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Recent progress of research for graphene applications in electronic and optoelectronic devices is reviewed, and recent developments in circuits based on graphene devices are summarized. The bandgap—mobility tradeoff inevitably constrains the application of graphene for the conventional field-effect transistor (FET) devices in digital applications. However, this shortcoming has not dampened the enthusiasm of the research community toward graphene electronics. Aside from high mobility, graphene offers numerous other amazing electrical, optical, thermal, and mechanical properties that continually motivate innovations. [ABSTRACT FROM AUTHOR]

We present a continuous-wave squeezed vacuum generation system at a telecommunication wavelength of 1.3 μm. By employing a home-made single-frequency Nd:YVO4 laser with dual wavelength outputs as the pump source, via an optical parameter oscillator based on periodically poled KTP, a squeezed vacuum of 6.1 dB±0.1 dB below the shot noise limit at 1342 nm is experimentally measured. This system could be utilized for demonstrating practical quantum information networks. [ABSTRACT FROM AUTHOR]

To explore the dependences of polyaniline (PANI) morphology on the oxidant and the initial pH value (referred to as 'pH-initial') of the reaction system, a series of oxidative polymerization experiments on aniline using chloroaurate acid (HAuCl4) as the oxidant are carried out in aqueous solutions with different values of pH-initial. The smooth morphology transition of PANI nanostructures from nanofibers to solid and hollow nanospheres can be controlled by simply changing pH-initial for the reaction solution using HAuCl4 as the oxidant. In aqueous solutions with different values of pH-initial, the anilinium ions and neutral aniline molecules coexist in different proportions, leading to different PANI nanostructures under different nucleation mechanisms. In strongly acidic media (pH-initial < 2), the homogeneous nucleation of PANI will result in PANI nanofibers. When pH-initial is raised to 2 or above, the heterogeneous nucleation will lead to solid or hollow PANI nanospheres. The solid PANI nanospheres are obtained in mildly acidic media (pH-initial =2-4) and the diameter decreases as the initial pH value of the reaction solution increases from 2 to 4. However, in weakly acidic and neutral media (pH-initial = 5-7), hollow PANI nanospheres are formed and the diameter increases with the increase of pH-initial for the solution from 5 to 7. [ABSTRACT FROM AUTHOR]

Electrospinning is becoming an efficient method to produce fibers in the submicron range, but the bending instability of conventional electrospinning system (CES) brings limitations in the distinctive deposition of electrospun fibers. Herein, we proposed a strategy to update the electrospinning system through establishment of a uniform electric field, realizing 3D printing of electrospun fibers with well-controlled, low-cost, and template-free manners. The uniform field electrospinning (UFES) apparatus is configured by inserting the electrospinning nozzle into the center of an aided metal plate. The electric field simulation of UFES indicates a uniform distribution between the aided metal plate and the collector, while a diverging and weaker electric field is produced by CES. The collector of UFES is mounted on a translation stage, which moves along x and y axes under computer control. The distinctive deposition of electrospun fibers produces fibrous mats with rectangular patterns of different grid sizes, and butterfly and TaiJi figures with high resolutions are directly written by UFES. The layer-by-layer deposition of electrospun fibers under UFES produces microscale Mongolian yurts with distinct hollow structure. Fibrous blocks with an average width of 120 μm and height of 630 μm were printed by UFES from conductive polymer composites and constructed into strain sensors. The electric current strength of fibrous microblocks changes sharply in response to the finger bending and release, indicating the capability to monitor human motions. Thus, this study demonstrates that the UFES becomes an easy-handling strategy for 3D printing of electrospun fibers to create complex geometries. [ABSTRACT FROM AUTHOR]

