The magnetic properties of RCo3B2 compounds, with heavy rare earth elements were investigated using magnetic measurements and electronic structure calculations. The cobalt sublattice magnetizations are very small and antiparallel oriented to heavy rare earth moments. The contributions of cobalt moments to the Curie constants are also shown. The magnetic behavior of cobalt has been analyzed in the spin fluctuations model. The presence of short -range order above the Curie temperatures in RCo3B2 compounds with R = Tb, Dy, and Ho has been attributed to reminiscent R5d-Co3d interactions.

The exchange interactions in R2Fe14B and R2Fe14C compounds, where R is a rare-earth element, are analysed within the 4f-5d-3d model, using the data obtained from electronic structure calculations. The iron moments are dependent on site location and follow linear dependences on the De Gennes factor, with rates depending on their local environment. The contributions of local 4f-5d and 5d-3d short range interactions to the R5d band polarizations, M5d, are discussed. For a given series, the Curie temperatures of both the light and heavy rare-earths compounds follow the same dependence on the M5d values. The same trend is observed for the pseudo-ternary systems with substitution at the R site. The R5d band polarizations, M5d, reflect all changes in the magnetic properties when substitutions at the R and Fe positions are performed.

Co1−xZnxFe2O4 nanoparticles (0 ≤ x ≤ 1) have been synthesized via a green sol–gel combustion method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), Raman, and magnetic measurements. All samples were found to be single phases and have a cubic Fd-3m structure. EDS analysis confirmed the presence of cobalt, zinc, iron, and oxygen in all studied samples. Raman spectra clearly show that Zn ions are preferentially located in T sites for low Zn concentrations. Due to their high crystallinity, the nanoparticles show high values of the magnetization, which increases with the Zn content for x < 0.5. The magnetic properties are discussed based on Raman results. Co ferrite doped with 30% of Zn produced the largest SAR values, which increase linearly from 148 to 840 W/gMNPs as the H is increased from 20 to 60 kA/m.

The crystal structures and magnetic properties of RCo2 (R = Tb, Dy, Ho and Er) compounds are investigated in the temperature range 4 K <= T <= 300 K and pressures <= 5.6 GPa. There is a strong correlation between evolution with pressure of structural parameters and magnetic properties. Although the magnetic moments of R atoms are little affected by pressure, those of Co change sensitively, with higher rates at lower pressures (<2 GPa). Depending on magnitude of the exchange interactions between R and Co sublattices, their magnetisations can be decoupled or collapse at the same Curie temperature. The first-order transitions are correlated with the collapse of Co moments when the internal fields acting on Co atoms are below a critical value. The experimental data are correlated with the presence of the internal fields as determined by the pressure and temperature as well as of external fields.

We report the successful synthesis and a complete magnetic characterization of CoFe2O4@SiO2@Au magnetoplasmonic nanoparticles. The CoFe2O4 magnetic nanoparticles were prepared using the hydrothermal method. A subsequent SiO2 shell followed by a plasmonic Au shell were deposited on the magnetic core creating magnetoplasmonic nanoparticles with a core–shell architecture. A spin-glass-type magnetism was shown at the surface of the CoFe2O4 nanograins. Depending on the external magnetic field, two types of spin-glass were identified and analyzed in correlation with the exchange field acting on octahedral and tetrahedral iron sites. The magnetization per formula unit of the CoFe2O4 core is not changed in the case of CoFe2O4@SiO2@Au nanocomposites. The gold nanoparticles creating the plasmonic shell show a giant diamagnetic susceptibility, dependent on their crystallite sizes.

