Dynamics of superparamagnetic nanoparticles in viscous liquids in rotating magnetic fields

• Nikolai A. Usov,
• Ruslan A. Rytov and
• Vasiliy A. Bautin

Beilstein J. Nanotechnol. 2019, 10, 2294–2303, doi:10.3762/bjnano.10.221

• .10.221 Abstract The dynamics of magnetic nanoparticles in a viscous liquid in a rotating magnetic field has been studied by means of numerical simulations and analytical calculations. In the magneto-dynamics approximation three different modes of motion of the unit magnetization vector and particle

• director are distinguished depending on frequency and amplitude of the rotating magnetic field. The specific absorption rate of a dilute assembly of superparamagnetic nanoparticles in rotating magnetic field is calculated by solving the Landau–Lifshitz stochastic equation for the unit magnetization vector

• and the stochastic equation for the particle director. At elevated frequencies an optimal range of particle diameters is found where the specific absorption rate of an assembly in a rotating magnetic field has a maximum. It is shown that with an optimal choice of the particle sizes sufficiently large

Targeted therapeutic effect against the breast cancer cell line MCF-7 with a CuFe₂O₄/silica/cisplatin nanocomposite formulation

• B. Rabindran Jermy,
• Vijaya Ravinayagam,
• Widyan A. Alamoudi,
• Dana Almohazey,
• Hatim Dafalla,
• Lina Hussain Allehaibi,
• Abdulhadi Baykal,
• Muhammet S. Toprak and
• Thirunavukkarasu Somanathan

Beilstein J. Nanotechnol. 2019, 10, 2217–2228, doi:10.3762/bjnano.10.214

• expected health crisis [1]. However, the single modal drug delivery system is hampered by low bioavailability (about 5–10%), burst release, and lower target efficiency. Multifunctional theranostic nanoparticles that can respond to an external magnetic field for drug release and assist in bioimaging

• external magnetic field [18]. In the case of CuFe2O4 with x value between 0.08 and 0.15, a lower saturated magnetization value was observed (≤1.0 emu/g), while increasing the x value to 0.17 showed a high magnetization of 7.65 emu/g. In order to understand the cisplatin coordination environment of CuFe2O4

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

• MRI as a medical technique, with the purpose of imaging soft body tissues and organs through the excitation of their atomic nuclei with high-frequency radio pulses and the measurement of the response in a strong magnetic field. Recent research has included using MRI for nanoscale imaging, enabling

• hyperpolarized. The large-sized particles were hyperpolarized at 25 mK using the brute force polarization method based on the application of a high magnetic field (4T) to increase the Boltzmann population difference in the nuclear spins. In this case, the spin system thermalizes (loses polarization) on

• detectable by conventional EPR methods. The procedure involves an AC RF magnetic field in resonance with the EPR spin frequency, driving the ND electron spin polarization which is then transferred to the interacting 1H nuclei in the water containing the ND. 1H nuclei resonance is then detected by using a

Improved adsorption and degradation performance by S-doping of (001)-TiO₂

• Xiao-Yu Sun,
• Xian Zhang,
• Xiao Sun,
• Ni-Xian Qian,
• Min Wang and
• Yong-Qing Ma

Beilstein J. Nanotechnol. 2019, 10, 2116–2127, doi:10.3762/bjnano.10.206

• (De), and the apparent reaction rate constant Kapp for the samples prepared at 250 °C and for P25 TiO2. Textural parameters of all samples. Acknowledgements Part of this work was performed at the Steady High Magnetic Field Facilities, High Magnetic Field Laboratory, CAS. This work was supported by

Review of advanced sensor devices employing nanoarchitectonics concepts

• Katsuhiko Ariga,
• Tatsuyuki Makita,
• Masato Ito,
• Taizo Mori,
• Shun Watanabe and
• Jun Takeya

Beilstein J. Nanotechnol. 2019, 10, 2014–2030, doi:10.3762/bjnano.10.198

• sensing of general external environments such as pH, humidity, pressure, and magnetic field is undoubtedly important. Spanu et al. reported sensitive pH sensors based on organic charge-modulated field-effect transistor structures with 6,13-bis(triisopropylsilylethynyl)pentacene [95]. The fabricated

