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Whilst the synthesis of magnetic nanoparticles via the non‐aqueous thermal decomposition method has proven to lead to the most defined products, the tailoring of their properties is still largely achieved empirically, in particular for metal oxide nanoparticles. In this paper, the influence of ligands with varying length and concentration on the properties of the resulting magnetic nanoparticles is studied, and it is shown that the reaction temperature rather than the ligand length or concentration crucially influences the properties in various ways. The obtained particles are characterized with regard to their size, morphology, crystallinity, and magnetic characteristics, using techniques like transmission electron microscopy (TEM), X‐ray diffraction (XRD), and superconducting quantum interference device (SQUID) magnetometry measurements. It is thereby shown that the optimum choice of ligand and synthesis conditions not only serves to ensure monodispersity of the resulting particles but also to realize high colloidal stability and redispersibility. [ABSTRACT FROM AUTHOR]

The combination of materials with different magnetic properties at the nanoscale can lead to phenomena such as exchange bias via coupling effects, which shows huge potential for applications, e.g., in storage media or magnetic sensors. Whilst such structures so far are obtained via complex processes of alternating deposition from the gas phase hampering their application, their preparation from nanoparticle dispersions would not only be simplified but also enable a broad variety of possible material combinations and structures. Thereby, the processing of hard magnetic nanoparticles is challenging but can be circumvented by the use of precursor materials with subsequent phase transformation. [ABSTRACT FROM AUTHOR]

The magnetic entropy change [Δ S M ( T , H )] around the phase transition temperature T C is investigated by the scaling method for Fe 0.5 Co 0.5 Si, which exhibits a Skyrmion phase below T C . The parameters of Δ S M ( T , H ) exhibit field dependent behaviors. The Δ S M ( T , H ) curves under high field can be well scaled into a single universal curve independent of external field and temperature. However, Δ S M ( T , H ) curves under low field become divergent just below T C , which indicates a characteristic of first-order transition. The scaling investigation of Δ S M ( T , H ) curves indicates that the phase transition in Fe 0.5 Co 0.5 Si is of a weak first-order type in low field region, while it is driven into a second-order one under high field. This weak first-order phase transition in low field region resembles that in typical skyrmion system MnSi which is caused by the critical fluctuation. The result suggests that critical fluctuation plays an important role in the phase transition and formation of skyrmion state. [ABSTRACT FROM AUTHOR]

The critical behavior of the single-crystal helimagnet MnSi is investigated by means of bulk dc magnetization at the boundary between the conical state and paramagnetic phase. We obtain the critical exponents (β = 0.242 ± 0.006, γ = 0.915 ± 0.003, and δ = 4.734 ± 0.006), where the self-consistency and reliability are verified by the Widom scaling law and the scaling equation. The critical exponents of MnSi belong to the universality class of tricritical mean-field theory, which unambiguously indicates a tricritical phenomenon at the boundary between the first-order phase transition and the second-order one induced by the external magnetic field. The tricritical point (TCP) is determined as HTCP ≈ 3200 Oe at the critical temperature, consistent with the previous report [A. Bauer, M. Garst, and C. Pfleiderer, Phys. Rev. Lett. 110, 177207 (2013)]. The critical behavior suggests a long-range magnetic coupling with the exchange distance decaying as J(r) ≈ r -4.3 in MnSi. [ABSTRACT FROM AUTHOR]

Abstract: Powdered Fe2O3 –Fe2(MoO4)3 with different amounts of iron and molybdate precursors was prepared by a solvothermal route, followed by a supercritical drying and oxidation at 500°C. The possibility to arrange Fe or Mo precursors in excess into a methanol solution makes one accessible to the preparation of iron(III) molybdate samples with different composition. The structural parameters and relationship between different phases in the composition are obtained from Rietveld profile refinement. Our intention was to modify the magnetic properties of Fe2(MoO4)3 by adding the crystalline phase of Fe2O3, which carries a Fe–O magnetic component. A possible contribution to the magnetization and the magnetic susceptibility by this magnetic component is analyzed in the temperature range 2–300K. The observed higher magnetic susceptibilities are compared to those reported. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to analyze the relation of low or high serum thyrotropin (TSH) with mortality in patients with invasively treated coronary artery disease. We followed-up 942 patients who underwent coronary angioplasties or coronary artery bypass graft surgery over a mean follow-up period of 6.4±1.6 years. The study population was divided into three groups using the reference limits of serum TSH (0.25–2.12 mIU/l) as cut-offs. There were 118 patients (12.5%) with low and 125 patients (13.3%) with high serum TSH. One hundred and seventy-four subjects (18.5%) deceased during follow-up. Multivariable analyses revealed that both subjects with low and high serum TSH had a lower all-cause and circulatory mortality than subjects with serum TSH within the reference range. We conclude that low and high serum TSH levels are associated with a reduced all-cause and circulatory mortality in patients with coronary artery disease. [Copyright &y& Elsevier]

