Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• the field is switched off. Acknowledgements The work has been funded by University Politehnica of Bucharest, through the ’Excellence Research Grants’ Program, UPB–GEX. Identifier: UPB–EXCELENŢĂ–2016 Research project title Phase modulation in nematic liquid crystals subjected to magnetic field

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• the 5CB + SWCNTs mixture. Acknowledgements The work has been funded by University Politehnica of Bucharest, through the ’Excellence Research Grants’ Program, UPB–GEX. Identifier: UPB–EXCELENŢĂ–2016 Research project title Phase modulation in nematic liquid crystals subjected to magnetic field

Atomic layer deposition and properties of ZrO₂/Fe₂O₃ thin films

• Kristjan Kalam,
• Helina Seemen,
• Peeter Ritslaid,
• Mihkel Rähn,
• Aile Tamm,
• Kaupo Kukli,
• Aarne Kasikov,
• Joosep Link,
• Raivo Stern,
• Salvador Dueñas,
• Helena Castán and
• Héctor García

Beilstein J. Nanotechnol. 2018, 9, 119–128, doi:10.3762/bjnano.9.14

• performed using a vibrating sample magnetometer (VSM) option of the physical property measurement system (14T, Quantum Design) by scanning the magnetic field from −1 T to 1 T parallel to the film surface at room temperature. Results and Discussion Film growth and composition The film thickness varied

Review on optofluidic microreactors for artificial photosynthesis

• Xiaowen Huang,
• Jianchun Wang,
• Tenghao Li,
• Jianmei Wang,
• Min Xu,
• Weixing Yu,
• Abdel El Abed and
• Xuming Zhang

Beilstein J. Nanotechnol. 2018, 9, 30–41, doi:10.3762/bjnano.9.5

• profound and meaningful work is expected to appear in the field of optofluidics-based APS since the optofluidic devices are versatile and can be integrated together with other functions, for instance, deoxygenation, temperature control, electricity/magnetic field and pressure [118][119][120][121]. (A) A

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

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

Beilstein J. Nanotechnol. 2017, 8, 2807–2817, doi:10.3762/bjnano.8.280

• Danil A. Petrov Pavel K. Skokov Alexander N. Zakhlevnykh Physics of Phase Transitions Department, Perm State University, Bukireva St. 15, 614990 Perm, Russia 10.3762/bjnano.8.280 Abstract We propose a continuum theory of orientational phase transitions induced by an external magnetic field in a

• suspension of carbon nanotubes in a nematic liquid crystal. It is shown that in a magnetic field a non-uniform and two different uniform phases are possible in the suspension. The uniform phases of the suspension differ by the type of orientational coupling of nanotubes with the liquid crystal matrix (the

• and non-uniform phases of the suspension are found analytically. It is shown that, when the nanotubes are weakly coupled to the matrix, the magnetic field induces reentrant transitions (uniform planar phase–non-uniform phase–uniform homeotropic phase–non-uniform phase). These transitions can be of

Dry adhesives from carbon nanofibers grown in an open ethanol flame

• Christian Lutz,
• Julia Syurik,
• C. N. Shyam Kumar,
• Christian Kübel,
• Michael Bruns and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2017, 8, 2719–2728, doi:10.3762/bjnano.8.271

• , 76344 Eggenstein-Leopoldshafen, Germany Institute for Applied Materials, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany 10.3762/bjnano.8.271 Abstract Based on magnetic-field-assisted growth of carbon nanofibers in an open ethanol flame we

• linear with preload force. Carbon nanofibers oriented by a magnetic field show a 68% higher adhesion (0.66 N/cm2) than the randomly oriented fibers. Endurance tests revealed that the carbon nanofiber arrays withstand 50.000 attachment/detachment cycles without observable wear. Keywords: adhesion; atomic

• demonstrated possible alignment during growth with an external electric [6] or magnetic field [9]. Surprisingly, these alternative growth methods for 1D-CNs did not receive much attention so far. One among many promising applications of carbon nanotubes are dense arrays that feature interesting adhesion

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

• zero static power dissipation inside the cryogenic cooler. The bias current is terminated off the chip at room temperature. (ii) A well-known design problem of RSFQ circuits is the large magnetic field of the returning bias current affecting the logic cells. It is recommended [45] to keep the maximum

Interactions of low-energy electrons with the FEBID precursor chromium hexacarbonyl (Cr(CO)₆)