Porous silver-coated pNIPAM-co-AAc hydrogel nanocapsules

• William W. Bryan,
• Riddhiman Medhi,
• Maria D. Marquez,
• Supparesk Rittikulsittichai,
• Michael Tran and
• T. Randall Lee

Beilstein J. Nanotechnol. 2019, 10, 1973–1982, doi:10.3762/bjnano.10.194

• polymers to create a nanocomposite system in which the outer polymer shell can be thermally activated by absorption of light or by a magnetic field [41][61]. By combining the optical properties of nanoshells and the thermo-responsive activity of hydrogel polymers, the present study seeks to develop a

Magnetic properties of biofunctionalized iron oxide nanoparticles as magnetic resonance imaging contrast agents

• Natalia E. Gervits,
• Andrey A. Gippius,
• Alexey V. Tkachev,
• Evgeniy I. Demikhov,
• Sergey S. Starchikov,
• Igor S. Lyubutin,
• Alexander L. Vasiliev,
• Vladimir P. Chekhonin,
• Maxim A. Abakumov,
• Alevtina S. Semkina and
• Alexander G. Mazhuga

Beilstein J. Nanotechnol. 2019, 10, 1964–1972, doi:10.3762/bjnano.10.193

• nanoparticles, has been repeatedly emphasized, and the exact composition of the MNPs is usually determined using X-ray diffraction (XRD) or Mössbauer spectroscopy with and without magnetic field [12][13][14]. In this work, we show other options for solving this problem using Raman and nuclear magnetic resonance

• . Another method that makes it possible to evaluate the magnetic structure of the sample is solid-state 57Fe NMR. This method avoids the use of ionizing radiation and allows data on the structure of the magnetic sample to be obtained under a magnetic field similar to that used in MRI. The purpose of this

• NMR spectra of 57Fe nuclei in uncoated and HSA-coated samples measured at zero external magnetic field at 4.2 K are shown in Figure 9. The spectra demonstrate a very broad intensity distribution in the range from approximately 62–76 MHz and contain two distinct peaks at 70.9 and 73.0 MHz and a broad

Oblique angle deposition of nickel thin films by high-power impulse magnetron sputtering

• Hamidreza Hajihoseini,
• Movaffaq Kateb,
• Snorri Þorgeir Ingvarsson and
• Jon Tomas Gudmundsson

Beilstein J. Nanotechnol. 2019, 10, 1914–1921, doi:10.3762/bjnano.10.186

• that a small decrease in the magnetic field strength in the HiPIMS process can lead to a significant increase in the deposition rate in that case [28][29]. We have recently reported an increase by a factor of 2 and 2.6 of the HiPIMS deposition rate by 83% and 53% weakening of the magnetic field

• valve located between the chamber and a turbomolecular pump. The nickel target was 75 mm in diameter, of 99.95% purity, and 1.59 mm thick but almost 40% eroded at the racetrack center. The magnetic field measured at the target surface over the racetrack shows the value of 39 and 0 mT parallel and

• incoming flux to the substrate in those discharges. There have been a few investigations on this matter that all agree that the magnetic field plays a significant role in the profile of deposition. We have recently shown that, depending on the stationary magnetic field configuration, HiPIMS deposition may

Fabrication and characterization of Si_1−xGe_x nanocrystals in as-grown and annealed structures: a comparative study

• Muhammad Taha Sultan,
• Adrian Valentin Maraloiu,
• Ionel Stavarache,
• Jón Tómas Gudmundsson,
• Andrei Manolescu,
• Valentin Serban Teodorescu,
• Magdalena Lidia Ciurea and
• Halldór Gudfinnur Svavarsson

Beilstein J. Nanotechnol. 2019, 10, 1873–1882, doi:10.3762/bjnano.10.182

• employed. The Ge target experienced a stronger magnetic field strength |B| than the Si target, opposite to our previous study [22]. Since the deposition rate of Ge is usually higher than that of Si, the |B| is selected accordingly. It has been acknowledged for both dcMS and HiPIMS that the increase in |B

Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson “atoms”

• Daria V. Popolitova,
• Nikolay V. Klenov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2019, 10, 1548–1558, doi:10.3762/bjnano.10.152

• reversal in superconducting meta-atoms induced by picosecond unipolar pulses of a magnetic field is developed. A promising scheme based on the regime of stimulated Raman Λ-type transitions between qubit states via upper-lying levels is suggested in order to provide ultrafast quantum operations on the

• a magnetic field with picosecond duration and almost rectangular envelopes. Such pulses seem to be very attractive due to their broad frequency spectrum with pronounced near-zero components. The possibilities to control (as well as to read out the states of) either “charge” (including transmons) or

• interaction of a multilevel superconducting meta-atom with unipolar magnetic field pulse. The considered model seems to be fairly general since it takes into account the multilevel structure of a real superconducting system and can be applied to describe the dynamics of qubit states in different types of

Magnetic segregation effect in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov,
• Alexander N. Zakhlevnykh and
• Dmitriy V. Makarov

Beilstein J. Nanotechnol. 2019, 10, 1464–1474, doi:10.3762/bjnano.10.145

• study the orientational transitions in a suspension of carbon nanotubes in a nematic liquid crystal induced by an external magnetic field. The case of a finite orientational anchoring of liquid crystal molecules at the surface of doped carbon nanotubes is considered. It is shown that in a magnetic field

• the initial homogeneous planar texture of the liquid crystal–carbon nanotubes mixture is disturbed in a threshold manner (Fréedericksz transition). The orientational and concentration distributions of the suspension are studied for different values of the magnetic field strength and segregation

• tricritical behavior is related to the redistribution of the carbon nanotubes (segregation effect) inside the layer. Keywords: carbon nanotubes; liquid crystal; magnetic field; orientational transitions; segregation effect; Introduction Composites of liquid crystals (LCs) and nanoparticles are actively

Superconducting switching due to a triplet component in the Pb/Cu/Ni/Cu/Co₂Cr_1−xFe_xAl_y spin-valve structure

• Andrey Andreevich Kamashev,
• Nadir Nurgayazovich Garif’yanov,
• Aidar Azatovich Validov,
• Joachim Schumann,
• Vladislav Kataev,
• Bernd Büchner,
• Yakov Victorovich Fominov and
• Ilgiz Abdulsamatovich Garifullin

Beilstein J. Nanotechnol. 2019, 10, 1458–1463, doi:10.3762/bjnano.10.144

• magnetic field of 3 kOe possibly due to some magnetic inhomogeneity of the HA layer. We note that the magnetic response from the Ni layer cannot be resolved here due to its small value. The electrical resistivity was measured using the standard four-point method. The top insulating layer (Si3N4) was

• width in zero magnetic field varied from 20 to 50 mK depending on the particular series of the samples and increased with the applied field up to ca. 250 mK (see Figure 2 below). The narrow SC transition is a characteristic feature of the high-quality Pb layer. For the optimal operation of the SSV it is

• parameter of the S/F2 interface . For the measurements of the angular dependence of Tc in the prepared SSV multilayers we have fixed the magnetization of the F2 layer (Ni) in a certain direction by cooling the sample in a magnetic field down to the operational temperatures of the SSV. The magnetization of

The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

• Hajar Jalili,
• Bagher Aslibeiki,
• Ali Ghotbi Varzaneh and
• Volodymyr A. Chernenko

Beilstein J. Nanotechnol. 2019, 10, 1348–1359, doi:10.3762/bjnano.10.133

• ) and especially magnetic hyperthermia therapy, which is one of the efficient and new approaches for cancer treatment [4][15]. When magnetic NPs concentrated in tumor tissue are exposed to an ac magnetic field, the electromagnetic energy is converted into thermal energy, and the generated heat is used