Electromagnetic properties of complex oxide solid solutions containing Ce and Y attract increasing interests due to their high application potential. Their properties are known to be dependent on many factors including grain size and crystal defects. Here we focus on unique features of nanocrystalline Ce 1-x Y x O 2-δ (x ≤ 0.3) solid solutions prepared via a mechanosynthesis. Mechanically activated CeO 2-δ and mechanosynthesized Ce 1-x Y x O 2-δ exhibit room-temperature ferromagnetism. The saturation magnetization reaches maximum for the Ce 0.9 Y 0.1 O 2-δ solid solution. XPS and Raman spectra show that Ce4+ ions are partially reduced to Ce3+, with simultaneous introduction of oxygen vacancies accumulated on surface of the solid solutions. An analysis of the experimental magnetization data and the determination of both the spin state and the concentration of magnetic carriers revealed that a small part of the Ce3+ spins (<1%) is responsible for the magnetic state of the Ce 1-x Y x O 2-δ system. Existence of clusters with a short-range antiferromagnetic order is also suspected. Image 1 • Mechanosynthesized Ce 1-x Y x O 2-δ solid solutions exhibit room temperature ferromagnetism. • Experimental magnetization curves are described by the Brillouin function. • Free Ce3+ magnetic carriers possess low concentration. • Antiferromagnetic short-range interaction between Ce3+ carriers is also observed. [ABSTRACT FROM AUTHOR]

An universal line revealing an independence of spin fluctuation contributions to the heat capacity on impurity content and its nature is discovered in the helical phase of Mn(Co,Fe)Si. This situation declares an invariance of the heat capacity of spin subsystem under doping, which probably arises as a result of relative stiffness of the helical spin structure in respect to the impurity spins. On the other hand the situation drastically changes at the helical fluctuation region when no long range spin order exists. At low temperatures the spin fluctuation contributions to the heat capacity for a whole set of compositions of Mn(Co,Fe)Si are described by a single power expression with an exponent less then unity, which implies divergence of the ratio C p / T at T → 0. The current data are revealing that a singular quantum critical point does not exist in the system under study. In its place, one can see some sort of a quantum critical cloud covering a significant range of dopant concentrations. • The helical magnet MnSi has played a special role in efforts of investigations of quantum criticality phenomena. • We used so-called "chemical" pressure technique • Mysterious universal line of spin fluctuation heat capacity of Mn(Fe,Co)Si was found. • The latter shows that a singular quantum critical point does not exist in the system under study. • Instead, one can see a sort of quantum critical cloud covering a range of dopant concentrations. [ABSTRACT FROM AUTHOR]

The B20 compound MnSi exhibits a skyrmion phase in a certain range of temperature ( T ) and external magnetic field ( H ) in addition to the helimagnetic ordering. In this work, the magnetic entropy change (Δ S M ) in the single crystal helimagnet MnSi has been investigated by the scaling analysis. The Δ S M ( T , H ) curves in higher field range (2 kOe < H < 5.6 kOe) collapse onto an universal curve after scaling, which is independent of T and H . Based on this universal curve, the Δ S M ( T , H ) (excluding the skyrmion entropy change) at any T and H can be calculated. On the other hand, a small valley is found on the Δ S M ( T ) curve at ∼28.5 K in the field range from ∼1 kOe to ∼2 kOe, which is resulted from the skyrmion phase. Subsequently, the magnetic entropy change of the skyrmion phase [ Δ S M s k X ( T , H ) ] can be derived by subtraction of the calculated Δ S M c a l ( T , H ) from the experimental Δ S M e x p ( T , H ) . The obtained results show that Δ S M s k X reaches the maximum at ∼1.6 kOe, which indicates the highest number of skyrmion vortices at that field. [ABSTRACT FROM AUTHOR]

