Magneto-structural Correlations in Ni-Halide···Halide-Ni Chains.

We present the magnetic properties of a new family of = 1 molecule-based magnets, NiF(3,5-lut)·2HO and NiX(3,5-lut), where X = HF, Cl, Br, or I (lut = lutidine CHN). Upon creation of isolated Ni-X···X-Ni and Ni-F-H-F···F-H-F-Ni chains separated by bulky and nonbridging lutidine ligands, the effect that halogen substitution has on the magnetic properties of transition-metal-ion complexes can be investigated directly and in isolation from competing processes such as Jahn-Teller distortions. We find that substitution of the larger halide ions turns on increasingly strong antiferromagnetic interactions between adjacent Ni ions via a novel through-space two-halide exchange.

Spin-resolved atomic orbital model refinement for combined charge and spin density analysis: application to the YTiO perovskite.

A new crystallographic method is proposed in order to refine a spin-resolved atomic orbital model against X-ray and polarized neutron diffraction data. This atomic orbital model is applied to the YTiO perovskite crystal, where orbital ordering has previously been observed by several techniques: X-ray diffraction, polarized neutron diffraction and nuclear magnetic resonance. This method gives the radial extension, orientation and population of outer atomic orbitals for each atom.

Spin resolved electron density study of YTiO in its ferromagnetic phase: signature of orbital ordering.

The present work reports on the charge and spin density modelling of YTiO in its ferromagnetic state ( = 27 K). Accurate polarized neutron diffraction and high-resolution X-ray diffraction (XRD) experiments were carried out on a single crystal at the ORPHÉE reactor (LLB) and SPRING8 synchrotron source. The experimental data are modelled by the spin resolved pseudo-atomic multipolar model (Deutsch , 2012 ▸).

Probing the Local Magnetic Structure of the [Fe (Tp)(CN) ] Building Block Via Solid-State NMR Spectroscopy, Polarized Neutron Diffraction, and First-Principle Calculations.

The local magnetic structure in the [Fe (Tp)(CN) ] building block was investigated by combining paramagnetic Nuclear Magnetic Resonance (pNMR) spectroscopy and polarized neutron diffraction (PND) with first-principle calculations. The use of the pNMR and PND experimental techniques revealed the extension of spin-density from the metal to the ligands, as well as the different spin mechanisms that take place in the cyanido ligands: Spin-polarization on the carbon atoms and spin-delocalization on the nitrogen atoms. The results of our combined density functional theory (DFT) and multireference calculations were found in good agreement with the PND results and the experimental NMR chemical shifts.

Mapping the Magnetic Anisotropy at the Atomic Scale in Dysprosium Single-Molecule Magnets.

The anisotropy of the magnetic properties of molecular magnets is a key descriptor in the search for improved magnets. Herein, it is shown how an analytical approach using single-crystal polarized neutron diffraction (PND) provides direct access to atomic magnetic susceptibility tensors. The technique was applied for the first time to two Dy-based single-molecule magnets and showed clear axial atomic susceptibility for both Dy ions.

Joint refinement model for the spin resolved one-electron reduced density matrix of YTiO using magnetic structure factors and magnetic Compton profiles data.

In this paper, we propose a simple cluster model with limited basis sets to reproduce the unpaired electron distributions in a YTiO ferromagnetic crystal. The spin-resolved one-electron-reduced density matrix is reconstructed simultaneously from theoretical magnetic structure factors and directional magnetic Compton profiles using our joint refinement algorithm. This algorithm is guided by the rescaling of basis functions and the adjustment of the spin population matrix.

The Neuronal Correlates of Indeterminate Sentence Comprehension: An fMRI Study.

Sentences such as are indeterminate because they do not make explicit what the subject () started doing with the object (). In principle, indeterminate sentences allow for an infinite number of interpretations. One theory, however, assumes that these sentences are resolved by , a linguistic process that forces the noun to be interpreted as an (e.

Polarized Neutron Diffraction to Probe Local Magnetic Anisotropy of a Low-Spin Fe(III) Complex.