The impact of the variations of threshold voltage (Vth) and hold voltage (Vhold) of threshold switching (TS) selector in 1S1R crossbar array is investigated. Based on ON/OFF state I–V curves measurements from a large number of Ag-filament TS selectors, Vth and Vhold are extracted and their variations distribution expressions are obtained, which are then employed to evaluate the impact on read process and write process in 32 × 32 1S1R crossbar array under different bias schemes. The results indicate that Vth and Vhold variations of TS selector can lead to degradation of 1S1R array performance parameters, such as minimum read/write voltage, bit error rate (BER), and power consumption. For the read process, a small Vhold variation not only results in the minimum read voltage increasing but it also leads to serious degradation of BER. As the standard deviation of Vhold and Vth increases, the BER and the power consumption of 1S1R crossbar array under 1/2 bias, 1/3 bias, and floating scheme degrade, and the case under 1/2 bias tends to be more serious compared with other two schemes. For the write process, the minimum write voltage also increases with the variation of Vhold from small to large value. A slight increase of Vth standard deviation not only decreases write power efficiency markedly but also increases write power consumption. These results have reference significance to understand the voltage variation impacts and design of selector properly. [ABSTRACT FROM AUTHOR]

CdTe quantum dots (QDs) with red fluorescence have been used to study their transdermal delivery capacity through mouse skin. The results showed that the QDs could permeate through skin, either separated from or still attached to live mice. Although the fluorescence emitted by the QDs could only be found in the skin and muscle cells located under the mouse skins coated with QDs, an inductive coupled plasma atomic emission spectrometry (ICP-AES) study indicated that the main organs, such as the heart, liver, spleen, lung, kidney and brain, all contained a significant quantity of Cd atoms. Moreover, these Cd atoms could remain in vivo for at least one week. As a control, the concentration of Cd atoms in normal mice not coated with QDs was very low. [ABSTRACT FROM AUTHOR]

In this paper, an MoOx film is deposited on a polyethylene terephthalate (PET) substrate as a buffer layer to improve the surface roughness of the flexible PET substrate. With an optimized MoOx thickness of 100 nm, the surface roughness of the PET substrate can be reduced to a very small value of 0.273 nm (much less than 0.585 nm of the pure PET). Flexible white top-emitting organic light-emitting diodes (TEOLEDs) with red and blue dual phosphorescent emitting layers are constructed based on a low-reflectivity Sm/Ag semi-transparent cathode. The flexible white emission exhibits the best luminance and current injection characteristics with the 100-nm-thick MoOx buffer layer and this result indicates that a smooth substrate is beneficial to the enhancement of device electrical and electroluminescence performances. However, the white TEOLED with a 50-nm-thick MoOx buffer layer exhibits a maximum current efficiency of 4.64 cd/A and a power efficiency of 1.9 lm/W, slightly higher than those with a 100-nm MoOx buffer layer, which is mainly due to an obvious intensity enhancement but limited current increases in 50-nm MoOx-based white TEOLED. The change amplitudes of the Commission International de l'Eclairage (CIE) chromaticity coordinates are less than (0.016, 0.005) for all devices in a wide luminance range over 100 cd/m2, indicating an excellent color stability in our white flexible TEOLEDs. Additionally, the flexible white TEOLED with an MoOx buffer layer shows excellent flexibility to withstand more than 500 bending times under a curvature radius of approximately 9 mm. Research demonstrates that it is mainly attributed to the high surface energy of the MoOx buffer layer, which is conducible to the improvement of the surface adhesion to the PET substrate and the Ag anode. [ABSTRACT FROM AUTHOR]

High pressure and high temperature properties of AB (A  =  6Li, 7Li; B  =  H, D, T) are comprehensively investigated with first-principles methods. It is found that H−sublattice features in the low-pressure electronic structure near the Fermi level of LiH are shifted to that dominated by the Li+ sublattice under compression. The lattice dynamics are studied in quasi-harmonic approximation, from which the phonon contribution to the free energy and the isotopic effects are accurately modelled with the aid of a parameterized double-Debye model. The equation of state (EOS) obtained matches perfectly with available static experimental data. The calculated principal Hugoniot is also in accordance with that derived from shock wave experiments. Using the calculated principal Hugoniot and the previous theoretical melting curve, we predict a shock melting point at 56 GPa and 1923 K. In order to establish the phase diagram for LiH, the phase boundaries between the B1 and B2 solid phases are explored. The B1–B2-liquid triple point is determined at about 241 GPa and 2413 K. The remarkable shift in the phase boundaries with isotopic effect and temperature reveal the significant role played by lattice vibrations. Furthermore, the Hugoniot of the static-dynamic coupling compression is assessed. Our EOS suggests that a precompression of the sample to 50 GPa will allow the shock Hugoniot to pass through the triple point and enter the B2 solid phase. This transition leads to a discontinuity with 4.6% volume collapse—about four times greater than the same B1–B2 transition at zero temperature. [ABSTRACT FROM AUTHOR]

