Isotopically enriched polymorphs of dysprosium single molecule magnets.

A triclinic polymorph Dy(t) and a monoclinic polymorph Dy(m) of [Dy(tta)3(L)] with L = 4-[6-(1,3-benzothiazol-2-yl)pyridin-3-yl]-4',5'-bis(methylthio)tetrathiafulvene behave as Single-Molecule Magnets with hysteresis loops opened at zero field. Magnetic properties were enhanced through magnetic dilution and 164Dy isotopic enrichment which definitively support the importance of isotopes for the control of quantum magnets.

New method of synthesis and in vitro studies of a porous biomaterial.

Biomaterials for bone reconstruction represent a widely studied area. In this paper, a new method of synthesis of a porous glass-ceramic obtained by thermal treatment is presented. The prepared biomaterial was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and induced couple plasma-optical emission spectroscopy (ICP-OES), mercury porosimetry and by the Archimedes method. In vitro evaluations in a simulated body fluid (SBF) and in contact with SaOS2 human osteoblasts were also carried out. The porous glass-ceramic is composed of a total porous network of 60% suitable for body fluid and cell infiltration, with pore sizes varying from 60 nm to 143 µm. The presence of two crystalline phases decreases the kinetic of bioactivity compared to an amorphous biomaterial (bioactive glass). A hydroxyapatite layer appears from 15 days of immersion on the surface and inside the pores, showing a biodegradation and a bioactivity in four steps. Cytotoxicity assessments present an increase of the cellular viability after 72 h proving the non-cytotoxic effect of the glass-ceramic. Thus, the results of these different studies indicate that the porous biomaterial may have a potential application for the bone regeneration. This paper also presents the novelty of this method. It is a rapid synthesis which combines simplicity and low cost. This represents an advantage for an eventual industrialization.

Rational Design of a Lanthanide-Based Complex Featuring Different Single-Molecule Magnets.

The rational synthesis of the 2-{1-methylpyridine-N-oxide-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl}pyridine ligand (L) is described. It led to the tetranuclear complex [Dy4(tta)12(L)2] (Dy-Dy2-Dy) after coordination reaction with the precursor Dy(tta)3⋅2 H2O (tta(-) = 2-thenoyltrifluoroacetonate). The X-ray structure of Dy-Dy2-Dy can be described as two terminal mononuclear units bridged by a central antiferromagnetically coupled dinuclear complex. The terminal N2O6 and central O8 environments are described as distorted square antiprisms. The ac magnetism measurements revealed a strong out-of-phase signal of the magnetic susceptibility with two distinct sets of data. The high- and low-frequency components were attributed to the two terminal mononuclear single-molecule magnets (SMMs) and the central dinuclear SMM, respectively. A magnetic hysteresis loop was detected at very low temperature. From both structural and magnetic points of view, the tetranuclear SMM Dy-Dy2-Dy is a self-assembly of two known mononuclear SMMs bridged by a known dinuclear SMM.

Parental occupation, occupational exposure to solvents and polycyclic aromatic hydrocarbons and risk of childhood brain tumors (Italy, France, Spain)

The role of parental occupational exposure in childhood brain tumors was investigated in a population-based case-control study grouping 251 cases and 601 controls from three European centers: Milan (Italy), Paris (France), and Valencia (Spain). Parental occupational exposure to solvents and polycyclic aromatic hydrocarbons (PAH) during the five-year period before birth was estimated using a job-exposure matrix developed earlier in the same countries. Odds ratios (OR) of brain tumors for each occupation and occupational exposure were estimated by logistic regression, adjusting for child's age, gender, exposure to tobacco smoke and ionizing radiation, mother's age and years of schooling, and center. The risk of childhood brain tumors rose when fathers worked in agriculture (OR = 2.2, 95 percent confidence interval [CI] = 1.0-4.7) and motor-vehicle-related occupations. In the latter group, the risk increased for primitive neuroectodermal tumors in particular (OR = 2.7, CI = 1.1-6.6). Astroglial tumors were more frequent among children of mothers in health services (OR = 2.2, CI = 1.0-4.9). Paternal exposure to PAHs was associated with an increased, but not dose-related, risk of primitive neuroectodermal tumors (OR = 2.0, CI = 1.0-4.0), and maternal exposure to solvents at a high level was associated with an increased risk of both astroglial (OR = 2.3, CI = 0.9-5.8) and primitive neuroectodermal tumors (OR = 3.2, CI = 1.0-10.3).

Innervation regulates myosin heavy chain isoform expression in developing skeletal muscle fibers.

The influence of innervation on primary and secondary myogenesis and its relation to fiber type diversity were investigated in two specific wing muscles of quail embryo, the posterior (PLD) and anterior latissimus dorsi (ALD). In the adult, these muscles are composed almost exclusively of pure populations of fast and slow fibers, respectively. When slow ALD and fast PLD muscles developed in ovo in an aneurogenic environment induced after neural tube ablation, the cardiac ventricular myosin heavy chain (MHC) isoform was not expressed. The adult slow MHC isoform, SM2, appeared by embryonic day 7 (ED 7) in normal innervated slow ALD but was not expressed in denervated muscle. Analysis of in vitro differentiation of myoblasts from fast PLD and slow ALD muscles isolated from ED 7 control and neuralectomized quail embryos showed no fundamental differences in the pattern of MHC isoform expression. Newly differentiated fibers accumulated cardiac ventricular, embryonic fast, slow SM1 and SM3 MHC isoforms. Nevertheless, the expression of slow SM2 isoform in myotubes formed from slow ALD myoblasts only occurred when myoblasts were cultured in the presence of embryonic spinal cord. Our studies demonstrate that the neural tube influences primary as well as secondary myotube differentiation in avian forelimb and facilitates the expression of different MHC, particularly slow SM2 MHC gene expression in slow myoblasts.