Thermoelectric Transport by Surface States in Bi2Se3-Based Topological Insulator Thin Films

We develop a tractable theoretical model to investigate the thermoelectric （TE） transport properties of surface states in topological insulator thin films （TITFs） of Bi2Sea at room temperature. The hybridization between top and bottom surface states in the TITF plays a significant role. With the increasing hybridization-induced surface gap, the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases. This is due to the metal-semiconductor transition induced by the surface-state hybridization. Based on these TE transport coefficients, the TE figure-of-merit ZT is evaluated. It is shown that ZT can be greatly improved by the surface-state hybridization. Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of Bi2Sea-based TITFs as high-performance TE materials and devices.

Electrical-Controlled Transport for Surface States in a Dirac Semimetal Quantum Wire

The transport properties of a Dirac semimet^l quantum wire with two side gates are theoretically studied by adopting the lattice Green function method. It is found that a residual conductance quantum contributed from the surface states can be switched on or off by tuning the electron energy or the side gates voltage. This ideal switching effect for the surface Dirac electron results from the transversal quantum confinement of the quantum wire in combination with the electrostatic potential induced by the side gates. These findings may provide useful guidance for designing all-electrical topological nanoelectronic devices.

Liquid marbles containing petroleum and their properties

Liquid marbles （non-stick droplets） containing crude petroleum are reported. Liquid marbles were ob- tained by use of fluorinated decyl polyhedral oligomeric silsequioxane （FD-POSS） powder. Marbles containing crude petroleum remained stable on a broad diversity of solid and liquid supports. The effective surface tension of marbles filled with petroleum was established. The mechanism of friction of the marbles is discussed. Actuation of liquid marbles containing crude petroleum with an electric field is presented.

Electric Field Driven Surface Ion Transport in Hydrophobic Nanopores

Water behavior in nanoconfined hydrophobic environment is different from that in the bulk,which greatly influences mass transport.Hydrophobicity switching of nanopores showing great potential for controlled water or ion transport has been realized through several methods,especially the voltage-triggered wetting/dewetting inspired by biological ion channels.However,in the hydrophobic silanized nanopores,the finite ionic current is still observed and the ion transport mechanism is not yet clear.Here,we explore the ion transport behavior in the hydrophobic silanized anodic aluminum oxide(AAO).Ion transport through this hydrophobic membrane is confirmed,although no aqueous pathway was observed.Results show that ions transport through the cross-linked silane layer on the inner surface.It is revealed that metal ions,not just the protons or hydroxide ions,are involved in the ion transport driven by external electric field.This study provides a new insight into the ion transport in nanoconfined hydrophobic environment which is helpful to understand the biological processes and design new nanofluidic devices.

Two-year measurements of surface ozone at Dangxiong,a remote highland site in the Tibetan Plateau

Measurements of surface O3 and carbon monoxide（CO） were made from September 2009 to August 2011 at Dangxiong（30.48°N, 91.10°E, 4187 m a.s.l.）, a remote highland site in a southern valley of the Nyainqêntanglha Mountains in the Tibetan Plateau, China. The monthly mean O3 mixing ratio ranged from 29.1 to 51.4 ppb, with an average of 38.5 ppb, and the maximum value was observed in May. The average diurnal cycle of O3 concentration showed a minimum in early morning and a maximum in the afternoon, with a broader ＂high platform＂ from the late morning to the late afternoon, and resembled that of surface wind speed. The concentration of surface O3 was highly significantly correlated with tropospheric column O3 over the regions surrounding Dangxiong and with that of surface O3 observed at a site north of the Nyainqêntanglha Mountains, suggesting a good regional representativeness of surface O3 at Dangxiong. In the afternoon when stronger winds blew, surface air showed distinct features of free-atmospheric air, with higher O3, lower CO, and lower relative humidity（RH）. The negative O3-CO and O3-RH correlations in most months indicate a significant influence of air masses from the free troposphere. Trajectory analysis suggests that air masses originating from the south of the site make a negative net contribution to surface O3 and a positive contribution to CO and humidity, and those from the northwest sector contribute conversely to the respective quantities.

Graphene surface plasmon polaritons transport on curved substrates

We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by an analytical method and compared with those on planar substrates. Based on our theory, the bend of graphene nearly does not affect the property of GSPPs except for an extremely small shift to the lower frequency for the same effective mode index. The field distributions and the eigenfrequencies of GSPPs on planar and cylindrical substrates are calculated by the finite element method, which validates our theoretical analysis. Moreover, three types of graphene-guided optical interconnections of GSPPs, namely, planar to curved graphene film, curved to planar graphene film, and curved to curved graphene film, are proposed and examined in detail. The theoretical results show that the GSPPs propagation on curved graphene substrates and interconnections will not induce any additional losses if the phase-matching condition is satisfied. Additionally, the extreme tiny size of curved graphene for interconnection at a certain spectra range is predicted by our theory and validated by the simulation of 90° turning of GSPPs. The bending effect on the property of GSPPs is systematically analyzed and identified. Our studies would be helpful to instruct design of plasmonic devices involving curved GSPPs, such as nanophotoniccircuits, flexible plasmonic, and biocompatible devices.