In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter. [ABSTRACT FROM AUTHOR]

We observe the phenomenon of priority oscillation of the unexpected σ-polarization in high-power Nd:YVO4 ring laser. The severe thermal lens of the σ-polarized lasing, compared with the π-polarized lasing, is the only reason for the phenomenon. By designing a wedge Nd:YVO4 crystal as the gain medium, the unexpected σ-polarization is completely suppressed in the entire range of pump powers, and the polarization stability of the expected π-polarized output is enhanced. With the output power increasing from threshold to the maximum power, no σ-polarization lasing is observed. As a result, 25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated. [ABSTRACT FROM AUTHOR]

Coherent backscattering of light from a water suspension of zirconium silicate microcrystals is experimentally studied. Optically controlled weak localization of photons is realized, which is due to the reorientation behaviors of positive uniaxial microcrystals induced by a linearly polarized pump beam. Because zirconium silicate particles are positive uniaxial microcrystals, their reorientation behaviors are contrary to negative ones. Our work widely extends the materials used in the light-controllable weak localization of photons. [ABSTRACT FROM AUTHOR]

A novel plasmonic polarization filter based on the diamond-shape photonic crystal fiber (PCF) is proposed. The resonant coupling characteristics of the PCF polarization filter are investigated by the full-vector finite-element method. By optimizing the geometric parameters of the PCF, when the fiber length is 5 mm, the polarization filter has a bandwidth of 990 nm and an extinction ratio (ER) of lower than –20 dB. Moreover, a single wavelength polarization filter can also be achieved, along with an ER of –279.78 dB at wavelength 1.55 μm. It is believed that the proposed PCF polarization filter will be very useful in laser and optical communication systems. [ABSTRACT FROM AUTHOR]

In situ synchrotron angle-dispersive x-ray diffraction experiments on niobium powders have been conducted at pressures up to 61 GPa and room temperature using the diamond anvil cell technique. From the full width at half maximum of the measured diffraction lines, the yield strength was derived with the line-width analysis theory. The niobium powder sample was found to be compressed more packed firstly and then yielded at ∼14 GPa–18 GPa. Following an initial increase in the yield strength with pressure, an obvious decrease was observed occurring at ∼42 GPa–47 GPa accompanying with a typical pressure dependence above 47 GPa. The experimentally observed anomalous softening of the yield strength in niobium surprisingly follows the trend of the predicted unusual softening in the shear modulus by the recent theoretical investigations. The possible mechanisms, applicable to interpret the yield strength softening of materials at high pressure, were also discussed in detail. [ABSTRACT FROM AUTHOR]

By a method of population synthesis we construct a model of dark matter (DM) accretion onto binary black holes (BHs) and investigate the merger rate of the binary BHs. We find that the merger rate can weakly increase (less than 10%). However, the DM accretion can efficiently enhance the masses of binary BHs. In our model, the result for Z = 0.01 without the DM accretion cannot explain GW170104, GW170814, and GW150914, while with the DM accretion it can cover all observations well. For the higher metallicity (Z = 0.02), our model cannot explain the mergers of high-mass binary BHs like GW170104, GW170814, and GW150914. We estimate that the merger rate of binary BHs lies between 55 and 197 Gpc−3 yr−1. [ABSTRACT FROM AUTHOR]

The application of high pressure can fundamentally modify the crystalline and electronic structures of elements as well as their chemical reactivity, which could lead to the formation of novel materials. Here, we explore the reactivity of lithium with sodium under high pressure, using a swarm structure searching techniques combined with first-principles calculations, which identify a thermodynamically stable Li–Na compound adopting an orthorhombic oP8 phase at pressure above 355 GPa. The formation of Li–Na may be a consequence of strong concentration of electrons transfering from the lithium and the sodium atoms into the interstitial sites, which also leads to open a relatively wide band gap for LiNa-oP8. This is substantially different from atoms sharing or exchanging electrons in common compounds and alloys. In addition, lattice-dynamic calculations indicate that LiNa-oP8 remains dynamically stable when pressure decompresses down to 70 GPa. [ABSTRACT FROM AUTHOR]

