Experimental and numerical analysis of magnetic susceptibility of the tetranuclear heterometallic SMM complexes [Me2 IIFe2 III(L)4(OH)2⋅EtOH)2⋅(Et2O)2], Me = Co, Ni with dicubane structure

Magnetic susceptibilities of the two isostructural heterometallic complexes, [Me2 IIFe2 III(L)4(OH)2,(EtOH)2,(Et2O)2], Me = Co, Ni, with triketonate ligands L = dianion of 1,1,1,7,7,7-hexa-fluoroheptane-2,4,6-trione, were studied experimentally and theoretically. Extended theoretical analysis included a phenomenological approach as well as quantum calculations in several numerical schemes. Magnetic ground states of Co2 IIFe2 III(L)4 and Ni2 IIFe2 III(L)4 complexes were resolved as an interplay of two intrinsic superexchange interactions with the constants J FeFe and J CoFe/J NiFe. The first system was described by two non interacting AFM-coupled pairs Co-Fe with J CoFe = - 4.2 cm-1 and zero-field splitting parameter D = -0.15 cm-1. The second one revealed the ferromagnetic coupling between the AFM dimers, J NiFe = -12.1 cm-1, J FeFe = 1.3 cm-1 and D = -0.5 cm-1. © Published under licence by IOP Publishing Ltd

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

© 2017 Elsevier B.V.The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300 K). It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles

Genetic diversity of potato varieties bred in Russia and near-abroad countries based on polymorphism of SSR-loci and markers associated with resistance R-genes

The genetic diversity of potato varieties from the VIR collection was analyzed based on microsatellite analysis. These varieties have been bred in Russia and near-abroad countries since the 1931. Application of 14 highly polymorphic nuclear microsatellites (SSR) enabled the complete discrimination of all 113 varieties. Additionally, we have studied these varieties for the distribution of 8 DNA markers associated with three R-genes involved in the control of resistance to two quarantine objects: the potato wart Synchytrium endobioticum and golden potato cyst nematode Globodera rostochiensis, which occur locally in some regions of the Russian Federation. All the analyzed varieties with resistance to S. endobioticum pathotype 1 revealed the diagnostic marker Nl-251400 of the Sen1 gene and a few susceptible cultivars lost this diagnostic fragment. The tested markers of the H1 and Gro1-4 genes, which confer resistance to G. rostochiensis pathotype Ro1 revealed different predictiveness. In the molecular screening of potato varieties, it is better to use several markers of these genes. Results of molecular screening using six markers of the H1 and Gro1-4 genes allowed us to detect 6 haplotypes in the tested subset. Five haplotypes include varieties with different combinations of the markers tested, the majority (87.9 %) of these varieties were highly resistant or moderately resistant to G. rostochiensis. The most numerous haplotype H1/0 included 76 varieties, which did not possess any marker; 96.1 % of these varieties were susceptible to G. rostochiensis. Predictive associations between haplotype content, wart and nematode resistance, pedigree and ‘variety age’ are discussed

Influence of alternating temperature preculture on cryopreservation results for potato shoot tips

Cryopreservation is the most suitable long-term storage method for genetic resources of vegetatively maintained crops like potato. In the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) the DMSO droplet method is applied, and so far more than 1000 accessions are cryopreserved with an average regeneration rate of 58%. New experiments with four potato accessions using alternating temperatures (22/8°C day/night temperature, 8 h photoperiod, 7 d) prior to cryopreservation showed improved regeneration. The influence of this preculture on the shoot tips was studied for two wild, frost resistant species Solanum acaule and S. demissum and for two cultivated, frost sensitive potatoes S. tuberosum ‘Désirée’ and ‘King Edward’. Comparison of liquid and solid media after cryopreservation showed improved regeneration on solid media with higher regeneration percentages, less callus formation and better plantlet structure. In comparative analyses biochemical factors like soluble sugars, starch, and amino acid concentrations were measured. Shoot tips after constant and after alternating temperature preculture were analyzed. Total concentrations of soluble sugars (glucose, fructose, and sucrose) were higher for all accessions after the alternating temperature preculture, which could be the reason for improved cryopreservation results

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

© 2017 Elsevier B.V.The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300 K). It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

© 2017 Elsevier B.V.The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300 K). It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

© 2017 Elsevier B.V.The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300 K). It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles