Giant Blistering of Nanometer-Thick Al2O3/ZnO Films Grown by Atomic Layer Deposition: Mechanism and Potential Applications.

Giant circular blisters of up to 300 µm diameter and 10 µm deflection have been produced on nanometer-thick Al2O3-on-ZnO stacks grown by atomic layer deposition at 150 °C followed by annealing at elevated temperatures. Their shape changes upon varied ambient pressures provide evidence that their formation is related to an anneal-induced outgassing combined with their impermeability. The former mainly occurs in the bottom ZnO layer that recrystallizes and releases residual hydroxide ions at elevated temperatures while the latter is dominantly contributed by the pinhole-free Al2O3 layer on top. Vibrations at a resonant frequency of ∼740 kHz are mechanically actuated and optically probed from an individual blister. By modulating the thickness and stacking sequence of Al2O3 and ZnO, we further demonstrate a localized circular film swelling upon electron-beam irradiation and its recovery after reducing the irradiation flux. The elastic blistering and the recoverable swelling of the nanometer-thick films represent a miniaturized event-driven mechanical system for potential functioning applications.

Optimal Shell Thickness of Metal@Insulator Nanoparticles for Net Enhancement of Photogenerated Polarons in P3HT Films.

Embedding metal nanoparticles in the active layer of organic solar cells has been explored as a route for improving charge carrier generation, with localized field enhancement as a proposed mechanism. However, embedded metal nanoparticles can also act as charge recombination sites. To suppress such recombination, the metal nanoparticles are commonly coated with a thin insulating shell. At the same time, this insulating shell limits the extent that the localized enhanced electric field influences charge generation in the organic medium. It is presumed that there is an optimal thickness which maximizes field enhancement effects while suppressing recombination. Atomic Layer Deposition (ALD) was used to deposit Al2O3 layers of different thicknesses onto silver nanoparticles (Ag NPs), in a thin film of P3HT. Photoinduced absorption (PIA) spectroscopy was used to study the dependence of the photogenerated P3HT(+) polaron population on the Al2O3 thickness. The optimal thickness was found to be 3-5 nm. This knowledge can be further applied in the design of metal nanoparticle-enhanced solar cells.

Atomic layer deposition of a MoS2 film.

A mono- to multilayer thick MoS2 film has been grown by using the atomic layer deposition (ALD) technique at 300 °C on a sapphire wafer. ALD provides precise control of the MoS2 film thickness due to pulsed introduction of the reactants and self-limiting reactions of MoCl5 and H2S. A post-deposition annealing of the ALD-deposited monolayer film improves the crystallinity of the film, which is evident from the presence of triangle-shaped crystals that exhibit strong photoluminescence in the visible range.

[Influence of combined ecological floating bed on nitrogen and phosphorus between overlying water and sediment].

A new type of combined ecological floating bed was developed on Swan Lake. It was combined with aquatic and hydrophilous plants and ancillary equipments that included floating controllers, water-cycling aerator systems and wave-making systems. Combined ecological floating bed changed the physical and chemical environment of Swan Lake and had an effect on the transportation and transformation of TN, NH4(+) -N and TP between overlying water and sediment during the experiment. The concentration change of TN, NH4(+) -N and TP and the effect of DO, Eh and pH on the nutrient in the overlying water and sediment were investigated. The results indicated that: in overlying water, the removal efficiencies of TN, NH4(+) -N and TP were 61.92%, 63.09% and 80.0%, respectively; the removal efficiencies of TN and NH4(+) -N were 23.79% and 37.04%, respectively; the concentration of TP increased by 43.71% in sediment during the experiment. The combined ecological floating bed influenced environmental factors such as DO, Eh and pH in overlying water in some degree. DO concentration rose from 8.7-8.9 mg x L(-1) to 9.3-10.4 mg x L(-1), and Eh concentration was from 163-178 mV to 191-198 mV. Both of them were higher than those in the contrast area. Phosphorus release was inhibited, and phosphorus adsorption was promoted through improving DO and Eh of the overlying water. The pH volatility was less and maintained between 7.51 and 8.32, and did not promote phosphorus release in sediment. TN, TP and NH4(+) -N in overlying water and TN and NH4(+) -N in sediment were significantly positively correlated with each other and with TP in sediment. The pH had no significant correlation with TN, TP and NH4(+) -N in overlying water and sediment. DO was significantly positively corrected with Eh in overlying water and was significantly negatively corrected with TP in sediment.

[Experimental studies on stability of flocs from cadmium pollution emergency treatment].

