A novel magnetic resonance imaging postprocessing technique for the assessment of intervertebral disc degeneration-Correlation with histological grading in a rabbit disc degeneration model.

Introduction:Estimation of intervertebral disc degeneration on magnetic resonance imaging (MRI) is challenging. Qualitative schemes used in clinical practice correlate poorly with pain and quantitative techniques have not entered widespread clinical use. Methods:As part of a prior study, 25 New Zealand white rabbits underwent annular puncture to induce disc degeneration in 50 noncontiguous lumbar discs. At 16 weeks, the animals underwent multi-echo T2 MRI scanning and were euthanized. The discs were stained and examined histologically. Quantitative T2 relaxation maps were prepared using the nonlinear least squares method. Decay Variance maps were created using a novel technique of aggregating the deviation in the intensity of each echo signal from the expected intensity based on the previous rate of decay. Results:Decay Variance maps showed a clear and well demarcated nucleus pulposus with a consistent rate of decay (low Decay Variance) in healthy discs that showed progressively more variable decay (higher Decay Variance) with increasing degeneration. Decay Variance maps required significantly less time to generate (1.0 ± 0.0 second) compared with traditional T2 relaxometry maps (5 (±0.9) to 1788.9 (±116) seconds). Histology scores correlated strongly with Decay Variance scores (r = 0.82, P < .01) and weakly with T2 signal intensity (r = 0.32, P < .01) and quantitative T2 relaxometry (r = 0.39, P < .01). Decay Variance had superior sensitivity and specificity for the detection of degenerate discs when compared to T2 signal intensity or Quantitative T2 mapping. Conclusion:Our results show that using a multi-echo T2 MRI sequence, Decay Variance can quantitatively assess disc degeneration more accurately and with less image-processing time than quantitative T2 relaxometry in a rabbit disc puncture model. The technique is a viable candidate for quantitative assessment of disc degeneration on MRI scans. Further validation on human subjects is needed

A monoclinic polymorph of N,N′-bis­(2,6-diisopropyl­phen­yl)formamidine

A new polymorph of N,N′-bis­(2,6-diisopropyl­phen­yl)formamidine, C25H36N2, is reported, which is different from the previously reported ortho­rhom­bic structure. The mol­ecule crystallizes in the E–anti configuration, with tautomeric disorder of the N-bonded H atoms and no clear distinction between imine and amine functionalities. The mol­ecules form hydrogen-bonded dimers with inter­molecular N⋯N distances shorter than those in the ortho­rhom­bic polymorph

Bimetallic Pt(II)-bipyridyl-diacetylide/Ln(III) tris-diketonate adducts based on a combination of coordinate bonding and hydrogen bonding between the metal fragments: syntheses, structures and photophysical properties

The luminescent Pt(II) complex [Pt(4,4'-Bu-t(2)-bipy){CC-(5-pyrimidinyl)}(2)] (1) was prepared by coupling of [Pt(4,4'-Bu-t(2)-bipy)Cl-2] with 5-ethynyl-pyrimidine, and contains two pyrimidinyl units pendant from a Pt(H) bipyridyl diacetylide core; it shows luminescence at 520 nm which is typical of Pt(II) luminophores of this type. Reaction with [Ln(hfac)(3)(H2O)(2)] (hfac = anion of hexafluoroacetylacetone) affords as crystalline solids the compounds [1 center dot {Ln(hfac)(3)(H2O)}{Ln(hfac)(3)(H2O)(2)}] (Ln = Nd, Gd, Er, Yb), in which the {Ln(hfac)(3)(H2O)} unit is coordinated to one pyrimidine ring via an N atom, whereas the {Ln(hfac)(3)(H2O)(2)} unit is associated with two N atoms, one from each pyrimidine ring of 1, via N center dot center dot center dot HOH hydrogen-bonding interactions involving the coordinated water ligands on the lanthanide centre. Solution spectroscopic studies show that the luminescence of 1 is partly quenched on addition of [Ln(hfac)(3)(H2O)(2)] (Ln = Er, Nd) by formation of Pt(II)/Ln(III) adducts in which Pt(II)-> Ln(III) photoinduced energy-transfer occurs to the low-lying f-f levels of the Ln(Ill) centre. Significant quenching occurs with both Er(Ill) and Nd(III) because both have several f-f states which match well the (MLCT)-M-3 emission energy of 1. Time-resolved luminescence studies show that Pt(II)-Er(III) energy-transfer (7.0 x 10(7) M-1) is around three times faster than Pt(II)-> Nd(III) energy-transfer (approximate to 2 x 10(7) M-1) over the same distance because the luminescence spectrum of l overlaps better with the absorption spectrum of Er(111) than with Nd(III). In contrast Yb(111) causes no significant quenching of 1 because it has only a single f-f excited level which is a poor energy match for the Pt(II)-based excited state

NaV2O4: a Quasi-1D Metallic Antiferromagnet with Half-Metallic Chains

NaV2O4 crystals were grown under high pressure using a NaCl flux, and the crystals were characterized with X-ray diffraction, electrical resistivity, heat capacity, and magnetization. The structure of NaV2O4 consists of double chains of edge-sharing VO6 octahedra. The resistivity is highly anisotropic, with the resistivity perpendicular to the chains more than 20 times greater than that parallel to the chains. Magnetically, the intrachain interactions are ferromagnetic and the interchain interactions are antiferromagnetic; 3D antiferromagnetic order is established at 140 K. First principles electronic structure calculations indicate that the chains are half metallic. Interestingly, the case of NaV2O4 seems to be a quasi-1D analogue of what was found for half-metallic materials.Comment: 14 pages, including 4 figures and 1 table, accepted for publication in PR

