Characterization of SnO2 nanowires synthesized from SnO by carbothermal reduction process

In this paper, single-crystalline SnO₂ nanowires have been successfully prepared by a carbothermal reduction process employing SnO as the starting material and CuO as the catalyst. Their morphologies, purity and sizes of the products were characterized by transmission electron microscopy (TEM), selected area electron diffraction, X-ray diffraction, field emission scanning electron microscopy (FESEM) and Raman spectroscopy, respectively. The FESEM images reveal wire-like and rod-shaped nanowires of about 100–800 μm in length and 30–200 nm in the transverse dimensions. The three observed Raman peaks at 474, 634 and 774 cm⁻¹ indicate the typical rutile phase of the SnO₂ which is in agreement with the X-ray diffraction results. The influence of some reaction parameters, including the temperature and the reaction duration, on the forming, morphology and particle size of SnO₂ crystallize is discussed.     

Ethanol sensing properties of CuO nanowires prepared by an oxidation reaction

The ethanol sensing properties of CuO nanowires prepared by oxidation reaction of copper plate have been examined. The characterization of CuO nanowires by FE-SEM, EDS, and TEM revealed diameters of 100–400 nm and a monoclinic structure with a growth direction along 〈1 1 0〉 direction. The ethanol sensing characteristics of CuO nanowires were studied at ethanol concentrations of 100–1000 ppm and working temperatures of 200–280 °C. An increase of resistance was observed under an ethanol vapor atmosphere due to the p-type semi-conducting property of CuO. It was found that the sensitivity, the response and the recovery time depended on the working temperatures and also ethanol concentration. The sensor exhibited the optimum sensitivity of 1.5 to ethanol vapor concentration of 1000 ppm at the working temperature of 240 °C with a response and recovery time of 110 and 120 s, respectively.     

Raman scattering and electrical conductivity of nitrogen implanted MoO3 whiskers

Whiskers of MoO₃ have been grown by a thermal transport process. A set of samples was then implanted with nitrogen ions at a dose of 5 × 10¹⁶ ion/cm². The implanted whiskers changed from transparent to semi-transparent. Raman spectroscopy of the whiskers was observed and compared with those of unimplanted whiskers. The results revealed that the Raman intensity of the implanted whiskers was decreased about 10 times with respect to that of unimplanted whiskers. Only the case of the wave propagation parallel to the a-axis, a lower suppression ratio of the B_3g modes was observed. No extra mode due to the nitrogen implantation was observed. This indicates that implantation could only induce defects and oxygen vacancies but not the structural transformation. From electrical conductivity and Hall measurement, it was found that the whiskers exhibited an n-type semiconductor and its conductivity drastically increased due to the defects and oxygen vacancies.     

Synthesis of MoO3 nanobelts by medium energy nitrogen ion implantation

Ion implantation has been revealed as a potential technique to modify the surface of materials. In this work, MoO₃ nanobelts were synthesized on MoO₃ whisker surfaces by means of ion implantation with 60 keV nitrogen ions at a dose of 1 × 10¹⁶ atom/cm² and characterized by scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. The result showed that the nanostructures of MoO₃ occurred over the whisker surfaces and had belt-like shapes. The size of the synthesized MoO₃ nanobelts mostly ranged from 20 to 60 nm in width and 300 to 800 nm in length. The nanobelts were found to have an orthorhombic crystal structure with growth preferential in the [001] direction. The growth process of the nanobelts based on the common vapor-solid mechanism is discussed.     

Repeated phosphate removal from recirculating aquaculture system using cyanobacterium remediation and chitosan flocculation

Unicellular cyanobacterium Synechocystis sp. was used for phosphate removal in a recirculating aquaculture system. The cell harvesting was performed using chitosan solution in this study. The parameters (i.e. cell density, pH of cell suspension and chitosan concentration) affecting the flocculation efficiency of chitosan were investigated. With the optimal condition, the repeated flocculation for phosphate removal in a photobioreactor was demonstrated. The results show that the flocculation efficiency of chitosan depends on cell density, pH of cell suspension and chitosan concentration. The optimal flocculation process could be accomplished by adjusting the pH to 7.2 before adding 20 mg/L chitosan followed by pH adjustment to 7.5. With single inoculation, the sequential process of phosphate removal using cyanobacterial uptake followed by cell flocculation using chitosan with the optimal condition in the photobioreactor was successfully achieved for 12 cycles with water from a recirculating fish tank.     

Ethanol sensor based on ZnO and Au-doped ZnO nanowires

ZnO nanowires and Au-doped ZnO nanowires were prepared by oxidation reaction. The oxidation was performed by heating zinc powder and a mixture of zinc and 1 wt% gold powder which was pressed into a tube shape at 600 °C for 24 h. The ethanol sensors based on ZnO nanowires were simply fabricated by applying silver electrode at each end of the tube and inserting a coil heater into the tube. The ethanol sensing properties of ZnO nanowires were observed from the resistance change under ethanol vapor atmosphere. By considering the sensitivity and response time, the optimum operating temperature of the ethanol sensor was found to be 240 °C. Also, it was found that the sensitivity of the sensor based on Au-doped ZnO nanowires exhibits higher value than that of the sensor based on undoped ZnO nanowires.     

