Distinctive Features of the Human Marginal Zone and Cajal-Retzius Cells: Comparison of Morphological and Immunocytochemical Features at Midgestation

Despite a long history of research of cortical marginal zone (MZ) organization and development, a number of issues remain unresolved. One particular issue is the problem of Cajal-Retzius cells (C-R) identification. It is currently based on morphology and Reelin expression. The aim of this research is to investigate MZ cytoarchitectonics and Reelin-producing cells morphotypes in the superior temporal, pre- and postcentral cortex at GW24-26. We used Reelin (Reln) as the marker for C-R cells and microtubule-associated protein 2 (MAP2) and neurofilament heavy chain protein (N200) as markers of neuronal maturation. The MZ of all of the investigated areas had the distinct cytoarchitectonic of alternating cell sparse (MZP, SR) and cell dense (SGL, DGL) layers. The distribution of the neuromarkers across the MZ also showed layer specificity. MAP2-positive cells were only found in the SGL. N200 and Reelin-positive neurons in the MZP. N200-positive processes were forming a plexus at the DGL level. All of the N200-positive neurons found were in the MZP and had distinctive morphological features of C-R cells. All of the N200-positive neurons in MZ were also positive for Reelin, whereas MAP2-positive cells lack Reelin. Thus, the joint use of two immunomarkers allowed us to discern the C-R cells based on their morphotype and neurochemistry and indicate that the Reelin-positive cells of MZ at 24-26 GW were morphologically C-R cells. In the current study, we identified three C-R cells morphotypes. Using a 3D reconstruction, we made sure that all of them belonged to the single morphotype of triangular C-R cells. This approach will allow future studies to separate C-R cells from other Reelin-producing neurons which appear at later corticogenesis stages. In addition, our findings support the assumption that a plexus could be formed not only with C-R cells processes but also possibly by other cell processes by the poorly researched DGL, which is only allocated as a part of the human MZ

Anthocyanin Composition and Content in Rye Plants with Different Grain Color

The color of grain in cereals is determined mainly by anthocyanin pigments. A large level of genetic diversity for anthocyanin content and composition in the grain of different species was observed. In rye, recessive mutations in six genes (vi1...vi6) lead to the absence of anthocyanins in all parts of the plant. Moreover, dominant genes of anthocyanin synthesis in aleurone (gene C) and pericarp (gene Vs) also affect the color of the grain. Reverse phase high-performance liquid chromatography and mass spectrometry were used to study anthocyanins in 24 rye samples. A lack of anthocyanins in the lines with yellow and brown grain was determined. Delphinidin rutinoside and cyanidin rutinoside were found in the green-seeded lines. Six samples with violet grains significantly varied in terms of anthocyanin composition and content. However, the main aglycone was cyanidin or peonidin in all of them. Monosaccharide glucose and disaccharide rutinose served as the glycoside units. Violet-seeded accession forms differ in the ratio of the main anthocyanins and the range of their acylated derivatives. The acyl groups were presented mainly by radicals of malonic and sinapic acids. For the colored forms, a profile of the revealed anthocyanins with the indication of their contents was given. The obtained results are discussed in connection to similar data in rice, barley, and wheat, which will provide a perspective for future investigations

Cobalt-Based Single-Ion Magnets on an Apatite Lattice: Toward Patterned Arrays for Magnetic Memories

Single-ion magnets (SIMs) that can maintain magnetization direction on an individual transition metal atom represent the smallest atomic-scale units for future magnetic data storage devices and molecular electronics. Here we present a robust extended inorganic solid hosting efficient SIM centers, as an alternative to molecular SIM crystals. We show that unique dioxocobaltate­(II) ions, confined in the channels of strontium hydroxyapatite, exhibit classical SIM features with a large energy barrier for magnetization reversal (<i>U</i>_eff) of 51–59 cm^–1. The samples have been tuned such that a magnetization hysteresis opens below 8 K and <i>U</i>_eff increases by a factor of 4 and can be further enhanced to the highest values among 3d metal complexes of 275 cm^–1 when Ba is substituted for Sr. The SIM properties are preserved without any tendency toward spin ordering up to a high Co concentration. At a maximal Co content, a hypothetical regular hexagonal grid of SIMs with a 1 nm interspacing on the (001) crystal facet would allow a maximal magnetic recording density of 10⁵ Gb/cm²

Cobalt-Based Single-Ion Magnets on an Apatite Lattice: Toward Patterned Arrays for Magnetic Memories

Single-ion magnets (SIMs) that can maintain magnetization direction on an individual transition metal atom represent the smallest atomic-scale units for future magnetic data storage devices and molecular electronics. Here we present a robust extended inorganic solid hosting efficient SIM centers, as an alternative to molecular SIM crystals. We show that unique dioxocobaltate­(II) ions, confined in the channels of strontium hydroxyapatite, exhibit classical SIM features with a large energy barrier for magnetization reversal (<i>U</i>_eff) of 51–59 cm^–1. The samples have been tuned such that a magnetization hysteresis opens below 8 K and <i>U</i>_eff increases by a factor of 4 and can be further enhanced to the highest values among 3d metal complexes of 275 cm^–1 when Ba is substituted for Sr. The SIM properties are preserved without any tendency toward spin ordering up to a high Co concentration. At a maximal Co content, a hypothetical regular hexagonal grid of SIMs with a 1 nm interspacing on the (001) crystal facet would allow a maximal magnetic recording density of 10⁵ Gb/cm²

Slow Spin Relaxation in Dioxocobaltate(II) Anions Embedded in the Lattice of Calcium Hydroxyapatite

Pure-phase cobalt-doped calcium hydroxyapatite ceramic samples with composition Ca₁₀(PO₄)₆[(CoO₂)_<i>x</i>(OH)_{1–2<i>x</i>}]₂, where <i>x</i> = 0–0.2, were synthesized by high-temperature solid-state reaction, and their crystal structures, vibrational spectra, and magnetic properties were studied. Co atoms are found to enter into the apatite trigonal channel formally substituting H atoms and forming bent dioxocobaltate­(II) anions. The anion exhibits single-molecule-magnet (SMM) behavior: slow relaxation of magnetization below 8 K under a nonzero magnetic field with an energy barrier of 63 cm^–1. The barrier value does not depend on the concentration of Co ions, virtually coincides with the zero-field-splitting energy as determined from direct-current magnetization, and is very close to the value obtained earlier for cobalt-doped strontium hydroxyapatite. Moreover, the vibration frequencies of the dioxocobaltate­(II) anion are found to be the same in calcium and strontium apatite matrixes. The very weak dependence of the SMM parameters on the matrix nature in combination with good chemical and thermal stabilities of the compounds provides wide opportunities to exploit the intrinsic properties of such a SMM-like anion