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In the present work we demonstrate that C-doped Zr$_{5}$Pt$_{3}$ is an electron-phonon superconductor (with critical temperature T$_\mathrm{C}$ = 3.7\,K) with a nonsymmorphic topological Dirac nodal-line semimetal state, which we report here for the first time. The superconducting properties of Zr$_{5}$Pt$_{3}$C$_{0.5}$ have been investigated by means of magnetization and muon spin rotation and relaxation ($\mu$SR) measurements. We find that at low temperatures the depolarization rate is almost constant and can be well described by a single-band $s-$wave model with a superconducting gap of $2\Delta(0)/k_\mathrm{B}T_\mathrm{C}$ = 3.84, close to the value of BCS theory. From transverse field $\mu$SR analysis we estimate the London penetration depth $\lambda_{L}$ = 469 nm, superconducting carrier density $n_{s}$ = 2$\times$10$^{26}$ $m^{-3}$, and effective mass m$^{*}$ = 1.584 $m_{e}$. Zero field $\mu$SR confirms the absence of any spontaneous magnetic moment in the superconducting ground state. To gain additional insights into the electronic ground state of C-doped Zr$_5$Pt$_3$, we have also performed first-principles calculations within the framework of density functional theory (DFT). The observed homogenous electronic character of the Fermi surface as well as the mutual decrease of $T_\mathrm{C}$ and density of states at the Fermi level are consistent with the experimental findings. However, the band structure reveals the presence of robust, gapless fourfold-degenarate nodal lines protected by $6_{3}$ screw rotations and glide mirror planes. Therefore, Zr$_5$Pt$_3$ represents a novel, unprecedented condensed matter system to investigate the intricate interplay between superconductivity and topology., Comment: 9 pages, 5 figures

In the present work, we demonstrate that C-doped Zr

The effects of Fe3O4 nanoparticles (NPs) and Rhizobium inoculation on nodulation, nitrogen fixation and plant growth of common bean (cv. Red Guama, Phaseolus vulgaris) plants were investigated in growth chambers. Plants were exposed to: Fe3O4 NPs (2000 mg/L) (T1), Rhizobium inoculation (T2) and Fe3O4 NPs + Rhizobium inoculation (T3); non-treated plants were considered as controls. Harvested 35-day-old treated plants showed improved symbiotic performance including increased nitrogenase activity (51.2–90.7%), nodule leghaemoglobin (44.8–80.9%) and iron content (83.4–84.2%), number of active nodules per plant (58.7–122%) and nodule dry weight (40.2–70.6%). This resulted in enhanced symbiotic nitrogen fixation,and increased shoot (26.5–50.2%) and root (24.1–48.2%) total nitrogen content in treated plants in comparison with the controls. The best result was obtained using treatment T3. Furthermore, Fe3O4 NPs were taken up by bean plants in treatments T1 and T3, and these accumulated in their organs, including in nodules. All treatments led to an increase in root (51.9–79.8%) and shoot (27.5–52.7%) lengths, in leaf area (10.9–16.8%) and in root (10.1–17.8%), stem (9.8–12.7%) and leaf dry weight (8–17.3%) compared to control plants. Thus applied treatments have the potential to improve common bean plant growth through enhancement of nodulation and nitrogen fixation during vegetative growth.This study also provides strong evidence that the presence Fe3O4 NPs in nodules improves the symbiotic performance between Rhizobium (leguminosarum CF1 strain) and the common bean plant, due to enhanced nodulation and nitrogen fixation.

We study the electronic structure of GdCrTiO 5 polycrystals by means of magnetic susceptibility and heat capacity measurements, as well as x-ray absorption spectroscopies on the Cr 2 p , Ti 2 p and O 1 s levels. The experimental results were interpreted with Charge Transfer Multiplet and Density Functional Theory calculations. Magnetic susceptibility and specific heat measurements indicate a long-range antiferromagnetic ordering at 0.9 K probably related to the Gd sublattice. The results indicate that spin-orbit interaction, rather than hybridization, may be crucial for the stabilization of magnetic ordering in the RCrTiO 5 (R = rare earth) family.

Magnetic separation can be considered a green technology because it is fast, efficient, consumes low energy, and minimizes the use of solvents and the generation of waste. It has been successfully used in laboratory scale to facilitate supported catalysts’ handling, separation, recovery, and recycling. Only few materials are intrisically magnetic, hence the application of magnetic materials as catalyst supports has broaden the use of magnetic separation. Iron oxides, silica-coated iron oxides, and carbon-coated-cobalt are among the most studied catalyst supports; however, other metal oxide coatings, such as ceria and titania, are also very interesting for application in catalysis. Here we report the preparation of magnetically recoverable magnetic supports containing silica, ceria, and titania. We found that the silica shell protects the iron oxide core and allows the crystalization of ceria and titania at high temperature without compromising the magnetic properties of the catalyst supports.

