienda Ospedaliero Brotzu (A.O.B.), Department of Radiology (Italy); Saba, Luca, E-mail: lucasaba@tiscali.it [Azienda Ospedaliero Universitaria (A.O.U.), Department of Radiology (Italy)

2016-09-15

ObjectiveThe purpose of this study was to assess, by the mean apparent diffusion coefficient (ADC), if a relationship exists between disc ADC and MR findings of adjacent disc degeneration after thoracolumbar fractures treated by anatomic reduction using vertebral augmentation (VAP).Materials and MethodsTwenty non-consecutive patients (mean age 50.7 years; range 45–56) treated because of vertebral fractures, were included in this study. There were 10 A3.1 and 10 A1.2 fractures (AO classification). Surgical treatment using VAP was applied in 14 cases, and conservative in 6 patients. MRI T2-weighted images and mapping of apparent diffusion coefficient (ADC) of the intervertebral disc adjacent to the fractured segment were performed after a mean follow-up of 32 months. A total of 60 discs, 3 per patient, were analysed: infra-adjacent, supra-adjacent and a control disc one level above the supra-adjacent.ResultsNo differences between patients surgically treated and those following a conservative protocol regarding the average ADC values obtained in the 20 control discs analysed were found. Considering all discs, average ADC in the supra-adjacent level was lower than in the infra-adjacent (1.35 ± 0.12 vs. 1.53 ± 0.06; p < 0.001). Average ADC values of the discs used as a control were similar to those of the infra-adjacent level (1.54 ± 0.06). Compared to surgically treated patients, discs at the supra-adjacent fracture level showed statistically significant lower values in cases treated conservatively (p < 0.001). The variation in the delay of surgery had no influence on the average values of ADC at any of the measured levels.ConclusionsADC measurements of the supra-adjacent discs after a mean follow-up of 32 months following thoracolumbar fractures, showed that restoration of the vertebral collapse by minimally invasive VAP prevents posttraumatic disc degeneration.

Anisotropic charge transport in large single crystals of π-conjugated organic molecules.

Science.gov (United States)

Hourani, Wael; Rahimi, Khosrow; Botiz, Ioan; Koch, Felix Peter Vinzenz; Reiter, Günter; Lienerth, Peter; Heiser, Thomas; Bubendorff, Jean-Luc; Simon, Laurent

2014-05-07

The electronic properties of organic semiconductors depend strongly on the nature of the molecules, their conjugation and conformation, their mutual distance and the orientation between adjacent molecules. Variations of intramolecular distances and conformation disturb the conjugation and perturb the delocalization of charges. As a result, the mobility considerably decreases compared to that of a covalently well-organized crystal. Here, we present electrical characterization of large single crystals made of the regioregular octamer of 3-hexyl-thiophene (3HT)8 using a conductive-atomic force microscope (C-AFM) in air. We find a large anisotropy in the conduction with charge mobility values depending on the crystallographic orientation of the single crystal. The smaller conduction is in the direction of π-π stacking (along the long axis of the single crystal) with a mobility value in the order of 10(-3) cm(2) V(-1) s(-1), and the larger one is along the molecular axis (in the direction normal to the single crystal surface) with a mobility value in the order of 0.5 cm(2) V(-1) s(-1). The measured current-voltage (I-V) curves showed that along the molecular axis, the current followed an exponential dependence corresponding to an injection mode. In the π-π stacking direction, the current exhibits a space charge limited current (SCLC) behavior, which allows us to estimate the charge carrier mobility.

Machine learning for the structure-energy-property landscapes of molecular crystals.

Science.gov (United States)

Musil, Félix; De, Sandip; Yang, Jack; Campbell, Joshua E; Day, Graeme M; Ceriotti, Michele

2018-02-07

Molecular crystals play an important role in several fields of science and technology. They frequently crystallize in different polymorphs with substantially different physical properties. To help guide the synthesis of candidate materials, atomic-scale modelling can be used to enumerate the stable polymorphs and to predict their properties, as well as to propose heuristic rules to rationalize the correlations between crystal structure and materials properties. Here we show how a recently-developed machine-learning (ML) framework can be used to achieve inexpensive and accurate predictions of the stability and properties of polymorphs, and a data-driven classification that is less biased and more flexible than typical heuristic rules. We discuss, as examples, the lattice energy and property landscapes of pentacene and two azapentacene isomers that are of interest as organic semiconductor materials. We show that we can estimate force field or DFT lattice energies with sub-kJ mol -1 accuracy, using only a few hundred reference configurations, and reduce by a factor of ten the computational effort needed to predict charge mobility in the crystal structures. The automatic structural classification of the polymorphs reveals a more detailed picture of molecular packing than that provided by conventional heuristics, and helps disentangle the role of hydrogen bonded and π-stacking interactions in determining molecular self-assembly. This observation demonstrates that ML is not just a black-box scheme to interpolate between reference calculations, but can also be used as a tool to gain intuitive insights into structure-property relations in molecular crystal engineering.

Correlation between crystallization behaviour and interfacial interactions in plasticized PLA/POSS nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Kodal, Mehmet, E-mail: mehmet.kodal@kocaeli.edu.tr; Şirin, Hümeyra; Özkoç, Güralp, E-mail: guralp.ozkoc@kocaeli.edu.tr [Department of Chemical Engineering, Kocaeli University, 41380, Kocaeli Turkey (Turkey)

2016-03-09

In this study, the correlation between crystallization behavior and surface chemistry of polyhedral oligomeric silsesquioxanes (POSS) for plasticized poly(lactic acid) (PLA)/POSS nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. Poly(ethylene glycol) (PEG, 8000 g/mol) was utilized as the plasticiser. The nanocomposites were melt-compounded in an Xplore Instruments 15 cc twin screw microcompounder at 180°C barrel temperature and 100 rpm screw speed. Non-isothermal crystallization behaviour of PLA/PEG/POSS nanocomposites were evaluated from common kinetic models such as Avrami and Avrami-Ozawa and Kissinger by using the thermal data obtained from differantial scanning calorimetry (DSC). A polarized optical microscope (POM) equipped with a hot-stage was used to examine the morphology during the crystal growth. In order to investigate the interfacial interactions between POSS particles and plasticized PLA, thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies. A strong correlation was obtained between interfacial chemistry and the nucleation rate in plasticized PLA/POSS nanocomposites. It was found that the polar interactions were the dominating factor which determines the nucleation activity of the POSS particles.

Correlation between crystallization behaviour and interfacial interactions in plasticized PLA/POSS nanocomposites

International Nuclear Information System (INIS)

Kodal, Mehmet; Şirin, Hümeyra; Özkoç, Güralp

2016-01-01

In this study, the correlation between crystallization behavior and surface chemistry of polyhedral oligomeric silsesquioxanes (POSS) for plasticized poly(lactic acid) (PLA)/POSS nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. Poly(ethylene glycol) (PEG, 8000 g/mol) was utilized as the plasticiser. The nanocomposites were melt-compounded in an Xplore Instruments 15 cc twin screw microcompounder at 180°C barrel temperature and 100 rpm screw speed. Non-isothermal crystallization behaviour of PLA/PEG/POSS nanocomposites were evaluated from common kinetic models such as Avrami and Avrami-Ozawa and Kissinger by using the thermal data obtained from differantial scanning calorimetry (DSC). A polarized optical microscope (POM) equipped with a hot-stage was used to examine the morphology during the crystal growth. In order to investigate the interfacial interactions between POSS particles and plasticized PLA, thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies. A strong correlation was obtained between interfacial chemistry and the nucleation rate in plasticized PLA/POSS nanocomposites. It was found that the polar interactions were the dominating factor which determines the nucleation activity of the POSS particles.

Defect sensitive etching of hexagonal boron nitride single crystals

Science.gov (United States)

Edgar, J. H.; Liu, S.; Hoffman, T.; Zhang, Yichao; Twigg, M. E.; Bassim, Nabil D.; Liang, Shenglong; Khan, Neelam

2017-12-01

Defect sensitive etching (DSE) was developed to estimate the density of non-basal plane dislocations in hexagonal boron nitride (hBN) single crystals. The crystals employed in this study were precipitated by slowly cooling (2-4 °C/h) a nickel-chromium flux saturated with hBN from 1500 °C under 1 bar of flowing nitrogen. On the (0001) planes, hexagonal-shaped etch pits were formed by etching the crystals in a eutectic mixture of NaOH and KOH between 450 °C and 525 °C for 1-2 min. There were three types of pits: pointed bottom, flat bottom, and mixed shape pits. Cross-sectional transmission electron microscopy revealed that the pointed bottom etch pits examined were associated with threading dislocations. All of these dislocations had an a-type burgers vector (i.e., they were edge dislocations, since the line direction is perpendicular to the [ 2 11 ¯ 0 ]-type direction). The pit widths were much wider than the pit depths as measured by atomic force microscopy, indicating the lateral etch rate was much faster than the vertical etch rate. From an Arrhenius plot of the log of the etch rate versus the inverse temperature, the activation energy was approximately 60 kJ/mol. This work demonstrates that DSE is an effective method for locating threading dislocations in hBN and estimating their densities.

Diffusion of chlorine in single-crystal (Sr,Y)Cl2.03

International Nuclear Information System (INIS)

Goff, J.P.; Hayes, W.; Ward, R.C.C; Hull, S.; Hutchings, M.T.

1992-01-01

Quasielastic energy broadening of the incoherent neutron scattering from single-crystal (Sr,Y)Cl 2.03 has been studied at elevated temperatures using the time-of-flight spectrometer IRIS at the Rutherford-Appleton Laboratory. Incoherent spectra measured at temperatures of 923 and 973 K have been fitted by a Chudley-Elliott model, in which individual anions occupy sites for a mean residence time τ before hopping to adjacent regular lattice sites. These results obtained from an anion-excess system are compared with a previous investigation of chlorine diffusion in pure SrCl 2 . (orig.)

Photorefractive features of non-stoichiometry codoped Hf:Fe:LiNbO3 single crystals

International Nuclear Information System (INIS)

Liu, Bo; Li, Chunliang; Bi, Jiancong; Sun, Liang; Xu, Yuheng

2008-01-01

Hf(2mol%):Fe(0.05wt%):LiNbO 3 crystals with various [Li]/[Nb] ratios of 0.94, 1.05, 1.2 and 1.38 have been grown. The photorefractive resistant ability increases with the accretion of [Li]/[Nb] ratio. When the ratio of [Li]/[Nb] is 1.20 or 1.38, the OH - absorption band shifts to about 3477cm -1 . The mechanisms of the photorefractive resistant ability increase and the absorption band shift have been discussed. The exponential gain coefficient (Γ) of the crystals was measured with two-beam coupling method and the effective charge carrier concentration (N eff ) was calculated. The results show that Γ and N eff increase with the accretion of [Li]/[Nb] ratio. The temperature effect of codoped Hf:Fe:LiNbO 3 crystals was also studied, it was found that the exponential gain coefficient increase dramatically at about 55 C, 70 C and 110 C, this is due to the inner electric field which is resulted from structure phase change. (copyright 2007 WILEY -VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-diphenyl-2-[4-(pyren-1-ylphenyl]acrylonitrile

Directory of Open Access Journals (Sweden)

Bao-Xi Miao

2018-05-01

Full Text Available The title organic compound, C37H23N, crystallizing in the triclinic space group P\\overline{1}, has been designed, synthesized and characterized by single-crystal X-ray diffaction, MS, NMR and elemental analysis. There are alternating relatively strong and weak intermolecular π–π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE characteristics.

Effect of Y{sub 2}O{sub 3} addition on the crystal growth and sintering behavior of YSZ nanopowders prepared by a sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Kuo, C.-W.; Shen, Y.-H. [Department of Resources Engineering, National Chen Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hung, I-M. [Yuan Ze Fuel Cell Center, Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Yuan-Tung Road, Chung-Li, Taoyuan 320, Taiwan (China)], E-mail: imhung@saturn.yzu.edu.tw; Wen, S.-B. [General Education Center, Meiho Institute of Technology, 23 Pingguang Road, Neipu, Pingtung 91202, Taiwan (China); Lee, H.-E. [Faculty of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw

2009-03-20

The effect of Y{sub 2}O{sub 3} (8 mol% {<=} Y{sub 2}O{sub 3} {<=} 10 mol%) addition on the crystal growth and sintering behavior of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol-gel process with various mixtures of ZrOCl{sub 2}.8H{sub 2}O and Y(NO{sub 3}){sub 3}.6H{sub 2}O ethanol-water solutions at low temperatures has been studied. X-ray diffraction (XRD), Brunauer-Emmett-Teller specific surface area analyses (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and dilatometric analysis (DA) have been utilized to characterize the YSZ nanocrystallites. Characterization reveals that the YSZ nanopowders are weakly agglomerated. When calcined at various temperatures for 2 h, the crystallite size increases and the surface area of the YSZ powders decreases when the calcination temperature increased from 673 to 1273 K. A nanocrystallite size distribution between 10 and 15 nm is obtained in the TEM examination, which is consistent with the XRD investigation. The activation energy for crystal growth were determined as 5.75 {+-} 0.68, 4.22 {+-} 0.51, and 5.24 {+-} 0.20 kJ/mol for 8, 9 and 10 YSZ precipitates, respectively. The morphology of the YSZ sintered at high temperature indicates the abnormal growth is due to the low activation energy for crystallite growth.

Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In(1-x)Fe(x))2O3.

Science.gov (United States)

Green, R J; Regier, T Z; Leedahl, B; McLeod, J A; Xu, X H; Chang, G S; Kurmaev, E Z; Moewes, A

2015-10-16

Dilute magnetic semiconductors (DMSs) show great promise for applications in spin-based electronics, but in most cases continue to elude explanations of their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and Anderson impurity model calculations to study ferromagnetic Fe-substituted In2O3 films, and we identify a subset of Fe atoms adjacent to oxygen vacancies in the crystal lattice which are responsible for the observed room temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map out the near gap electronic structure and provide further support for this conclusion. Serving as a concrete verification of recent theoretical results and indirect experimental evidence, these results solidify the role of impurity-vacancy coupling in oxide-based DMSs.

Interactions between tenocytes and monosodium urate monohydrate crystals: implications for tendon involvement in gout.

Science.gov (United States)

Chhana, Ashika; Callon, Karen E; Dray, Michael; Pool, Bregina; Naot, Dorit; Gamble, Greg D; Coleman, Brendan; McCarthy, Geraldine; McQueen, Fiona M; Cornish, Jillian; Dalbeth, Nicola

2014-09-01

Advanced imaging studies have demonstrated that urate deposition in periarticular structures, such as tendons, is common in gout. The aim of this study was to investigate the effects of monosodium urate monohydrate (MSU) crystals on tenocyte viability and function. The histological appearance of tendons in joints affected by advanced gout was examined using light microscopy. In vitro, colorimetric assays and flow cytometry were used to assess cell viability in primary rat and primary human tenocytes cultured with MSU crystals. Real-time PCR was used to determine changes in the relative mRNA expression levels of tendon-related genes, and Sirius red staining was used to measure changes in collagen deposition in primary rat tenocytes. In joint samples from patients with gout, MSU crystals were identified within the tendon, adjacent to and invading into tendon, and at the enthesis. MSU crystals reduced tenocyte viability in a dose-dependent manner. MSU crystals decreased the mRNA expression of tendon collagens, matrix proteins and degradative enzymes and reduced collagen protein deposition by tenocytes. These data indicate that MSU crystals directly interact with tenocytes to reduce cell viability and function. These interactions may contribute to tendon damage in people with advanced gout. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Crystal growth and scintillation properties of Pr-doped oxyorthosilicate for different concentration

Energy Technology Data Exchange (ETDEWEB)

Totsuka, Daisuke, E-mail: totsuka@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co. Ltd (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Fujimoto, Yutaka [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Pejchal, Jan [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Institute of Physics AS CR, Cukrovarnicka 10, Prague 6, 162-53 (Czech Republic); Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

2011-07-01

0.05, 0.1 and 0.25 mol% Pr (with respect to Lu) doped Lu{sub 2}SiO{sub 5} (LSO) single crystals were grown by the micro-pulling down ({mu}-PD) method. The grown crystals were transparent, and a slight segregation of Pr{sup 3+} was observed both in the crystal cross-section and growth direction. Transparency in the visible wavelength range was about 80% in all the crystals. Intense absorptions related with the Pr{sup 3+} 4f-5d transitions were observed around 230 and 255 nm, and weak absorptions due to the 4f-4f transitions were detected around 450 nm. In radioluminescence spectra, the Pr{sup 3+} 5d-4f transitions were observed around 275and 310 nm, and emissions due to the 4f-4f transition were observed around 500 nm. In the pulse height analysis using {sup 137}Cs gamma-ray excitation, Pr 0.1% doped sample showed the highest light yield of 2,800 ph/MeV. In the decay time measurements using different excitation sources (photoluminescence, X- and gamma-ray), two different processes related to the 5d-4f emission peaks were found. Fast decay component corresponds to direct excitation of Pr{sup 3+} (4-6 ns) and slower component (25 ns) reflects the energy migration process from the host lattice to the emission center.

Imprinting of slip bands in mechanically deformed MgO crystals using lithium impurities

Energy Technology Data Exchange (ETDEWEB)

Orera, V M; Chen, Y; Abraham, M M

1980-01-01

Lithium impurities in MgO can be used to imprint slip bands produced by plastic deformation. The imprinting is obtained by means of (Li)/sup 0/ defects (subtitutional Li/sup +/ ions each with an adjacent O/sup -/ ion) which absorb light at 680 nm (1.8 eV). Slip bands are observed as discolored regions against the background of dark blue coloration due to these defects. The decoloration can be achieved by two different processes: either by oxidation at 1275 K of a deformed crystal, or by the reverse procedure - deformation of a previously oxidized crystal. The mechanisms involved in the decoloration are different; the former is due to ionic motion, and the latter is an electronic effect. Similar procedures involving surface indentation by sharp objects also result in decoloration patterns.

Creating physically-based three-dimensional microstructures: Bridging phase-field and crystal plasticity models.

Energy Technology Data Exchange (ETDEWEB)

Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Owen, Steven J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Abdeljawad, Fadi F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hanks, Byron [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-01

In order to better incorporate microstructures in continuum scale models, we use a novel finite element (FE) meshing technique to generate three-dimensional polycrystalline aggregates from a phase field grain growth model of grain microstructures. The proposed meshing technique creates hexahedral FE meshes that capture smooth interfaces between adjacent grains. Three dimensional realizations of grain microstructures from the phase field model are used in crystal plasticity-finite element (CP-FE) simulations of polycrystalline a -iron. We show that the interface conformal meshes significantly reduce artificial stress localizations in voxelated meshes that exhibit the so-called "wedding cake" interfaces. This framework provides a direct link between two mesoscale models - phase field and crystal plasticity - and for the first time allows mechanics simulations of polycrystalline materials using three-dimensional hexahedral finite element meshes with realistic topological features.

Crystal structure and physical properties of new Ca{sub 2}TGe{sub 3} (T = Pd and Pt) germanides

Energy Technology Data Exchange (ETDEWEB)

Klimczuk, T., E-mail: tomasz.klimczuk@pg.gda.pl [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80–233 Gdansk (Poland); Xie, Weiwei [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Winiarski, M.J.; Kozioł, R.; Litzbarski, L.S. [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80–233 Gdansk (Poland); Luo, Huixia; Cava, R.J. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States)

2016-11-15

The crystallographic, electronic transport and thermal properties of Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3} are reported. The compounds crystalize in an ordered variant of the AlB{sub 2} crystal structure, in space group P6/mmm, with the lattice parameters a = 8.4876(4) Å/8.4503(5) Å and c = 4.1911(3) Å/4.2302(3) Å for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The resistivity data exhibit metallic behavior with residual-resistivity-ratios (RRR) of 13 for Ca{sub 2}PdGe{sub 3} and 6.5 for Ca{sub 2}PtGe{sub 3}. No superconducting transition is observed down to 0.4 K. Specific heat studies reveal similar values of the Debye temperatures and Sommerfeld coefficients: Θ{sub D} = 298 K, γ = 4.1 mJ mol{sup −1} K{sup −2} and Θ{sub D} = 305 K, γ = 3.2 mJ mol{sup −1} K{sup −2} for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The low value of γ is in agreement with the electronic structure calculations.

Self-powdering and nonlinear optical domain structures in ferroelastic β'-Gd2(MoO4)3 crystals formed in glass

International Nuclear Information System (INIS)

Tsukada, Y.; Honma, T.; Komatsu, T.

2009-01-01

Ferroelastic β'-Gd 2 (MoO 4 ) 3 , (GMO), crystals are formed through the crystallization of 21.25Gd 2 O 3 -63.75MoO 3 -15B 2 O 3 glass (mol%), and two scientific curious phenomena are observed. (1) GMO crystals formed in the crystallization break into small pieces with a triangular prism or pyramid shape having a length of 50-500 μm spontaneously during the crystallizations in the inside of an electric furnace, not during the cooling in air after the crystallization. This phenomenon is called 'self-powdering phenomenon during crystallization' in this paper. (2) Each self-powdered GMO crystal grain shows a periodic domain structure with different refractive indices, and a spatially periodic second harmonic generation (SHG) depending on the domain structure is observed. It is proposed from polarized micro-Raman scattering spectra and the azimuthal dependence of second harmonic intensities that GMO crystals are oriented in each crystal grain and the orientation of (MoO 4 ) 2- tetrahedra in GMO crystals changes periodically due to spontaneous strains in ferroelastic GMO crystals. - Graphical abstract: This figure shows the polarized optical photograph at room temperature for a particle (piece) obtained by a heat treatment of the glass at 590 deg. C for 2 h in an electric furnace in air. This particle was obtained through the self-powdering behavior in the crystallization of glass. The periodic domain structure is observed. Ferroelastic β'-Gd 2 (MoO 4 ) 3 crystals are formed in the particle, and second harmonic generations are detected, depending on the domain structure.

Early Verb Constructions in French: Adjacency on the Left Edge

Science.gov (United States)

Veneziano, Edy; Clark, Eve V.

2016-01-01

Children acquiring French elaborate their early verb constructions by adding adjacent morphemes incrementally at the left edge of core verbs. This hypothesis was tested with 2657 verb uses from four children between 1;3 and 2;7. Consistent with the Adjacency Hypothesis, children added clitic subjects frst only to present tense forms (as in…

Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.

Science.gov (United States)

Muñoz-Caro, Guillermo Manuel

Las nubes moleculares son regiones de formación de estrellas, con temperaturas cinéticas entre 10-50 K y densidades de 103-106 átomos cm-3. Su materia está formada por gas y polvo interestelar. Estas partículas de polvo están cubiertas por una fina capa de hielo, de unos 0.01 μm, que contiene H2O y a menudo CO, CO2, CH3OH y NH3. El hielo es presumiblemente irradiado por fotones ultravioleta y rayos cósmicos en las zonas poco profundas de las nubes moleculares y las regiones circunestelares. En un sistema de vacío, P ˜ 10-7 mbar, simulamos la deposición de hielo a partir de 10 K y la irradiación ultravioleta por medio de una lámpara de descarga de hidrógeno activada con microondas. La evolución del hielo se observa por medio de un espectrómetro infrarrojo. De este modo es posible determinar la composición del hielo observado en el medio interestelar y predecir la presencia de moléculas aún no detectadas en el espacio, que han sido producto del procesamiento del hielo en nuestros experimentos. También es posible calentar el sistema hasta temperatura ambiente para sublimar el hielo depositado. Cuando el hielo ha sido previamente irradiado, se observa un residuo compuesto por moléculas orgánicas complejas, algunas prebióticas, como varios ácidos carboxílicos, aminas, amidas, ésteres y en menor proporción moléculas heterocíclicas y aminoácidos. Algunas de estas moléculas podrían detectarse en estado gaseoso por medio de observaciones milimétricas y de radio. También podrían estar presentes en el polvo cometario, cuyo análisis químico está planeado por las misiones Stardust y Rosetta. Mientras tanto, nuestro grupo está llevando a cabo el análisis de partículas de polvo interplanetario (IDPs), algunas de las cuales pueden ser de origen cometario. Al igual que ocurre con los productos obtenidos por irradiación del hielo en nuestros experimentos, algunas IDPs son ricas en material orgánico que contiene oxígeno.

Effect of Fe2O3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

Science.gov (United States)

Liu, Hong-pan; Huang, Xiao-feng; Ma, Li-ping; Chen, Dan-li; Shang, Zhi-biao; Jiang, Ming

2017-03-01

CaO-Al2O3-SiO2 (CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3 on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson-Mehl-Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol-1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively.

Crystallization and Martensitic Transformation Behavior of Ti-Ni-Si Alloy Ribbons Prepared via Melt Spinning.

Science.gov (United States)

Park, Ju-Wan; Kim, Yeon-Wook; Nam, Tae-Hyun

2018-09-01

Ti-(50-x)Ni-xSi (at%) (x = 0.5, 1.0, 3.0, 5.0) alloy ribbons were prepared via melt spinning and their crystallization procedure and transformation behavior were investigated using differential scanning calorimtry, X-ray diffraction, and transmission electron microscopy. Ti-Ni-Si alloy ribbons with Si content less than 1.0 at% were crystalline, whereas those with Si content more than 3.0 at% were amorphous. Crystallization occurred in the sequence of amorphous →B2 → B2 → Ti5Si4 + TiNi3 → B2 + Ti5Si4 + TiNi3 + TiSi in the Ti-47.0Ni-3.0Si alloy and amorphous →R → R + Ti5Si4 + TiNi3 → R + Ti5Si4 + TiNi3 + TiSi in the Ti-45.0Ni-5.0Si alloy. The activation energy for crystallization was 189 ±8.6 kJ/mol for the Ti-47Ni-3Si alloy and 212±8.6 kJ/mol for the Ti-45Ni-5Si alloy. One-stage B2-R transformation behavior was observed in Ti-49.5Ni-0.5Si, Ti-49.0Ni-1.0Si, and Ti-47.0Ni- 3.0Si alloy ribbons after heating to various temperatures in the range of 873 K to 1073 K. In the Ti-45.0Ni-5.0Si alloy, one-stage B2-R transformation occurred after heating to 893 K, two-stage B2-R-B19' occurred after heating to 973 K, and two-stage B2-R-B19' occurred on cooling and one-stage B19'-B2 occurred on heating, after heating to 1073 K.