• Jusuf M. Khreis,
• João Ameixa,
• Filipe Ferreira da Silva and
• Stephan Denifl

Beilstein J. Nanotechnol. 2017, 8, 2583–2590, doi:10.3762/bjnano.8.258

• by a repeller lens out of the interaction region, accelerated by a voltage drop of 6 kV, momentum-selected by the magnetic sector, energy-selected by the electric sector, and detected by a channel electron multiplier (Dr. Sjuts, Germany). Mass scans were taken by varying the magnetic field while the

Ferrocholesteric–ferronematic transitions induced by shear flow and magnetic field

• Dmitriy V. Makarov,
• Alexander A. Novikov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2552–2561, doi:10.3762/bjnano.8.255

• magnetic field and a shear flow. Both influences are able to induce the ferrocholesteric–ferronematic transition independently; however, the differences between the magnetic field orientation and the flow alignment direction lead to a competition between magnetic and hydrodynamic mechanisms of influence on

• the ferrocholesteric structure. We analyze various orientations of a magnetic field relative to the direction of a shear flow. The pitch of the ferrocholesteric helix is obtained as function of the strength and the orientation angle of the magnetic field, the shear velocity gradient and a reactive

• parameter. Phase diagrams of ferrocholesteric–ferronematic transition and the pitch of the ferrocholesteric helix as functions of the material and the governing parameters are calculated. We find out that imposing a shear flow leads to a shift of the magnetic field threshold. The value of the critical

Alternating current magnetic susceptibility of a ferronematic

• Natália Tomašovičová,
• Jozef Kováč,
• Veronika Gdovinová,
• Nándor Éber,
• Tibor Tóth-Katona,
• Jan Jadżyn and
• Peter Kopčanský

Beilstein J. Nanotechnol. 2017, 8, 2515–2520, doi:10.3762/bjnano.8.251

• , that in the isotropic phase of a ferronematic, a weak dc bias magnetic field of a few oersteds increases the ac magnetic susceptibility. This increment vanishes irreversibly if the substance is cooled down to the nematic phase, but can be reinduced by applying the dc bias field again in the isotropic

• phase [Tomašovičová, N. et al. Soft Matter 2016, 12, 5780–5786]. The effect has no analogue in the neat host liquid crystal. Here, we demonstrate that by doubling the concentration of the magnetic nanoparticles, the range of the dc bias magnetic field to which the ferronematic is sensitive without

• saturation can be increased by about two orders of magnitude. This finding paves a way to application possibilities, such as low magnetic field sensors, or basic logical elements for information storage. Keywords: ac magnetic susceptibility; ferronematics; magnetic particles; Introduction The great

Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• analyzed. Experimental data indicate a high stability of the nematic director in the mixture compared to a reference 5CB sample in the magnetic field. The ferrite nanoparticles agglomerate forming long chains as observed in polarized microscopy images. These chains have a very high influence on the magneto

• -optic effect of the cell. When the magnetic field is applied on the mixture, the chains tend to align with the field direction but, due to their large size, they remain oriented obliquely between the support plates. Thus, the nematic molecules anchored on their surface can not reorient with the field

• magnetic field to reorient the LC molecules and faster decrease the transition threshold. A mixture of 1% CoFe2O4 and the nematic 4-cyano-4′-pentylbiphenyl (5CB, Aldrich) was used in a 180 micrometer thick planar cell subjected to an external magnetic field. Due to their magnetic properties, the

Towards molecular spintronics

• Georgeta Salvan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2017, 8, 2464–2466, doi:10.3762/bjnano.8.245

• applications. Horizontally stacked two-terminal and four-terminal devices photo sensors and magnetic field sensors were developed for large-scale integration purposes. This complex research and development chain required various synthesis methods and theoretical approaches for prediction of molecular and

The interplay between spin densities and magnetic superexchange interactions: case studies of mono- and trinuclear bis(oxamato)-type complexes

• Azar Aliabadi,
• Bernd Büchner,
• Vladislav Kataev and
• Tobias Rüffer

Beilstein J. Nanotechnol. 2017, 8, 2245–2256, doi:10.3762/bjnano.8.224

• term represents the Zeeman interaction of an electron spin S with an external magnetic field B0, while g and μB stand for the g-tensor and the Bohr magneton, respectively. The hyperfine (HF) interaction between the electron spin S of Cu(II) and the 63Cu, 65Cu and 14N nuclear spins ICu and IN is

