Silver catalyzed gallium phosphide nanowires integrated on silicon and in situ Ag-alloying induced bandgap transition.

In this work, we demonstrate a silver catalyzed heteroepitaxial growth of gallium phosphide nanowires (GaP NWs) on silicon. The morphology and growth direction of GaP NWs on differently orientated Si substrates were investigated. From crystallographic analysis, we inferred that Ag from catalyst is incorporated into the GaP during the chemical beam epitaxy (CBE) process. Using the PL spectrum and time-resolved emission spectroscopy, the optical properties of Ag-catalyzed GaP NWs were greatly modified, with bandgap transitions in the blue range. The Raman characterizations further confirmed the Ag incorporation into GaP during the growth. From the bandgap calculations, it was deduced that Ag was substituted on the Ga site with bandgap broadening. The in situ Ag-alloying during the growth of Ag-catalyzed GaP NWs greatly modified the band structure of GaP, and could lead to further applications in optoelectronics for low-dimensional GaP-based nanomaterials.

Sensitization of Mn2+ luminescence via efficient energy transfer to suit the application of high color rendering WLEDs.

Developing novel luminescent materials with ideal properties is an endless project, urged by growing requirements of advances in energy saving, healthy lighting and environmental friendliness. Herein, a series of ScCaOBO3:Ce3+,Mn2+ phosphors with excellent luminescence properties were synthesized by the high temperature solid state method. X-ray diffraction was applied to analyse the phase composition of the obtained phosphors. The morphology and dopant distribution were observed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The Rietveld refinements and luminescence spectra indicate that Ce3+ preferentially occupies the Sc3+ site and produces a blue emission band at around 460 nm, which originates from the characteristic 5d-4f transitions, while Mn2+ preferentially occupies the Ca2+ site and emits red light due to its characteristic 4T1(4G)-6A1(6S) transitions. Upon excitation at 354 nm, both Ce3+ and Mn2+ emissions can be obtained and further investigations evidenced that the broad and intense light emission of Mn2+ located in the red spectral region is the result of energy transfer from Ce3+ to Mn2+. Theoretical calculations reveal that the energy transfer process from Ce3+ to Mn2+ is of the resonance type and is governed by electric dipole-dipole interactions. Since the ScCaOBO3:Ce3+,Mn2+ phosphors are capable of producing broadband emissions that widely cover the blue and red spectral regions, the introduction of a green light-emitting phosphor CMA:Tb3+ can conveniently generate high quality white light. Therefore, a white light-emitting diode device with extremely high color rendering indices, Ra = 93.7 and R9 = 91.9, was successfully obtained.

MicroRNA-34a inhibits cells proliferation and invasion by downregulating Notch1 in endometrial cancer.

MicroRNAs (miRNAs) are small non-coding RNAs composed of 18-25 nucleotides that regulate the expression of approximately 30% of human protein coding genes. Dysregulation of miRNAs plays a pivotal role in the initiation and progression of malignancies. Our study has shown that microRNA-34a (miR-34a) was upregulated in human endometrial cancer stem cells (ECSCs). However, it is unknown how miR-34a regulates endometrial cancer itself. Here, we report that miR-34a directly and functionally targeted Notch1. MiR-34a inhibited the proliferation, migration, invasion, EMT-associated phenotypes by downregulating Notch1 in endometrial cancer cells. Overexpression of miR-34a also suppressed tumor growth in nude mice. Importantly, further results suggested miR-34a was significantly downregulated in endometrial cancer tissues and negatively correlated with Notch1 expression. There was a significant association between decreased miR-34a expression and worse patient prognosis. Taken together, our results suggest that miR-34a plays tumor-suppressive roles in endometrial cancer through downregulating Notch1. Thus miR-34a could be a potential therapeutic target for prevention and treatment of endometrial cancer.

Vertically Free-Standing Ordered Pb(Zr0.52Ti0.48)O3 Nanocup Arrays by Template-Assisted Ion Beam Etching.

