Investigation of ion induced bending mechanism for nanostructures

Ion induced bending is a promising controlled technique for manipulating nanoscale structures. However, the underlying mechanism of the process is not well understood. In this letter, we report a detailed study of the bending mechanism of Si nanowires (NWs) under Ga+ irradiation. The microstructural changes in the NW due to ion beam irradiation are studied and molecular dynamics simulations are used to explore the ion–NW interaction processes. The simulation results are compared with the microstructural studies of the NW. The investigations inform a generic understanding of the bending process in crystalline materials, which we suggest to be feasible as a versatile manipulation and integration technique in nanotechnology

Nuclear magnetic resonance probes for the Kondo scenario for the 0.7 feature in semiconductor quantum point contact devices

We propose a probe based on nuclear relaxation and Knight shift measurements for the Kondo scenario for the "0.7 feature" in semiconductor quantum point contact (QPC) devices. We show that the presence of a bound electron in the QPC would lead to a much higher rate of nuclear relaxation compared to nuclear relaxation through exchange of spin with conduction electrons. Furthermore, we show that the temperature dependence of this nuclear relaxation is very non-monotonic as opposed to the linear-T relaxation from coupling with conduction electrons. We present a qualitative analysis for the additional relaxation due to nuclear spin diffusion (NSD) and study the extent to which NSD affects the range of validity of our method. The conclusion is that nuclear relaxation, in combination with Knight shift measurements, can be used to verify whether the 0.7 feature is indeed due to the presence of a bound electron in the QPC.Comment: Published version. Appears in a Special Section on the 0.7 Feature and Interactions in One-Dimensional Systems. 16 page

On the Laminar Flow of Viscous Incompressible Fluid Through a Pipe Bounded by a Hyperbola and a Line

The present paper deals with laminar flow of a viscous incompressible fluid through a pipe bounded by a hyperbola and a line. The expressions, for the discharge of flux, maximum velocity and the coefficients k, k' as introduced by Boussinosqu (Bateman et al 1932) have been obtained. Graphs representing variations of velocity within the pipe give the final result

An artificial neural network model for rainfall forecasting in Bangkok, Thailand

This paper presents a new approach using an Artificial Neural Network technique to improve rainfall forecast performance. A real world case study was set up in Bangkok; 4 years of hourly data from 75 rain gauge stations in the area were used to develop the ANN model. The developed ANN model is being applied for real time rainfall forecasting and flood management in Bangkok, Thailand. Aimed at providing forecasts in a near real time schedule, different network types were tested with different kinds of input information. Preliminary tests showed that a generalized feedforward ANN model using hyperbolic tangent transfer function achieved the best generalization of rainfall. Especially, the use of a combination of meteorological parameters (relative humidity, air pressure, wet bulb temperature and cloudiness), the rainfall at the point of forecasting and rainfall at the surrounding stations, as an input data, advanced ANN model to apply with continuous data containing rainy and non-rainy period, allowed model to issue forecast at any moment. Additionally, forecasts by ANN model were compared to the convenient approach namely simple persistent method. Results show that ANN forecasts have superiority over the ones obtained by the persistent model. Rainfall forecasts for Bangkok from 1 to 3 h ahead were highly satisfactory. Sensitivity analysis indicated that the most important input parameter besides rainfall itself is the wet bulb temperature in forecasting rainfall

Bio-efficacy of phytoextracts and oil cakes on Macrophomina phaseolina (Tassi) causing stem rot disease of jute, Corchorus spp.

In the present study efforts were made to explore the efficacy of various plant extracts and oil cakes against Macrophomina phaseolina. The efficacy of eight different plant species, Zingiber officianale, Aloe indica, Lawsonia inermis, Chenopodium album, Allium cepa, Piper betel, Murraya koenigii, Parthenium hysterophorus aqueous extracts including oil cakes of mustard and neem were evaluated by using of poisoned food technique in vitro for their inhibitory effect on mycelial growth of M. phaseolina causing stem rot of jute (Corchorus olitorius and C. capsularis). The rhizome extract of Z. officinale produced maximum growth inhibition (74.59%) of the pathogen followed by leaf extracts of A. indica (63.57%), and leaf extract of L. inermis (60.17%) at the concentration of 10%. The maximum mycelial growth inhibition (52.40%) was recorded with neem cake (Azadirachta indica) at the concentrations of 20% followed by 42.61% and 29.60% with concentration of 15% and 10%, respectively. However, maximum mycelial growth inhibition (19.42%) was recorded with mustard cake (Brassica juncea) at the concentration of 20% followed by 16.64% and 12.20% at the concentration of 15% and 10% respectively. In general mycelial growth inhibition was dose dependent and it was maximum in case of neem cake than mustard cake. The present study revealed that, these plant extracts and oilcake extracts could be exploited for the possible control of deadly pathogen M. phaseolina. Accordingly, this is an important proactive measure in preventing the spread of the stem rot disease through a more ecofriendly approach

Flow injection analysis of iron in rain water with thiocyanate and surfactant

This paper explains a new procedure for flow injection analysis (FIA) determination of iron in rain water based on the colour reaction of Fe3+ with thiocyanate ions in the presence of the cationic surfactant cetylpyridinium chloride (CPC). The value of apparent molar absorptivity of the complex in terms of iron is (2.00) x 104 l mole-1 cm-1 at an absorption maximum of 490 nm. The detection limit of the method is 8 ppb Fe. The sample throughput is 90 samples/h at a flow rate of 4.0 ml/min. The reaction mechanism, optimization of FIA variables, and effect of various types of surfactant are described. None of the tested anions and cations interfered with the determination of iron. The method was used for the quantification and flux determination of iron in rain water

Nanoscale quantum dot infrared sensors with photonic crystal cavity

We report high performance infrared sensors that are based on intersubband transitions in nanoscale self-assembled quantum dots combined with a microcavity resonator made with a high-index-contrast two-dimensional photonic crystal. The addition of the photonic crystal cavity increases the photocurrent, conversion efficiency, and the signal to noise ratio (represented by the specific detectivity D*) by more than an order of magnitude. The conversion efficiency of the detector at Vb=–2.6 V increased from 7.5% for the control sample to 95% in the PhC detector. In principle, these photonic crystal resonators are technology agnostic and can be directly integrated into the manufacturing of present day infrared sensors using existing lithographic tools in the fabrication facility