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The unique electronic properties of the surface electrons in a topological insulator are protected by time-reversal symmetry. Circularly polarized light naturally breaks time-reversal symmetry, which may lead to an exotic surface quantum Hall state. Using time-and angle-resolved photoemission spectroscopy, we show that an intense ultrashort midinfrared pulse with energy below the bulk band gap hybridizes with the surface Dirac fermions of a topological insulator to form Floquet-Bloch bands. These photon-dressed surface bands exhibit polarization-dependent band gaps at avoided crossings. Circularly polarized photons induce an additional gap at the Dirac point, which is a signature of broken time-reversal symmetry on the surface. These observations establish the Floquet-Bloch bands in solids and pave the way for optical manipulation of topological quantum states of matter.

Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.

Although significant advances have recently been made in the diagnosis and treatment of cervical carcinoma, the long-term survival rate for advanced cervical cancer remains low. Therefore, an urgent need exists to both uncover the molecular mechanisms and identify potential therapeutic targets for the treatment of cervical cancer. MicroRNAs (miRNAs) have important roles in cancer progression and could be used as either potential therapeutic agents or targets. miR-506 is a component of an X chromosome-linked miRNA cluster. The biological functions of miR-506 have not been well established. In this study, we found that miR-506 expression was downregulated in approximately 80% of the cervical cancer samples examined and inversely correlated with the expression of Ki-67, a marker of cell proliferation. Gain-of-function and loss-of-function studies in human cervical cancer, Caski and SiHa cells, demonstrated that miR-506 acts as a tumor suppressor by inhibiting cervical cancer growth in vitro and in vivo . Further studies showed that miR-506 induced cell cycle arrest at the G1/S transition, and enhanced apoptosis and chemosensitivity of cervical cancer cell. We subsequently identified Gli3, a hedgehog pathway transcription factor, as a direct target of miR-506 in cervical cancer. Furthermore, Gli3 silencing recapitulated the effects of miR-506, and reintroduction of Gli3 abrogated miR-506-induced cell growth arrest and apoptosis. Taken together, we conclude that miR-506 exerts its anti-proliferative function by directly targeting Gli3. This newly identified miR-506/Gli3 axis provides further insight into the pathogenesis of cervical cancer and indicates a potential novel therapeutic agent for the treatment of cervical cancer.

The evolution of physical, chemical and optical properties of urban aerosol particles was characterized during an extreme haze episode in Beijing, PRC, from 24 through 31 January 2013 based on in situ measurements. The average mass concentrations of PM1, PM2.5 and PM10 were 99 ± 67 μg m−3 (average ± SD), 188 ± 128 μg m−3 and 265 ± 157 μg m−3, respectively. A significant increase in PM1-2.5 fraction was observed during the most heavily polluted period. The average scattering coefficient at 550 nm was 877 ± 624 Mm−1. An increasing relative amount of coarse particles can be deduced from the variations of backscattering ratios, asymmetry parameter and scattering Ångström exponent. Particle number-size distributions between 14 and 2500 nm diameter showed high number concentrations, particularly in the nucleation mode and accumulation mode. Size-resolved chemical composition of submicron aerosol from a high-resolution time-of-flight aerosol mass spectrometer showed that the mass concentrations of organic, sulfate, nitrate, ammonium and chlorine mainly resided on particles between 500 and 800 nm (vacuum diameter), and nitrate and ammonium contributed greatly to particle growth during the heavily polluted day (28 January). Increasing relative humidity and stable synoptic conditions on 28 January combined with heavy pollution on 28 January, leading to enhanced water uptake by the hygroscopic submicron particles and formation of secondary aerosol, which might be the main reasons for the severity of the haze episode. Light-scattering apportionment showed that organic, sulfate, ammonium nitrate and ammonium chloride compounds contributed to light-scattering fractions of 54, 24, 12 and 10%, respectively. This study indicated that the organic component in submicron aerosol played an important role in visibility degradation during the haze episode in Beijing.

Breast cancer is the most common type of cancer among women worldwide, and metastasis represents the most devastating stage of the disease. Recent studies have revealed that microRNAs (miRNA) have critical roles to regulate cancer cell invasion and metastasis. Here we present evidence to show the role of miR-182 in breast cancer metastasis. miR-182 is upregulated in the malignant cell line variants of both human MCF10 and mouse 4T1 series. Ectopic expression of miR-182 enhanced breast cancer cell motility and invasiveness, whereas miR-182 inhibition resulted in opposite changes. In nude mice, miR-182 led to increased pulmonary colonization of cancer cells. We further demonstrated that miR-182 directly targets MIM (Missing in Metastasis), which suppresses metastasis by inhibiting ras homolog family member A (RhoA) activity and stress fiber formation in breast cancer cells. Restoring MIM expression completely blocked the pro-metastasis function of miR-182, while RhoA inhibition reversed the phenotypes of both miR-182 overexpression and MIM knockdown. In breast tumor samples, miR-182 induction is linked to downregulation of MIM , RhoA activation and poor prognosis. Hence, our data delineates the molecular pathway by which miR-182 promotes breast cancer invasion and metastasis, and may have important implication for the treatment of metastatic cancers.

Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centers around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.

In this study on the surface charges and structural characterization of kaolinite clay, it is found that the highly pH dependent edge charges are important to the interparticle forces and associated fabric formations. When the pH is below the isoelectrical point of the edge surfaces, IEP edge , the Coulombian attraction between faces and edges dominates, which favors the formation of an opened edge-to-face (EF) association and a higher final sediment volume. At pH > IEP edge , the double-layer repulsion prevails at all surfaces to result in a deflocculated and dispersed fabric, which tends to form denser soil packing in the sediment. Increasing the ionic strength (with NaCl as the electrolyte) leads to the opposite behavior in clay suspensions below and above the IEP edge : the degree of fabric flocculation and the final sediment volume decrease with an increased ionic strength at pH < IEP edge but increase at pH > IEP edge . The measured pore-size distribution reveals a distinct dual-porosity characteristic in the pH 4 with salts (0.15 mol/L NaCl) specimen: it consists of inter-aggregate spaces (~1.10 µm) and intra-aggregate pores (~0.30 µm). Soils with a higher degree of EF flocculation due to the prevailing Coulombian or van der Waals attraction can render a higher liquid limit.Key words: pH, fabric associations, isoelectrical point, dual porosity, interparticle forces, liquid limit.

Plant embryo development is regulated by a network of transcription factors that include LEAFY COTYLEDON 1 (LEC1), LEC1-LIKE (L1L), and B3 domain factors, LEAFY COTYLEDON 2 (LEC2), FUSCA3 (FUS3), and ABSCISIC ACID INSENSITIVE 3 (ABI3) of Arabidopsis (Arabidopsis thaliana). Interactions of these genes result in temporal progression of overlapping B3 gene expression culminating in maturation and desiccation of the seed. Three VP1/ABI3-LIKE (VAL) genes encode B3 proteins that include plant homeodomain-like and CW domains associated with chromatin factors. Whereas val monogenic mutants have phenotypes similar to wild type, val1 val2 double-mutant seedlings form no leaves and develop embryo-like proliferations in root and apical meristem regions. In a val1 background, val2 and val3 condition a dominant variegated leaf phenotype revealing a VAL function in vegetative development. Reminiscent of the pickle (pkl) mutant, inhibition of gibberellin biosynthesis during germination induces embryonic phenotypes in val1 seedlings. Consistent with the embryonic seedling phenotype, LEC1, L1L, ABI3, and FUS3 are up-regulated in val1 val2 seedlings in association with a global shift in gene expression to a profile resembling late-torpedo-stage embryogenesis. Hence, VAL factors function as global repressors of the LEC1/B3 gene system. The consensus binding site of the ABI3/FUS3/LEC2 B3 DNA-binding domain (Sph/RY) is strongly enriched in the promoters and first introns of VAL-repressed genes, including the early acting LEC1 and L1L genes. We suggest that VAL targets Sph/RY-containing genes in the network for chromatin-mediated repression in conjunction with the PKL-related CHD3 chromatin-remodeling factors.

The transient photocurrent is one of the key parameters of the spatial radiation effect of photoelectric devices, and the energy level defect affects the transient photocurrent. In this paper, by studying the deep level transient spectrum of a self-designed Schottky diode, the defect properties of the interface region of the anode metal AlCu and Si caused by high-temperature annealing at 150 ℃, 200 ℃ and 300 ℃ for 1200 h have been quantitatively analyzed. The study shows that the defect is located at the position of + 0.41 eV on the valence band, the concentration is 2.8  ×  10 13 /cm 2 , and the capture cross section is σ  = 8.5  ×  10 17 . The impurity energy level mainly comes from the diffusion of Al atom in anode metal. We found that the defect did not cause the electrical performance degradation and obvious morphology change of the device, but the transient photocurrent increased significantly. The reason is that the high temperature treatment results in a growth in the density of states at the interface between AlCu–Si. The more mismatched dislocations and recombination center increased the reverse current of the heterojunction. The above view is proved by the TCAD simulation test.