Q. Chen

Synthesis and characterization of K2Ti6O13 nanowires

Abstract K2Ti6O13 nanowires with an average diameter of about 10 nm were synthesized by a simple hydrothermal reaction between Na2Ti3O7 and KOH. The nanowires were characterized by TEM, XRD, and EDX, and their growth was found to result from an ion exchange induced phase transition process. UV–Vis absorption spectrum of the nanowires shows a red shift relative to that of the raw materials.

Exfoliating KTiNbO5 particles into nanosheets

Abstract KTiNbO 5 nanosheets have been prepared by a simple intercalation and exfoliation method. The structures of these nanosheets were analyzed, the formation mechanism was discussed and bandgap was measured to be about 3.2 eV.

Imaging helical potassium hexaniobate nanotubes

Potassium hexaniobate nanotubes have been synthesized at room temperature and characterized by high-resolution transmission electron microscopy (HRTEM) and energy-dispersive x-ray analysis. It is shown that HRTEM images may be used effectively to determine the helicity of the nanotubes, and, in particular, it is found that almost all nanotubes have their axes pointing within a few degrees from the [100] direction of the K4Nb6O17 structure.

Nanosecond pulsed electric fields as a novel drug free therapy for breast cancer: An in vivo study

Nanosecond pulsed electric fields (nsPEFs) is a novel non-thermal approach to induce cell apoptosis. NsPEFs has been proven effective in treating several murine tumors, but few studies focus on its efficacy in treating human tumors. To determine if nsPEFs is equally effective in treatment of human breast cancer, 30 human breast cancer tumors across 30Balb/c (nu/nu) mice were exposed to 720 pulses of 100ns duration, at 4pulsespersecond and 30kV/cm. Two weeks after treatment, the growth of treated tumors was inhibited by 79%. Morphological changes of tumors were observed via a 3.0T clinical magnetic resonance imaging (MRI) system with a self-made surface coil. Pulsed tumors exhibited apoptosis evaluated by TUNEL staining, inhibition in Bcl-2 expression and decreased blood vessel density. Notably, CD34, vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) expression in treated tumors were strongly suppressed. To evaluate the might-be adverse effects of nsPEFs in healthy tissues, normal skin was treated exactly the same way as tumors, and pulsed skin showed no permanent damages. The results suggest nsPEFs is able to inhibit human breast cancer development and suppress tumor blood vessel growth, indicating nsPEFs may serve as a novel therapy for breast cancer in the future.

Dielectric barrier structure with hollow electrodes and its recoil effect

A dielectric barrier structure with hollow electrodes (HEDBS), in which gas flow oriented parallel to the electric field, was proposed. Results showed that with this structure, air can be effectively ignited, forming atmospheric low temperature plasma, and the proposed HEDBS could achieve much higher electron density (5 × 1015/cm3). It was also found that the flow condition, including outlet diameter and flow rate, played a key role in the evolution of electron density. Optical emission spectroscopy diagnostic results showed that the concentration of reactive species had the same variation trend as the electron density. The simulated distribution of discharge gas flow indicated that the HEDBS had a strong recoil effect on discharge gas, and could efficiently promote generating electron density as well as reactive species.

Controlled synthesis and phase transformation of ferrous nanowires inside carbon nanotubes

Abstract Carbon nanostructures filled with Fe were synthesized. It was found that both the shape and the phase of the carbon nanocapsulate may be controlled during the growth, and controlled ferrous amorphous–crystalline phase transformation may be realized via electron beam irradiation. Since an electron beam may be focused into a nanoscale probe, this method may in principle be used for fabricating amorphous–crystalline heterostructures inside carbon nanotubes.

Nanosecond pulsed electric fields inhibit breast cancer development and suppress tumor blood vessel growth

Breast cancer is one of the most threatening malignant tumors among women, the incidence of which is rising year by year. Despite of early screening and improvement in breast cancer management that have increased the 5-year survive rate, the requirement for novel and more efficient therapy for breast cancer is still quite urgent. In the recent decades, nanosecond pulsed electric fields, known as NsPEFs, have been proved to be able to induce cell apoptosis and tumor inhibition in various cancers. In this study, we established breast cancer animal model with MCF-7 cell line on Balb/c nude mice. An electric field over 30kV/cm was generated between to the two pads of the clamp, where the tumor was placed. Tumors were treated with nsPEFs on three consecutive days, and day 0 was set as the day when nsPEFs treatment was finished. Within 2 weeks after treatment, it was observed that tumor growth was significantly inhibited. The average volume and weight of pulsed tumors was almost 1/9 of that of unpulsed tumors. Morphological changes were observed in a 3.0T clinical magnetic resonance imaging (MRI) system with an own-made surface coil on day0, day7 and day14, which showed the shrinkage of the tumors. Apoptosis and hemorrhagic necrosis in tumor cells were inspected after nsPEFs treatement by H&E staining. Immuno-histological tests indicated VEGF expression in tumor cells was strongly suppressed. Tumor blood vessel density was calculated and found decreased after nsPEFs treatment. The results suggest nsPEFs can inhibit breast cancer development and suppress tumor blood vessel growth, which may serve as a novel therapy for breast cancer in the future.