We report a very simple, rapid and reproducible method for the fabrication of anisotropic silver nanostars (AgNS) that can be successfully used as highly efficient SERS substrates for different bioanalytes, even in the case of a near-infra-red (NIR) excitation laser. The nanostars have been synthesized using the chemical reduction of Ag+ ions by trisodium citrate. This is the first research reporting the synthesis of AgNS using only trisodium citrate as a reducing and stabilizing agent. The key elements of this original synthesis procedure are rapid hydrothermal synthesis of silver nanostars followed by a cooling down procedure by immersion in a water bath. The synthesis was performed in a sealed bottom flask homogenously heated and brought to a boil in a microwave oven. After 60 s, the colloidal solution was cooled down to room temperature by immersion in a water bath at 35 °C. The as-synthesized AgNS were washed by centrifugation and used for SERS analysis of test molecules (methylene blue) as well as biological analytes: pharmaceutical compounds with various Raman cross sections (doxorubicin, atenolol & metoprolol), cell lysates and amino acids (methionine & cysteine). UV-Vis absorption spectroscopy, (Scanning) Transmission Electron Microscopy ((S)TEM) and Atomic Force Microscopy (AFM) have been employed for investigating nanostars' physical properties.

The magnetic properties of nanocrystalline MxFe3−xO4 ferrites with M=Fe, Co, and Zn were investigated. The data support a core–shell model, where the core is ferrimagnetically ordered, and the shell shows a spin glass type behavior. The reduced magnetizations of spin glass components follow an mg = (1 – b/H−1/2) field dependence. The b values are strongly correlated with the intensities of exchange interactions. The field dependences of the magnetoresistances of Fe3O4 and ZnxFe3−xO4 nanoparticles pellets, experimentally determined, are well described if instead of the core reduced magnetization, commonly used, that of the shell is taken into account. For similar compositions of the nanoparticles, identical b values are obtained both from magnetization isotherms and magnetoresistances studies. The half-metallic behavior of spinel Fe3O4 based nanoparticles is discussed comparatively with those of double perovskites.

The complex and interdependent exchange interactions in RCo2 compounds with heavy rare-earths are analysed. Reminiscent R5d-Co3d magnetic couplings are still present above the Curie temperatures in a fairly large temperature range T-c < T < T-1 with T-1 congruent to T-c +300 K. In this temperature range paramagnetic entities of R moments couple antiparallely to those of neighbouring cobalt atoms. The ratio of rare-earth and cobalt moments projected along the field direction (M-R/M-Co) is not dependent on the external applied fields nor on temperature. At temperatures higher than T > T-1 the rare-earths and cobalt moments decouple, and the cobalt magnetic susceptibilities increase with temperature as predicted by the spin fluctuations model. The saturated effective cobalt moments decrease when the internal mean-field at the cobalt positions increases, a behaviour connected with partial quenching of spin fluctuations.

The magnetic properties of Sr2Fe1−xNixMoO6 perovskites, with x ≤ 0.2, in a large temperature range, are reported. The saturation magnetizations decrease, while the Curie temperatures increase, as the nickel content is higher. These trends are correlated with the distribution of magnetic ions in B and B’ sites. The reciprocal susceptibilities follow non linear temperature dependences. The magnetic properties are analysed assuming a two sublattices model, in the mean field approximation.

The magnetic and transport properties of polycrystalline Sr2FeMoO6 perovskites are strongly dependent on their microstructure. A cluster glass type behavior was shown at the grain boundaries. The increase of the sintering time from 4 to 8 hrs in Sr2FeMo1-xWxO6 and Ca1.5La0.5FeMo1-xWxO6 series improves the crystallographic order. As a result there is an increase of both the saturation magnetizations and of spin polarizations.

Magnetite nanoparticles with 15-30 nm average sizes were prepared by thermal decomposition. Their crystal structures and morphology were analyzed in correlation with the magnetic properties. Magnetic features, characteristic to Verwey transition were shown. The magnetizations and coercive fields increase parallelly with the nanoparticles sizes.

Two series of octahedral Fe3-xZnxO4 nanoparticles with mean sizes of 27 nm and 73 nm were prepared by thermal decomposition. All samples crystallize in inverse spinel cubic type structure with the Zn2+ ions located in tetrahedral sites. Magnetic measurements indicate an increase of the saturation magnetizations by 20% for a Zn content of x=0.12. The estimated anisotropy constants are close to that of pure magnetite. The physical properties of the investigated series are analysed in correlation with their structural properties.