Crucial role of molecular planarity on the second order nonlinear optical property of pyridine based chalcone single crystals

Science.gov (United States)

Menezes, Anthoni Praveen; Jayarama, A.; Ng, Seik Weng

2015-05-01

An efficient nonlinear optical material 2E-3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (BPP) was synthesized and single crystals were grown using slow evaporation solution growth technique at room temperature. Grown crystal had prismatic morphology and its structure was confirmed by various spectroscopic studies, elemental analysis, and single crystal X-ray diffraction (XRD) technique. The single crystal XRD of the crystal showed that BPP crystallizes in monoclinic system with noncentrosymmetric space group P21 and the cell parameters are a = 5.6428(7) Å, b = 3.8637(6) Å, c = 26.411(2) Å, β = 97.568(11) deg and v = 575.82(12) Å3. The UV-Visible spectrum reveals that the crystal is optically transparent and has high optical energy band gap of 3.1 eV. The powder second harmonic generation efficiency (SHG) of BPP is 6.8 times that of KDP. From thermal analysis it is found that the crystal melts at 139 °C and decomposes at 264 °C. High optical transparency down to blue region, higher powder SHG efficiency and better thermal stability than that of urea makes this chalcone derivative a promising candidate for SHG applications. Furthermore, effect of molecular planarity on SHG efficiency and role of pyridine ring adjacent to carbonyl group in forming noncentrosymmetric crystal systems of chalcone family is also discussed.

Objectifying the Adjacent and Opposite Angles: A Cultural Historical Analysis

Science.gov (United States)

Daher, Wajeeh; Musallam, Nadera

2018-01-01

The angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles'…

The Effect of Adjacent Materials on the Propagation of Phonon Polaritons in Hexagonal Boron Nitride.

Science.gov (United States)

Kim, Kris S; Trajanoski, Daniel; Ho, Kevin; Gilburd, Leonid; Maiti, Aniket; van der Velden, Luuk; de Beer, Sissi; Walker, Gilbert C

2017-07-06

In order to apply the ability of hexagonal boron nitride (hBN) to confine energy in the form of hyperbolic phonon polariton (HPhP) modes in photonic-electronic devices, approaches to finely control and leverage the sensitivity of these propagating waves must be investigated. Here, we show that by surrounding hBN with materials of lower/higher dielectric responses, such as air and silicon, lower/higher surface momenta of HPhPs can be achieved. Furthermore, an alternative method for preparing thin hBN crystals with minimum contamination is presented, which provides opportunities to study the sensitivity of the damping mechanism of HPhPs on adsorbed materials. Infrared scanning near-field optical microscopy (IR-SNOM) results suggest that the reflections at the upper and lower hBN interfaces are primary causes of the damping of HPhPs, and that the damping coefficients of propagating waves are highly sensitive to adjacent layers, suggesting opportunities for sensor applications.

The Volpe Center GPS Adjacent Band Compatibility Program Plan : GPS Adjacent Band Compatibility Workshop, Volpe Center, Cambridge MA

Science.gov (United States)

2014-09-18

Approach to DOT GPS Adjacent Band Compatibility Assessment. Identify forums and provide public outreach to make sure the progress and work are as open and transparent as possible. Develop an implementation plan that incorporates aspects from the DOT ...

Crystallization kinetics of Fe-B based amorphous alloys studied in-situ using X-rays diffraction and differential scanning calorimetry

Directory of Open Access Journals (Sweden)

Santos D.R. dos

2001-01-01

Full Text Available The crystallization processes for the amorphous metallic alloys Fe74B17Si2Ni4Mo3 and Fe86B6Zr7Cu1 (at. % were investigated using X-rays diffraction measurements performed in-situ during Joule-heating, with simultaneous monitoring of the electrical resistance. We determined the main structural transitions and crystalline phases formed during heating, and correlated these results to the observed resistance variations. As the annealing current is increased, the resistance shows an initial decrease due to stress relaxation, followed by a drop to a minimum value due to massive nucleation and growth of alpha-Fe nanocrystals. Further annealing causes the formation of small fractions of Fe-B, B2Zr or ZrO2, while the resistance increases due to temperature enhancement. In situ XRD measurements allowed the identification of metastable phases, as the gamma-Fe phase which occurs at high temperatures. The exothermal peaks observed in the differential scanning calorimetry (DSC for each alloy corroborate the results. We also have performed DSC measurements with several heating rates, which allowed the determination of the Avrami exponent and crystallization activation energy for each alloy. The obtained activation energies (362 and 301 kJ/mol for Fe-B-Zr-Cu; 323 kJ/mol for Fe-B-Si-Ni-Mo are comparable to reported values for amorphous iron alloys, while the Avrami exponent values (n = 1.0 or n = 1.2 are consistent with diffusion controlled crystallization processes with nucleation rates close to zero.

Do Mangroves Subsidize Carbon to Adjacent Mudflat Fish Communities?

Science.gov (United States)

Henkel, S.; Kasten, S.; Hartmann, J.; Staubwasser, M.; Hernandez, M. F.; West, L.; Midway, S. R.; Polito, M. J.

2017-12-01

Mangroves are often implicated as energetic sources for fisheries productivity. However, the validity of this connection still remains in contention. Stable isotopes may provide answers by tracking the use of specific basal carbon sources in fish and invertebrates living in mangrove-mudflat habitat mosaics. We analyzed 307 consumer samples representing n=44 fish and invertebrate species collected from mangrove forest creeks and adjacent mudflats in coastal Tanzania using bulk carbon and nitrogen stable isotope analysis. Given the proposed high productivity of mangrove habitats, we hypothesize that mudflat communities will have carbon stable isotope values similar to mangrove communities either through the flux of mangrove carbon into adjacent mudflats and/or via the movement of mudflat fish communities into and out of mangrove habitats. Alternatively, mangrove carbon is often refractory, which may result in mudflat communities with isotopic values that differ from those found in adjacent mangrove communities. This scenario would suggest limited carbon flow between mudflat and mangrove food webs and that the movement of fish into and out of mangrove habitats is related to shelter from predation more than feeding. Data analysis is ongoing to test these competing hypotheses. By understanding the contribution of mangrove carbon to adjacent habitats, managers in Tanzania can make better informed decisions regarding the protection of mangroves and the local fisheries, which are a crucial source of income and food.

Crystallization mechanisms of acicular crystals

Science.gov (United States)

Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

2008-01-01

In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.

Electron paramagnetic resonance and optical absorption study of V{sup 4+} centres in YVO{sub 4} crystals

Energy Technology Data Exchange (ETDEWEB)

Garces, N Y [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Stevens, K T [Northrop Grumman Space Technology, Synoptics, Charlotte, NC 28273 (United States); Foundos, G K [Northrop Grumman Space Technology, Synoptics, Charlotte, NC 28273 (United States); Halliburton, L E [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

2004-10-06

Electron paramagnetic resonance (EPR) has been used to characterize three distinct V{sup 4+} centres in undoped Czochralski-grown yttrium orthovanadate (YVO{sub 4}) crystals. These EPR signals are observed at low temperatures, and their average c-axis splittings between adjacent {sup 51}V hyperfine lines are 40 G, 123 G, and 140 G. We refer to these centres as [V{sup 4+}]{sub A}, [V{sup 4+}]{sub B}, and [V{sup 4+}]{sub C}, respectively. The [V{sup 4+}]{sub A} and [V{sup 4+}]{sub B} centres are present in as-grown crystals. Exposure at 77 K to ionizing radiation (x-rays or an ultraviolet laser beam) destroys these centres and creates the [V{sup 4+}]{sub C} centres. The as-grown state of the crystal is restored upon returning to room temperature. Angular dependence data are used to determine the principal values and principal directions of the g tensor and the {sup 51}V hyperfine tensor for each of the centres. We suggest that the [V{sup 4+}]{sub A} centre is a V{sup 4+} ion adjacent to an oxygen vacancy and that the [V{sup 4+}]{sub B} centre is a V{sup 4+} ion substituting for a Y{sup 3+} ion (i.e. a vanadium antisite defect). The [V{sup 4+}]{sub C} centre is assigned to a V{sup 4+} ion at a regular vanadium site with a nearby stabilizing defect, possibly a Zr{sup 4+} on a Y{sup 3+} site. In as-grown crystals, there is a correlation between the number of [V{sup 4+}]{sub A} centres and the intensity (at 380 nm) of a broad near-edge optical absorption band. This band, now associated with oxygen vacancies, gives YVO{sub 4} a 'yellow' appearance.

Procedimiento de obtención de nanopartículas metálicas funcionalizadas con moléculas orgánicas fluorescentes

OpenAIRE

Zaderenko, Paula; Caro Salazar, Carlos Alberto; Mejías Romero, José Antonio; Sayagués, María Jesús

2011-01-01

[ES] La presente invención se refiere a un procedimiento de obtención de nanopartículas metálicas funcionalizadas con moléculas orgánicas fluorescentes mediante el tratamiento de una o más sales metálicas con un agente reductor en presencia de una molécula orgánica fluorescente. La invención se refiere también a las nanopartículas metálicas obtenibles por dicho procedimiento y a su uso para la detección de moléculas yanalitos.

Crystallographic Investigation of Ag (4 mol%) Doped ZnO (SZO) Thin Films by XRD

International Nuclear Information System (INIS)

Lwin Lwin Nwe; Sandar Dwe; Khant Khant Lin; Khin Thuzar; Than Than Win; Ko Ko Kyaw Soe

2008-03-01

Silver doped ZnO(SZO) thin films are prepared by sol-based method. The silver dopant concentration is 4 mol % in this case. XRD analysis carried out to determine, crystallographic properties such as lattice parameters and crystallite size of SZO thin films.

Bio-inspired photonic-crystal microchip for fluorescent ultratrace detection.

Science.gov (United States)

Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Song, Yanlin; Jiang, Lei

2014-06-02

Ultratrace detection attracts great interest because it is still a challenge to the early diagnosis and drug testing. Enriching the targets from highly diluted solutions to the sensitive area is a promising method. Inspired by the fog-collecting structure on Stenocara beetle's back, a photonic-crystal (PC) microchip with hydrophilic-hydrophobic micropattern was fabricated by inkjet printing. This device was used to realize high-sensitive ultratrace detection of fluorescence analytes and fluorophore-based assays. Coupled with the fluorescence enhancement effect of a PC, detection down to 10(-16) mol L(-1) was achieved. This design can be combined with biophotonic devices for the detection of drugs, diseases, and pollutions of the ecosystem. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ethyl 2-(1,2,3,4-tetrahydro­spiro­[carba­zole-3,2′-[1,3]dioxolan]-9-yl)acetate

Science.gov (United States)

Löffler, Philipp M. G.; Ulven, Trond; Bond, Andrew D.

2009-01-01

In the title compound, C18H21NO4, the hydrogenated six-membered ring of the carbazole unit adopts a half-chair conformation. The dioxolane ring and ethyl­acetate substituent point to opposite sides of the carbazole plane. The ethyl­acetate substituent adopts an essentially fully extended conformation, and its mean plane forms a dihedral angle of 83.8 (1)° with respect to the carbazole mean plane. The mol­ecules are arranged into stacks in which the carbazole planes form a dihedral angle of 4.4 (1)° and have an approximate inter­planar separation of 3.6 Å. PMID:21582427

(Di­methyl­phosphor­yl)methanaminium hydrogen oxalate–oxalic acid (2/1)

OpenAIRE

Bialek, Sebastian; Clemens, Rebecca; Reiss, Guido J.

2014-01-01

The reaction of (di­methyl­phosphor­yl)methanamine (dpma) with oxalic acid in ethanol yielded the title solvated salt, C3H11NOP+·C2HO4 −·0.5C2H2O4. Its asymmetric unit consists of one dpmaH+ cation, one hydrogen oxalate anion and a half-mol­ecule of oxalic acid located around a twofold rotation axis. The H atom of the hydrogen oxalate anion is statistically disordered over two positions that are trans to each other. The hydrogen oxalate monoanion is not planar (bend angle ∼16°) whereas the ox...