Does Aphid Infestation Interfere with Indirect Plant Defense against Lepidopteran Caterpillars in Wild Cabbage?

Attraction of parasitoids to plant volatiles induced by multiple herbivory depends on the specific combinations of attacking herbivore species, especially when their feeding modes activate different defense signalling pathways as has been reported for phloem feeding aphids and tissue feeding caterpillars. We studied the effects of pre-infestation with non-host aphids (Brevicoryne brassicae) for two different time periods on the ability of two parasitoid species to discriminate between volatiles emitted by plants infested by host caterpillars alone and those emitted by plants infested with host caterpillars plus aphids. Using plants originating from three chemically distinct wild cabbage (Brassica oleracea) populations, Diadegma semiclausum switched preference for dually infested plants to preference for plants infested with Plutella xylostella hosts alone when the duration of pre-aphid infestation doubled from 7 to 14 days. Microplitis mediator, a parasitoid of Mamestra brassicae caterpillars, preferred dually-infested plants irrespective of aphid-infestation duration. Separation of the volatile blends emitted by plants infested with hosts plus aphids or with hosts only was poor, based on multivariate statistics. However, emission rates of individual compounds were often reduced in plants infested with aphids plus hosts compared to those emitted by plants infested with hosts alone. This effect depended on host caterpillar species and plant population and was little affected by aphid infestation duration. Thus, the interactive effect of aphids and hosts on plant volatile production and parasitoid attraction can be dynamic and parasitoid specific. The characteristics of the multi-component volatile blends that determine parasitoid attraction are too complex to be deduced from simple correlative statistical analyses.     

Characterization of perovskite LaFeO3 synthesized by microwave plasma method for photocatalytic applications

Perovskite LaFeO₃ nanoparticles were successfully synthesized by microwave plasma method combined with high temperature calcination at 700–1000?°C. The influences of calcination temperature on morphology, crystalline structure, purity and the atomic compositions of samples were studied. The photocatalytic performance of LaFeO₃ was evaluated though the photodegradation of Rhodamine B (RhB) under visible light. In this research, the orthorhombic LaFeO₃ nanoparticles showed band gaps in the range of 2.15–2.30?eV. The particle size increased with increasing in the calcination temperature, leading to the decreasing in the surface area. The LaFeO₃ sample calcined at 900?°C showed the highest photodegradation of 77.8% and the apparent rate constant of 0.0077?min^?1 within 180?min because of the narrower of band gap and the higher crystalline degree and oxygen adsorption.     

A Domain-Driven Approach for Detecting Event Patterns in E-Markets

An e-market can be thought of as a distributed event system where an event is generated every time the market’s state changes in response to a number of human or computing agents. The paper describes a practical application of event processing in an e-market context through conventional Event Processing Systems (EPSs). A new EPS architecture that allows the integration of several existing EPSs under a unified domain-specific user interface and execution environment is proposed. We assess the performance of a prototype system for a case study in financial market surveillance and its ability to provide a common interface for two existing EPSs–SMARTS and Coral8. A discussion on the experimental results and the issues arising from the proposed EPS architecture are also provided. Data supplied by Securities Industry Research Centre of Asia-Pacific (SIRCA) on behalf of Reuters. The data pre-processing step is not required when selecting SMARTS since it has the ability to process real-time market data as well.     

Three-dimensionality of field-induced magnetism in a high-temperature superconductor

Many physical properties of high-temperature superconductors are two-dimensional phenomena derived from their square-planar CuO2 building blocks. This is especially true of the magnetism from the copper ions. As mobile charge carriers enter the CuO2 layers, the antiferromagnetism of the parent insulators, where each copper spin is antiparallel to its nearest neighbours, evolves into a fluctuating state where the spins show tendencies towards magnetic order of a longer periodicity. For certain charge-carrier densities, quantum fluctuations are sufficiently suppressed to yield static long-period order, and external magnetic fields also induce such order. Here we show that, in contrast to the chemically controlled order in superconducting samples, the field-induced order in these same samples is actually three-dimensional, implying significant magnetic linkage between the CuO2 planes. The results are important because they show that there are three-dimensional magnetic couplings that survive into the superconducting state, and coexist with the crucial inter-layer couplings responsible for three-dimensional superconductivity. Both types of coupling will straighten the vortex lines, implying that we have finally established a direct link between technical superconductivity, which requires zero electrical resistance in an applied magnetic field and depends on vortex dynamics, and the underlying antiferromagnetism of the cuprates.