In this work, structural and physical properties are revisited in the MoO2 compound. MoO2 single crystals have been prepared by chemical vapor transport technique and characterized by X-ray diffraction, neutron diffraction, high-resolution thermal expansion, electrical resistance measurements, and heat capacity. Electrical resistivity, heat capacity, and thermal expansion measurements show two clear features which are related to phase transitions on the MoO2 compound. These results suggest that an electronic-type transition occurs near 220 K and a structural transition at ∼267 K.

The effect of Fe3O4 nanoparticles (NPs) on chemical properties of the soil rhizosphere and on the accumulation of nutrients in common bean plants was studied for two different concentrations of Fe3O4 NPs. The root-to-leaves translocation index for micro- and macronutrients was calculated. The results showed that Fe3O4 NP treatments had a significant effect ( $$P < 0.05$$ ) on the chemical properties of soil rhizosphere in terms of an increase in the contents of total P, extractable P, total K, extractable K, Ca, total Mn, total Fe and cation exchange capacity and of a decrease in Cl content in soil. The treatments led to a marked increase in the accumulation of nutrients in plants by revealing a higher content of total P, K, Ca, Mn and Fe in roots, stems and leaves. In addition, the plants treated with Fe3O4 NPs showed lower translocation of total Mn and Fe to stems and leaves compared with the control plants. The results indicate that Fe3O4 NPs may contribute to the conversion of the insoluble forms of total P, extractable P, total K, extractable K, Ca, total Mn and total Fe in soil into soluble forms that can dissolve in the soil solution and be taken up by plants. A greater capability in the roots, stems and leaves of Fe3O4-NP-treated plants to take up the nutrients suggests a beneficial effect for plant development and health. Likewise, the roots of plants treated with Fe3O4 NPs absorbed and accumulated the greatest quantities of Mn and Fe compared with the control plants.

Thermal expansion of ${\mathrm{H}}_{2}\mathrm{O}$ and ${\mathrm{D}}_{2}\mathrm{O}$ ice Ih with relative resolution of 1 ppb is reported. A large transition in the thermal expansion coefficient at 101 K in ${\mathrm{H}}_{2}\mathrm{O}$ moves to 125 K in ${\mathrm{D}}_{2}\mathrm{O}$, revealing one of the largest-known isotope effects. Rotational oscillatory modes that couple poorly to phonons, i.e., lattice solitons, may be responsible.

Magnetic properties of dilute single crystals of ${\mathrm{Gd}}_{1\ensuremath{-}x}{\mathrm{Y}}_{x}{\mathrm{B}}_{4}$ ($x=0$, 0.2, and 0.4) were systematically studied. These antiferromagnetic Shastry-Sutherland compounds display a remnant magnetization $M{}_{\mathrm{R}}$ when field cooled below the N\'eel temperature ${T}_{\mathrm{N}}$. The magnitude of $M{}_{\mathrm{R}}$ at low magnetic fields is magnetic field dependent, increasing with increasing magnetic fields, and it saturates for $H\ensuremath{\le}30$ Oe. The ${M}_{R}(T)$ data for both $x\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}0.2$ and 0.4 compositions overlap, and the remnant magnetization follows a universal behavior. We argue that these findings are explained by taking into account the formation of magnetic domains within the crystals, originating from the dilution of a magnetically frustrated, antiferromagnetic sublattice.

We report on the physical properties of the intermetallic series $R{\mathrm{NiSi}}_{3}\phantom{\rule{4pt}{0ex}}(R=\text{Y}$, Gd-Tm, Lu). High quality single crystals with platelike morphology were grown using the Sn flux method. X-ray powder diffraction data show that this series crystallizes in the orthorhombic space group Cmmm, and Laue patterns indicate that the b axis remains perpendicular to the plane of the plates. Magnetization measurements show anisotropic antiferromagnetic ground states for $R$ = Gd-Tm with N\'eel temperatures ranging from ${T}_{N}=2.6$ K $({\mathrm{TmNiSi}}_{3})$ up to 32.2 K $({\mathrm{TbNiSi}}_{3})$, as well as metamagnetic transitions that in some cases appear together with hysteresis $({\mathrm{TbNiSi}}_{3},{\mathrm{DyNiSi}}_{3}$, and ${\mathrm{HoNiSi}}_{3})$. The easy axis changes from a axis to b axis on going from $R$ = Gd-Ho to $R$ = Er-Tm. All transitions from antiferromagnetic to paramagnetic states are clearly marked by sharp peaks in specific heat as well as in the derivative of resistivity measurements, which show metallic temperature dependence for all compounds and residual values in the range of $1\ensuremath{\mu}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$. ${\mathrm{DyNiSi}}_{3}$ has two close phase transitions, while ${\mathrm{HoNiSi}}_{3}$ presents distinct critical temperatures for applied fields in the $a$ or $c$ directions (10.4 and 6.3 K, respectively), pointing to possible component-specific ordering of the local magnetic moments.