Lower-temperature crystallization of CoFeB in MgO magnetic tunnel junctions by using Ti capping layer

International Nuclear Information System (INIS)

Ibusuki, Takahiro; Miyajima, Toyoo; Umehara, Shinjiro; Eguchi, Shin; Sato, Masashige

2009-01-01

Effects of capping materials on magnetoresistance (MR) properties of MgO magnetic tunnel junctions (MTJs) with a CoFeB free layer were investigated. MR ratios of samples with various capping materials showed a difference in annealing temperature dependence. MTJ with a Ti capping layer annealed at 270 deg. C showed a MR ratio 1.4 times greater than that with a conventional Ta or Ru capping layer. Secondary ion mass spectroscopy and high-resolution transmission electron microscopy images revealed that crystallization of CoFeB was remarkably affected by adjacent materials and the Ti capping layer adjoining CoFeB acted as a boron-absorption layer. These results suggest that the crystallization process can be controlled by choosing proper capping materials. Ti is one of the effective materials that accelerate the crystallization of CoFeB layers at lower annealing temperature

Bioactive Glass-Ceramic Scaffolds from Novel ‘Inorganic Gel Casting’ and Sinter-Crystallization

Science.gov (United States)

Elsayed, Hamada; Rincón Romero, Acacio; Ferroni, Letizia; Gardin, Chiara; Zavan, Barbara; Bernardo, Enrico

2017-01-01

Highly porous wollastonite-diopside glass-ceramics have been successfully obtained by a new gel-casting technique. The gelation of an aqueous slurry of glass powders was not achieved according to the polymerization of an organic monomer, but as the result of alkali activation. The alkali activation of a Ca-Mg silicate glass (with a composition close to 50 mol % wollastonite—50 mol % diopside, with minor amounts of Na2O and P2O5) allowed for the obtainment of well-dispersed concentrated suspensions, undergoing progressive hardening by curing at low temperature (40 °C), owing to the formation of a C–S–H (calcium silicate hydrate) gel. An extensive direct foaming was achieved by vigorous mechanical stirring of partially gelified suspensions, comprising also a surfactant. The open-celled structure resulting from mechanical foaming could be ‘frozen’ by the subsequent sintering treatment, at 900–1000 °C, causing substantial crystallization. A total porosity exceeding 80%, comprising both well-interconnected macro-pores and micro-pores on cell walls, was accompanied by an excellent compressive strength, even above 5 MPa. PMID:28772531

33 CFR 148.217 - How can a State be designated as an adjacent coastal State?

Science.gov (United States)

2010-07-01

... an adjacent coastal State? 148.217 Section 148.217 Navigation and Navigable Waters COAST GUARD... General § 148.217 How can a State be designated as an adjacent coastal State? (a) Adjacent coastal States... as an adjacent coastal State in the notice may request to be designated as one if the environmental...

''Dural tail'' adjacent to acoustic neuroma on MRI: a case report

International Nuclear Information System (INIS)

Lunardi, P.; Mastronardi, L.; Nardacci, B.; Acqui, M.; Fortuna, A.

1993-01-01

A 'dural tail' on Gd-DTPA-enhanced MRI has been often observed adjacent to meningiomas and considered to be useful in distinguishing meningioma of the cerebellopontine angle from acoustic neuroma. However, demonstration of a dural tail adjacent to an acoustic neuroma indicates that this sign is not specific. (orig.)

Crystallization kinetics and optical properties of titanium-lithium tetraborate glass containing europium oxide

Energy Technology Data Exchange (ETDEWEB)

Mohamed, E.A. [Al Azhar University, Department of Physics, Faculty of Science (Girl' s Branch), Cairo (Egypt); Ratep, A. [Ain Shams University, Physics Department, Faculty of Girls, Cairo (Egypt); Abdel-Khalek, E.K.; Kashif, I. [Al-Azhar University, Department of Physics, Faculty of Science, Cairo (Egypt)

2017-07-15

The crystallization kinetics and optical properties of [60 Li{sub 2}B{sub 4}O{sub 7}-30 TiO{sub 2}-10 Eu{sub 2}O{sub 3}] (mol%) glass sample have been investigated. The present glass sample exhibits three crystallization exothermic peaks (T{sub p1}, T{sub p2,} and T{sub p3}) corresponding to the formation of LiBO{sub 2}, Li{sub 2}B{sub 4}O{sub 7,} and EuTiO{sub 3} phases, respectively. The presence of phase separation in the glass sample has been confirmed by scanning electron microscopic (SEM). The mean values of Avrami exponent (n = 3.1 and 4) around T{sub p1} and T{sub p2}, indicate that the bulk crystallization with a constant number of nuclei and with an increasing number of nuclei, respectively. The values of the local activation energy as a function of the fraction of crystallization (0.1 ≤ χ ≤ 0.9) decrease for the crystallization of LiBO{sub 2} and EuTiO{sub 3} and increase for the crystallization of Li{sub 2}B{sub 4}O{sub 7}. The values of n(χ) for T{sub p3} and T{sub p2} in the range (0.1 ≤ χ ≤ 0.9) and (0.1 ≤ χ ≤ 0.4), respectively, are larger than 4 indicate that the presence of anomalous in Avrami exponent. The trend of Judd-Ofelt intensity parameters (Ω{sub 2} > Ω{sub 4} > Ω{sub 6}) and the bonding parameter (δ) indicate that the lower symmetry and the highest covalent nature of the bonding around Eu{sup 3+} ions. (orig.)

Las moléculas de adhesión y la respuesta inmune

Directory of Open Access Journals (Sweden)

C. I. Vergara

1994-09-01

Full Text Available Las moléculas de adhesión (MA participan en el reconocimiento antigénico y en la migración celular. Determinan el contacto entre varios grupos celulares y la relación entre algunas células y la matriz extracelular, actuando además como señales que contribuyen directamente a la activación celular. Con base en su estructura y características funcionales se pueden agrupar como: superfamilia de las inmunoglobulinas, las integrinas (que a su vez se subdividen en tres grupos: antígenos muy tardíos, integrinas leucocitarias y citoadhesinas y las selectinas (E-selectinas, P-selectinas y L-selectinas. Su mecanismo de acción se ha estudiado en detalle en los procesos de migración leucocitaria que comprende: marginación por medio de selectinas, adhesión al endotelio y quimiotaxis a través de integrinas y, en menor grado, por miembros de la superfamilia de la inmunoglobulinas. La manipulación de los procesos en los cuales intervienen estas moléculas, permitiría que en un futuro sean utilizados como terapia antiinflamatoria en medicina y biología

Oxalates in oca (New Zealand yam) (Oxalis tuberosa Mol.).

Science.gov (United States)

Ross, A B; Savage, G P; Martin, R J; Vanhanen, L

1999-12-01

Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analyzed for total and soluble oxalate contents of the tubers. The range of total oxalate levels was 92-221 mg/100 g of fresh weight. Levels of soluble and total oxalate extracted from the tubers were not significantly different, suggesting that no calcium oxalate is formed in the tubers. The oxalate concentrations obtained in this study for oca suggest that previously reported values are too low and that oca is a moderately high oxalate-containing food. This is the first report of a tuber crop containing moderate to high levels of soluble oxalates in the tubers and no insoluble oxalates.

Fluorides leaching from restorative materials and the effect on adjacent teeth

DEFF Research Database (Denmark)

Qvist, Vibeke; Poulsen, Agneta; Teglers, Poul Thorpen

2010-01-01

Placing a Class II restoration in a tooth changes the local environment, including that for the adjacent tooth. Apart from the change to a less- or non-cariogenic environment for the restored tooth, the effect of leachable components from a restoration in the adjacent tooth should be taken into c...

Moléculas de adesão celular: papel do microambiente tumoral na carcinogénese

OpenAIRE

Cardoso, Edgar António Delgado

2009-01-01

Trabalho final do 6º ano médico com vista à atribuição do grau de mestre (área científica de patológica) no âmbito do ciclo de estudos de Mestrado Integrado em Medicina. As moléculas de adesão celular determinam estimulação funcional, migração, ancoragem, diferenciação fenotípica e multiplicação celular. A capacidade da célula tumoral se movimentar, atravessar as paredes dos vasos e se localizar e proliferar no processo de metastização, está dependente das moléculas de adesão e da...

Packing motifs as predictors of the propensity of antibody fragments to crystallize

Science.gov (United States)

Edmundson, Allen B.; DeWitt, Christina R.; Goldsteen, Benjamin Z.; Ramsland, Paul A.

1999-01-01

A recurring theme in the crystallization of antibody fragments in our laboratory has been a packing pattern involving formation of intermolecular, antiparallel β-pleated sheets across two-fold axes. The most common motif is the antiparallel stacking of constant (C) domains of light (L) chain dimers or Fab molecules. Here, cross-molecule six-stranded sheets are produced by hydrogen-bonding interactions of three-residue polypeptide segments (triads), in the i, i+2 and i+4 positions of the final strands (designated 3-3) of the three-chain layers from two adjacent molecules. In the variable (V) domains the triads are supplied by the first strands (4-1) of the four-chain layers and the resulting cross-molecule sheets contain eight strands. The latter type of packing is more likely to be seen in crystals of Fv fragments (V domains only) than in those of L chain dimers or Fabs. Amongst the triads from either the V or C domains, there are on average four sets of backbone carbonyl and amide groups within hydrogen bonding distance (chain dimers, Fab and Fvs are likely to crystallize in these packing patterns.

Crystal structure of 4-methylsulfanyl-2-phenylquinazoline

Directory of Open Access Journals (Sweden)

Mohammed B. Alshammari

2014-08-01

Full Text Available In the title compound, C15H12N2S, the methylthioquinazoline group is planar with the methyl C displaced by only 0.116 (3 Å from the plane of the quinazoline moiety. The dihedral angle between the phenyl ring and the quinazoline ring system is 13.95 (5°. In the crystal, each molecule is linked by π–π stacking between to two adjacent inversion-related molecules. On one side, the inverted quinazoline groups interact with a centroid–centroid distance of 3.7105 (9 Å. On the other side, the quinazoline group interacts with the pyrimidine and phenyl rings of the second neighbour with centroid–centroid distances of 3.5287 (8 and 3.8601 (9 Å, respectively.

A numerical study on buoyancy-driven flow in an inclined square enclosure heated and cooled on adjacent walls

International Nuclear Information System (INIS)

Aydin, O.; Uenal, A.; Ayhan, T.

1999-01-01

Buoyancy-driven flows in enclosures play a vital role in many engineering applications such as double glazing, ventilation of rooms, nuclear reactor insulation, solar energy collection, cooling of electronic components, and crystal growth in liquids. Here, numerical study on buoyancy-driven laminar flow in an inclined square enclosure heated from one side and cooled from the adjacent side is conducted using finite difference methods. The effect of inclination angle on fluid flow and heat transfer is investigated by varying the angle of inclination between 0 degree and 360degree, and the results are presented in the form of streamlines and isotherms for different inclination angles and Rayleigh numbers. On the basis of the numerical data, the authors determine the critical values of the inclination angle at which the rate of the transfer within the enclosure is either maximum or minimum

Studying effect of MoO{sub 3} on elastic and crystallization behavior of lithium diborate glasses

Energy Technology Data Exchange (ETDEWEB)

Shaaban, KH.S.; Abd Elnaeim, A.M. [El-Azhar University, Physics Department, Faculty of Science, Assiut (Egypt); Abo-naf, S.M. [National Research Centre, Glass Research Department, Cairo (Egypt); Hassouna, M.E.M. [Beni-Suef University, Chemistry Department, Faculty of Science, Beni Suef (Egypt)

2017-06-15

The effect of MoO{sub 3} addition on the crystallization characteristics of 2Al{sub 2}O{sub 3}-23Li{sub 2}O-(75 - x) B{sub 2}O{sub 3} glass (where x MoO{sub 3} = 0, 10, 20, and 40 mol %) has been investigated. The compositional dependence of the glass transition (T{sub g}), and crystallization (T{sub c}) temperatures was determined by the differential thermal analysis (DTA). It was found that both the T{sub g} and T{sub c} decrease with increasing MoO{sub 3} content. The amorphous nature of the as-quenched glass and crystallinity of the produced glass-ceramics were confirmed by X-ray powder diffraction (XRD) analysis. Glass-ceramics embedded with diomignite (lithium diborate, Li{sub 2}B{sub 4}O{sub 7}) were produced from all investigated glasses by heat-treating the as-quenched glasses at the appropriate temperatures obtained from the DTA traces. Addition of MoO{sub 3} to the glass composition at 10% MoO{sub 3}, causes the formation of lithium molybdenum oxide (Li{sub 4}MoO{sub 5}) crystalline phase in addition to the diomignite phase. Increasing MoO{sub 3} content to 20% causes a phase transformation of lithium molybdenum oxide from the (Li{sub 4}MoO{sub 5}) to the (Li{sub 2}MoO{sub 4}) phase and the formation of another lithium borate (Li{sub 4}B{sub 2}O{sub 5}) phase in addition to the diomignite. Further increase of MoO{sub 3} content to 40% results in another phase transformation to the lithium aluminum molybdenum oxide [LiAl(MoO{sub 4}){sub 2}], and, in this case, the molybdenum content was excess enough to crystallize the molybdate (MoO{sub 3}) itself. Scanning electron microscopy (SEM) was used to characterize the morphology and microstructure of the formed solid solution phases. The values of the T{sub g} decrease with increasing the MoO{sub 3} content. The ultrasonic wave velocities and elastic moduli were determined using the pulse-echo method. Both velocities (v{sub L} and v{sub T}) were increased as the MoO{sub 3} content, this increase can be

Thermochemical reactivity of 5–15 mol% Fe, Co, Ni, Mn-doped cerium oxides in two-step water-splitting cycle for solar hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Gokon, Nobuyuki, E-mail: ngokon@eng.niigata-u.ac.jp [Center for Transdisciplinary Research, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Suda, Toshinori [Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan); Kodama, Tatsuya [Department of Chemistry & Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

2015-10-10

Highlights: • 5–15 mol% M-doped ceria are examined for thermochemical two-step water-splitting. • 5 mol% Fe- and Co-doped ceria have stoichiometric production of oxygen and hydrogen. • 10–15 mol% Fe- and Mn-doped ceria showed near-stoichiometric production. - Abstract: The thermochemical two-step water-splitting cycle using transition element-doped cerium oxide (M–CeO{sub 2−δ}; M = Fe, Co, Ni, Mn) powders was studied for hydrogen production from water. The oxygen/hydrogen productivity and repeatability of M–CeO{sub 2−δ} materials with M doping contents in the 5–15 mol% range were examined using a thermal reduction (TR) temperature of 1500 °C and water decomposition (WD) temperatures in the 800–1150 °C range. The temperature, steam partial pressure, and steam flow rate in the WD step had an impact on the hydrogen productivity and production rate. 5 mol% Fe- and Co-doped CeO{sub 2−δ} enhances hydrogen productivity by up to 25% on average compared to undoped CeO{sub 2}, and shows stable repeatability of stoichiometric oxygen and hydrogen production for the cyclic thermochemical two-step water-splitting reaction. In addition, 5 mol% Mn-doped CeO{sub 2−δ}, 10 and 15 mol% Fe- and Mn-doped CeO{sub 2−δ} show near stoichiometric reactivities.