• described by the second and the third term, respectively. Here, ACu and AN are the on-site Cu and transferred N HF coupling tensors, respectively. The last term describes the nuclear Zeeman interaction of the 63Cu, 65Cu and 14N nuclear spins ICu and IN with the external magnetic field B0, which is not

• magnetic field B0 in the plane perpendicular to the molecular plane to obtain anisotropic ESR parameters. A standard manually controlled goniometer from Bruker was used for this purpose with the sample attached to a quartz-rod sample holder. As an example, experimental and simulated X-band ESR spectra of 4

Magnetic properties of optimized cobalt nanospheres grown by focused electron beam induced deposition (FEBID) on cantilever tips

• Soraya Sangiao,
• César Magén,
• Darius Mofakhami,
• Grégoire de Loubens and
• José María De Teresa

Beilstein J. Nanotechnol. 2017, 8, 2106–2115, doi:10.3762/bjnano.8.210

• , we take advantage of them being attached at the end of very sensitive force sensors to perform cantilever magnetometry. The mechanical resonance frequency of the cantilever is monitored as a function of the applied magnetic field while it is positioned in a strong field gradient created by a

• nanosphere [11]. From the maximal relative variation of the cantilever frequency (1.2% in Figure 6a) and knowing the cantilever spring constant and the second spatial derivative of the magnetic field ((1.5 ± 0.3) × 109 T/m2) in which the measurements are operated, one can estimate the magnetic moment of the

• cobalt particle is: where k is the cantilever spring constant, Bz the vertical component of the magnetic field from the cylinder, and z0 is the equilibrium position of the particle in the field gradient. STEM-EELS chemical mapping and quantification was carried out at an acceleration voltage of 300 kV in

Electronic structure, transport, and collective effects in molecular layered systems

• Torsten Hahn,
• Tim Ludwig,
• Carsten Timm and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 2094–2105, doi:10.3762/bjnano.8.209

• in the eigenbasis of Hmol (i.e., coherences) vanish if the system is non-magnetic or all magnetic axes (applied magnetic field, magnetization, easy anisotropy axis) are parallel. Then one obtains rate equations for the diagonal components, i.e., for the probabilities of molecular states, where m and

Advances and challenges in the field of plasma polymer nanoparticles

• Andrei Choukourov,
• Pavel Pleskunov,
• Daniil Nikitin,
• Valerii Titov,
• Artem Shelemin,
• Mykhailo Vaidulych,
• Anna Kuzminova,
• Pavel Solař,
• Jan Hanuš,
• Jaroslav Kousal,
• Ondřej Kylián,
• Danka Slavínská and
• Hynek Biederman

Beilstein J. Nanotechnol. 2017, 8, 2002–2014, doi:10.3762/bjnano.8.200

• the intensity of the magnetic field above the magnetron target [55]. Figure 10a,b shows SEM images of the NPs prepared under identical conditions in the GAS but with different permanent magnet circuits installed in the magnetron, giving either a 100 G or 250 G field above the position of the erosion

• track on the PTFE target. An increase of the intensity of the magnetic field leads to a decrease of the magnetron self-bias from 620 V to 350 V due to more effective trapping of electrons within the magnetic channel. This in turn results in the formation of particles which are an order of magnitude

• larger (250 nm) as compared to the ones fabricated with the weaker magnetic field (30 nm). Apparently, the differences in intensity of ion bombardment should be manifested in the change of the plasma chemistry, although the exact reason for this interesting phenomenon is still not clear and requires

Spin-dependent transport and functional design in organic ferromagnetic devices

• Guichao Hu,
• Shijie Xie,
• Chuankui Wang and
• Carsten Timm

Beilstein J. Nanotechnol. 2017, 8, 1919–1931, doi:10.3762/bjnano.8.192

• spintronics. Using a magnetic interlayer in a sandwich structure is a valid method that has been reported in inorganic devices, such as Ag/EuSe/Al and Ag/EuS/Al [40][41]. To obtain a current with strong SP in those devices, a strong magnetic field is usually necessary to generate either spin-selective

• spintronics for magnetic storage. By manipulating the relative magnetic magnetization of the two electrodes with a magnetic field, e.g., parallel or antiparallel, the resistance of the device can be switched between low-resistance and high-resistance states. The utilization of organic molecules as the

