[Surveillance of potential transmission factors of schistosomiasis in Xiuzhou District of Jiaxing City from 2013 to 2015]

OBJECTIVE

To understand the potential risk of schistosomiasis transmission in Xiuzhou District of Jiaxing City, so as to provide the scientific evidence for consolidating schistosomiasis control achievements.

METHODS

Fixed and mobile surveillance sites were set up in Xiuzhou District of Jiaxing City from 2013 to 2015. Oncomelania hupensis snails was surveyed historical snail habitats, current snail habitats, and suspected snail habitats. The schistosome infections were identified using serological and parasitological testing among local residents and mobile populations. In addition, the survival and reproduction of snails imported into Xiuzhou District was observed, and the schistosome infection in wild reservoir hosts was detected.

RESULTS

A total of 540.14 hm² of settings were surveyed in Xiuzhou District, Jiaxing City from 2013 to 2015, and 1.65 hm² of snail habitats were identified. The snail habitats were mainly located in dry lands, and no infected snails or importation of snails were found. During the period from 2013 to 2015, a total of 7 668 local residents and mobile populations were examined in Xiuzhou District, and no new local infections were detected; however, three imported schistosomiasis cases were identified. Field simulation experiment showed that the imported snails laid eggs and reproduced in Xiuzhou District, and no schistosome infections were found in wild animals.

CONCLUSIONS

There are still residual Oncomelania snails and imported schistosomiasis patients in Xiuzhou District of Jiaxing City; therefore, the surveillance and management of local Oncomelania snails and imported schistosomiasis should be intensified to reduce the risk of schistosomiasis transmission.

Universal conductance fluctuations and phase-coherent transport in a semiconductor Bi2O2Se nanoplate with strong spin-orbit interaction

We report on phase-coherent transport studies of a Bi2O2Se nanoplate and on observation of universal conductance fluctuations and spin-orbit interaction induced reduction in fluctuation amplitude in the nanoplate. Thin-layered Bi2O2Se nanoplates are grown by chemical vapor deposition (CVD) and transport measurements are made on a Hall-bar device fabricated from a CVD-grown nanoplate. The measurements show weak antilocalization at low magnetic fields at low temperatures, as a result of spin-orbit interaction, and a crossover toward weak localization with increasing temperature. Temperature dependences of characteristic transport lengths, such as spin relaxation length, phase coherence length, and mean free path, are extracted from the low-field measurement data. Universal conductance fluctuations are visible in the low-temperature magnetoconductance over a large range of magnetic fields and the phase coherence length extracted from the autocorrelation function is consistent with the result obtained from the weak localization analysis. More importantly, we find a strong reduction in amplitude of the universal conductance fluctuations and show that the results agree with the analysis assuming strong spin-orbit interaction in the Bi2O2Se nanoplate.

Measurements of Strain and Bandgap of Coherently Epitaxially Grown Wurtzite InAsP-InP Core-Shell Nanowires

We report on experimental determination of the strain and bandgap of InAsP in epitaxially grown InAsP-InP core-shell nanowires. The core-shell nanowires are grown via metal-organic vapor phase epitaxy. The as-grown nanowires are characterized by transmission electron microscopy, X-ray diffraction, micro-photoluminescence (μPL) spectroscopy, and micro-Raman (μ-Raman) spectroscopy measurements. We observe that the core-shell nanowires are of wurtzite (WZ) crystal phase and are coherently strained with the core and the shell having the same number of atomic planes in each nanowire. We determine the predominantly uniaxial strains formed in the core-shell nanowires along the nanowire growth axis and demonstrate that the strains can be described using an analytical expression. The bandgap energies in the strained WZ InAsP core materials are extracted from the μPL measurements of individual core-shell nanowires. The coherently strained core-shell nanowires demonstrated in this work offer the potentials for use in constructing novel optoelectronic devices and for development of piezoelectric photovoltaic devices.

Crossover from Coulomb blockade to ballistic transport in InAs nanowire devices

We report on the observation of a crossover from the single electron Coulomb blockade regime to the ballistic transport in individual InAs semiconducting nanowire devices. The InAs nanowires studied here were grown by molecular-beam epitaxy (MBE), which provides a clean system to study the intrinsic electrons transport in a quasi-one-dimensional system. Quantized conductance plateaus are observed for an InAs nanowire-based device by changing the Fermi level with a global back gate at low temperature, suggesting the ballistic transport of electrons. Further lowering the temperature, we observe the Coulomb blockade phenomenon with the formation of the quantum dot between the two normal metal contacts. By increasing the electron density, the characteristic Fabry-Pérot oscillations are observed, which further provides evidence for the ballistic nature of transport in the InAs nanowire device. Our observations indicate that high-quality InAs nanowires grown by MBE behave as clean quantum wires at low temperatures, which enables us to investigate novel phenomena in the quasi-one-dimensional system.

[Correlation of health literacy and mobile phone use dependence with psychopathological symptoms in middle school students]

Objective: To explore the correlation of health literacy and mobile phone use dependence with psychopathological symptoms in middle school students. Methods: 22 628 middle school students in Shenyang, Bengbu, Xinxiang, Ulanqab, Chongqing and Yangjiang were enrolled by multistage cluster sampling method from November 2015 to January 2016. Chinese Adolescent Interactive Health Literacy Questionnaire (CAIHLQ), Self-rating Questionnaire for Adolescent Problematic Mobile Phone Use (SQAPMPU) and Multidimensional Sub-health Questionnaire of Adolescents (MSQA) were applied to acquire basic characteristics, health literacy, mobile phone use dependence and psychopathological symptoms of subjects. Subjects were classified into three groups, low level (<P(25)), medium level (P(25)-P(75)) and high level (>P(75)), according to the percentile of the questionnaire score. Multivariate logistic regression model was used to analyze the correlation of health literacy, mobile phone with psychopathological symptoms. Results: The students were (15.4±1.8) years old with 10 990 boys (48.6%). The score of health literacy of students were (104.1±18.7) points. The rate of mobile phone use dependence was 25.4% (5 752/22 628) and the rate of psychopathological symptoms was 29.1% (6 581/22 628). Compared with high health literacy level, medium and low health literacy levels were related to psychopathological symptoms, with OR (95%CI) about 2.30 (2.10-2.52) and 5.40 (4.89-5.97), respectively. Compared with mobile phone use independence, mobile phone use dependence was related to psychopathological symptoms, with OR (95%CI) about 3.60(3.37-3.85). The highest rate of psychopathological symptoms occurred in students with mobile phone use dependence and low health literacy level [68.0% (1 345/1 977)], with OR (95%CI) about 19.59 (17.07-22.48). Conclusion: Health literacy and mobile phone use dependence are related factors of psychopathological symptoms in middle school students.

[Interactive effects between health literacy and mobile phone dependence as well as its relation with unintentional injuries in middle school students]

Objective: To investigate the interaction between health literacy, mobile phone dependence and unintentional injuries in middle school students, and to provide guidance for prevention on unintentional injuries in adolescents. Methods: From November 2015 to January 2016, a questionnaire survey was conducted among 22 628 middle school students in Shenyang of Liaoning province, Bengbu of Anhui province, Xinxiang of Henan province, Ulanqab of Inner Mongolia Autonomous Region, Chongqing and Yangjiang of Guangdong province. Chinese Adolescent Interactive Health Literacy Questionnaire (CAIHLQ), Self-rating Questionnaire for Adolescent Problematic Mobile Phone Use (SQAPMPU), and Unintentional Injuries Assessment Scale and demographic variables were used to measure the health literacy, mobile phone dependence and unintentional injuries among the Chinese middle school students. Results: The detection rates of mobile phone dependence and unintentional injuries were 25.4% and 46.7%, respectively. The rates of unintentional injuries of middle school students with mobile phone dependence and with low, medium and high health literacy were 53.6%, 44.4% and 48.8%, 48.1%, 41.7%. Factors as mobile phone dependence, low and middle health literacy were positively related to unintentional injuries (OR=1.452, 1.196, 1.364). However, the multiplicative interaction between mobile phone dependence and health literacy on unintentional injuries was noticed significant (OR=1.217, 95%CI: 1.041-1.422). Conclusions: Our results showed that the prevalence of unintentional injuries was relatively high in middle school students. Health literacy and mobile phone dependence seemed related to unintentional injuries. Interaction between health literacy and mobile phone dependence on unintentional injuries appeared significant.