1,3-Bis(2,6-diisopropyl­phen­yl)-4,5-dihydro-1H-imidazol-3-ium triiodide

In the crystal structure of the title compound, C27H39N2 +·I3 −, the imidazolidinium ring is perpendicular to a mirror plane which bis­ects the cation. The dihedral angle between the imidazolidinium ring and the benzene ring is 89.0 (2)°. The triiodide anion also lies on a mirror plane and is almost linear with an I—I—I bond angle of 178.309 (18)°

(Biphenyl-2-yl)bromidobis(2-methyl­tetra­hydro­furan-κO)magnesium(II)

In the title Grignard reagent, [MgBr(C12H9)(C5H10O)2], the Mg centre adopts a distorted tetra­hedral MgCO2Br arrangement. The dihedral angle between the two aromatic rings of the biphenyl residue is 44.00 (14)°. Each mol­ecule incorporates one R- and one S-configured 2-methyl­tetra­hydro­furan mol­ecule

2,3-Dimethoxy-10-oxostrychnidinium 2-(2,4,6-trinitroanilino)benzoate monohydrate: a 1:1 proton-transfer salt of brucine with o-picraminobenzoic acid

In the structure of the 1:1 proton-transfer compound of brucine with 2-(2,4,6-trinitroanilino)benzoic acid C23H27N2O4+ . C13H7N4O8- . H~2~O, the brucinium cations form the classic undulating ribbon substructures through overlapping head-to-tail interactions while the anions and the three related partial water molecules of solvation (having occupancies of 0.73, 0.17 and 0.10) occupy the interstitial regions of the structure. The cations are linked to the anions directly through N-H...O(carboxyl) hydrogen bonds and indirectly by the three water molecules which form similar conjoint cyclic bridging units [graph set R2/4(8)] through O-H...O(carbonyl) and O(carboxyl) hydrogen bonds, giving a two-dimensional layered structure. Within the anion, intramolecular N-H...O(carboxyl) and N H...O(nitro) hydrogen bonds result in the benzoate and picrate rings being rotated slightly out of coplanarity inter-ring dihedral angle 32.50(14)\%]. This work provides another example of the molecular selectivity of brucine in forming stable crystal structures and also represents the first reported structure of any form of the guest compound 2-(2,4,6-trinitroanilino)benzoic acid

Novel Polypyridyl Ruthenium(II) Complexes Containing Oxalamidines as Ligands.

The complexes [Ru(bpy)2(H2TPOA)](PF6)2 ⋅ 4H2O, (1); [Ru(Me-bpy)2(H2TPOA)](PF6)2 ⋅ 2H2O, (2); [Ru(bpy)2(H2TTOA)](PF6)2 ⋅ 2H2O, (3); [Ru(Me-bpy)2(H2TTOA)](PF6)2 ⋅ 2H2O, (4) and {[Ru(bpy)2]2(TPOA)}(PF6)2 ⋅ 2H2O, (5) (where bpy is 2,2´bipyridine; Me-bpy is 4,4´- dimethyl-2,2´-bipyridine; H2TPOA is N, N´, N´´, N´´´- tetraphenyloxalamidine; H2TTOA is N, N´, N´´, N´´´- tetratolyloxalamidine) have been synthesized and characterized by 1H-NMR, FAB-MS, infrared spectroscopy and elemental analysis. The X-ray investigation shows the coordination of the still protonated oxalamidine moiety via the 1,2−diimine unit. The dimeric compound (5) could be separated in its diastereoisomers (5´) and (5´´) by repeated recrystallisation. The diastereomeric forms exhibit different 1H-NMR spectra and slightly shifted electronic spectra. Compared with the model compound [Ru(bpy)3]2+, the absorption maxima of (1)–(5) are shifted to lower energies. The mononuclear complexes show Ru(III/II)- couples at about 0.9 V vs SCE, while for the dinuclear complex two well defined metal based redox couples are observed at 0.45 and 0.65 V indicating substantial interaction between the two metal centres

Single crystal of superconducting SmFeAsO1-xFy grown at high pressure

Single crystals of SmFeAsO1-xFy of a size up to 120 micrometers have been grown from NaCl/KCl flux at a pressure of 30 kbar and temperature of 1350-1450 C using the cubic anvil high-pressure technique. The superconducting transition temperature of the obtained single crystals varies between 45 and 53 K.Obtained crystals are characterized by a full diamagnetic response in low magnetic fields and by a high critical current density in high magnetic fields. Structural refinement has been performed on single crystal. Differential thermal analysis investigations at 1 bar Ar pressure show decomposition of SmFeAsO1-xFy at 1302 C.Comment: 12 pages, 3 tables, 6 figure

Methyl 2,2-bis­(2,4-dinitro­phen­yl)ethano­ate

In the title compound, C15H10N4O10, the dihedral angle between the aromatic rings is 89.05 (16)°. One O atom of one of the nitro groups is disordered over two sites in a 0.70:0.30 ratio. In the crystal, the mol­ecules are linked by weak C—H⋯O inter­actions