Symmetry breaking of adjacent tracks in perpendicular recording system

International Nuclear Information System (INIS)

Xie Huang; Wei Dan

2007-01-01

The track density increase in a perpendicular magnetic recording system is limited by the adjacent-track interference (ATI). In this work, a composite micromagnetic simulation model of the read/write process is developed to analyse ATI by the symmetry of signal and noise in two adjacent W = 60 nm tracks with the track pitch of the order of 100 nm. Based on the two-dimensional medium noise distribution of dibit recording, it is found that the noise in the first and later recorded tracks start to be asymmetric when the track pitch is lower than 2 W; if the read width is limited within 2/3 of the write width, the asymmetry of noise appears when the track pitch is less than 1.5 W. At higher recording densities, the signal-to-noise ratio degradation is mainly due to the noise caused by the interference from the signal of the adjacent track. Side writing can be effectively eliminated by the use of a guard band whose width is at least half the track width

Tl and OSL on diopside crystal

International Nuclear Information System (INIS)

Cano, N.F.; Watanabe, S.; Mittani, J.C.R.; Yukihara, E.G.

2006-01-01

The diopside with chemical composition CaMgSi 2 O 6 is part of an important solid solution series of the pyroxene group. The mineral is commonly found in meteorites and it is an important rock forming mineral of medium and high grade metamorphic rocks which are rich in calcium. In the bibliography it is possible to found several studies on electron spin resonance (ESR), reflectance, etc. but not on thermoluminescence (TL) or optically stimulated luminescence (OSL). In the present work we studied diopside TL and OSL behaviour on natural and natural irradiated samples. The sample used in our study is a white coloured diopside provided by Mineracao Sao Judas located in Sao Paulo, Brazil. The X-Ray Fluorescence technique has shown high concentrations of SiO 2 (55.81 % mol), CaO (23.47 % mol), MgO (18.03 % mol), Al 2 O 3 (1.56 % mol), Fe 2 O 3 (0.53 % mol), K 2 O (0.44 % mol), TiO 2 (0.065 % mol), P 2 O 5 (0.026 % mol), and MnO (0.013 % mol). TL measurements on natural samples show four TL peaks at 160, 260, 360, and 450 C. After beta-irradiation an increment mainly in the low temperature peaks is observed. As for OSL measurements, low OSL signal was observed on natural samples using blue light stimulation and UV detection. The intensity of the signal was observed to increase with the irradiation dose. (Author)

Procedimiento de obtención de nanopartículas metálicas funcionalizadas con moléculas orgánicas fluorescentes

OpenAIRE

Zaderenko, Paula; Caro Salazar, Carlos Alberto; Mejías Romero, José Antonio; Sayagués, María Jesús

2011-01-01

Procedimiento de obtención de nanopartículas metálicas funcionalizadas con moléculas orgánicas fluorescentes. La presente invención se refiere a un procedimiento de obtención de nanopartículas metálicas funcionalizadas con moléculas orgánicas fluorescentes mediante el tratamiento de una o más sales metálicas con un agente reductor en presencia de una molécula orgánica fluorescente. La invención se refiere también a las nanopartículas metálicas obtenibles por dicho procedimiento y a su uso ...

MolPrint3D: Enhanced 3D Printing of Ball-and-Stick Molecular Models

Science.gov (United States)

Paukstelis, Paul J.

2018-01-01

The increased availability of noncommercial 3D printers has provided instructors and students improved access to printing technology. However, printing complex ball-and-stick molecular structures faces distinct challenges, including the need for support structures that increase with molecular complexity. MolPrint3D is a software add-on for the…

PERBEDAAN FISIK DAN KIMIA KOMPOS DAUN YANG MENGGUNAKAN BIOAKTIVATOR MOL DAN EM 4

Directory of Open Access Journals (Sweden)

Priyantini Widiyaningrum

2013-02-01

Full Text Available Tujuan penelitian ini untuk mengetahui kemampuan mikroorganisme lokal (MOL sebagai aktivator dalam proses pengomposan sampah daun, serta membandingkan penampilan fisik, penyusutan bahan, kadar air dan C/N rasio kompos yang dihasilkan dengan kompos yang menggunakan EM sebagai bioaktivator. Bahan baku kompos terdiri dari daun kering cacah dan kotoran kambing. Kompos dipanen setelah proses pengomposan berlangsung selama 6 minggu. Setiap perlakuan dibuat tiga ulangan. Data kualitatif yang diamati meliputi tekstur, warna dan bau, sedangkan data kuantitatif yang diukur meliputi persentase penyusutan bahan, persentase kompos yang terbentuk, kadar air, dan C/N rasio. Analisis data kualitatif dilakukan secara deskriptif, sedangkan data kuantitatif menggunakan uji t. Hasil pengamatan menunjukkan bahwa kompos kedua perlakuan memiliki penampilan fisik tidak berbeda. Berdasarkan uji t, ratarata penyusutan bahan, kadar air dan C/N rasio kompos matang tidak berbeda nyata, akan tetapi persentase kompos yang terbentuk menunjukkan perbedaan nyata. Dari penelitian ini disimpulkan bahwa kompos daun kedua perlakuan memperlihatkan penampilan fisik, penyusutan, kadar air dan C/N rasio yang tidak berbeda, sedangkan persentase kompos yang terbentuk pada kompos + EM lebih tinggi dibanding kompos + MOL. Secara umum kedua kompos masuk kategori layak digunakan berdasarkan standar SNI No. 19-7030-2004. 4 4

Calculation of Five Thermodynamic Molecular Descriptors by Means of a General Computer Algorithm Based on the Group-Additivity Method: Standard Enthalpies of Vaporization, Sublimation and Solvation, and Entropy of Fusion of Ordinary Organic Molecules and Total Phase-Change Entropy of Liquid Crystals

Directory of Open Access Journals (Sweden)

Rudolf Naef

2017-06-01

Full Text Available The calculation of the standard enthalpies of vaporization, sublimation and solvation of organic molecules is presented using a common computer algorithm on the basis of a group-additivity method. The same algorithm is also shown to enable the calculation of their entropy of fusion as well as the total phase-change entropy of liquid crystals. The present method is based on the complete breakdown of the molecules into their constituting atoms and their immediate neighbourhood; the respective calculations of the contribution of the atomic groups by means of the Gauss-Seidel fitting method is based on experimental data collected from literature. The feasibility of the calculations for each of the mentioned descriptors was verified by means of a 10-fold cross-validation procedure proving the good to high quality of the predicted values for the three mentioned enthalpies and for the entropy of fusion, whereas the predictive quality for the total phase-change entropy of liquid crystals was poor. The goodness of fit (Q2 and the standard deviation (σ of the cross-validation calculations for the five descriptors was as follows: 0.9641 and 4.56 kJ/mol (N = 3386 test molecules for the enthalpy of vaporization, 0.8657 and 11.39 kJ/mol (N = 1791 for the enthalpy of sublimation, 0.9546 and 4.34 kJ/mol (N = 373 for the enthalpy of solvation, 0.8727 and 17.93 J/mol/K (N = 2637 for the entropy of fusion and 0.5804 and 32.79 J/mol/K (N = 2643 for the total phase-change entropy of liquid crystals. The large discrepancy between the results of the two closely related entropies is discussed in detail. Molecules for which both the standard enthalpies of vaporization and sublimation were calculable, enabled the estimation of their standard enthalpy of fusion by simple subtraction of the former from the latter enthalpy. For 990 of them the experimental enthalpy-of-fusion values are also known, allowing their comparison with predictions, yielding a correlation

Calculation of Five Thermodynamic Molecular Descriptors by Means of a General Computer Algorithm Based on the Group-Additivity Method: Standard Enthalpies of Vaporization, Sublimation and Solvation, and Entropy of Fusion of Ordinary Organic Molecules and Total Phase-Change Entropy of Liquid Crystals.

Science.gov (United States)

Naef, Rudolf; Acree, William E

2017-06-25

The calculation of the standard enthalpies of vaporization, sublimation and solvation of organic molecules is presented using a common computer algorithm on the basis of a group-additivity method. The same algorithm is also shown to enable the calculation of their entropy of fusion as well as the total phase-change entropy of liquid crystals. The present method is based on the complete breakdown of the molecules into their constituting atoms and their immediate neighbourhood; the respective calculations of the contribution of the atomic groups by means of the Gauss-Seidel fitting method is based on experimental data collected from literature. The feasibility of the calculations for each of the mentioned descriptors was verified by means of a 10-fold cross-validation procedure proving the good to high quality of the predicted values for the three mentioned enthalpies and for the entropy of fusion, whereas the predictive quality for the total phase-change entropy of liquid crystals was poor. The goodness of fit ( Q ²) and the standard deviation (σ) of the cross-validation calculations for the five descriptors was as follows: 0.9641 and 4.56 kJ/mol ( N = 3386 test molecules) for the enthalpy of vaporization, 0.8657 and 11.39 kJ/mol ( N = 1791) for the enthalpy of sublimation, 0.9546 and 4.34 kJ/mol ( N = 373) for the enthalpy of solvation, 0.8727 and 17.93 J/mol/K ( N = 2637) for the entropy of fusion and 0.5804 and 32.79 J/mol/K ( N = 2643) for the total phase-change entropy of liquid crystals. The large discrepancy between the results of the two closely related entropies is discussed in detail. Molecules for which both the standard enthalpies of vaporization and sublimation were calculable, enabled the estimation of their standard enthalpy of fusion by simple subtraction of the former from the latter enthalpy. For 990 of them the experimental enthalpy-of-fusion values are also known, allowing their comparison with predictions, yielding a correlation coefficient R

Formation of a new crystalline form of anhydrous β-maltose by ethanol-mediated crystal transformation.