Homoleptic iron complexes of six bis(pyridylimino)isoindoline (bpi) ligands with different substituents (H, Me, Et, tBu, OMe, NMe2) at the 4-positions of the pyridine moieties have been prepared and studied with regard to temperature-dependent spin and redox states by a combination of 57Fe Mössbauer spectroscopy, SQUID magnetometry, single-crystal X-ray diffraction analysis, X-band EPR, and 1H NMR spectroscopy. While the H-, methyl-, and ethyl-substituted complexes remain in a pure high-spin state irrespective of the temperature, the 4- tert-butyl-substituted derivative shows spin-crossover behavior. The methoxy- and dimethylamino-substituted compounds were found to easily undergo oxidation. In the crystalline state, valence tautomeric behavior was observed for the methoxy derivative as a thermally activated charge-transfer transition, accompanied by a spin crossover above 200 K. The valence tautomerism leads to a chelate with one of the bpi ligands as a dianion radical L2−. and with an effective spin of S=2. [ABSTRACT FROM AUTHOR]

The enhanced thermopower of the correlated semiconductor FeSi is found to be robust against the sign of the relevant charge carriers. At T≈70 K, the position of both the high-temperature shoulder of the thermopower peak and the nonmagnetic-enhanced paramagnetic crossover, the Nernst coefficient ν assumes a large maximum and the Hall mobility μH diminishes to below 1 cm2/V s. These cause the dimensionless ratio ν/μH—a measure of the energy dispersion of the charge scattering time τ(ε)—to exceed that of classical metals and semiconductors by two orders of magnitude. Concomitantly, the resistivity exhibits a hump and the magnetoresistance changes its sign. Our observations hint at a resonant scattering of the charge carriers at the magnetic crossover, imposing strong constraints on the microscopic interpretation of the robust thermopower enhancement in FeSi. [ABSTRACT FROM AUTHOR]

The formation of iron oxide nanoparticles in a solvothermalsynthesiswith two different nonaqueous solvents, benzyl alcohol (BA) and triethyleneglycol (TEG), was studied. Additionally, a scale-up of the synthesisfrom lab scale autoclaves (45 mL volume) to a 1.5 L reactor was performed.The differences in both reaction vessels as well as for both solventswere investigated regarding the particle size and crystallinity, themagnetic properties, and the stability of the produced particles.A two-step mechanism was identified, with a fast particle formationstep and a distinct, slower crystallization step resulting in a strongincrease in magnetization. Strong differences in the particle formationbetween the two reaction media were identified. The stability of theproduced particles against agglomeration was screened by a qualitativecomparison of sedimentation time in different polar and nonpolar solvents. [ABSTRACT FROM AUTHOR]

Abstract: Mn0.5Zn0.5Fe2O4 nanoparticles (10–30nm) have been prepared via mechanochemical processing, using a mixture of two single-phase ferrites, MnFe2O4 and ZnFe2O4. SQUID measurements (field-cooled magnetization curves and hysteresis loops) were performed to follow the mechanically induced evolution of the MnFe2O4/ZnFe2O4 mixture submitted to the high-energy milling process. The resulting single MnZn nanoferrite phase was characterized by SQUID (M–H curve), Faraday balance (M–T curve) and transmission electron microscopy. The magnetic characteristics of the mechanosynthesized material were compared with those of bulk Mn0.5Zn0.5Fe2O4. It was found that the saturation magnetization of nanostructured Mn0.5Zn0.5Fe2O4 (87.2emu/g) is lower than that of the bulk Mn0.5Zn0.5Fe2O4, but, the Néel temperature of the sample (583K) is higher than that of the bulk Mn0.5Zn0.5Fe2O4. [Copyright &y& Elsevier]