Tunable Low Loss 1D Surface Plasmons in InAs Nanowires

Due to the ability to manipulate photons at nanoscale, plasmonics has become one of the most important branches in nanophotonics. The prerequisites for the technological application of plasmons include high confining ability (λ₀ /λ_p ), low damping, and easy tunability. However, plasmons in typical plasmonic materials, i.e., noble metals, cannot satisfy these three requirements simultaneously and cause a disconnection to modern electronics. Here, the indium arsenide (InAs) nanowire is identified as a material that satisfies all the three prerequisites, providing a natural analogy with modern electronics. The dispersion relation of InAs plasmons is determined using the nanoinfrared imaging technique, and show that their associated wavelengths and damping ratio can be tuned by altering the nanowire diameter and dielectric environment. The InAs plasmons possess advantages such as high confining ability, low loss, and ease of fabrication. The observation of InAs plasmons could enable novel plasmonic circuits for future subwavelength applications.

Low-field magnetotransport in graphene cavity devices

Confinement and edge structures are known to play significant roles in the electronic and transport properties of two-dimensional materials. Here, we report on low-temperature magnetotransport measurements of lithographically patterned graphene cavity nanodevices. It is found that the evolution of the low-field magnetoconductance characteristics with varying carrier density exhibits different behaviors in graphene cavity and bulk graphene devices. In the graphene cavity devices, we observed that intravalley scattering becomes dominant as the Fermi level gets close to the Dirac point. We associate this enhanced intravalley scattering to the effect of charge inhomogeneities and edge disorder in the confined graphene nanostructures. We also observed that the dephasing rate of carriers in the cavity devices follows a parabolic temperature dependence, indicating that the direct Coulomb interaction scattering mechanism governs the dephasing at low temperatures. Our results demonstrate the importance of confinement in carrier transport in graphene nanostructure devices.

Strong spin-orbit interaction and magnetotransport in semiconductor Bi2O2Se nanoplates

Semiconductor Bi₂O₂Se nanolayers of high crystal quality have been realized via epitaxial growth. These two-dimensional (2D) materials possess excellent electron transport properties with potential application in nanoelectronics. It is also strongly expected that the 2D Bi₂O₂Se nanolayers can be an excellent material platform for developing spintronic and topological quantum devices if the presence of strong spin-orbit interaction in the 2D materials can be experimentally demonstrated. Herein, we report the experimental determination of the strength of spin-orbit interactions in Bi₂O₂Se nanoplates through magnetotransport measurements. The nanoplates are epitaxially grown by chemical vapor deposition, and the magnetotransport measurements are performed at low temperatures. The measured magnetoconductance exhibits a crossover behavior from weak antilocalization to weak localization at low magnetic fields with increasing temperature or decreasing back gate voltage. We have analyzed this transition behavior of magnetoconductance based on an interference theory, which describes quantum correction to the magnetoconductance of a 2D system in the presence of spin-orbit interaction. Dephasing length and spin relaxation length are extracted from the magnetoconductance measurements. Compared to the case of other semiconductor nanostructures, the extracted relatively short spin relaxation length of ∼150 nm indicates the existence of a strong spin-orbit interaction in Bi₂O₂Se nanolayers.