Science.gov (United States)

Verhoeven, Nicolas; Neoh, Tze Loon; Ohashi, Tetsuya; Furuta, Takeshi; Kurozumi, Sayaka; Yoshii, Hidefumi

2012-04-01

β-Maltose monohydrate was transformed into an anhydrous form by ethanol-mediated method under several temperatures with agitation. A new stable anhydrous form of β-maltose (Mβ(s)) was obtained, as substantiated by the X-ray diffraction patterns. Mβ(s) obtained by this method presented a fine porous structure, resulting in greater specific surface area compared to those of β-maltose monohydrate and anhydrous β-maltose obtained by vacuum drying (Mβ(h)). The crystal transformation presumably consisted of two steps: dehydration reaction from the hydrous to amorphous forms and crystal formation from the amorphous forms to the noble anhydrous form. The kinetics of these reactions were determined by thermal analysis using Jander's equation and Arrhenius plots. The overall activation energies of the dehydration reaction and the formation of anhydrous maltose were evaluated to be 100 and 90 kJ/mol, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Magnetic phase transitions and large mass enhancement in single crystal CaFe4As3

International Nuclear Information System (INIS)

Zhang Xiao-Dong; Wu Wei; Zheng Ping; Wang Nan-Lin; Luo Jian-Lin

2012-01-01

High quality single crystal CaFe 4 As 3 was grown by using the Sn flux method. Unlike layered CaFe 2 As 2 , CaFe 4 As 3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at ∼ 90 K and ∼ 27 K, respectively. The high temperature transition is an antiferromagnetic(AF) ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol·K 2 , showing a heavy fermion behavior. (rapid communication)

Crystallite growth kinetics of TiO{sub 2} surface modification with 9 mol% ZnO prepared by a coprecipitation process

Energy Technology Data Exchange (ETDEWEB)

Ko, Horng-Huey [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Zhao, Xiujian, E-mail: opluse@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China)

2014-03-05

Highlights: • TiO{sub 2} powder surface modification with 9 mol% ZnO was obtained. • Phase transformation from anatase to rutile was hindered by ZnO added. • Growth kinetic of anatase TiO{sub 2} nanocrystallites in T-9Z powders was described as: D{sub A,9}{sup 2}=2.42×10{sup 5}×exp(-39.9×10{sup 3}/RT). • Growth kinetic of rutile TiO{sub 2} nanocrystallites in T-9Z powders was described as: D{sub R,9}{sup 2}=8.49×10{sup 5}×exp(-47.6×10{sup 3}/RT) rutile TiO{sub 2}. -- Abstract: The nanocrystallite growth of TiO{sub 2} surface modification with 9 mol% ZnO prepared by a coprecipitation process has been studied. Thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–VIS–NIR spectrophotometry have been utilized to characterize the TiO{sub 2} nanocrystallites surface modification with 9 mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO{sub 2} first formed at 533 K and the completion of anatase TiO{sub 2} crystallization occurred at 745 K for the T-9Z freeze-dried precursor powders. XRD results reveal that the anatase and rutile TiO{sub 2} coexist when the T-9Z freeze-dried precursor powders were calcined at 523–973 K for 2 h. When the T-9Z freeze-dried precursor powders were calcined at 973 K for 2 h, rutile TiO{sub 2} was the major phase, and the minor phases were anatase TiO{sub 2} and Zn{sub 2}Ti{sub 3}O{sub 8}. The phase was composed of the rutile TiO{sub 2} and Zn{sub 2}TiO{sub 4} for the T-9Z freeze-dried precursor powders after calcination at 1273 K for 2 h. The growth kinetics of TiO{sub 2} nanocrystallites in T-9Z powders were described as: D{sub A,9}{sup 2}=2.42×10{sup 5}×exp(-39.9×10{sup 3}/RT)and D{sub R,9}{sup 2}=8.49×10{sup 5}×exp(-47.6×10{sup 3}/RT) for anatase and rutile TiO{sub 2} nanocrystallites respectively. The analysis results of UV/VIS/NIR spectra reveal that the T-9Z freeze

`Pd20Sn13' revisited: crystal structure of Pd6.69Sn4.31

Directory of Open Access Journals (Sweden)

Wilhelm Klein

2015-07-01

Full Text Available The crystal structure of the title compound was previously reported with composition `Pd20Sn13' [Sarah et al. (1981. Z. Metallkd, 72, 517–520]. For the original structure model, as determined from powder X-ray data, atomic coordinates from the isostructural compound Ni13Ga3Ge6 were transferred. The present structure determination, resulting in a composition Pd6.69Sn4.31, is based on single crystal X-ray data and includes anisotropic displacement parameters for all atoms as well as standard uncertainties for the atomic coordinates, leading to higher precision and accuracy for the structure model. Single crystals of the title compound were obtained via a solid-state reaction route, starting from the elements. The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids. One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3:0.62 (3. One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b.

Spin dynamics, electronic, and thermal transport properties of two-dimensional CrPS4 single crystal

Science.gov (United States)

Pei, Q. L.; Luo, X.; Lin, G. T.; Song, J. Y.; Hu, L.; Zou, Y. M.; Yu, L.; Tong, W.; Song, W. H.; Lu, W. J.; Sun, Y. P.

2016-01-01

2-Dimensional (2D) CrPS4 single crystals have been grown by the chemical vapor transport method. The crystallographic, magnetic, electronic, and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, electrical resistivity ρ(T), specific heat CP(T), and the electronic spin response (ESR) measurements. CrPS4 crystals crystallize into a monoclinic structure. The electrical resistivity ρ(T) shows a semiconducting behavior with an energy gap Ea = 0.166 eV. The antiferromagnetic transition temperature is about TN = 36 K. The spin flipping induced by the applied magnetic field is observed along the c axis. The magnetic phase diagram of CrPS4 single crystal has been discussed. The extracted magnetic entropy at TN is about 10.8 J/mol K, which is consistent with the theoretical value R ln(2S + 1) for S = 3/2 of the Cr3+ ion. Based on the mean-field theory, the magnetic exchange constants J1 and Jc corresponding to the interactions of the intralayer and between layers are about 0.143 meV and -0.955 meV are obtained based on the fitting of the susceptibility above TN, which agree with the results obtained from the ESR measurements. With the help of the strain for tuning the magnetic properties, monolayer CrPS4 may be a promising candidate to explore 2D magnetic semiconductors.

Crystallization studies and dielectric properties of (Ba0.7Sr0.3)TiO3 in bariumaluminosilicate glass

Science.gov (United States)

Divya, P. V.; Vignesh, G.; Kumar, V.

2007-12-01

Ferroelectric glass-ceramics with a basic composition (1 - y)(Ba0.70Sr0.30)TiO3 : y(BaO : Al2O3 : 2SiO2) have been synthesized by the sol-gel method. The major crystalline phase is the perovskite. The crystallization of the ferroelectric phase in the glass matrix have been studied using differential thermal analysis and x-ray diffraction and the kinetic parameters characterizing the crystallization have been determined using an Arrhenius model. Glass contents <= 5 mol% promoted liquid phase sintering, which reduced the sintering temperature to 1250 °C. The dielectric permittivity of the glass-ceramic samples decreased and the ferroelectric-paraelectric phase transition became more diffuse with increasing glass content. The dielectric connectivity of the ferroelectric phase in the composite have also been investigated and are reported.

Computational investigation on 2,4,6-trinitrochlorobenzene crystal

Energy Technology Data Exchange (ETDEWEB)

Ju, Xue-Hai; Qiu, Ling; Xiao, He-Ming [Department of Chemistry, Nanjing University of Science and Technology, Nanjing 210094 (China)

2006-02-15

Density functional theory calculations at the B3LYP level were performed on crystalline 2,4,6-trinitrochlorobenzene. The carbon, oxygen, and chlorine atoms make up the narrow lower energy bands, while the nitrogen, carbon, and oxygen atoms make up the higher energy bands. Besides, the contributions of these atomic orbitals to the frontier bands are somewhat well-proportioned. The Mulliken populations obviously demonstrate that the C-N bonds are the weakest, indicating that the C-NO{sub 2} is prone to rupture upon stimuli. An anisotropic impact on the bulk makes the electron transfer from chlorine to its neighbor carbon atom and from nitrogen atoms to oxygen atoms. The crystal lattice energy is predicted to be -50.99 kJ/mol, after being corrected for basis set superposition error. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Extraosseous Gaucher cell deposition without adjacent bone involvement.

Science.gov (United States)

Meyer, Brendan J; Mills, Anne M; Gaskin, Cree M

2014-10-01

Extraosseous Gaucher cell deposits are a rare complication of Gaucher disease that can mimic malignancy. We describe a case of Gaucher cell deposition in the subcutaneous soft tissues overlying the lower thoracic spine in an 18-year-old woman with known type III Gaucher disease. This case is unique in the literature because this subcutaneous Gaucher mass was not associated with extension from underlying bone involvement or clear lymph node origin. It demonstrated no discernible continuity with the adjacent thoracic spinous processes, the cortices of which appeared intact. Although patients with Gaucher disease are at increased risk of malignancy, Gaucher cell deposition should remain a differential consideration for soft tissue masses with or without adjacent bone involvement in patients with known Gaucher disease.

Crystal structure of 2,5-di-methyl-anilinium salicylate.

Science.gov (United States)

Mani, A; Kumar, P Praveen; Chakkaravarthi, G

2015-09-01

The title mol-ecular salt, C8H12N(+)·C7H5O3 (-) arose from the proton-transfer reaction between 2,5-xylidine and salicylic acid. In the anion, the dihedral angle between the planes of the aromatic ring and the -CO2 (-) group is 11.08 (8)°; this near planarity is consolidated by an intra-molecular O-H⋯O hydrogen bond. In the crystal, the components are connected by N-H⋯O hydrogen bonds, with all three O atoms in the anion acting as acceptors; the result is a [100] chain. The structure also features weak C-H⋯O bonds and aromatic π-π stacking [centroid-to-centroid distance = 3.7416 (10) Å] inter-actions, which lead to a three-dimensional network.

Crystallization kinetic study of the lithium-disilicate bioceramic obtained from rice-husk silica starting powder; Estudo cinetico da cristalizacao da bioceramica de dissilicato de litio obtida atraves da silica da casca de arroz

Energy Technology Data Exchange (ETDEWEB)

Santos, F.A.; Santos, C.; Pinatti, D.G., E-mail: elipeantunes@usp.br [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Lazar, D.R.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Davim, E.; Fernandes, M.H.F.V. [Universidade de Aveiro, Campos Universitario de Santiago, Aveiro (Portugal)

2011-07-01

In this work, the study of crystallization of the lithium disilicate glass-ceramic produced for alternative source (rice husk silica), and comparatively by commercial source (commercial silica) it was carried through. The stoichiometry 66%.mol SiO{sub 2}: 33%.mol LiO{sub 2} was used. The kinetic studies of crystallization and calculations had been carried through thermal analysis (DTA), and were possible to study the behavior of the curves in accordance with the variation of taxes (5; 10; 15; e 20°C/min), of the granulometries 63 μm, 250μm and 1mm), and for the influence of the substitution commercial SiO{sub 2} by rice husk. The structural characterization was carried through by X-Ray diffractometry (DRX) and scanning electron microscopy (MEV), for chemical characterization used X-Ray fluorescence (FRX). The preliminary results show that the substitution of the silica source is sufficiently promising, since the gotten properties are similar. (author)

Growth of large PbTiO[sub 3] crystals by a self-flux technique

Energy Technology Data Exchange (ETDEWEB)

Sun, B.N. (Dept. of Materials Science and Engineering, Materials Research Lab., and Beckman Inst., Univ. of Illinois, Urbana-Champaign (United States)); Huang, Y. (Dept. of Materials Science and Engineering, Materials Research Lab., and Beckman Inst., Univ. of Illinois, Urbana-Champaign (United States)); Payne, D.A. (Dept. of Materials Science and Engineering, Materials Research Lab., and Beckman Inst., Univ. of Illinois, Urbana-Champaign (United States))

1993-03-01

Pure lead titanate (PbTiO[sub 3]) crystals (5x5x5 mm[sup 3]) were grown from high-temperature solutions by a slow cooling technique using PbO as a self-flux. The optimum growth conditions were determined to be: (1) (1-x) TiO[sub 2]+x PbO with x (in mol%) varying from 0.78 to 0.82 for the starting compositions, (2) 930-1050 C as the growth temperature range and (3) 0.4-1.5 C/h as the cooling rates. Evaporation of PbO was significantly reduced by use of a double-crucible technique. The grown crystals were characterized by X-ray diffraction, chemical analysis and optical microscopy. The transformation temperatures (onset) of 492.5 C (on heating) and 491.3 C (on cooling) were determined by differential scanning calorimetry. The transformation process had a thermal hysteresis of 1.2 C from onset data. (orig.)

Crystallization and melting behavior of poly(ethylene oxide) and its blend with styrene-based ionomer using time-resolved SAXS/WAXS experiments

Energy Technology Data Exchange (ETDEWEB)

Slusarczyk, CzesLaw, E-mail: cslusarczyk@ath.bielsko.pl [Institute of Textile Engineering and Polymer Materials, University of Bielsko-BiaLa, ul. Willowa 2, 43-309 Bielsko-BiaLa (Poland)

2011-10-15

Time-resolved synchrotron wide- and small-angle X-ray scattering experiments were used to investigate the crystallization behavior and microstructure development of neat poly(ethylene oxide) (PEO) and its 50/50 blend with ionomer containing 6.4 mol% of sodium acrylate. The apparent lateral crystal sizes D{sub (120)} and D{sub (112)/(004)} were derived from the WAXS profiles. It was found that D{sub (120)} and D{sub (112)/(004)} of PEO in the blend are almost independent of temperature and are smaller when compared to those of neat PEO sample. The evolution of morphological parameters extracted from time-resolved SAXS profiles such as the long period L, the lamellar crystal thickness l{sub C} and the amorphous layer thickness l{sub A}, shows that the crystallization process of neat PEO follows the nucleation theory. The lamellar crystal thickness l{sub C} shows a single linear dependence on inverse supercooling, over the whole temperature range investigated. In contrast, the crystallization process of PEO in the blend (i.e. in the presence of interactions with the ionomer) follows the nucleation theory only in the narrow supercooling range. It was found also that the morphology of the blend consists of a broad population of lamellar crystal thicknesses. During heating lamellae melt in the reversed sequence of their formation.

Impact of body mass index on adjacent segment disease after lumbar fusion for degenerative spine disease.