• strengths. Barrera et al. prepared Co1−xZnxFe2O4 NPs and studied the dynamic energy losses of nanoparticles under an extended range of applied magnetic field strengths. They show that NPs with a larger anisotropy reveal smaller energy losses [22]. For a more systematic study of the effect of magnetic

• anisotropy in the cubic spinel structure. The effective anisotropy constant (Keff) of particles was estimated using the law of approach to saturation (LAS), which describes the dependence of the magnetization (M) on the applied magnetic field (H) at high field strengths (H ≫ Hc). According to the LAS, the

On the relaxation time of interacting superparamagnetic nanoparticles and implications for magnetic fluid hyperthermia

• Andrei Kuncser,
• Nicusor Iacob and
• Victor E. Kuncser

Beilstein J. Nanotechnol. 2019, 10, 1280–1289, doi:10.3762/bjnano.10.127

• , with the only effect of the perturbation reflected in the expression of the relaxation time. Accordingly, the dissipated power is where τ is the effective relaxation time (only the Néel component), f and H are the frequency and the amplitude of the applied AC magnetic field, µ0 is the permittivity of

• evaluated versus parameters specific to P* by the numerical integration of the last part of Equation 6. On the other hand, T(t) can be also experimentally obtained by heating the ferrofluid under a completely characterized AC magnetic field and using specific methodologies to minimize the heat losses [16

• samples were magnetically excited by a radiofrequency magnetic field with a constant frequency of 235 kHz (single radiofrequency inductor) and at four amplitude values: 14 kA m−1, 21 kA m−1, 28 kA m−1 and 35 kA m−1. As expected, the experimental SAR values increase with the volume fraction (in a more

Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower

• Rouzhaji Tuerhong,
• Mauro Boero and
• Jean-Pierre Bucher

Beilstein J. Nanotechnol. 2019, 10, 1243–1250, doi:10.3762/bjnano.10.124

• tunneling microscope (Modified Createc LT-STM) equipped with a vector magnetic field of 1 T. As described in [21], the Au(111) single crystal was cleaned by repeated cycles of Ne+ ion bombardment followed by thermal annealing at 800 K. The MnPc molecules were evaporated from an Al2O3 crucible heated by

Tailoring the magnetic properties of cobalt ferrite nanoparticles using the polyol process

• Malek Bibani,
• Romain Breitwieser,
• Alex Aubert,
• Vincent Loyau,
• Silvana Mercone,
• Souad Ammar and
• Fayna Mammeri

Beilstein J. Nanotechnol. 2019, 10, 1166–1176, doi:10.3762/bjnano.10.116

• shape change of the magnetostrictive component under an external magnetic field. Here, the size of the interface between the two components plays a crucial role. Therefore, the development of nanomaterials exhibiting large surface-to-volume ratios can help to respond to such a requirement. However, the

• magnetometry. To measure the magnetostrictive response of the particles, the particles were sintered to dense pellets on which strain gauges were bonded, measuring the size variation radially, as a function of a dc magnetic field. Findings: We found two samples, the first one being stoichiometric and

• viewpoint paper about the current limits of such nanostructures [4]. In these materials, the ME coupling arises from a mechanical transmission of strain originating from the shape change of the magnetostrictive component under an external magnetic field, or of the piezoelectric component under an external

Scavenging of reactive oxygen species by phenolic compound-modified maghemite nanoparticles

• Małgorzata Świętek,
• Yi-Chin Lu,
• Rafał Konefał,
• Liliana P. Ferreira,
• M. Margarida Cruz,
• Yunn-Hwa Ma and
• Daniel Horák

Beilstein J. Nanotechnol. 2019, 10, 1073–1088, doi:10.3762/bjnano.10.108

• , because superparamagnetic particles behave as nonmagnetic materials in the absence of a magnetic field, and consequently, aggregation of the nanoparticles induced by magnetic forces is minimized. Heparin-coated γ-Fe2O3 nanoparticles The role of the heparin layer is to isolate the inorganic core from the