We have determined by polarized neutron diffraction (PND) the low-temperature molecular magnetic susceptibility tensor of the anisotropic low-spin complex PPh4 [Fe(III) (Tp)(CN)3]⋅H2O. We found the existence of a pronounced molecular easy magnetization axis, almost parallel to the C3 pseudo-axis of the molecule, which also corresponds to a trigonal elongation direction of the octahedral coordination sphere of the Fe(III) ion. The PND results are coherent with electron paramagnetic resonance (EPR) spectroscopy, magnetometry, and ab initio investigations.

Polarized Neutron Diffraction as a Tool for Mapping Molecular Magnetic Anisotropy: Local Susceptibility Tensors in Co(II) Complexes.

Polarized neutron diffraction (PND) experiments were carried out at low temperature to characterize with high precision the local magnetic anisotropy in two paramagnetic high-spin cobalt(II) complexes, namely [Co(II) (dmf)6 ](BPh4 )2 (1) and [Co(II) 2 (sym-hmp)2 ](BPh4 )2 (2), in which dmf=N,N-dimethylformamide; sym-hmp=2,6-bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate, and BPh4 (-) =tetraphenylborate. This allowed a unique and direct determination of the local magnetic susceptibility tensor on each individual Co(II) site. In compound 1, this approach reveals the correlation between the single-ion easy magnetization direction and a trigonal elongation axis of the Co(II) coordination octahedron.

Adoptive Transfer of Renal Allograft Tolerance in a Large Animal Model.

Our recent studies in an inbred swine model demonstrated that both peripheral and intra-graft regulatory cells were required for the adoptive transfer of tolerance to a second, naïve donor-matched kidney. Here, we have asked whether both peripheral and intra-graft regulatory elements are required for adoptive transfer of tolerance when only a long-term tolerant (LTT) kidney is transplanted. Nine highly-inbred swine underwent a tolerance-inducing regimen to prepare LTT kidney grafts which were then transplanted to histocompatible recipients, with or without the peripheral cell populations required for adoptive transfer of tolerance to a naïve kidney.

An unprecedented up-field shift in the 13C NMR spectrum of the carboxyl carbons of the lantern-type dinuclear complex TBA[Ru2(O2CCH3)4Cl2] (TBA+ = tetra(n-butyl)ammonium cation).

A large up-field shift (-763 ppm) has been observed for the carboxyl carbons of the dichlorido complex TBA[Ru(2)(O(2)CCH(3))(4)Cl(2)] (TBA(+) = tetra(n-butyl)ammonium cation) in the (13)C NMR spectrum (CD(2)Cl(2) at 25 °C). The DFT calculations showed spin delocalization from the paramagnetic Ru(2)(5+) core to the ligands, in agreement with the large up-field shift.

Direct observation of finite size effects in chains of antiferromagnetically coupled spins.

Finite spin chains made of few magnetic ions are the ultimate-size structures that can be engineered to perform spin manipulations for quantum information devices. Their spin structure is expected to show finite size effects and its knowledge is of great importance both for fundamental physics and applications. Until now a direct and quantitative measurement of the spatial distribution of the magnetization of such small structures has not been achieved even with the most advanced microscopic techniques.

The rejuvenating effects of leuprolide acetate on the aged baboon's thymus.

Background: We have previously demonstrated that the juvenile thymus plays an essential role in tolerance induced by both renal transplantation and a short course of calcineurin inhibitors. Aged thymi have a decreased ability to induce tolerance. Luteinizing hormone-releasing hormone (LHRH) is known to pharmacologically rejuvenate the thymus in rodents.

Abrogation of renal allograft tolerance in MGH miniature swine: the role of intra-graft and peripheral factors in long-term tolerance.

We have previously demonstrated that long-term tolerance (LTT) of an MHC class-I mismatched renal allograft can be achieved with a short course of cyclosporine. In order to examine regulatory mechanisms underlying tolerance in this model, we assessed the contributions of factors within the graft and in the peripheral blood for their relative roles in the maintenance of stable tolerance. Twelve LTT recipients of MHC class-I mismatched primary kidneys were subjected to a treatment consisting of donor-specific transfusion followed by leukapheresis, in order to remove peripheral leukocytes, including putative regulatory T cells (Tregs).

First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments.

Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density) and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment.

Development of antidonor antibody directed toward non-major histocompatibility complex antigens in tolerant animals.

