Articles in 2017

Fluorine, the element with the highest electronegativity and low electric polarizability, can produce a variety of characteristics, including specific adsorption sites for molecules as well as flexibility to the host materials. In this review, we will introduce fluorine-functionalized metal–organic frameworks/porous coordination polymers that show unique and unprecedented structures, structural transformations, and gas and vapor adsorption/separation properties derived from the fluorine characteristics.

In this work, we report a novel Dean vortices-induced particle migration phenomenon in spiral inertial microfluidics, which can be utilized for high throughput size-based separation of sub-micrometer synthetic or biological components, aptly termed as high-resolution Dean flow fractionation (HiDFF). We demonstrated enhanced drug release effects in particle-based drug delivery system, as well as single-step purification of circulating extracellular microvesicles from whole blood for rapid immune and vascular health profiling.

The stretchable and transparent, large-area electrode using electrospun, ultra-long metal nanofibers (mNFs) shows excellent optoelectronic and mechanical properties. It is mass-producible because of the roll-to-roll process and its fast production speed. The optoelectronic properties can be controlled by adjusting area fraction of mNF network. The large-area heater based on the mNF network exhibits outstanding power efficiency and mechanical reliability. The wireless operation of the wearable heater using Bluetooth is demonstrated.

Ni ions can be aligned by a double-stranded DNA and form a Ni–DNA nanowire. By integrating with the semiconductor circuits it becomes a novel molecular device, which is the first real dual memelement that exhibits functionalities of novel resistor and capacitor with memory, and redox-induced negative differential resistance (NDR) properties. The working mechanism of this novel device is similar to the memcomputing in brain.

Solution-grown single crystals (SCs) of semiconducting methylammonium lead halide perovskites are promising materials for full-colour imaging. Here we show one-pixel photodetector prototype, constructed by stacking three layers of blue-, green- and red-sensitive MAPbCl₃, MAPbBr₃ and MAPb(Br/I)₃ crystals, respectively. This layered structure concept has several advantages: imparting a two- to three-fold reduction in the number of required pixels, three times more efficient light utilization (and thus higher sensitivity) than common Bayer filters scheme, colour moiré suppression and no need for de-mosaic image processing. In addition, the direct band gap structure of perovskites results in optical absorption that is several orders of magnitude greater than silicon.

SnSe has a layered-like crystal structure and shows high thermoelectric performance along the b-crystal axis. Due to low textured degree, polycrystalline SnSe process poor electrical properties and overall thermoelectric performance. Here, we show that by increasing the textured degree, enhanced thermoelectric performance with a peak ZT of 1.3 at 793 K is achieved in Ag-doped SnSe polycrystals.

Learning from the antimalarial mechanism of artemisinin in nature, we explored the methemoglobin as a smart nanocarrier of artemisinin. While the methemoglobin reacts very slow with artemisinin, the upregulated reducing capacity of tumor tissue can work as an excellent biogenic trigger to reduce ferric iron in methemoglobin to ferrous state, hence turn on the free radical generation ability and cytotoxicity of artemisinin in situ. The bioinspired nanocarrier may pave a new way to achieve targeted toxicity to cancer cells with extremely low side effects.

Electronic and geometric controlling the magnetization orientation of a material in nanoscale is key in developing spintronics, which correlates with tuning its magnetocrystalline anisotropy energy (MCAE). Although the MCAE of a Fe thin film is measured to oscillate with the film thickness and to vary with the amount of injected charges, switching the magnetization orientation electrically is desired. In this work, we provide a microscopic picture based on Fe quantum-well states and spin orbital coupling to explain experimental results (a), and thus predict that the magnetization orientation of a 5-ML Fe film can be switched electrically (b).

We propose and experimentally demonstrate spoof plasmonic metasurfaces with a hyperbolic dispersion, where the spoof SPPs propagate on complementary H-shaped perfectly conducting surfaces at low frequencies. In this way, non-divergent diffractions, negative refraction, and dispersion-dependent spin-momentum locking are observed as the spoof SPPs travel over the hyperbolic spoof plasmonic metasurfaces. They show great capabilities to design advanced surface wave devices such as spatial multiplexers, focusing and imaging devices, planar hyperlenses, and dispersion-dependent directional couplers, at both microwave and terahertz frequencies.

Optically and spatially templated polymer architectures were formed by photopolymerizing reactive mesogens (RMs) in periodically deformed liquid crystals (LCs). Without using lithographic or holographic implements, various polymer patterns could be produced by employing nematic LCs as reaction solvents and spatially nonuniform electric fields with patterned electrodes. The mechanism underlying the observed elastic energy-driven templated phase separation was determined by performing numerical computations of the director field and associated elastic energy. The spatial patterns coincided precisely with the profiles of highly deformed regions, and optical patterns were templated by the local director of the reaction medium. The proposed method provides versatility in forming organized polymer architectures for functional materials requiring both positional and orientational order for their application.

The optical and plasmonic properties of (Bi,Sb)₂(Te,Se)₃ trichalcogenide topological insulator crystals are studied systematically by first-principles density functional theory. These materials exhibit bulk plasmonic properties, dominated by interband transitions, which are better than gold and silver at blue and UV wavelengths. Moreover, topologically protected surface states are also capable of supporting propagating plasmon polariton modes over an extremely broad spectral range, due to a combination of interband and intraband transitions.

Graphene nanomaterials hold great promise for the development of advanced water purification membranes, especially for water desalination. Their atomic thickness, extraordinary mechanical stability and potential for size-selective transport are ideal features, encouraging the membrane scientist across the world to investigate their applicability for water desalination. Graphene can potentially desalinate water either as monolayer or as multilayer membranes. In this review, we discuss these different classes of graphene membranes and highlight their merits and shortcomings. In addition, the theory behind their performance is presented in detail.

A universal dual-electrochromic platform that could operate various advanced logic devices whose outputs visualized by the naked eye was constructed for the first time by introducing the electrochemical oxidation of 2, 2′ -azinobis (3-ethylbenzthiazoline-6-sulfonic acid) and electrodeposition of Prussian blue into one closed bipolar electrode system.

New intrinsic self-healing polymers with outstanding mechanical performance are presented. For this purpose, sterically hindered amines were utilized to crosslink isocyanate containing poly(methacrylates) resulting in urea crosslinked networks. The reversibility of the urea bond during thermal treatment could be utilized to induce self-healing ability and could be proven using various techniques.

The nano-bio interactions of 1D and 2D carbon nanomaterials (COOH-functionalized carbon nanotube (CNT-COOH), graphene nanoplatelet (GNP) and porous graphene oxide (PGO)) with blood plasma proteins (albumin, globulin and fibrinogen) are evaluated in this work. It is demonstrated that these associations may be significantly influenced by the density of the oxygenated functionalities of the nanomaterials and to a certain extent, their dimensionality and surface area. This work offers a broad insight into the carbon nanomaterial–plasma protein interactions and provides a strong basis for the design and use of low-dimensional carbon nanomaterials for a wide variety of biological and biomedical applications.

SEM image of FeCo₂O₄ nanowire arrays on a stainless steel mesh with the schematic of MnO₂//FeCo₂O₄ asymmetric cell and its CV curves.

Here, we present a pressure-modulated heterojunction photodiode composed of n-type multilayer MoS₂ and p-type GaN film by piezo-phototronic effect. Under the illumination of 365 nm incident light, strong photo-response is observed with a response time and recovery time of ~66 and 74 ms, respectively. Upon the pressure of 258 MPa, the photoresponsivity of this photodiode can be enhanced for about 3.5 times by piezo-phototronic effect arising from the GaN film. Due to the lowered junction barrier upon applying an external pressure (strain), more photo-generated carriers can successfully pass through the junction area without recombination, resulting in the enhancement effect.

A new hygromorphic actuator made by hydrophilic metal oxide film was developed, which is moved by the fluid spread on film and the imbibition within a nano-capillary forest. This system possesses a great stability and repeatability for long time and has a very high energy density of ~1250 kJ m^–3. The research results suggest that the actuating nano-capillary forest film could be applicable to humidity-responsive actuators, high-efficiency energy converters and others.

The contact time of droplets impacting on macroscopic anisotropic superhydrophobic surfaces (macro-aniso-SHSs) decreases with an increase in the spacing and the underlying mechanism includes the mass distribution and the momentum anisotropy induced by the parralel macrostripes and macrogrooves. As the figure shows, although the impacting drop on the macro-aniso-SHS with a narrow spacing (400 μm) cannot be divided by the stripes, the anisotropy of the surface concentrates the momentum in the direction parallel to the stripes, leading to breakup and thus reducing the contact time by 15–30% compared with the contact time on the SHS and micro-aniso-SHS. For macro-aniso-SHSs with wide spacing of 1200 μm, the contact time is reduced by 40–50%. The contact time for an impact centered on the stripe is not significantly different from that in the groove, whereas the impact centered in the groove produces new hydrodynamics characterized by extended spreading, easy break-up, and flying-eagle behavior. We envision that understanding the droplet behavior on macro-aniso-SHSs not only extends our fundamental understanding of classical impacting phenomena but also has potential for a broad range of applications, such as anti-icing, self-cleaning and heating transfer.

A single-pass self-assembly approach was developed to demonstrate enhanced antitumor activities from drug-loaded fully lateral nanodimensional graphene oxide flakes under near-infrared irradiation.