The nonmonotonic behavior of the magnetic field dependence H of the superparamagnetic blocking temperature TB(H) (or Tmax(H)) of an assembly of magnetic nanoparticles NPs was studied both experimentally and theoretically. We have combined the measurements of zero-field cooling ZFC magnetization curves under H performed on samples with increasing concentration of Ni nanoparticles and Monte Carlo simulations. As a result, we have found that increasing the strength of the dipolar interaction between granules and the occurrence of a very narrow width of a log-normal volume particle size distribution of the NPs suppress the nonmonotonic behavior of Tmax(H).

Structural phase transitions at 87 K and 103 K are reported for single-crystalline Han Blue (BaCuSi4O10) by means of high-resolution thermal-expansion, thermal conductivity and heat capacity measurements. The phase transition at 103 K results in differing lengths of the a and b lattice parameters, and thus a lowering of the crystallographic symmetry. Negative thermal-expansion coefficients are observed perpendicular to the c-axis over a wide temperature range T 108 K 350 K (<

Magnetic carriers are an effective option to withdraw selected target molecules from complex mixtures or to immobilize enzymes. This paper describes the synthesis of robust silica magnetic microparticles (SMMps), particularly designed for applications in bioprocesses. SMMps were synthesized in a micro-emulsion, using sodium silicate as the silica source and superparamagnetic iron oxide nanoparticles as the magnetic core. Thermally resistant particles, with high and accessible surface area, narrow particle size distribution, high saturation magnetization, and with superparamagnetic properties were obtained. Several reaction conditions were tested, yielding materials with saturation magnetization between 45 and 63 emu g −1 , particle size between 2 and 200 μm and average diameter between 11.2 and 15.9 μm, surface area between 49 and 103 m 2 g −1 and pore diameter between 2 and 60 nm. The performance of SMMps in a bioprocess was evaluated by the immobilization of Pseudomonas fluorescens lipase on to octyl modified SMMp, the biocatalyst obtained was used in the production of butyl butyrate with good results.

We propose goethite nanorods as suitable antiferromagnetic substrates. The great advantage of using these inorganic nanostructures as building blocks comes from the fact that it permits the design and fabrication of colloidal and supracolloidal assemblies knowing first their magnetic characteristics. As a proof of concept, we have developed mix multifunctional systems, driving on the surface of these AFM substrates, cobalt ferrite nanoparticles (the study of bimagnetic systems opens new degrees of freedom to tailor the overall properties and offers the Meiklejohn-Bean paradigm, but inverted), a silica shell (protection purposes, but also as a tailored spacer that permits controlling magnetic interactions), and metallic gold clusters (seeds that can favor the acquisition of optical or catalytic properties). © 2011 American Chemical Society.

We here report the first magnetically recoverable Rh(0) nanoparticle-supported catalyst with extraordinary recovery and recycling properties. Magnetic separation has been suggested as a very promising technique to improve recovery of metal-based catalysts in liquid-phase batch reactions. The separation method is significantly simple, as it does not require filtration, decantation, centrifugation, or any other separation technique thereby, overcoming traditional time- and solvent-consuming procedures. Our new magnetically separable catalytic system, comprised of Rh nanoparticles immobilized on silica-coated magnetite nanoparticles, is highly active and could be reused for up to 20 times for hydrogenation of cyclohexene (180,000 mol/molRh) and benzene (11,550 mol/molRh) under mild conditions.

Common bean plants were grown in soil and irrigated with water solutions containing different concentrations of $$\hbox{Fe}_3\hbox{O}_4$$ nanoparticles (NPs) with a mean diameter close to 10 nm. No toxicity on plant growth has been detected as a consequence of Fe deficiency or excess in leaves. In order to track the $$\hbox{Fe}_3\hbox{O}_4$$ NPs, magnetization measurements were performed in soils and in three different dried organs of the plants: roots, stems, and leaves. Some magnetic features of both temperature and magnetic field dependence of magnetization M(T, H) arising from $$\hbox{Fe}_3\hbox{O}_4$$ NPs were identified in all the three organs of the plants. Based on the results of saturation magnetization $$M_\mathrm{s}$$ at 300 K, the estimated number of $$\hbox{Fe}_3\hbox{O}_4$$ NPs was found to increase from 2 to 3 times in leaves of common bean plants irrigated with solutions containing magnetic material. The combined results indicated that M(T, H) measurements, conducted in a wide range of temperature and applied magnetic fields up to 70 kOe, constitute a useful tool through which the uptake, translocation, and accumulation of magnetic nanoparticles by plant organs may be monitored and tracked.

