Several features already qualified the invasive bivalve species Crassostrea gigas as a valuable non-standard model organism in genome research. C. gigas is characterized by the low contribution of satellite DNAs (satDNAs) vs. mobile elements and has an extremely low amount of heterochromatin, predominantly built of DNA transposons. In this work, we have identified 52 satDNAs composing the satellitome of C. gigas and constituting about 6.33% of the genome. Satellitome analysis reveals unusual, highly scattered organization of relatively short satDNA arrays across the whole genome. However, peculiar chromosomal distribution and densities are specific for each satDNA. The inspection of the organizational forms of the 11 most abundant satDNAs shows association with constitutive parts of Helitron mobile elements. Nine of the inspected satDNAs are dominantly found in mobile element-associated form, two mostly appear standalone, and only one is present exclusively as Helitron-associated sequence. The Helitron-related satDNAs appear in more chromosomes than other satDNAs, indicating that these mobile elements could be leading satDNA propagation in C. gigas. No significant accumulation of satDNAs on certain chromosomal positions was detected in C. gigas, thus establishing a novel pattern of satDNA organization on the genome level.

The prospect of carbon-based magnetic materials is of immense fundamental and practical importance, and information on atomic-scale features is required for a better understanding of the mechanisms leading to carbon magnetism. Here we report the first direct detection of the microscopic magnetic field produced at 13C nuclei in a ferromagnetic carbon material by zero-field nuclear magnetic resonance (NMR). Electronic structure calculations carried out in nanosized model systems with different classes of structural defects show a similar range of magnetic field values (18–21 T) for all investigated systems, in agreement with the NMR experiments. Our results are strong evidence of the intrinsic nature of defect-induced magnetism in magnetic carbons and establish the magnitude of the hyperfine magnetic field created in the neighbourhood of the defects that lead to magnetic order in these materials.

We present an experimental investigation of the magnetic structure in a tetramer system SeCuO3 using neutron diffraction and nuclear resonance techniques. We establish a non-collinear, commensurate antiferromagnetic ordering with a propagation vector k = (0, 0, 1). The order parameter follows a critical behavior near TN = 8 K, with a critical exponent β = 0.32 in agreement with a 3D universality class. Evidence is presented that a singlet state starts to form on tetramers at temperatures as high as 200 K, and its signature is preserved within the ordered state through a strong renormalization of the ordered magnetic moment on two non-equivalent copper sites, mCu1 ≈ 0.4 µB and mCu2 ≈ 0.7 µB at 1.5 K. S1 S2 S3 S4 J 11 J 12 J 12 Cu2 Cu1 FIG. 1. (Color online) A single Cu2 -Cu1 -Cu1 -Cu2 tetramer, with shaded CuO4 plaquettes. Below a schematic drawing of spins and exchange interactions between them (see Eq. 1).

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We report the design and construction of a two-axis goniometer capable of any sample orientation with respect to the external magnetic field. The advantage of this design is that it allows free rotations around a single axis independent of the other which minimizes rotational error without reduction of angle range. Goniometer is capable of operating with high precision at both low and high temperatures and in high magnetic fields. It was mounted on the custom made nuclear magnetic resonance probe for use in Oxford Instruments wide-bore variable field superconducting magnet.