The high-pressure polymorphs and structural transformation of Sn were experimentally investigated using angle-dispersive synchrotron x-ray diffraction up to 108.9 GPa. The results show that at least at 12.8 GPa β-Sn→bct structure transformation was completed and no two-phase coexistence was found. By using a long-wavelength x-ray, we resolved the diffraction peaks splitting and discovered the formation of a new distorted orthorhombic structure bco from the bct structure at 31.8 GPa. The variation of the lattice parameters and their ratios with pressure further validate the observation of the bco polymorph. The bcc structure appears at 40.9 GPa and coexists with the bco phase throughout a wide pressure range of 40.9 GPa–73.1 GPa. Above 73.1 GPa, only the bcc polymorph is observed. The systematically experimental investigation confirms the phase transition sequence of Sn as β-Sn→bct→bco→bco+bcc→bcc upon compression to 108.9 GPa at room temperature. [ABSTRACT FROM AUTHOR]

In this paper, small diameter InP nanowires with high crystal quality were synthesized through a chemical vapor deposition method. Benefitting from the high crystallinity and large specific surface area of InP nanowires, the simply constructed photodetector demonstrates a high responsivity of up to 1170 A·W−1 and an external quantum efficiency of 2.8×105% with a fast rise time of 110 ms and a fall time of 130 ms, even at low bias of 0.1 V. The effect of back-gate voltage on photoresponse of the device was systematically investigated, confirming that the photocurrent dominates over thermionic and tunneling currents in the whole operation. A mechanism based on energy band theory at the junction between metal and semiconductor was proposed to explain the back-gate voltage dependent performance of the photodetectors. These convincing results indicate that fine InP nanowires will have a brilliant future in smart optoelectronics. [ABSTRACT FROM AUTHOR]

Noiseless linear amplification (NLA), first proposed by Ralpha et al., is a nondeterministic amplification process which gives gain to the Fock state |n〉 → gn|n〉, with g being the amplification gain. We here give a general framework for improving the NLA scheme with arbitrary general local unitary operations. We derive the improvement in the amplification gain in 0–1 photon subspace. In particular, we study if the local unitary is composed of single mode squeezing and coherent displacement operation. Finally, numerical simulations show that local unitary operation could give a further enhancement in the amplification gain as well as the success probability, making the NLA more feasible in future optic quantum communications. [ABSTRACT FROM AUTHOR]

Pt-Sn alloy nanoparticles were conveniently immobilized on nitrogen-doped carbon nanotubes (NCNTs) through microwave-assisted ethylene glycol reduction. The nanoparticles have a narrow particle size distribution with the average particle size around 3 nm as measured by transmission electron microscopy and x-ray diffraction. The binding energy of metallic Sn passively shifts due to the charge transfer from Sn to Pt, as revealed by x-ray photoelectron spectroscopy. In comparison with the commercial Pt/C catalyst, Pt/NCNT presents a clear increase in activity for alcohol electro-oxidation due to the improved support, while the bimetallic Pt-Sn/NCNT has even higher activity owing to the alloying of Pt with Sn. Both Pt-Sn/NCNT and Pt/NCNT catalysts exhibit competitive long-term stability to Pt/C catalyst. The low cost, simple preparation and superior electrocatalytic performance indicate the great potential of Pt-Sn/NCNT in direct alcohol fuel cells. [ABSTRACT FROM AUTHOR]

An all-fibre displacement sensor with a simple configuration and capable of monitoring sub-50 nm displacements is proposed and investigated experimentally. The proposed fibre displacement sensor consists of a half-loop structure of bare high bend loss single-mode fibre 1060XP and a ratiometric power interrogation system. By measuring the change in transmission ratio in the ratiometric system, a change in displacement can be measured. The displacement sensor is sensitive to temperature and an experimental investigation of this sensitivity is presented. It is found that the peak shift response has a linear variation with temperature; therefore, temperature dependence can be mitigated by a suitable displacement correction process. The proposed macrobending fibre based displacement sensor benefits from simplicity and low cost and achieves a comparable resolution as compared with other conventional fibre optic sensors. [ABSTRACT FROM AUTHOR]