Science.gov (United States)

Ou, Chien-Yu; Lee, Tao-Chen; Lee, Tsung-Han; Huang, Yu-Hua

2015-04-01

Adjacent segment disease is an important complication after fusion of degenerative lumbar spines. However, the role of body mass index (BMI) in adjacent segment disease has been addressed less. To examine the relationship between BMI and adjacent segment disease after lumbar fusion for degenerative spine diseases. For this retrospective study, we enrolled 190 patients undergoing lumbar fusion surgery for degeneration. BMI at admission was documented. Adjacent segment disease was defined by integration of the clinical presentations and radiographic criteria based on the morphology of the dural sac on magnetic resonance images. Adjacent segment disease was identified in 13 of the 190 patients, accounting for 6.8%. The interval between surgery and diagnosis as adjacent segment disease ranged from 21 to 66 months. Five of the 13 patients required subsequent surgical intervention for clinically relevant adjacent segment disease. In the logistic regression model, BMI was a risk factor for adjacent segment disease after lumbar fusion for degenerative spine diseases (odds ratio, 1.68; 95% confidence interval, 1.27-2.21; P disease rate by 67.6%. The patients were subdivided into 2 groups based on BMI, and up to 11.9% of patients with BMI ≥ 25 kg/m were diagnosed as having adjacent segment disease at the last follow-up. BMI is a risk factor for adjacent segment disease in patients undergoing lumbar fusion for degenerative spine diseases. Because BMI is clinically objective and modifiable, controlling body weight before or after surgery may provide opportunities to reduce the rate of adjacent segment disease and to improve the outcome of fusion surgery.

Developmental tumors and adjacent cortical dysplasia: single or dual pathology?

Science.gov (United States)

Palmini, André; Paglioli, Eliseu; Silva, Vinicius Duval

2013-12-01

Developmental tumors often lead to refractory partial seizures and constitute a well-defined, surgically remediable epilepsy syndrome. Dysplastic features are often associated with these tumors, and their significance carries both practical and conceptual relevance. If associated focal cortical dysplasia (FCD) relates to the extent of the epileptogenic tissue, then presurgical evaluation and surgical strategies should target both the tumor and the surrounding dyslaminated cortex. Furthermore, the association has been included in the recently revised classification of FCD and the epileptogenicity of this associated dysplastic tissue is crucial to validate such revision. In addition to the possibility of representing dual pathology, the association of developmental tumors and adjacent dysplasia may instead represent a single developmental lesion with distinct parts distributed along a histopathologic continuum. Moreover, the possibility that this adjacent dyslamination is of minor epileptogenic relevance should also be entertained. Surgical data show that complete resection of the solid tumors and immediately adjacent tissue harboring satellites may disrupt epileptogenic networks and lead to high rates of seizure freedom, challenging the epileptogenic relevance of more extensive adjacent dyslaminated cortex. Whether the latter is a primary or secondary abnormality and whether dyslaminated cortex in the context of a second lesion may produce seizures after complete resection of the main lesion is still to be proven. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

Crystallization kinetics of BaO-Al2O3-SiO2 glasses

Science.gov (United States)

Bansal, Narottam P.; Hyatt, Mark J.

1989-01-01

Barium aluminosilicate glasses are being investigated as matrix materials in high-temperature ceramic composites for structural applications. Kinetics of crystallization of two refractory glass compositions in the barium aluminosilicate system were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). From variable heating rate DTA, the crystallization activation energies for glass compositions (wt percent) 10BaO-38Al2O3-51SiO2-1MoO3 (glass A) and 39BaO-25Al2O3-35SiO2-1MoO3 (glass B) were determined to be 553 and 558 kJ/mol, respectively. On thermal treatment, the crystalline phases in glasses A and B were identified as mullite (3Al2O3-2SiO2) and hexacelsian (BaO-Al2O3-2SiO2), respectively. Hexacelsian is a high-temperature polymorph which is metastable below 1590 C. It undergoes structural transformation into the orthorhombic form at approximately 300 C accompanied by a large volume change which is undesirable for structural applications. A process needs to be developed where stable monoclinic celsian, rather than hexacelsian, precipitates out as the crystal phase in glass B.

Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

Energy Technology Data Exchange (ETDEWEB)

Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

2015-07-01

The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

μ-Carbonato-κ(4) O,O':O',O''-bis-{[2'-(di-tert-butyl-phosphan-yl)biphenyl-2-yl-κ(2) P,C (1)]palladium(II)} dichloro-methane monosolvate.

Science.gov (United States)

Muller, Alfred; Holzapfel, Cedric W

2012-12-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd(0) complex with (2-biphen-yl)P( (t) Bu)2. In the crystal, each palladium dimer is accompanied by a dichloro-methane solvent mol-ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd-P(av.) = 2.2135 (4) Å, Pd-C(av.) = 1.9648 (16) Å and P-Pd-C = 84.05 (5) and 87.98 (5)°, and O-Pd-O' = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd-O-Pd bridge, whereas other Pd-O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C-H⋯O interactions are observed propagating the molecules along the [100] direction.

μ-Carbonato-κ4 O,O′:O′,O′′-bis­{[2′-(di-tert-butyl­phosphan­yl)biphenyl-2-yl-κ2 P,C 1]palladium(II)} dichloro­methane monosolvate

Science.gov (United States)

Muller, Alfred; Holzapfel, Cedric W.

2012-01-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd0 complex with (2-biphen­yl)P(tBu)2. In the crystal, each palladium dimer is accompanied by a dichloro­methane solvent mol­ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd—P(av.) = 2.2135 (4) Å, Pd—C(av.) = 1.9648 (16) Å and P—Pd—C = 84.05 (5) and 87.98 (5)°, and O—Pd—O′ = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd—O—Pd bridge, whereas other Pd—O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C—H⋯O interactions are observed propagating the molecules along the [100] direction. PMID:23468771

Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

Energy Technology Data Exchange (ETDEWEB)

Warkentin, Matthew, E-mail: maw64@cornell.edu; Thorne, Robert E. [Physics Department, Cornell University, Ithaca, New York (United States)

2010-10-01

Radiation damage to protein crystals exhibits two regimes of temperature-activated behavior between T = 300 and 100 K, with a crossover at the protein glass transition near 200 K. These results have implications for mechanistic studies of proteins and for structure determination when cooling to T = 100 K creates excessive disorder. The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol{sup −1} indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol{sup −1}, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for

Crystal structure of chlorido(dimethyl sulfoxide-κSbis[4-(pyridin-2-ylbenzaldehyde-κ3C2,N]iridium(III acetonitrile monosolvate

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Andrew J. Peloquin

2017-09-01

Full Text Available The title compound, [IrCl(C12H8NO2{(CH32SO}]·H3CCN or [IrCl(fppy2(DMSO]·H3CCN [where fppy is 4-(pyridin-2-ylbenzaldehyde and DMSO is dimethyl sulfoxide], is a mononuclear iridium(III complex including two fppy ligands, a sulfur-coordinating DMSO ligand, and one terminal chloride ligand that define a distorted octahedral coordination sphere. The complex crystallizes from 1:1 DMSO–acetonitrile as an acetonitrile solvate. In the crystal, weak C—H...O and C—H...N hydrogen-bonding interactions between adjacent complexes and between the acetonitrile solvent and the complex consolidate the packing.

MgO reflectance data for Monte Carlo simulation of LaBr{sub 3}:Ce scintillation crystals

Energy Technology Data Exchange (ETDEWEB)

Scafè, Raffaele, E-mail: raffaele.scafe@uniroma1.it [Dept. of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 324, I-00161 Rome (Italy); Pani, Roberto; Pellegrini, Rosanna; Cinti, Maria Nerina [Dept. of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 324, I-00161 Rome (Italy); Bennati, Paolo [INFN-Roma I, Italian National Institute of Nuclear Physics, Piazzale Aldo Moro 5, I-00185 Rome (Italy); Lo Meo, Sergio [National Institution for Insurance against Accidents at Work, Via Fontana Candida 1, I-00040, Monte Porzio Catone (Italy)

2013-02-11

Present paper is aimed to estimate the spectral reflectance of MgO as a function of layer thickness around LaBr{sub 3}:5%Ce crystals. A reference emission spectrum of scintillator was calculated averaging 15 experimental trends from literature. A survey on MgO reflectance provided experimental data in the wavelength region of interest without thickness information, while trends with dimensional facts were found in the adjacent wavelength region. An algorithm was developed for interpolating spectral data in the wavelength region of interest for given thickness. A comparison between reflectors for LaBr{sub 3}:Ce is summarized in Appendix A. Results are presented in form of weighted average values as well as numerical trends suitable, in particular, as input for Monte Carlo simulations of encapsulated crystals.

Doping with lead of single crystals of solid solutions of Sbsub(1,5)Bisub(0,5)Tlsub(3)-Bisub(2)Sesub(3)

International Nuclear Information System (INIS)

Abrikosov, N.Kh.; Ivanova, L.D.; Polikarpova, N.V.; Galechyan, M.G.

1984-01-01

By the Czochralski method with liquid phase additional feeding single crystals of solid solutions of the Sbsub(1.5)Bisub(0.5)Tesub(3)-Bisub(2)Sesub(3) system with 0, 10 and 15 mol.% of Bi 2 Se 3 content doped with lead up to 1.37 at/cm 3 are grown. Lead content in crystals and alloys is determined by the atom-abmethod using the scale of standard solutions. It has been found that the effective coefficient of lead distribution in investigated solutions is approximately 0.5. It is shown that lead addition leads to increase of electric conductivity and heat conductivity and decrease of thermoelectric coeffcient at the expense of current carriers concentration growth, the lead in crystals of solid solutions of the Sbsub(1.5)Bisub(0.5)Tesub(3)-Bisub(2)Sesub(3) system being a single charge acceptor

Benign Lesions in Mucosa Adjacent to Intestinal-Type Sinonasal Adenocarcinoma

Directory of Open Access Journals (Sweden)

Blanca Vivanco

2011-01-01

Full Text Available Occupational exposure to wood dust is a strong risk factor for the development of intestinal-type sinonasal adenocarcinoma (ITAC; however, knowledge on possible precursor lesions or biomarkers is limited. Fifty-one samples of tumor-adjacent mucosa and 19 control samples of mucosa from the unaffected fossa of ITAC patients were evaluated for histological changes and p53 protein expression. Mild dysplasia was observed in 14%, cuboidal metaplasia in 57%, intestinal metaplasia in 8%, squamous metaplasia in 24%, and cylindrocellular hyperplasia in 53% of cases. P53 immunopositivity was generally weak occurring most frequently in squamous metaplasia. Wood dust etiology did not appear of influence on the histological changes, but p53 showed a tendency for higher positivity. Dysplasia adjacent to tumor was indicative of subsequent development of recurrence. In conclusion, precursor lesions do occur in mucosa adjacent to ITAC. This is clinically important, because it may justify the screening of high-risk individuals such as woodworkers.

THE MULTIBONUS FIDELITY PROGRAM – DEVELOPED AND USED BY MOL ROMANIA PETROLEUM PRODUCTS

OpenAIRE

Mihai Tichindelean

2009-01-01

Before choosing a strategic alternative, a company must analyze or scan its marketing environment, undertake market segmentation, target own market segments and position itself within these market segments. Adopting a relationship marketing strategy, in general, and an attachment strategy, in particular, requires the company to formalize a life cycle perspective. This paper correlates the theoretical background of an attachment strategy with an applicative case study to Mol Romania.

Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout.

Science.gov (United States)

Chhana, Ashika; Callon, Karen E; Pool, Bregina; Naot, Dorit; Watson, Maureen; Gamble, Greg D; McQueen, Fiona M; Cornish, Jillian; Dalbeth, Nicola

2011-09-01

Bone erosion is a common manifestation of chronic tophaceous gout. To investigate the effects of monosodium urate monohydrate (MSU) crystals on osteoblast viability and function. The MTT assay and flow cytometry were used to assess osteoblast cell viability in the MC3T3-E1 and ST2 osteoblast-like cell lines, and primary rat and primary human osteoblasts cultured with MSU crystals. Quantitative real-time PCR and von Kossa stained mineralised bone formation assays were used to assess the effects of MSU crystals on osteoblast differentiation using MC3T3-E1 cells. The numbers of osteoblasts and bone lining cells were quantified in bone samples from patients with gout. MSU crystals rapidly reduced viability in all cell types in a dose-dependent manner. The inhibitory effect on cell viability was independent of crystal phagocytosis and was not influenced by differing crystal length or addition of serum. Long-term culture of MC3T3-E1 cells with MSU crystals showed a reduction in mineralisation and decreased mRNA expression of genes related to osteoblast differentiation such as Runx2, Sp7 (osterix), Ibsp (bone sialoprotein), and Bglap (osteocalcin). Fewer osteoblast and lining cells were present on bone directly adjacent to gouty tophus than bone unaffected by tophus in patients with gout. MSU crystals have profound inhibitory effects on osteoblast viability and differentiation. These data suggest that bone erosion in gout occurs at the tophus-bone interface through alteration of physiological bone turnover, with both excessive osteoclast formation, and reduced osteoblast differentiation from mesenchymal stem cells.

Covalently Connecting Crystal Grains with Polyvinylammonium Carbochain Backbone To Suppress Grain Boundaries for Long-Term Stable Perovskite Solar Cells.

