Flow-induced fabrication of ZnO nanostructures in pillar-arrayed microchannels.

The emergence of microfluidic devices integrated with nanostructures enables highly efficient, flexible and controllable biosensing, among which zinc oxide (ZnO) nanostructure-based fluorescence detection has been demonstrated to be a promising methodology due to its high electrical point and unique fluorescence enhancement properties. The optimization of microfluidic synthesis of ZnO nanostructures for biosensing on chip has been in demand due to its low cost and high efficiency, but still the flow-induced growth of ZnO nanostructures is not extensively studied. Here, we report a simple and versatile strategy that could manipulate the local flow field by creating periodically arranged micropillars within a straight microchannel.

Stabilizing High-Frequency Magnetic Properties of Stretchable CoFeB Films by Ribbon-Patterned Periodic Wrinkles.

The intrinsic nonstretchable feature of magnetic films has significantly limited its applications on wearable high-frequency devices. Recent studies have proved that the wrinkling surface structure based on the growth on polydimethylsiloxane (PDMS) is an effective route to obtain stretchable magnetic films. However, it is still a great challenge to simultaneously achieve a desired stretchability and stretching-insensitive high-frequency properties of magnetic films.

Efficient Tuning of the Spin-Orbit Torque via the Magnetic Phase Transition of FeRh.

The understanding and control of the spin-orbit torque (SOT) are central to antiferromagnetic spintronics. Despite the fact that a giant SOT efficiency has been achieved in numerous materials, its efficient tuning in a given material has not been established. Materials with magnetic phase transitions (MPTs) offer a new perspective, as the SOT efficiency may vary significantly for the different magnetic orderings across the transition, and the transition itself can be readily tuned by various control parameters.

Recent developments on the magnetic and electrical transport properties of FeRh- and Rh-based heterostructures.

It is fascinating how the binary alloy FeRh has been the subject of a vast number of studies almost solely for a single-phase transition. This is, however, reasonable, considering how various degrees of freedom are intertwined around this phase transition. Furthermore, the tunability of this phase transition-the large response to tuning parameters, such as electric field and strain-endows FeRh huge potential in applications.

Stretching-Tunable High-Frequency Magnetic Properties of Wrinkled CoFeB Films Grown on PDMS.

We demonstrated a convenient method via applying uniaxial tensile strains to continuously tune the high-frequency properties of flexible magnetic films. CoFeB films were magnetron sputtered onto prestretched polydimethylsiloxane (PDMS) membranes. They exhibit a self-assembled periodic wrinkling surface structure because of the large mismatch of Young's moduli between the elastomeric PDMS substrates and the metal layers.

Magnetic Actuation of Hollow Swarming Spheres for Dynamic Catalysis.

Untethered robots with smart human-machine interactions can execute complex activities such as target cargo delivery or assembly of functional scaffolds. However, it remains challenging for fabricating microscale hollow hydrogel robots that can go with autonomous transformation of their geometric formations to adapt to unstructured environments. We herein report hydrogel-based microscopic hollow swarming spheres (HSSs) with anisotropic/isotropic alignments of FeO particles in the porous wall that can navigate under complex topography conditions by altering their geometric formation, including passing around or jumping over obstacles, assembling into various formation patterns, and swimming in a high-viscosity system.

Magnetic anisotropy and high-frequency property of flexible FeCoTa films obliquely deposited on a wrinkled topography.

We investigated the magnetic anisotropy and the high-frequency property of flexible FeCoTa (FeCoTa) thin films obtained by oblique sputtering onto a wrinkled surface. The sinuously wrinkled topography is produced by growing Ta layer on a pre-strained polydimethylsiloxane (PDMS) membrane. Due to the enhanced effect of shadowing, the oblique deposition of FeCoTa layer gives rise to a shift of wrinkle peak towards the incident atomic flux.

Manipulate the magnetic anisotropy of nanoparticle assemblies in arrays.