Background: The clinical significance of antibodies directed against antigens other than major histocompatibility complex (MHC) antigens is poorly understood, and there are few large animal models in which such antibodies can be examined. We studied, both retrospectively and prospectively, the development of antibodies to non-MHC antigens in tolerant miniature swine.

Methods: Our database was assessed for cases of antidonor antibody formation in tolerant animals over the last 20 years.

Vascularized composite allograft transplant survival in miniature swine: is MHC tolerance sufficient for acceptance of epidermis?

Background: We have previously reported that Massachusetts General Hospital miniature swine, which had accepted class I-mismatched kidneys long-term after 12 days of high-dose cyclosporine A, uniformly accepted donor-major histocompatibility complex (MHC)-matched kidneys without immunosuppression but rejected donor MHC-matched split-thickness skin grafts by day 25, without changes in renal graft function or antidonor in vitro responses. We have now tested whether this "split tolerance" would also be observed for the primarily vascularized skin of vascularized composite allografts (VCAs).

Methods: Group 1 animals (n=3) received donor MHC-matched VCAs less than 70 days after primary kidney transplant (KTx).

The induction of tolerance of renal allografts by adoptive transfer in miniature swine.

Our previous in vitro data have demonstrated that regulatory mechanisms are involved in tolerance of class I-mismatched renal allografts in miniature swine treated with 12 days of high dose Cyclsporin A. In this study, we attempted to induce tolerance of class I-mismatched kidneys by adoptive transfer of cells and/or kidneys from long-term tolerant animals. Fifteen SLA(dd) miniature swine received 1.

Tolerogenicity of donor major histocompatibility complex-matched skin grafts in previously tolerant Massachusetts general hospital miniature swine.

Background: Long-term tolerance of class I disparate renal allografts in miniature swine can be induced by a short course of cyclosporine and persists for 3 to 4 months after grafts are removed. Donor class I peptide immunization 6 weeks after graftectomy of tolerated kidneys leads to sensitization, but donor skin grafts do not. Here, we tested the hypothesis that skin grafts prevent rejection after simultaneous peptide administration and skin grafting.

Experimental determination of spin-dependent electron density by joint refinement of X-ray and polarized neutron diffraction data.

New crystallographic tools were developed to access a more precise description of the spin-dependent electron density of magnetic crystals. The method combines experimental information coming from high-resolution X-ray diffraction (XRD) and polarized neutron diffraction (PND) in a unified model. A new algorithm that allows for a simultaneous refinement of the charge- and spin-density parameters against XRD and PND data is described.

First experience with the use of a recombinant CD3 immunotoxin as induction therapy in pig-to-primate xenotransplantation: the effect of T-cell depletion on outcome.

Background: We have previously reported life-supporting kidney xenograft-survival greater than 80 days using a steroid-free antithymocyte globulin (ATG)-based induction regimen (ATG regimen) in a GalT-KO pig-to-baboon thymokidney (TK) model. We evaluated two induction regimens, a newly developed anti-monkey CD3 recombinant immunotoxin (anti-CD3 rIT) and an anti-human CD2 antibody (LoCD2), by assessing T-cell depletion (TCD) and graft survival.

Methods: Four baboons received anti-CD3 rIT; the time course of TCD was studied in two animals and the other two received GalT-KO TK transplants.

Structure, magnetic properties, polarized neutron diffraction, and theoretical study of a copper(II) cubane.

The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.

Phosphorus-containing block copolymer templates can control the size and shape of gold nanostructures.

Amphiphilic block copolymers containing phosphine moieties in the main chain are employed as macromolecular ligands for gold(I). The sequential living anionic copolymerization of isoprene (I) and the phosphaalkene, MesP CPh2 (Mes = 2,4,6-trimethylphenyl) affords the block copolymer [PI]404-b-[MesP-CPh2]32 (1a). The incorporation of gold(I) moieties into this functional copolymer is accomplished by treating 1 with THT.

Macromolecular complexation of poly(methylenephosphine) to gold(I): a facile route to highly metallated polymers.

Alternating phosphorus-carbon polymers are found to be effective ligands for gold(i) to afford [MesP(AuCl)-CPh2]n, a new class of macromolecule with high gold content.