• nanoparticles (MNPcell) and cell viability were determined after incubation of γ-Fe2O3, γ-Fe2O3@Hep, γ-Fe2O3@Hep-CS-G, γ-Fe2O3@Hep-CS-H, or γ-Fe2O3@Hep-CS-P nanoparticles (100 μg/mL) with L-929 or LN-229 cells for 3 h (Figure 5a,b). In the absence of a magnetic field, the heparin coating enhanced the MNPcell

• enhance nanoparticle internalization [34]. The application of a magnetic field during incubation with γ-Fe2O3 increased the MNPcell level by 2.7-fold compared with that without the magnet in L-929 cells. The γ-Fe2O3@Hep uptake in LN-229 cells was increased by 1.8-fold compared with that without magnetic

Influence of dielectric layer thickness and roughness on topographic effects in magnetic force microscopy

• Alexander Krivcov,
• Jasmin Ehrler,
• Marc Fuhrmann,
• Tanja Junkers and
• Hildegard Möbius

Beilstein J. Nanotechnol. 2019, 10, 1056–1064, doi:10.3762/bjnano.10.106

• magnetic field of the probe with a magnetic moment of 3·10−16 A·m2 is sufficient to induce a magnetic moment at lift heights up to 150 nm in superparamagnetic nanoparticles with 10 nm diameter. This results in attractive forces and, thus, negative phase shifts in MFM measurements. Therefore the magnetic

Magnetic field-assisted assembly of iron oxide mesocrystals: a matter of nanoparticle shape and magnetic anisotropy

• Julian J. Brunner,
• Marina Krumova,
• Helmut Cölfen and
• Elena V. Sturm (née Rosseeva)

Beilstein J. Nanotechnol. 2019, 10, 894–900, doi:10.3762/bjnano.10.90

• iron oxide-truncated nanocubes using the slow evaporation of the solvent within an externally applied homogeneous magnetic field. Anisotropic mesocrystals with an elongation along the direction of the magnetic field can be produced. The structure of the directed mesocrystals is compared to self

• -assembled mesocrystalline films, which are formed without the influence of a magnetic field. The remarkable structural difference of mesocrystals produced within the external magnetic field from those self-assembled without field indicates that the specific nanoparticle ordering within the superstructure is

• superparamagnetic nanoparticles and how a magnetic field can be used to design anisotropic mesocrystals with different structures. Keywords: directed assembly; magnetite; mesocrystal; nanoparticle; transmission electron microscopy; Findings In materials science, nanoparticles and their assemblies belong to the

Co-doped MnFe₂O₄ nanoparticles: magnetic anisotropy and interparticle interactions

• Bagher Aslibeiki,
• Parviz Kameli,
• Hadi Salamati,
• Giorgio Concas,
• Maria Salvador Fernandez,
• Alessandro Talone,
• Giuseppe Muscas and
• Davide Peddis

Beilstein J. Nanotechnol. 2019, 10, 856–865, doi:10.3762/bjnano.10.86

• to 5 K in a zero magnetic field; then a static magnetic field of 2.5 mT was applied. MZFC was measured during the warming up phase from 5 to 300 K, and MFC was recorded during the subsequent cooling down from 300 to 5 K. The field-dependent isothermal remanent magnetization (IRM) and direct current

• demagnetization (DCD) were measured at 5 K. In the IRM measurement process, the demagnetized samples were cooled from 300 to 5 K in a zero magnetic field. Then a small external field was applied only for a few seconds, and the remanence was measured (MIRM). The process was repeated, increasing the field in

• measurements were performed by an AC susceptometer system. The measurements were carried out by cooling the sample from room temperature to 100 K in zero magnetic field, then magnetic susceptibility was measured during the warming up process in a magnetic field of 1 mT at frequencies of 33, 111, 333, 666 and

Periodic Co/Nb pseudo spin valve for cryogenic memory

• Nikolay Klenov,
• Yury Khaydukov,
• Sergey Bakurskiy,
• Roman Morari,
• Igor Soloviev,
• Vladimir Boian,
• Thomas Keller,
• Mikhail Kupriyanov,
• Anatoli Sidorenko and
• Bernhard Keimer