The crystal structure and magnetic properties of YCo 5 compound have been studied by neutron diffraction,in the pressure range 0 ≤ p ≤ 7.2 GPa.The cobalt moments decrease with pressure,parallelly with anisotropic changes of lattice parameters.The experimental data are analyzed together with results from the combined Density Functional and Dynamical Mean-Field Theory.A rather good agreement between the experimentally determined and calculated values of cobalt moments is shown.Our scenario for the behavior of YCo 5 under pressure,is the combined action of the Lifshitz transition with a strong local electron-electron interaction.

The x-ray photoelectron spectroscopy (XPS) study, magnetic measurements and band structure calculations were performed on RNi2, RNi3, RNi5 and R2Ni17 compounds, where R is a rare-earth or yttrium. The presence of small nickel moments was shown in almost all compounds with magnetic rare-earths. The nickel moments are dependent on the site location, their local environment, respectively. The R5d bands are negatively polarized, their values M-5d, being determined by additive contributions resulting from local 4f-5d and short-range 5d-3d interactions. The R5d band polarizations mediate the exchange interactions within the spatial extension of the unit cell. The Curie temperatures for a given series are linearly dependent on M-5d values with the same rate for both heavy and light rare-earth compounds.

In this label-free surface-enhanced Raman scattering (SERS) study of genomic DNA, we demonstrate that the cancer-specific DNA methylation pattern translates into specific spectral differences. Thus, DNA extracted from an acute myeloid leukemia (AML) cell line presented a decreased intensity of the 1005 cm−1 band of 5-methylcytosine compared to normal DNA, in line with the well-described hypomethylation of cancer DNA. The unique methylation pattern of cancer DNA also influences the DNA adsorption geometry, resulting in higher adenine SERS intensities for cancer DNA. The possibility of detecting cancer DNA based on its SERS spectrum was validated on peripheral blood genomic DNA samples from n = 17 AML patients and n = 17 control samples, yielding an overall classification of 82% based on the 1005 cm−1 band of 5-methylcytosine. By demonstrating the potential of SERS in assessing the methylation status in the case of real-life DNA samples, the study paves the way for novel methods of diagnosing cancer.

We perform spin-polarized two-dimensional angular correlation of annihilation radiation (2D-ACAR) calculations for the recently predicted ZrCo2Sn-Weyl Heusler compound within the density functional theory using the generalized gradient approximation (GGA) and its extension GGA+U. We confirm that within the GGA+U method, a pair of Weyl-points are revealed, and that by doping with Niobium, for the composition Nb0.3Zr0.7Co2Sn, the Weyl points are reaching the Fermi level. Our 2D-ACAR results indicate the existence of the Weyl points, however, within the present calculation, it is uncertain if the smearing at the Fermi level can be attributed to the positron wave function.

Even if considered a cumulative and not a proliferative CD5+ B-cell neoplasm, chronic lymphocytic leukemia (CLL) has a proliferation rate higher than that recognized earlier, especially in the lymphoid tissues. Some patients with CLL develop a clinical syndrome entitled Richter syndrome (RS). Understanding CLL genetics and epigenetics may help to elucidate the molecular basics of the clinical heterogeneity of this type of malignancy. In the present project we aimed to identify a microRNA species that can predict the evolution of therapy-resistant CLL towards RS. In the first phase of our study, microRNA-19b was identified as a possible target, and in the second phase, we transfected three different CLL cell lines with microRNA-19b mimic and inhibitor and assessed the potential role on leukemia cells in vitro. The mechanism by which miR-19b acts were identified as the upregulation of Ki67 and downregulation of p53. This was further supported through RT-PCR and western blotting on CLL cell lines, as well as by next generation sequencing on two patients diagnosed with CLL that evolved into RS.