Parallel and orthogonal E-field alignment of single-walled carbon nanotubes by ac dielectrophoresis.

We designed planar electrodes, for dielectrophoretic manipulation of single-walled carbon nanotubes (SWNTs), built as metal-oxide-semiconductor nanogap capacitors with common substrate and oxide thicknesses of 17 and 150 nm. Such design generates high electric fields (10(9) V m(-1)) and also the fringing field is curved due to the conducting substrate, unlike fields generated by conventionally used planar electrodes. Scanning electron microscopy images showed SWNTs aligned parallel and perpendicular to the electrodes. Raman spectroscopic mapping was used to produce separate images of the metallic (m-SWNT) and semiconducting (s-SWNT) nanotube density distributions. As expected, parallel alignment of the m-SWNTs with the E-field was found; however, also a perpendicular alignment of s-SWNTs was observed. Such orthogonal alignment of s-SWNTs is a rare observation and has not been experimentally reported before in detail with Raman images. Due to the unique electrode design, we were able to obtain substantial separation of m-SWNTs and s-SWNTs. Numerical modeling of the electric field factor of the dielectrophoresis force was done, and it matched perfectly with the experimental results. The orthogonal alignment of s-SWNTs results from comparable values of parallel and perpendicular polarizability to the nanotube axis.

LncRNA SBF2-AS1 promotes hepatocellular carcinoma metastasis by regulating EMT and predicts unfavorable prognosis.

OBJECTIVE: Recent studies have furthered our understanding of the function of long noncoding RNAs (lncRNAs) in numerous biological processes, including cancer. The present study aimed to investigate the expression of lncRNA SBF2-AS1 (SBF2-AS1) in patients with hepatocellular carcinoma (HCC) and to investigate its effect on HCC cells. PATIENTS AND METHODS: Using quantitative reverse transcription-polymerase chain reaction, we detected SBF2-AS1 expression in HCC cell lines and primary tumor tissues. The associations between SBF2-AS1 expression and the clinicopathological factors and outcome of HCC patients were statistically analyzed. MTT assay and transwell assay were performed to determine the proliferation, migration and invasion, respectively. In addition, we evaluated the activation of Mesenchymal-epithelial transition (EMT) pathway by Western blot. RESULTS: We found that SBF2-AS1 expression levels were significantly up-regulated in HCC tissues and cell lines compared with the corresponding noncancerous liver tissues and normal hepatic cell line. In addition, high SBF2-AS1 expression levels were correlated with vein invasion (p = 0.008) and TNM stage (p = 0.013). Furthermore, Kaplan-Meier survival analysis indicated that high expressions of SBF2-AS1 were correlated with shorter overall survival of HCC patients. Univariate and multivariate analysis identified high SBF2-AS1 expression as an unfavorable prognostic factor for overall survival. Further functional analysis demonstrated that knockdown of SBF2-AS1 significantly inhibited HCC cells proliferation, migration and invasion. Mechanistically, we found that SBF2-AS1 could promote the activation of EMT pathway, which was demonstrated by measuring the expression levels of EMT-related markers. CONCLUSIONS: SBF2-AS1 might be considered as a novel molecule involved in HCC development, which provides a potential therapeutic target for HCC.

Two-dimensional transition metal dichalcogenide alloys: preparation, characterization and applications.

Engineering electronic structure of atomically thin two-dimensional (2D) materials is of great importance to their potential applications. In comparison to numerous other approaches, such as strain and chemical functionization, alloying can continuously tune the band gaps in a wide energy range. Atomically thin 2D alloys have been prepared and studied recently due to their potential use in electronic and optoelectronic applications. In this review, we first summarize the preparation methods of 2D alloys (mainly on transition metal dichalcogenide (TMD) monolayer alloys), including mechanical exfoliation, physical vapor deposition (PVD), chemical vapor deposition (CVD) and chalcogen exchange. Then, atomic-resolution imaging, Raman and photoluminescence (PL) spectroscopy characterization of 2D alloys are reviewed, in which band gap tuning is discussed in detail based on the PL experiments and theoretical calculations. Finally, applications of 2D alloys in field-effect transistors (FETs), photocurrent generation and hydrogen evolution catalysis are reviewed.