Low-Temperature and Rapid Growth of Large Single-Crystalline Graphene with Ethane

Future applications of graphene rely highly on the production of large-area high-quality graphene, especially large single-crystalline graphene, due to the reduction of defects caused by grain boundaries. However, current large single-crystalline graphene growing methodologies are suffering from low growth rate and as a result, industrial graphene production is always confronted by high energy consumption, which is primarily caused by high growth temperature and long growth time. Herein, a new growth condition achieved via ethane being the carbon feedstock to achieve low-temperature yet rapid growth of large single-crystalline graphene is reported. Ethane condition gives a growth rate about four times faster than methane, achieving about 420 µm min^-1 for the growth of sub-centimeter graphene single crystals at temperature about 1000 °C. In addition, the temperature threshold to obtain graphene using ethane can be reduced to 750 °C, lower than the general growth temperature threshold (about 1000 °C) with methane on copper foil. Meanwhile ethane always keeps higher graphene growth rate than methane under the same growth temperature. This study demonstrates that ethane is indeed a potential carbon source for efficient growth of large single-crystalline graphene, thus paves the way for graphene in high-end electronical and optoelectronical applications.

[Analysis of maternal deaths in Shanghai from 1996 to 2015]

Objective: To analyze the trend of maternal mortality ratio (MMR) and cause of death in Shanghai from 1996 to 2015. Methods: To collect the material about the maternal death and the maternal death audit from 1996 to 2015, and to analyze the MMR, the cause of death and the result of the maternal death audit of Shanghai from 1996 to 2015 retrospectively. Results: (1) The change of MMR: the MMR in Shanghai decreased from 28.84 per 100 000 live births in 1996 to 6.66 per 100 000 live births in 2015. (2) The characteristic of maternal death: the proportion of Shanghai citizens was 27.4%(121/441) and the proportion of migrant women was 72.6%(320/441). The women with advanced maternal age was 8.2% (20/243) since 1996 to 2005, and increased to 16.7% (33/198) since 2006 to 2015. Maternal deaths during pregnancy increased from 27.6%(67/243) in the first 10 years (1996-2005) to 35.4%(70/198) in the recent 10 years (2006-2015) . The intrapartum maternal deaths was 6.2%(15/243) in the first 10 years and in the recent 10 years it was zero. The proportion of postpartum deaths in the first 10 years and in the recent 10 years were 66.3% (161/243) and 64.6%(128/198) respectively. (3) The cause of maternal death: During the recent 10 years, indirect obstetric causes [63.1%(125/198)] was more than direct obstetric causes [36.9% (73/198) ] for the first time. The death causes changed significantly. Postpartum hemorrhage remained the leading cause of maternal deaths, but the specific mortality rate (SMR) of postpartum hemorrhage decreased significantly from 7.42 per 100 000 live births in the first 10 years to 1.51 per 100 000 live births in the recent 10 years. The maternal deaths because of heart disease and cerebrovascular disease rose to the second and the forth reasons. (4) Maternal death audit: the avoidable maternal death ratio decreased from 3.66 per 100 000 live births in the first 10 years to 1.86 per 100 000 live births in the recent 10 years. Conclusions: During the past 20 years, the MMR of Shanghai decreased significantly and was close to the level of developed countries. In recent years, the causes of maternal death become more complicated. With the implementation of the second child policy, women with high risk factors increase, so government investment, policy support should be strengthened to optimize the management.

Coherent Transport in a Linear Triple Quantum Dot Made from a Pure-Phase InAs Nanowire

A highly tunable linear triple quantum dot (TQD) device is realized in a single-crystalline pure-phase InAs nanowire using a local finger gate technique. The electrical measurements show that the charge stability diagram of the TQD can be represented by three kinds of current lines of different slopes and a simulation performed based on a capacitance matrix model confirms the experiment. We show that each current line observable in the charge stability diagram is associated with a case where a QD is on resonance with the Fermi level of the source and drain reservoirs. At a triple point where two current lines of different slopes move together but show anticrossing, two QDs are on resonance with the Fermi level of the reservoirs. We demonstrate that an energetically degenerated quadruple point at which all three QDs are on resonance with the Fermi level of the reservoirs can be built by moving two separated triple points together via sophistically tuning of energy levels in the three QDs. We also demonstrate the achievement of direct coherent electron transfer between the two remote QDs in the TQD, realizing a long-distance coherent quantum bus operation. Such a long-distance coherent coupling could be used to investigate coherent spin teleportation and superexchange effects and to construct a spin qubit with an improved long coherent time and with spin state detection solely by sensing the charge states.