The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate economically attractive alternatives for the synthesis of iron oxide nanoparticles without compromising their size and shape control. We have found that some affordable and reasonably less priced alcohols, such as 1,2-octanediol and cyclohexanol, may replace the commonly used and expensive 1,2-hexadecanediol, providing an economically attractive route for the synthesis of high quality magnetic nanoparticles. The relative cost for the preparation of Fe3O4 NPs is reduced to only 21% and 9% of the original cost when using 1,2-octanediol and cyclohexanol, respectively.

The synthesis of nickel catalysts for industrial applications is relatively simple; however, nickel oxidation is usually difficult to avoid, which makes it challenging to optimize catalytic activities, metal loadings, and high-temperature activation steps. A robust, oxidation-resistant and very active nickel catalyst was prepared by controlled decomposition of the organometallic precursor [bis(1,5-cyclooctadiene)nickel(0)], Ni(COD)2, over silica-coated magnetite (Fe3O4@SiO2). The sample is mostly Ni(0), and surface oxidized species formed after exposure to air are easily reduced in situ during hydrogenation of cyclohexene under mild conditions recovering the initial activity. This unique behavior may benefit several other reactions that are likely to proceed via Ni heterogeneous catalysis.

The energy barrier distribution Eb of five samples with different concentrations x of Ni nanoparticles using scaling plots from ac magnetic susceptibility data has been determined. The scaling of the imaginary part of the susceptibility Chi"(nu, T) vs. Tln(t/tau_0) remains valid for all samples, which display Ni nanoparticles with similar shape and size. The mean value increases appreciably with increasing x, or more appropriately with increasing dipolar interactions between Ni nanoparticles. We argue that such an increase in constitutes a powerful tool for quality control in magnetic recording media technology where the dipolar interaction plays an important role., Comment: 3 pages, 3 figures, 1 table

The role of dipolar interactions among Ni nanoparticles (NP) embedded in an amorphous SiO2/C matrix with different concentrations has been studied performing ac magnetic susceptibility Chi_ac measurements. For very diluted samples, with Ni concentrations < 4 wt % Ni or very weak dipolar interactions, the data are well described by the Neel-Arrhenius law. Increasing Ni concentration to values up to 12.8 wt % Ni results in changes in the Neel-Arrhenius behavior, the dipolar interactions become important, and need to be considered to describe the magnetic response of the NPs system. We have found no evidence of a spin-glasslike behavior in our Ni NP systems even when dipolar interactions are clearly present., 7 pages, 5 figures, 3 tables

K0.05MoO2 has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO2 compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature.

CuO nanograins (NGs) and CuO nanowires (NWs) on the top of nanograins samples were produced by the electrical resistive heating method. The NGs sample shows absence of long range magnetic order and strong field-induced ferromagnetic behavior. In the sample comprised of NWs on the top of NGs, a long-ranged antiferromagnetic ordering is induced by a magnetic field of 5 kOe and coexists with an enhanced ferromagnetic-like contribution. The ferromagnetic behavior is observed below and above the temperature-induced TN suggesting that this behavior is not dependent on the original magnetic state of the system, whether it is paramagnetic (PM) or antiferromagnetic.

The effect of weak dipolar interactions (DIs) between Ni nanoparticles (NPs) in samples with different Ni concentrations was investigated by performing a detailed characterization of their structural and magnetic properties. From the determination of several physical parameters of Ni NP assemblies, it was found that the ac and dc magnetic susceptibility measurements are valuable for identifying the DIs between NPs while hysteresis loops measurements showed to be very insensitive, provided that the strength of the DI field is much smaller than the maximum coercive field. Therefore, the sensitivity of the observed static and dynamical magnetic properties to the effect of weak DI depends on the measurement protocols used.

Polycrystalline La5∕8−yPryCa3∕8MnO3, 0⩽y⩽0.625, samples were synthesized by the solid-state reaction method and studied using x-ray powder diffraction, magnetic susceptibility [χ(T)], and magnetoresistivity [ρ(T,H)] measurements. Some features such as an appreciable thermal hysteresis observed in both ρ(T) and χ(T) curves indicated a competing scenario due to the coexistence of different phases. We have also found that there is a critical region in the phase diagram, for the Pr concentration ranging from ∼0.30 to 0.40, where the magnitude of the insulator to metal transition temperature (TMI), the Curie temperature (TC), the magnetoresistance, and the residual resistivity (ρ0) are characterized by abrupt changes with little increase in y. Our data also indicate that the physical properties of these manganites in this critical region are dominated by a strong competition between coexisting ferromagnetic metallic and charge-ordered insulating phases.

The use of double charge exchange reactions is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The strategy adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud and in the analysis methods within the NUMEN project is briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis. An overview on the research and development activities on the MAGNEX magnetic spectrometer is also given, with a focus on the chosen technological solutions for the focal plane detector which will guarantee the performances at high-rate conditions.