330 research outputs found

    Four New Trinuclear {Cu3(μ3-OH)(oximate)3}2+ Clusters: Crystal Structure and Magnetic Behavior

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    Four new triangular copper(II) complexes with the fragment {Cu3(μ3-OH)(oximate)3}2+ and formulae [Cu3(μ3-OH)(μ-Cl)(Py2CNO)3(tBuPO3H)]·4H2O (1), [Cu3(μ3-OH)(μ-Br)(Py2CNO)3(tBuPO3H)]·3.5H2O (2), [Cu3(μ3-OH)(μ-Br)(PhPyCNO)3(tBuPO3H)(MeOH)]·1.5 MeOH (3), [Cu3(μ3-OH)Cl2(PhPyCNO)3]·0.5H2O (4), (Py2CNO = di(2-pyridyl)ketoximate, PhPyCNO = phenyl(2-pyridyl)ketoximate, tBuPO3H2 = tert-butylphosphonic acid) are reported. The magnetic properties of compounds 1-4 were studied. The compounds were found to exhibit strong antiferromagnetic coupling and antisymmetric exchange interaction

    Field-Induced SMM and Visible/NIR-Luminescence Behaviour of Dinuclear LnIII Complexes with 2-Fluorobenzoate

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    The reaction of Ln(NO3)2·6H2O salts (Ln = Nd, Eu, Gd, Tb, Dy, Er and Yb) with 2-fluorobenzoic acid (H-2-FBz) and 1,10-phenanthroline (phen) in ethanol/water mixture allows the isolation of dinuclear compounds of the formula [Ln2(2-FBz)4- (NO3)2(phen)2] {Ln = Nd (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6)} and [Yb2(2-FBz)6(phen)2] (7). The solid-state photoluminescence study of the complexes shows the 4f-4f lanthanide transitions in the visible range, in the cases of 2, 4 and 5, and in the NIR range for 1, 6 and 7. Magnetic studies reveal field-induced single-molecule-magnet (SMM) behaviour for compounds 1, 5, 6 and 7

    A Ferromagnetic Salicylaldoximate/Azide MnII2MnIII6 Cluster with an S = 17 Ground State and a Single-Molecule-Magnet Response

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    One new MnII 2MnIII 6 cluster exhibiting an S = 17 spin ground state and single-molecule-magnet properties has been designed linking MnIII 3-salicylaldoximate triangles and tetracoordinated MnII cations by means of end-on azido bridges. The ferromagnetic coupling has been rationalized as a function of their structural parameters

    Circularly polarized luminescence on dinuclear Tb(III) and Eu(III) complexes with (S-) and (R-) 2-phenylpropionate

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    The reaction of Ln(NO3)(2)center dot 6H(2)O (Ln = Tb and Eu) with (S)-(+)-2-phenylpropionic acid (S-HL) and 1,10-phenanthroline (phen) in EtOH/H2O allows the isolation of the dinuclear chiral compounds of the formula [Ln(2)(S-L)(6)(phen)(2)]center dot 2.5 center dot S-HL in which Ln = Tb (S-1), Ln = Eu (S-2). The same synthesis by using (R)-(-)-2-phenylpropionic acid (R-HL) instead of (S)-(+)-2-phenylpropionic acid allows the isolation of the enantiomeric compounds with the formula [Ln(2)(R-L)(6)(phen)(2)]center dot 2 center dot 5 center dot R-HL where Ln = Tb (R-1), Ln = Eu (R-2). All compounds show sensitized luminescence. The luminescence study, including the circularly polarized luminescence spectra of the four compounds, is reported. The magnetic behavior of S-1 and S-2 is also reported

    Chiral Dinuclear Ln(III) Complexes Derived from S- and R-2-(6-methoxy-2-naphthyl)propionate. Optical and Magnetic Properties.