Beilstein J. Nanotechnol. 2019, 10, 833–839, doi:10.3762/bjnano.10.83

• alignment can be controlled with a magnetic field of only several tens of Oersted. Keywords: cryogenic computing; neutron scattering; spin valve; superconducting spintronics; Findings Superconductor digital devices have attracted growing attention due to their unique energy efficiency and performance [1

• reflectometer NREX at the research reactor FRM-2 (Munich, Germany). The neutron reflectivities were taken with a monochromatic polarized neutron beam of wavelength λ = 0.43 nm at a temperature T = 13 K with the magnetic field applied in-plane to the structure and normal to the scattering plane (see inset in

• Figure 3a). No spin analysis of the scattered beam was performed in this experiment. Figure 3a and Figure 3b shows reflectivities measured at H = 300 Oe and in magnetic field H = 30 Oe after magnetization of the sample in the negative direction. The curves in the saturated state are characterized by

Tungsten disulfide-based nanocomposites for photothermal therapy

• Tzuriel Levin,
• Hagit Sade,
• Rina Ben-Shabbat Binyamini,
• Maayan Pour,
• Iftach Nachman and
• Jean-Paul Lellouche

Beilstein J. Nanotechnol. 2019, 10, 811–822, doi:10.3762/bjnano.10.81

• . For WS2-NTs (red spectrum, inset image), the external magnetic field induces a very weak magnetic field in the opposite direction. This means that WS2-NTs are diamagnetic. The CAN-mag curve (green) demonstrates superparamagnetic behavior, where the magnetization increases with the strength of the

• magnetic field until it approaches saturation, and there is no hysteresis loop. Superparamagnetism is typical for iron-oxide nanoparticles [67]. The nanocomposite WS2-NT-CM (blue curve) maintains superparamagnetism, with a saturation value of about ±13 emu/g, which is a sixth of the saturation value for

Coexisting spin and Rabi oscillations at intermediate time regimes in electron transport through a photon cavity

• Vidar Gudmundsson,
• Hallmann Gestsson,
• Nzar Rauf Abdullah,
• Chi-Shung Tang,
• Andrei Manolescu and
• Valeriu Moldoveanu

Beilstein J. Nanotechnol. 2019, 10, 606–616, doi:10.3762/bjnano.10.61

• time regimes, the current and the average photon number are calculated by solving a Markovian master equation in the dressed-states picture, with the Coulomb interaction also taken into account. We predict that in the presence of a transverse magnetic field the interdot Rabi oscillations appearing in

• oscillations of the transport current in time still reveal Rabi oscillations, but in a complex many-level system other oscillations can be present. In particular we find that for a weak Rabi splitting the even weaker Zeeman spin splitting caused by a small external magnetic field plays a role in the transport

• = 3 × 10−7 (aw is defined below). In the second line of the Hamiltonian (Equation 2) are the para- and the diamagnetic electron–photon interactions, respectively. Aext (Equation 3) is a classical vector potential leading to a homogeneous, external, small magnetic field, Bext = 0.1 T, directed along

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

• Zoltán Scherübl,
• András Pályi and
• Szabolcs Csonka

Beilstein J. Nanotechnol. 2019, 10, 363–378, doi:10.3762/bjnano.10.36

• the states with odd number of electrons. Since we do not account for a magnetic field, these eight states are decomposed into two invariant subspaces with different total spin z component Each energy eigenvalue in one doublet subspace has an equal partner in the spectrum of the other doublet subspace

Geometrical optimisation of core–shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells

• Robin Vismara,
• Olindo Isabella,
• Andrea Ingenito,
• Fai Tong Si and
• Miro Zeman

Beilstein J. Nanotechnol. 2019, 10, 322–331, doi:10.3762/bjnano.10.31

• (in the active layer) or lost (in supporting layers, or due to reflection): where q is the elemental charge, X can be either Ai or R, and λ is the wavelength of light. Note that only the spectral range between 300 and 1200 nm was considered. In addition, the value of electric and magnetic field inside