Tuning the magnetic anisotropy of nanoparticle assemblies is critical for their applications such as on-chip magnetic electronic components and electromagnetic wave absorption. In this work, we developed a facile hierarchical self-assembly method to separately control the magnetic shape and magnetocrystalline anistropy of individual nanoparticle assemblies in arrays. Since magnetic nanoparticle assemblies in the array have the same size, shape and alignment, we are able to study the magnetic properties of individual nanoparticle assembly by measuring the whole arrays.

Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained.

Stretchable Spin Valve with Stable Magnetic Field Sensitivity by Ribbon-Patterned Periodic Wrinkles.

A strain-relief structure by combining the strain-engineered periodic wrinkles and the parallel ribbons was employed to fabricate flexible dual spin valves onto PDMS substrates in a direct sputtering method. The strain-relief structure can accommodate the biaxial strain accompanying with stretching operation (the uniaxial applied tensile strain and the induced transverse compressive strain due to the Poisson effect), thus significantly reducing the influence of the residual strain on the giant magnetoresistance (GMR) performance. The fabricated GMR dual spin-valve sensor exhibits the nearly unchanged MR ratio of 9.

Strain assisted electrocaloric effect in PbZr0.95Ti0.05O3 films on 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 substrate.

Solid state cooling technologies based on electrocaloric, magnetocaloric and mechanocaloric effects have received much attention during the past decade. To further improve the cooling efficiency and reduce the driving field, it is desirable to combine multiple effects in a single system. Here, we report on the caloric effects induced by both electric field and strain in PbZr0.

Thermally assisted electric field control of magnetism in flexible multiferroic heterostructures.

Thermal and electrical control of magnetic anisotropy were investigated in flexible Fe81Ga19 (FeGa)/Polyvinylidene fluoride (PVDF) multiferroic heterostructures. Due to the large anisotropic thermal deformation of PVDF (α1 = -13 × 10(-6) K(-1) and α2 = -145 × 10(-6) K(-1)), the in-plane uniaxial magnetic anisotropy (UMA) of FeGa can be reoriented 90° by changing the temperature across 295 K where the films are magnetically isotropic. Thus, the magnetization of FeGa can be reversed by the thermal cycling between 280 and 320 K under a constant magnetic field lower than coercivity.

Positive temperature coefficient of magnetic anisotropy in polyvinylidene fluoride (PVDF)-based magnetic composites.

The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the strain-induced anisotropy resulting from the anisotropic thermal expansion of the β-phase PVDF.

Electron holography study of remanence states in exchange-biased MnPd/Fe bilayers grown epitaxially on MgO(001).

We investigated magnetic remanence states of epitaxially grown, exchange-biased MnPd/Fe bilayers by electron holography emphasizing the crystallographic orientations of the layers. Thin-foil transmission electron microscopy (TEM) specimens were carefully prepared along both hard and easy axes of the Fe layer. The ex situ magnetization-reversal process was carried out using the TEM specimens, and magnetic flux densities of the ultra-thin Fe layers were evaluated at different remanence states.

Effect of top electrodes on photovoltaic properties of polycrystalline BiFeO3 based thin film capacitors.

We investigated capacitors based on polycrystalline narrow-band-gap BiFeO(3) (BFO) thin films with different top electrodes. The photovoltaic response for the capacitor with a Sn-doped In(2)O(3) (ITO) top electrode is about 25 times higher than that with a Au top electrode, which indicates that the electrode plays a key role in determining the photovoltaic response of ferroelectric thin film capacitors, as simulated by Qin et al (2009 Appl. Phys.

[Studies on the chemical constituents in vine stem of Bauhinia championii (I)].

Objective: To study the chemical constituents of Bauhinia championii.

Method: Compounds were isolated from the ethanolic extract of B. championii by silica gel column Chromatography, and their structures were elucidated by spectral analyses.

Two new bicoumarins from Trifolium repens L.

Two new bicoumarins, named repensin A (1) and B (2), have been isolated from Trifolium repens. On the basis of spectral data, the structures of 1 and 2 have been established as 7-methoxy-7',8'-dihydroxy-8,6'-bicoumarinyl and 7,5'-dihydroxy-3,6'-bicoumarinyl, respectively.