Science.gov (United States)

Li, Han; Liang, Chao; Liu, Yingliang; Zhang, Yiqiang; Tong, Jincheng; Zuo, Weiwei; Xu, Shengang; Shao, Guosheng; Cao, Shaokui

2017-02-22

Grain boundaries act as rapid pathways for nonradiative carrier recombination, anion migration, and water corrosion, leading to low efficiency and poor stability of organometal halide perovskite solar cells (PSCs). In this work, the strategy suppressing the crystal grain boundaries is applied to improve the photovoltaic performance, especially moisture-resistant stability, with polyvinylammonium carbochain backbone covalently connecting the perovskite crystal grains. This cationic polyelectrolyte additive serves as nucleation sites and template for crystal growth of MAPbI 3 and afterward the immobilized adjacent crystal grains grow into the continuous compact, pinhole-free perovskite layer. As a result, the unsealed PSC devices, which are fabricated under low-temperature fabrication protocol with a proper content of polymer additive PVAm·HI, currently exhibit the maximum efficiency of 16.3%. Remarkably, these unsealed devices follow an "outside-in" corrosion mechanism and respectively retain 92% and 80% of the initial PCE value after being exposed under ambient environment for 50 days and 100 days, indicating the superiority of carbochain polymer additives in solving the long-term stability problem of PSCs.

Poly (3-hydroxybutyrate-co-15 mol% 3hydroxyhexanoate)/ZnO nanocomposites by solvent casting method: a study of optical, surface, and thermal properties

Science.gov (United States)

Vishnu Chandar, J.; Shanmugan, S.; Mutharasu, D.; Azlan, A. A.

2017-01-01

Biopolymer nanocomposites are gaining interest due to their biodegradable and biocompatible nature, with exceptional properties which are superior to those of pure polymer and that can be used as a replacement for petroleum-based plastics. Pure poly (3-hydroxybutyrate-co-15 mol% 3hydroxyhexanoate) [P(3HB-co-15 mol% 3HHx)] and ZnO nanoparticles (NPs) reinforced P(3HB-co-15 mol% 3HHx) composite films were prepared and their morphological, optical, and thermal analyses were carried out to study the effect of ZnO NPs on P(3HB-co-15 mol% 3HHx) copolymer. From optical analysis, a strong absorbance peak at ˜358 nm with high intensity for 5%ZnO NPs reinforced P(3HB-co-15 mol% 3HHx) composite sample was observed. Nano-sized particles and their increased trend with increased ZnO NPs concentration were confirmed by UV-Vis spectral analysis. In addition to that, ZnO NPs reduced the reflectance behaviour of P(3HB-co-15 mol% 3HHx) copolymer in the UV region. Field emission scanning electron microscopy analysis evidenced that the pore numbers and their size in the composite matrix was decreased with increased ZnO NPs concentration. Improved thermal stability and melting temperature of the copolymer matrix was confirmed by thermogravimetric analysis and differential scanning calorimetry analysis, respectively. ZnO NPs acted as a retarding agent and showed a low degree of crystallinity (X c ) and enthalpy of melting (ΔH M ). From these observations, ZnO NPs reinforced P(3HB-co-15 mol% 3HHx) composites can be integrated with suitable resin and can be used as an LED encapsulant to block UV rays. They can also be used as a UV blocking coating material in the glass, plastic, and textile industries, for NIR shielding and food packaging applications.

Structure and Chemical Durability of Lead Crystal Glass.

Science.gov (United States)

Angeli, Frédéric; Jollivet, Patrick; Charpentier, Thibault; Fournier, Maxime; Gin, Stéphane

2016-11-01

Silicate glasses containing lead, also called lead crystal glasses, are commonly used as food product containers, in particular for alcoholic beverages. Lead's health hazards require major attention, which can first be investigated through the understanding of Pb release mechanisms in solution. The behavior of a commercial crystal glass containing 10.6 mol % of PbO (28.3 wt %) was studied in a reference solution of 4% acetic acid at 22, 40, and 70 °C at early and advanced stages of reaction. High-resolution solid-state 17 O and 29 Si NMR was used to probe the local structure of the pristine and, for the first time, of the altered lead crystal glass. Inserted into the vitreous structure between the network formers as Si-O-Pb bonds, Pb does not form Pb-O-Pb clusters which are expected to be more easily leached. A part of K is located near Pb, forming mixed Si-O-(Pb,K) near the nonbridging oxygens. Pb is always released into the solution following a diffusion-controlled dissolution over various periods of time, at a rate between 1 and 2 orders of magnitude lower than the alkalis (K and Na). The preferential release of alkalis is followed by an in situ repolymerization of the silicate network. Pb is only depleted in the outermost part of the alteration layer. In the remaining part, it stays mainly surrounded by Si in a stable structural configuration similar to that of the pristine glass. A simple model is proposed to estimate the Pb concentration as a function of glass surface, solution volume, temperature, and contact time.

Community conservation adjacent to Ruaha National Park, Tanzania

Science.gov (United States)

Sue Stolberger

2007-01-01

In the areas adjacent to Ruaha National Park where rural communities exist, much more work and education is required to enable them to benefit directly and indirectly from tourism and managing their own natural resources.

Crystallization and characterization of Y2O3-SiO2 glasses

Science.gov (United States)

Drummond, Charles H., III; Lee, William E.; Sanders, W. A.; Kiser, J. D.

1991-01-01

Glasses in the yttria-silica system with 20 to 40 mol pct Y2O3 were subjected to recrystallization studies after melting at 1900 to 2100 C in W crucibles in 1 and 50 atm N2. The TEM and XRD results obtained indicate the presence of the delta, gamma, gamma prime, and beta-Y2Si2O7 crystalline phases, depending on melting and quenching conditions. Heat treatment in air at 1100 to 1600 C increased the amount of crystallization, and led to the formation of Y2SiO5, cristabalite, and polymorphs of Y2Si2O7. Also investigated were the effects of 5 and 10 wt pct zirconia additions.

Random lasing of microporous surface of Cr2+:ZnSe crystal induced by femtosecond laser

International Nuclear Information System (INIS)

Yang, Xianheng; Feng, Guoying; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan

2015-01-01

We demonstrate a random lasing emission based on microporous surface of Cr 2+ :ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10 −4 Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ∼13 μm and smaller ones with ∼1.2 μm on the surface of Cr 2+ :ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr 2+ :ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr 2+ :ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength

Uplink scheduling and adjacent-channel coupling loss analysis for TD-LTE deployment.

Science.gov (United States)

Yeo, Woon-Young; Moon, Sung Ho; Kim, Jae-Hoon

2014-01-01

TD-LTE, one of the two duplexing modes in LTE, operates in unpaired spectrum and has the advantages of TDD-based technologies. It is expected that TD-LTE will be more rapidly deployed in near future and most of WiMax operators will upgrade their networks to TD-LTE gradually. Before completely upgrading to TD-LTE, WiMax may coexist with TD-LTE in an adjacent frequency band. In addition, multiple TD-LTE operators may deploy their networks in adjacent bands. When more than one TDD network operates in adjacent frequency bands, severe interference may happen due to adjacent channel interference (ACI) and unsynchronized operations. In this paper, coexistence issues between TD-LTE and other systems are analyzed and coexistence requirements are provided. This paper has three research objectives. First, frame synchronization between TD-LTE and WiMax is discussed by investigating possible combinations of TD-LTE and WiMax configurations. Second, an uplink scheduling algorithm is proposed to utilize a leakage pattern of ACI in synchronized operations. Third, minimum requirements for coexistence in unsynchronized operations are analyzed by introducing a concept of adjacent-channel coupling loss. From the analysis and simulation results, we can see that coexistence of TD-LTE with other TDD systems is feasible if the two networks are synchronized. For the unsynchronized case, some special cell-site engineering techniques may be required to reduce the ACI.

Bowl adamanzanes--bicyclic tetraamines: syntheses and crystal structures of complexes with cobalt(III) and chelating coordinated oxo-anions.

Science.gov (United States)

Broge, Louise; Søtofte, Inger; Jensen, Kristian; Jensen, Nicolai; Pretzmann, Ulla; Springborg, Johan

2007-09-14

Seven cobalt(III) complexes of the macrobicyclic tetraamine ligand [2(4).3(1)]adamanzane ([2(4).3(1)]adz) are reported along with the crystal structure of six of these complexes. The solid state and solution structures are discussed, and a detailed assignment of the NMR spectra of the sulfato complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion (sulfate, formiate, nitrate, carbonate). Equilibration of these species with the corresponding diaqua complex is generally slow. The rates of equilibration in 5 mol dm(-3) perchloric acid at 25 degrees C have been measured, yielding half lives of 20 min, 10 min and 3 h for the sulfato, formiato and carbonato species respectively. The corresponding reaction for the nitrato complex occurs with a half life of less than 3 min. The concentration acid dissociation constant for the Co([2(4).3(1)]adz)(HCO(3))(2+) ion has been measured to K(a) = 0.33 mol dm(-3) [25 degrees C, I = 2 mol dm(-3)] and K(a) = 0.15 mol dm(-3) [25 degrees C, I = 5 mol dm(-3)]. The propensity for coordination of sulfate was found to be large enough for a quantitative conversion of the carbonato complex to the sulfato complex to occur in 3 mol dm(-3) triflic acid containing a small sulfate contamination. On this basis the decarboxylation in 5 mol dm(-3) triflic acid of the corresponding cobalt(III) carbonato complex of the larger macrobicyclic tetraamine ligand [3(5)]adz was reinvestigated and found to lead to the sulfato complex as well. The difference in exchange rate of the oxo-anion ligands for the cobalt(III) complexes of the two adamanzane ligands is discussed and attributed to fundamental differences in the molecular structure where an inverted configuration of the secondary non-bridged amine groups is seen for the complexes of the larger [3(5)]adz ligand. The high affinity for chelating coordination of oxo-anions for these two cobalt(iii)-adamanzane-moieties is rationalised on basis of the N-Co-N angles. N

Sacroiliac Joint Fusion Minimally Affects Adjacent Lumbar Segment Motion: A Finite Element Study.

Science.gov (United States)

Lindsey, Derek P; Kiapour, Ali; Yerby, Scott A; Goel, Vijay K

2015-01-01

Adjacent segment disease is a recognized consequence of fusion in the spinal column. Fusion of the sacroiliac joint is an effective method of pain reduction. Although effective, the consequences of sacroiliac joint fusion and the potential for adjacent segment disease for the adjacent lumbar spinal levels is unknown. The objective of this study was to quantify the change in range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments due to sacroiliac joint fusion and compare these changes to previous literature to assess the potential for adjacent segment disease in the lumbar spine. An experimentally validated finite element model of the lumbar spine and pelvis was used to simulate a fusion of the sacroiliac joint using three laterally placed triangular implants (iFuse Implant System, SI-BONE, Inc., San Jose, CA). The range of motion of the sacroiliac joint and the adjacent lumbar spinal motion segments were calculated using a hybrid loading protocol and compared with the intact range of motion in flexion, extension, lateral bending, and axial rotation. The range of motions of the treated sacroiliac joints were reduced in flexion, extension, lateral bending, and axial rotation, by 56.6%, 59.5%, 27.8%, and 53.3%, respectively when compared with the intact condition. The stiffening of the sacroiliac joint resulted in increases at the adjacent lumbar motion segment (L5-S1) for flexion, extension, lateral bending, and axial rotation, of 3.0%, 3.7%, 1.1%, and 4.6%, respectively. Fusion of the sacroiliac joint resulted in substantial (> 50%) reductions in flexion, extension, and axial rotation of the sacroiliac joint with minimal (sacroiliac joint fusion, the long-term clinical results remain to be investigated.

Analysis of CD83 antigen expression in human breast fibroadenoma and adjacent tissue

Directory of Open Access Journals (Sweden)

Marcus Nascimento Borges

Full Text Available CONTEXT AND OBJECTIVE: Dendritic cell maturation is considered essential for starting an immune response. The CD83 antigen is an important marker of dendritic cell maturation. The objectives here were to analyze CD83 antigen expression in human breast fibroadenoma and breast tissue adjacent to the lesion and to identify clinical factors that might influence this expression. DESIGN AND SETTING: This was a retrospective study at a public university hospital, in which 29 histopathological samples of breast fibroadenoma and adjacent breast tissue, from 28 women of reproductive age, were analyzed. METHODS: The immunohistochemistry method was used to analyze the cell expression of the antigen. The antigen expression in the cells was evaluated by means of random manual counting using an optical microscope. RESULTS: Positive expression of the CD83 antigen in the epithelial cells of the fibroadenoma (365.52; standard deviation ± 133.13 in relation to the adjacent breast tissue cells (189.59; standard deviation ± 140.75 was statistically larger (P < 0.001. Several clinical features were analyzed, but only parity was shown to influence CD83 antigen expression in the adjacent breast tissue, such that positive expression was more evident in nulliparous women (P = 0.042. CONCLUSIONS: The expression of the CD83 antigen in the fibroadenoma was positive and greater than in the adjacent breast tissue. Positive expression of the antigen in the adjacent breast tissue was influenced by parity, and was significantly more evident in nulliparous women.

Risk Factors for the Development of Adjacent Segment Disease Following Anterior Cervical Arthrodesis

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