In this report, vertically free-standing lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanocup arrays with good ordering and high density (1.3 × 10(10) cm(-2)) were demonstrated. By a template-assisted ion beam etching (IBE) strategy, the PZT formed in the pore-through anodic aluminum oxide (AAO) membrane on the Pt/Si substrate was with a cup-like nanostructure. The mean diameter and height of the PZT nanocups (NCs) was about 80 and 100 nm, respectively, and the wall thickness of NCs was about 20 nm with a hole depth of about 80 nm. Uppermost, the nanocup structure with low aspect ratio realized vertically free-standing arrays when losing the mechanical support from templates, avoiding the collapse or bundling when compared to the typical nanotube arrays. X-ray diffraction (XRD) and Raman spectrum revealed that the as-prepared PZT NCs were in a perovskite phase. By the vertical piezoresponse force microscopy (VPFM) measurements, the vertically free-standing ordered ferroelectric PZT NCs showed well-defined ring-like piezoresponse phase and hysteresis loops, which indicated that the high-density PZT nanocup arrays could have potential applications in ultra-high non-volatile ferroelectric memories (NV-FRAM) or other nanoelectronic devices.

Ferroelectric Resistive Switching in High-Density Nanocapacitor Arrays Based on BiFeO3 Ultrathin Films and Ordered Pt Nanoelectrodes.

Ferroelectric resistive switching (RS), manifested as a switchable ferroelectric diode effect, was observed in well-ordered and high-density nanocapacitor arrays based on continuous BiFeO3 (BFO) ultrathin films and isolated Pt nanonelectrodes. The thickness of BFO films and the lateral dimension of Pt electrodes were aggressively scaled down to <10 nm and ∼60 nm, respectively, representing an ultrahigh ferroelectric memory density of ∼100 Gbit/inch(2). Moreover, the RS behavior in those nanocapacitors showed a large ON/OFF ratio (above 10(3)) and a long retention time of over 6,000 s. Our results not only demonstrate for the first time that the switchable ferroelectric diode effect could be realized in BFO films down to <10 nm in thickness, but also suggest the great potentials of those nanocapacitors for applications in high-density data storage.

One-Step Mask Etching Strategy Toward Ordered Ferroelectric Pb(Zr0.52Ti 0.48)O 3 Nanodot Arrays.

In this report, ordered lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanodot arrays were fabricated by an original one-step mask etching route. The one-step mask etching strategy is based on the patterned nanostructure of barrier layer (BL) at the bottom of anodic aluminum oxide (AAO), by a direct transfer of the nanopattern from BL to the pre-deposited PZT film, without introduction of any sacrifice layer and lithography. Therefore, the presented strategy is relatively simple and economical. X-ray diffraction and Raman analysis revealed that the as-prepared PZT was in a perovskite phase. Atomic and piezoresponse force microscopy indicated that the PZT nanodot arrays were with both good ordering and well-defined ferroelectric properties. Considering its universality on diverse substrates, the present method is a general approach to the high-quality ordered ferroelectric nanodot arrays, which is promising for applications in ultra-high density nonvolatile ferroelectric random access memories (NV-FRAM).

Current rectifying and resistive switching in high density BiFeO3 nanocapacitor arrays on Nb-SrTiO3 substrates.

Ultrahigh density well-registered oxide nanocapacitors are very essential for large scale integrated microelectronic devices. We report the fabrication of well-ordered multiferroic BiFeO3 nanocapacitor arrays by a combination of pulsed laser deposition (PLD) method and anodic aluminum oxide (AAO) template method. The capacitor cells consist of BiFeO3/SrRuO3 (BFO/SRO) heterostructural nanodots on conductive Nb-doped SrTiO3 (Nb-STO) substrates with a lateral size of ~60 nm. These capacitors also show reversible polarization domain structures, and well-established piezoresponse hysteresis loops. Moreover, apparent current-rectification and resistive switching behaviors were identified in these nanocapacitor cells using conductive-AFM technique, which are attributed to the polarization modulated p-n junctions. These make it possible to utilize these nanocapacitors in high-density (>100 Gbit/inch(2)) nonvolatile memories and other oxide nanoelectronic devices.