High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se

High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi₂O₂Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ∼0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm² V^-1 s^-1 is measured in as-grown Bi₂O₂Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO₃-SrTiO₃ interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi₂O₂Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm² V^-1 s^-1), large current on/off ratios (>10⁶) and near-ideal subthreshold swing values (∼65 mV dec^-1) at room temperature. Our results make Bi₂O₂Se a promising candidate for future high-speed and low-power electronic applications.

Electron-Hole Symmetry Breaking in Charge Transport in Nitrogen-Doped Graphene

Graphitic nitrogen-doped graphene is an excellent platform to study scattering processes of massless Dirac Fermions by charged impurities, in which high mobility can be preserved due to the absence of lattice defects through direct substitution of carbon atoms in the graphene lattice by nitrogen atoms. In this work, we report on electrical and magnetotransport measurements of high-quality graphitic nitrogen-doped graphene. We show that the substitutional nitrogen dopants in graphene introduce atomically sharp scatters for electrons but long-range Coulomb scatters for holes and, thus, graphitic nitrogen-doped graphene exhibits clear electron-hole asymmetry in transport properties. Dominant scattering processes of charge carriers in graphitic nitrogen-doped graphene are analyzed. It is shown that the electron-hole asymmetry originates from a distinct difference in intervalley scattering of electrons and holes. We have also carried out the magnetotransport measurements of graphitic nitrogen-doped graphene at different temperatures and the temperature dependences of intervalley scattering, intravalley scattering, and phase coherent scattering rates are extracted and discussed. Our results provide an evidence for the electron-hole asymmetry in the intervalley scattering induced by substitutional nitrogen dopants in graphene and shine a light on versatile and potential applications of graphitic nitrogen-doped graphene in electronic and valleytronic devices.

Epitaxial Growth of Ternary Topological Insulator Bi2 Te2 Se 2D Crystals on Mica

Nanostructures of ternary topological insulator (TI) Bi₂ Te₂ Se are, in principle, advantageous to the manifestation of topologically nontrivial surface states, due to significantly enhanced surface-to-volume ratio compared with its bulk crystals counterparts. Herein, the synthesis of 2D Bi₂ Te₂ Se crystals on mica via the van der Waals epitaxy method is explored and systematically the growth behaviors during the synthesis process are investigated. Accordingly, 2D Bi₂ Te₂ Se crystals with domain size up to 50 µm large and thickness down to 2 nm are obtained. A pronounced weak antilocalization effect is clearly observed in the 2D Bi₂ Te₂ Se crystals at 2 K. The method for epitaxial growth of 2D ternary Bi₂ Te₂ Se crystals may inspire materials engineering toward enhanced manifestation of the subtle surface states of TIs and thereby facilitate their potential applications in next-generation spintronics.

Synthesis of Bi₂Te₃ Nanotubes Using Te Nanotubes as a Template

Bi₂Te₃ nanotubes are synthesized by a facile two-step hydrothermal method. Te nanotubes are prepared firstly and then used as a template to produce Bi₂Te₃ nanotubes. The structure and morphology of the synthesized nanotubes are characterized by X-ray diffraction, field emission scanning electron microscope, and transmission electron microscope. The synthesized Bi₂Te₃ nanotubes are several microns in length and about 400 nm in diameter. The growth process is investigated in detail under different experimental conditions. The formation mechanism of Bi₂Te₃ nanotubes from the Te nanotube template is proposed and discussed. Electrical property of single Bi₂Te₃ nanotube is investigated. The synthesis of smooth Bi₂Te₃ nanotubes opens up the opportunities of investigating novel physical phenomena of topological insulators with two independent surfaces.