Abstract: Aims: We undertook this prospective observational study to investigate the long-term prognosis after balloon angioplasty (PTCA), coronary stenting (CS) and coronary artery bypass grafting (CABG). Methods and results: A total number of 1038 patients with PTCA (n =499), CS (n =294) or CABG (n =245) were followed-up over a mean time of 6.4±1.8 years. Forty-two patients (4.0%) were lost to follow-up, leaving a study population of 996 subjects who were available for analyses. The primary and secondary endpoints were mortality and major adverse cardiac events (MACE), respectively. Overall death rate was 19.3%. Age, pulse pressure, smoking, diabetes, serum LDL cholesterol levels and left ventricular ejection fraction rather than the intervention type independently predicted mortality. The incidence rate of MACE was 53.7%. Compared to PTCA patients, CS patients had lower (hazard ratio 0.693; 95% confidence interval 0.514–0.793) and CABG patients the lowest risk of MACE (hazard ratio 0.343; 95% confidence interval 0.261–0.450). Further risk factors for MACE were serum LDL cholesterol levels, three-vessel coronary artery disease and left ventricular ejection fraction of <30%. Conclusion: Long-term mortality does not differ among patients who received percutaneous interventions or CABG. Major adverse cardiac events occur more often in patients with previous percutaneous interventions, whereby CS has advantage over PTCA. [Copyright &y& Elsevier]

SpineMan is designed as a prototype of a soft robotic manipulator that is constructed of alternating hard and soft segments similar to the human spine. Implementing such soft segments allows to surpass the rigidity of conventional robots and ensures safer workspaces where humans and machines can work side by side with less stringent safety restrictions. Therefore, we used a hydrogel as viscoelastic material consisting of poly(vinyl alcohol) and borax. The mechanical properties of the hydrogel were tailored by embedding silica particles of various particles sizes as well as in different mass fractions. Increased mass contents as well as larger particle sizes led to strongly enhanced rigidity with a more than doubled storage modulus of the composite compared to the pure hydrogel. Furthermore, specific functionalities were induced by the incorporation of superparamagnetic Fe3O4 nanoparticles that can in principle be used for sensing robotic motion and detecting malfunctions. Therefore, we precisely adjusted the saturation magnetization of the soft segments using defined mass contents of the nanoparticles. To ensure long-time shape stability and prevention of atmospheric influences on the prepared composites, a silicone skin of specific shore hardness was used. The composites and the soft segments were characterized by oscillation measurements, cryo-SEM, bending tests and SQUID measurements, which give insights into the properties in the passive and in the moving state of SpineMan. The utilization of tailored composites led to highly flexible, reinforced and functional soft segments, which ensure stability, easy movability by springs of the shape memory alloy nitinol and prevention of total failure. [ABSTRACT FROM AUTHOR]

Background: The increasing interest in platelet-rich plasma (PRP) based therapies is as yet accompanied by inconsistent information regarding nearly all aspects of handling and application. Among these storage stability of processed plateletrich products may be the basis for a more flexible application mode. The objective of this study was (1) to estimate the storage stability of growth factors platelet derived growth factor BB (PDGF-BB) and transforming growth factor β1 (TGF-β1) in both, a single-step softspin centrifugation-based pure-PRP (P-PRP, ACP®), and a gravity filtration systembased leukocyte-rich-PRP (L-PRP, E-PET), over a six hours time span after preparation at room temperature and (2) to identify possible factors influencing these growth factor concentrations in an equine model. Results: Growth factor concentrations remained stable over the entire investigation period in L-PRP as well as P-PRP preparations revealing a mean of 3569 pg/ml PDGF-BB for E-PET and means of 1276 pg/ml PDGF-BB and 5086 pg/ml TGF-β1 for ACP®. Pearson correlations yielded no significant impact of whole blood platelet (PLT), white blood cell (WBC) and red blood cell (RBC) counts on resulting cytokine values. In case of ACP® no significant dependencies between PLT, WBC and RBC counts of the processed platelet-rich product and resulting cytokine content occurred with exception of TGF-β1 concentrations showing a strong correlation with the WBC content. PDGF-BB content of E-PET preparations showed a strong positive correlation with PLT and a strong negative with WBC of these preparations but not with RBC. Conclusions: L-PRP ad modum E-PET and P-PRP ad modum ACP® are applicable over at least a six hours time span at room temperature without loss of growth factor content. Based on the results of this study factors influencing the resulting growth factor concentrations still remain questionable. Additional studies implicating a further standardization of preparation protocols are necessary to identify consistent impact on cytokine content after PRP processing. [ABSTRACT FROM AUTHOR]