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    The reaction of LnCl3·6H2O with (S)-(+)-2-(6-methoxy-2-naphthyl)propionic acid (S-HL), best known as naproxen, and 1,10-phenanthroline (phen) in EtOH allows the isolation of dinuclear chiral compounds S-1-4 of the formula [Ln2(S-L)6(phen)2]·3DMF·H2O [Ln(III) = Eu (1), Gd (2), Tb (3) and Dy (4)]. The use of the R-enantiomeric species of the HL ligand led to complexes R-1-4 with the formula [Ln2(R-L)6(phen)2]·3DMF·H2O. Compounds R- and S-1, 3 and 4 show strong sensitized metal-centred luminescence in the visible region. Moreover, Dy(III) complexes R- and S-4 display field-induced singlemolecule magnet (SMM) behaviour. For chiral and emissive compounds circularly polarized luminescence (CPL) measurements have also been performed

    Surgical Interventions for Cervical Radiculopathy without Myelopathy:A Systematic Review and Meta-Analysis

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    BACKGROUND: The effectiveness of surgical interventions for cervical degenerative disorders has been investigated in multiple systematic reviews. Differences in study population (e.g., patients with myelopathy and/or radiculopathy) were often neglected. Therefore, the objective of this study was to investigate the effectiveness of surgical interventions for patients with symptoms of cervical radiculopathy without myelopathy by conducting a systematic review and meta-analysis based on randomized controlled trials (RCTs). METHODS: A comprehensive systematic search was conducted in MEDLINE, Embase, and CENTRAL (Cochrane Central Register of Controlled Trials) to identify RCTs that investigated the effectiveness of surgical interventions using an anterior or posterior approach compared with other interventions for patients with pure cervical radiculopathy. Outcomes were success rates (Odom criteria, similar rating scales, or percentage of patients who improved), complication and reoperation rates, work status, disability (Neck Disability Index), and pain (arm and neck). The Cochrane risk-of-bias tool was used to assess the likelihood of the risk of bias. A random-effects model was used. Heterogeneity among study results (I ≥ 50% or p < 0.05) was explored by conducting subgroup analyses. Funnel plots were used to assess the likelihood of publication bias. RESULTS: A total of 21 RCTs were included, comprising 1,567 patients. For all outcomes, among all surgical techniques, only 1 pooled estimate showed a significant effect on success rate, which was in favor of anterior cervical discectomy with fusion compared with anterior cervical discectomy without an intervertebral spacer (p = 0.02; risk ratio [RR] = 0.87; 95% confidence interval [CI] = 0.77 to 0.98). Complication rates were higher when autologous bone graft from the iliac crest was used as an intervertebral spacer (p < 0.01; RR = 3.40; 95% CI = 1.56 to 7.43), related to donor-site morbidity. CONCLUSIONS: This meta-analysis demonstrated consistent results regarding clinical outcome for pure cervical radiculopathy among all studied interventions. Complication and reoperation rates were also similar, with the exception of higher complication rates in patients in whom autologous bone grafts were used. On the basis of clinical outcome and safety, there is no superior surgical intervention for pure cervical radiculopathy. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence

    Dry and Humid Periods Reconstructed from Tree Rings in the Former Territory of Sogdiana (Central Asia) and Their Socio-economic Consequences over the Last Millennium

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    One of the richest societies along the Silk Road developed in Sogdiana, located in present-day Tajikistan, Uzbekistan, and Kyrgyzstan. This urban civilisation reached its greatest prosperity during the golden age of the Silk Road (sixth to ninth century ce). Rapid political and economic changes, accelerated by climatic variations, were observed during last millennium in this region. The newly developed tree-ring-based reconstruction of precipitation for the pastmillennium revealed a series of dry and wet stages. During the Medieval Climate Anomaly (MCA), two dry periods occurred (900–1000 and 1200–1250), interrupted by a phase of wetter conditions. Distinct dry periods occurred around 1510–1650, 1750–1850, and 1920–1970, respectively. The juniper tree-ring record of moisture changes revealed that major dry and pluvial episodes were consistent with those indicated by hydroclimatic proxy data from adjacent areas. These climate fluctuations have had longand short term consequences for human history in the territory of former Sogdiana
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