Taking the flocs from cadmium pollution emergency treatment of Longjiang River in Guangxi province as the research object, the stability of the flocs in the simulated static reservoirs and acidic floods was investigated based on the effects of disturbance and pH on the stability of the flocs. The results indicated that disturbance and pH had great effects on the stability of the flocs, and the concentrations of Cd2+ followed the order of pH 5.0 >> pH 6.0 > pH 7. 0 approximately pH 8.0 > pH 9.0 with the original pH of water. When the original pH of water was 5.0, the concentrations of Cd2+ in samples were 19-58 times higher than the national standard limit, and when the original pH of water were 6.0, 7.0, 8.0 and 9.0, respectively, the concentrations of Cd2+ in samples varied from below to 11 times higher than the national standard limit. The release of cadmium from the flocs was higher in the disturbed water, with the concentrations of Cd2+ in most samples higher than 5.0 microg x L(-1), and the highest was double of the national standard limit. In contrast, there was little release in the simulated static reservoirs, with the concentrations of Cd2+ in all samples below 5.0 microg x L(-1), which was lower than the national standard limit. Therefore, the flocs had good stability in the simulated static reservoirs. But it had poor stability in the simulated acidic floods, with higher release of cadmium, and the concentrations of Cd2+ in samples were 14-25 times higher than the national standard limit. Therefore, the monitoring of cadmium concentrations in the floods should be strengthened in the post project analysis for eco-environmental impact of Longjiang River.

A novel T-type overhangs improve the enzyme-free cloning of PCR products.

PCR product cloning is the foundational technology for almost all fields in the life sciences. Numerous innovative methods have been designed during the past few decades. Enzyme-free cloning is the only one that avoids post-amplification enzymatic treatments, making the technique reliable and cost effective. However, the complementary staggered overhangs used in enzyme-free cloning tend to result in self-ligation of the vector under some circumstances. Here, we describe a "T-type" enzyme-free cloning method: instead of designing the complementary staggered overhangs used in conventional enzyme-free cloning, we create "T-type" overhangs that reduce the possibility of self-ligation and are more convenient for multi-vector cloning. In this study, we systematically optimize "T-type" enzyme-free cloning, compare its cloning background with that in conventional enzyme-free cloning, and demonstrate a promising application of this technique in multi-vector cloning. Our method simplifies post-amplification procedures and greatly reduces cost, offering a competitive option for PCR product cloning.

Atomic layer deposition assisted template approach for electrochemical synthesis of Au crescent-shaped half-nanotubes.

This paper reports on a novel and versatile method to synthesize sharp-edged crescent-shaped half-nanotubes (HNTs) using a flexible template-based nanofabrication method assisted by atomic layer deposition. This was achieved by electrodeposition inside crescent-shaped nanochannels created by a controlled removal of a sacrificial layer, which was deposited by atomic layer deposition onto the pore walls of an anodic aluminum oxide template. This method provides a high degree of freedom in the manipulation of the morphological properties of HNTs such as the edge sharpness, opening, gap size, and the wall thickness. Initial optical investigations of the HNTs reveal distinct surface plasmon resonance by dark field scattering spectra and surface enhanced Raman spectrum.

The transition between conformal atomic layer epitaxy and nanowire growth.

Conformal atomic layer deposition of thin Sb(2)S(3) layers takes place epitaxially on suitable substrates at 90 degrees C. More elevated deposition temperatures increase the mobility of the solid and result in the diffusion of Sb(2)S(3) along surface energy gradients. On an Sb(2)Se(3) wire that presents the high-energy c facet at its extremity, this results in the axial elongation of the wire with a Sb(2)S(3) segment. When an Sb(2)S(3) wire whose c planes are exposed on the sides is used as the substrate, the homoepitaxy collects material laterally and yields a nano-object with a rectangular cross section.

Clomazone dissipation, adsorption and translocation in four paddy topsoils.

Laboratory experiments about the dissipation, adsorption and translocation in four paddy topsoils were conducted in this paper. From the results it can be concluded as follows: the dissipation rate of clomazone differed greatly in different paddy soil derived from different parent materials. The half-lives for clomazone degradation in paddy soils ranged from 5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy soil > alluvial sandy paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Clomazone sorption quantity was significantly correlated with organic carbon (R2 = 0.62) and clay content(R2 = 0.67) in the tested paddy soils. Positive correlation was found between apparent Kd value and cation exchange content(CEC). The consequences for the adsorption of different soils were purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm through four different unsaturated soil lysimeters over 24 h, clomazone was readily to be leached into lower surface soil and there was about 2.6%--4.2% of applied clomazone leached out of 20 cm cultivated soil layer. Translocation experiments showed that the order of clomazone leaching ability was: alluvial sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Simple regression results manifested that factors like CEC, organic carbon, clay, and adsorption rate constant had been negatively correlated with the percentage of clomazone loss from soil lysimeters.