Nickel, palladium, and copper complexes of the tripyrrolic ligand hexaethyltripyrrindione (H3Et6tpd, 1) have been prepared and characterized by UV/Vis and EPR spectroscopy, as well as by single-crystal X-ray structure determination. In all cases the metal ion is coordinated in a distorted square-planar geometry carrying a water ligand at the fourth coordination site. The Et6tpd ligand acts as a radical dianion in all cases. In solution, monomeric species are present in which the open-shell character of the ligand becomes apparent through EPR spectroscopic measurements. In the solid state, the compounds form polymorphs with tightly bonded π-π dimers and chains showing small interplanar distances of 3.191-3.493 Å to one or more neighboring molecules. Magnetic measurements on the complexes confirmed the radical character of the tripyrrindione ligand and revealed strong intermolecular magnetic interactions in these complexes. [ABSTRACT FROM AUTHOR]

In this paper, we critically review the usual explanation of the blue shift in the temperature dependence of the light emission, which is commonly observed for polar GalnN/GaN quantum wells at intermediate temperatures. We demonstrate that this blue shift is not necessarily caused by a thermally induced change of occupation in an inhomogeneously broadened density of states. Instead, different energy dependencies of radiative and nonradiative lifetimes may lead to an energy dependence of the internal quantum efficiency strongly influencing the peak position of the luminescence: the piezoelectric fields within the quantum well induce an approximately exponential relationship between the electron-hole overlap matrix element for the radiative transition between the lowest quantized states and the respective transition energy. Via time-resolved photoluminescence spectroscopy, we observe a corresponding exponential energy dependence of radiative lifetimes at low temperatures and almost energy independent nonradiative lifetimes toward room temperature throughout the emission of polar single quantum wells. An analytical model is demonstrated, predicting a significant blue shift of several 10 meV for polar and a negligible shift for nonpolar GalnN/GaN quantum wells at the transition from high to low internal quantum efficiency due to the energy-dependent competition between radiative and nonradiative recombination processes. This model consistently explains the lack of a blue shift in nonpolar quantum wells grown on m-plane bulk GaN as well as a reduced characteristic temperature for the onset of the blue shift after artificial defect generation via argon ion implantation. [ABSTRACT FROM AUTHOR]

Compounds within the solid solution(Co1–xNix)3Sb4O6F6wereprepared by the hydrothermal method. Thecompounds crystallize in the noncentrosymmetric cubic space group I4̅3mwith unit cell parameters a= 8.176(1) Å for M= Co and a= 8.0778(1) Å for M= Ni. The crystalstructure is made up by corner sharing [MO2F4] octahedra via the fluorine atoms. [Sb4O6E4] supertetrahedra (T2) consisting of four [SbO3E] groups (E being the stereochemically active lone-pair on Sb) thatshare O atoms with the [MO2F2]nnetwork. Magnetic ordering phenomena are observed withtwo characteristic temperatures, TNand T*, in the range from 67 to 170 K, that evolve graduallywith composition and collapse for M= Co (x= 0) to one transition. TNis assigned to a transition into a long-range ordered antiferromagneticphase, and T* marks a temperature in the range of45 to 65 K where field cooled (FC) and zero field cooled (ZFC) susceptibilitysplits. The latter is tentatively attributed to a canting of the spinmoments. [ABSTRACT FROM AUTHOR]