Growth of High Material Quality Group III-Antimonide Semiconductor Nanowires by a Naturally Cooling Process

We report on a simple but powerful approach to grow high material quality InSb and GaSb nanowires in a commonly used tube furnace setup. The approach employs a process of stable heating at a high temperature and then cooling down naturally to room temperature with the nanowire growth occurred effectively during the naturally cooling step. As-grown nanowires are analyzed using a scanning electron microscope and a transmission electron microscope equipped with an energy-dispersive X-ray spectroscopy setup. It is shown that the grown nanowires are several micrometers in lengths and are zincblende InSb and GaSb crystals. The FET devices are also fabricated with the grown nanowires and investigated. It is shown that the grown nanowires show good, desired electrical properties and should have potential applications in the future nanoelectronics and infrared optoelectronics.

InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition

We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core. The results obtained here show that the InAs/GaSb core-shell nanowires grown using the Si platform have strong potential in the fabrication of future nanometer-scale devices and in the study of fundamental quantum physics.

Schottky barrier and contact resistance of InSb nanowire field-effect transistors

Understanding of the electrical contact properties of semiconductor nanowire (NW) field-effect transistors (FETs) plays a crucial role in the use of semiconducting NWs as building blocks for future nanoelectronic devices and in the study of fundamental physics problems. Here, we report on a study of the contact properties of Ti/Au, a widely used contact metal combination, when contacting individual InSb NWs via both two-probe and four-probe transport measurements. We show that a Schottky barrier of height [Formula: see text] is present at the metal-InSb NW interfaces and its effective height is gate-tunable. The contact resistance ([Formula: see text]) in the InSb NWFETs is also analyzed by magnetotransport measurements at low temperatures. It is found that [Formula: see text] in the on-state exhibits a pronounced magnetic field-dependent feature, namely it is increased strongly with increasing magnetic field after an onset field [Formula: see text]. A qualitative picture that takes into account magnetic depopulation of subbands in the NWs is provided to explain the observation. Our results provide solid experimental evidence for the presence of a Schottky barrier at Ti/Au-InSb NW interfaces and can be used as a basis for design and fabrication of novel InSb NW-based nanoelectronic devices and quantum devices.

Covalently bonded single-molecule junctions with stable and reversible photoswitched conductivity

Through molecular engineering, single diarylethenes were covalently sandwiched between graphene electrodes to form stable molecular conduction junctions. Our experimental and theoretical studies of these junctions consistently show and interpret reversible conductance photoswitching at room temperature and stochastic switching between different conductive states at low temperature at a single-molecule level. We demonstrate a fully reversible, two-mode, single-molecule electrical switch with unprecedented levels of accuracy (on/off ratio of ~100), stability (over a year), and reproducibility (46 devices with more than 100 cycles for photoswitching and ~10(5) to 10(6) cycles for stochastic switching).

Probe of local impurity states by bend resistance measurements in graphene cross junctions

We report on low-temperature transport measurements on four-terminal cross junction devices fabricated from high-quality graphene grown by chemical vapor deposition. At high magnetic fields, the bend resistance reveals pronounced peak structures at the quantum Hall plateau transition, which can be attributed to the edge state transport through the junctions. We further demonstrate that the bend resistance is drastically affected by the presence of local impurity states in the junction regions, and exhibits an unusual asymmetric behavior with respect to the magnetic field direction. The observations can be understood in a model taking into account the combination of the edge transport and an asymmetric scatterer. Our results demonstrate that a graphene cross junction may serve as a sensitive probe of local impurity states in graphene at the nanoscale.

Inhibition of subcutaneously implanted human pituitary tumor cells in nude mice by LRIG1

The aim of this study was to explore the inhibition of subcutaneously implanted human pituitary tumor cells in nude mice by LRIG1 and its mechanism. For this study, athymic nude mice were injected with either normal pituitary tumor RC-4B/C cells or LRIG1-transfected RC-4B/C cells. We then calculated the volume inhibition rate of the tumors, as well as the apoptosis index of tumor cells and the expression of Ras, Raf, AKt, and ERK mRNA in tumor cells. Tumor cell morphological and structural changes were also observed under electron microscope. Our data showed that subcutaneous tumor growth was slowed or even halted in LRIG1-transfected tumors. The tumor volumes were significantly different between the two groups of mice (χ2 = 2.14, P < 0.05). The tumor apoptosis index was found to be 8.72% in the control group and 39.7% in LRIG1-transfected mice (χ2 = 7.59, P < 0.05). The levels of Ras, Raf, and AKt mRNA in LRIG1-transfected RC-4B/C cells were significantly reduced after transfection (P < 0.01). Transfected subcutaneous tumor cells appeared to be in early or late apoptosis under an electron microscope, while only a few subcutaneous tumor cells appeared to be undergoing apoptosis in the control group. In conclusion, the LRIG1 gene is able to inhibit proliferation and promote apoptosis in subcutaneously implanted human pituitary tumors in nude mice. The mechanism of LRIG1 may involve the inhibition of the PI3K/ Akt and Ras/Raf/ERK signal transduction pathways.