• four-state resistive devices have also been reported, where a ferroelectric barrier was introduced between two ferromagnets [48][49][50]. In these designs, both a magnetic field and an electric field are necessary to manipulate both the relative magnetization orientation of the electrodes and the

(Metallo)porphyrins for potential materials science applications

• Lars Smykalla,
• Carola Mende,
• Michael Fronk,
• Pablo F. Siles,
• Michael Hietschold,
• Georgeta Salvan,
• Dietrich R. T. Zahn,
• Oliver G. Schmidt,
• Tobias Rüffer and
• Heinrich Lang

Beilstein J. Nanotechnol. 2017, 8, 1786–1800, doi:10.3762/bjnano.8.180

• addition to what is easily readable in the UV–vis spectra [14]. The reason for the fine structure of the MCD spectra and hence for the higher sensitivity to the electronic properties lies in the Zeeman splitting of degenerate electronic levels induced by an external magnetic field. In addition to the

• corresponding to the observed features in the absorption spectra. This indicates that the LUMO of these molecules generating the Q band is a formerly degenerated state undergoing Zeeman splitting in the magnetic field. With respect to the spectroscopic ellipsometry and magneto-optical Kerr effect spectroscopy

• a magnetic field of 1 T. Reproduced with permission from [16], copyright 2014 Elsevier. Notice: H2TMPP, CuTMPP and NiTMPP refer to H2TPP(OMe)4, NiTPP(OMe)4 and CuTPP(OMe)4, respectively, as displayed in Scheme 1. MCD (ηF) spectra in the Q-band region for a) H2TMPP, b) CuTMPP and c) NiTMPP and the

Synthesis and catalytic application of magnetic Co–Cu nanowires

• Lijuan Sun,
• Xiaoyu Li,
• Zhiqiang Xu,
• Kenan Xie and
• Li Liao

Beilstein J. Nanotechnol. 2017, 8, 1769–1773, doi:10.3762/bjnano.8.178

• replacement under an external magnetic field. The characterization results confirmed that the as-prepared product was bimetallic Co–Cu nanowires with a desirable linear structure. Additionally, the magnetic hysteresis loop showed that the bimetallic Co–Cu nanowires were paramagnetic, which meant they could be

• difference between the Co–Cu nanowire synthesis with and without application of an external magnetic field. It was very evident that the linear structure of the Co–Cu nanowires prepared without an external magnetic field was undesirable. Moreover, the Co–Cu nanowires prepared without an external magnetic

• nanowires was measured under an applied magnetic field of up to 20,000 Oe at room temperature, and the variation of the magnetization versus magnetic field is exhibited in Figure 5a. The coercivity (Hc), saturation magnetization (Ms) and remnant magnetization (Mr) were 480.30 Oe, 90.47 emu·g−1 and 25.50

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications

• Arūnas Jagminas,
• Agnė Mikalauskaitė,
• Vitalijus Karabanovas and
• Jūrate Vaičiūnienė

Beilstein J. Nanotechnol. 2017, 8, 1734–1741, doi:10.3762/bjnano.8.174

• close proximity to the one calculated from the TEM data (5.8 nm, Figure 1b). Magnetization measurements were further performed to evaluate the gold deposition onto the surface of cobalt ferrite NPs. Figure 1d shows the room-temperature magnetization plots as a function of applied magnetic field for

• -sample magnetometer calibrated by a Ni sample of similar dimensions as the studied sample. The magnetometer was composed of the vibrator, the lock-in amplifier, and the electromagnet. The magnetic field was measured by a testameter FH 54 (Magnet-Physics Dr. Steingrover GmbH). a) TEM image of cobalt

Near-infrared-responsive, superparamagnetic Au@Co nanochains

• Varadee Vittur,
• Arati G. Kolhatkar,
• Shreya Shah,
• Irene Rusakova,
• Dmitri Litvinov and
• T. Randall Lee

Beilstein J. Nanotechnol. 2017, 8, 1680–1687, doi:10.3762/bjnano.8.168

• (superparamagnetism) and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field. Keywords: Au@Co; magneto-optical; nanochains; near-IR-active; superparamagnetic; Introduction The