A first systematic study upon the preparation and exploration of a series of iron 10-thiacorroles with simple halogenido (F, Cl, Br, I), pseudo-halogenido (N3, I3) and solvent-derived axial ligands (DMSO, pyridine) is reported. The compounds were prepared from the free-base octaethyl-10-thiacorrole by iron insertion and subsequent ligand-exchange reactions. The small N4 cavity of the ring-contracted porphyrinoid results in an intermediate spin (i.s., S=3/2) state as the ground state for the iron(III) ion. In most of the investigated cases, the i.s. state is found unperturbed and independent of temperature, as determined by a combination of X-ray crystallography and magnetometry with 1H NMR-, EPR-, and Mössbauer spectroscopy. Two exceptions were found. The fluorido iron(III) complex is inhomogenous in the solid and contains a thermal i.s. ( S=3/2)→high spin (h.s., S=5/2) crossover fraction. On the other side, the cationic bis(pyridine) complex resides in the expected low spin (l.s., S=1/2) state. Chemically, the iron 10-thiacorroles differ from the iron porphyrins mainly by weaker axial ligand binding and by a cathodic shift of the redox potentials. These features make the 10-thiacorroles interesting ligands for future research on biomimetic catalysts and model systems for unusual heme protein active sites. [ABSTRACT FROM AUTHOR]

We report electrical, magnetic, elastic, and thermodynamic properties of CoSi. A low resistivity residual ratio and tendency of the resistivity to saturate near room temperature identify CoSi as a disordered metal, which nevertheless reveals the clear presence of T² contribution of nonmagnetic nature below ~30 K. The Sommerfeld constant of CoSi, following from heat capacity measurements, does not show any enhancement over values typical of simple metals. The magnetic susceptibility of CoSi changes from diamagnetic at high temperature to paramagnetic at temperatures below ~25 K, indicating the existence of local magnetic moments. The elastic moduli of CoSi show an anomalous decrease on cooling. An explanation of these phenomena is based on the concept of electron localization with formation of local magnetic moments. These phenomena probably arise as a result of a self-doping effect due to the polyvalent character of Co and the nonstoichiometric nature of CoSi. [ABSTRACT FROM AUTHOR]

MnSi crystals with chemically induced negative pressure (doped by less than 1 % Ge) have been synthesized by the Czochralski method. X-ray powder diffraction has revealed that the samples are crystallized in the B20 structure, inherent to pure MnSi, without any impurity phases. The lattice constant a is slightly larger than that of undoped MnSi. The samples have a spiral spin structure with the wave vector |k| = 0.385 nm-1 at low temperatures. The ordering temperature is enhanced up to Tc = 39 K. The critical field HC2 shows an increase of about 25% for the doped samples. Close to the critical temperature the A phase occurs. The temperature range of the A phase in the (H-T) phase diagram for the doped compound ranges from TA = 27.5 K, characteristic for pure MnSi, to Tc = 39 K in the zero-field cooled (ZFC) regime of magnetization. The magnetic features of the (H-T) phase diagram of the compounds MnSi are reminiscent of those observed for the MnSi thin films on the Si substrate. [ABSTRACT FROM AUTHOR]

The synthesis of FePt nanocrystals is typically performed in an organic solvent at rather high temperatures, demanding the addition of the in situ stabilizers oleic acid and oleylamine to produce monomodal particles with well-defined morphologies. Replacing frequently-used solvents with organic media bearing functional moieties, the use of the stabilizers can be completely circumvented. In addition, various morphologies and sizes of the nanocrystals can be achieved by the choice of organic solvent. The kinetics of particle growth and the change in the magnetic behavior of the superparamagnetic FePt nanocrystals during the synthesis with a set of different solvents, as well as the resulting morphologies and stoichiometries of the nanoparticles were determined by powder X-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES)/mass spectrometry (ICP-MS), and superconducting quantum interference device (SQUID) measurements. Furthermore, annealing of the as-prepared FePt nanoparticles led to the ordered L10 phase and, thus, to hard magnetic materials with varying saturation magnetizations and magnetic coercivities. [ABSTRACT FROM AUTHOR]

In the Comment, it is argued that concentrations of paramagnetic centers in our CoSi crystals were estimated incorrectly [Phys. Rev. B 86, 064433 (2012)]. Doubts also are raised about the temperature dependence of the resistivity of four CoSi crystals prepared in different laboratories. These criticisms, even if they were valid, do not invalidate our main conclusions [Phys. Rev. B 86, 064433 (2012)]. [ABSTRACT FROM AUTHOR]