Coherent Charge Transport in Ballistic InSb Nanowire Josephson Junctions

Hybrid InSb nanowire-superconductor devices are promising for investigating Majorana modes and topological quantum computation in solid-state devices. An experimental realisation of ballistic, phase-coherent superconductor-nanowire hybrid devices is a necessary step towards engineering topological superconducting electronics. Here, we report on a low-temperature transport study of Josephson junction devices fabricated from InSb nanowires grown by molecular-beam epitaxy and provide a clear evidence for phase-coherent, ballistic charge transport through the nanowires in the junctions. We demonstrate that our devices show gate-tunable proximity-induced supercurrent and clear signatures of multiple Andreev reflections in the differential conductance, indicating phase-coherent transport within the junctions. We also observe periodic modulations of the critical current that can be associated with the Fabry-Pérot interference in the nanowires in the ballistic transport regime. Our work shows that the InSb nanowires grown by molecular-beam epitaxy are of excellent material quality and hybrid superconducting devices made from these nanowires are highly desirable for investigation of the novel physics in topological states of matter and for applications in topological quantum electronics.

Electronic structures of [1 1 1]-oriented free-standing InAs and InP nanowires

We report on a theoretical study of the electronic structures of the [1 1 1]-oriented, free-standing, zincblende InAs and InP nanowires with hexagonal cross sections by means of an atomistic sp(3)s*, spin-orbit interaction included, nearest-neighbor, tight-binding method. The band structures and the band state wave functions of these nanowires are calculated and the symmetry properties of the bands and band states are analyzed based on the C(3v) double point group. It is shown that all bands of these nanowires are doubly degenerate at the Γ-point and some of these bands will split into non-degenerate bands when the wave vector k moves away from the Γ-point as a manifestation of spin-splitting due to spin-orbit interaction. It is also shown that the lower conduction bands of these nanowires all show simple parabolic dispersion relations, while the top valence bands show complex dispersion relations and band crossings. The band state wave functions are presented by the spatial probability distributions and it is found that all the band states show 2π/3-rotation symmetric probability distributions. The effects of quantum confinement on the band structures of the [1 1 1]-oriented InAs and InP nanowires are also examined and an empirical formula for the description of quantization energies of the lowest conduction band and the highest valence band is presented. The formula can simply be used to estimate the enhancement of the band gaps of the nanowires at different sizes as a result of quantum confinement.

Surface Engineering of Copper Foils for Growing Centimeter-Sized Single-Crystalline Graphene

The controlled growth of high-quality graphene on a large scale is of central importance for applications in electronics and optoelectronics. To minimize the adverse impacts of grain boundaries in large-area polycrystalline graphene, the synthesis of large single crystals of monolayer graphene is one of the key challenges for graphene production. Here, we develop a facile surface-engineering method to grow large single-crystalline monolayer graphene by the passivation of the active sites and the control of graphene nucleation on copper surface using the melamine pretreatment. Centimeter-sized hexagonal single-crystal graphene domains were successfully grown, which exhibit ultrahigh carrier mobilities exceeding 25,000 cm(2) V(-1) s(-1) and quantum Hall effects on SiO2 substrates. The underlying mechanism of melamine pretreatments were systematically investigated through elemental analyses of copper surface in the growth process of large single-crystals. This present work provides a surface design of a catalytic substrate for the controlled growth of large-area graphene single crystals.