• minimally absorbed by tissue chromophores and water [24]. Therefore, tunable plasmonic nanoparticles that can respond to NIR light and can be manipulated with a magnetic field hold great promise. Among various magnetic nanoparticles, cobalt nanoparticles have attracted much interest due to their strong

• modulated depending on the noble metal selected [28]. Duan et al. synthesized Pt-coated Co nanochains in an aqueous medium by magnetic-field induced assembly and galvanic replacement reaction, and Lu et al. synthesized Au-coated Co nanochains in a similar fashion [29][30]. However, none of these studies

Light-induced magnetoresistance in solution-processed planar hybrid devices measured under ambient conditions

• Sreetama Banerjee,
• Daniel Bülz,
• Danny Reuter,
• Karla Hiller,
• Dietrich R. T. Zahn and
• Georgeta Salvan

Beilstein J. Nanotechnol. 2017, 8, 1502–1507, doi:10.3762/bjnano.8.150

• devices, in which the active organic layer is sandwiched between two conductive metal layers [3][4][8]. Saragi et al. carried out studies on the magnetic field effect on three terminal bottom-contact organic field-effect transistors (OFET) and showed the existence of light-induced magnetoresistance in

• already shown for thermally evaporated films by Saragi et al. [9]. In order to investigate the influence of the electrode distance on the OMAR magnitude and on the timeline of the OMAR response to the switching of magnetic field, we used two planar device geometries: i) commercially available micro

• ) designed and developed in this work. Negative magnetoresistance (positive magnetoconductance) was observed for both types of devices similar to the observations in [9]. Magnetoresistance is defined as the change in resistivity of a material/device due to application of an external magnetic field

Spin-chemistry concepts for spintronics scientists

• Konstantin L. Ivanov,
• Alexander Wagenpfahl,
• Carsten Deibel and
• Jörg Matysik

Beilstein J. Nanotechnol. 2017, 8, 1427–1445, doi:10.3762/bjnano.8.143

• fields has been very limited. In this review, we compile the two “languages” in an effort to enhance communication. We expect that knowledge of spin chemistry will accelerate progress in spintronics. Keywords: CIDEP; magnetic field effects; photo-CIDNP; radical pairs; triplet states; Review

• reaction the spin multiplicity is changed, spin rules apply and magnetic field effects (MFE), magnetic isotope effects (MIE), as well as electron and nuclear spin polarizations might occur. This is the field of spin chemistry [1][2][3]. The field of spin chemistry emerged with the discovery of anomalous

• , and that the resulting triplets subsequently dissociate into pairs of free charge carriers. The singlet fission process is also known to spin chemists; furthermore, it is known that this process is magnetic field-dependent [40][41]. Another approach for harvesting low energy photons is TTA [42] (see

Deposition of exchange-coupled dinickel complexes on gold substrates utilizing ambidentate mercapto-carboxylato ligands

• Martin Börner,
• Laura Blömer,
• Marcus Kischel,
• Peter Richter,
• Georgeta Salvan,
• Dietrich R. T. Zahn,
• Pablo F. Siles,
• Maria E. N. Fuentes,
• Carlos C. B. Bufon,
• Daniel Grimm,
• Oliver G. Schmidt,
• Daniel Breite,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Nanotechnol. 2017, 8, 1375–1387, doi:10.3762/bjnano.8.139

• recorded on a Bruker Daltronics ESQUIRE3000 PLUS spectrometer. Temperature-dependent magnetic susceptibility measurements on powdered solid samples were carried out using a MPMS 7XL SQUID magnetometer (Quantum Design) over a temperature range 2–330 K at an applied magnetic field of 0.1, 0.5, and 1.0 Tesla

Characterization of ferrite nanoparticles for preparation of biocomposites

• Urszula Klekotka,
• Magdalena Rogowska,
• Dariusz Satuła and
• Beata Kalska-Szostko

Beilstein J. Nanotechnol. 2017, 8, 1257–1265, doi:10.3762/bjnano.8.127

• , interaction with living cells can be obtained. The use of an external magnetic field quite often helps in removing toxins from healthy cells [13][14] via modified nanoparticles having a sieve-like property. The main aim of this work is to study immobilization effects of biological particles to the selected

• external magnetic field while the size of the particles is a critical parameter. It was observed that superparamagnetic fluctuations are blocked (or not blocked) at RT for nanoparticles with a diameter smaller than the reference magnetite due to elemental substitution. Therefore, at any stage of the