Electrical and optical properties of ZrxLa1−xOy nanocrystallites as an advanced dielectric for the next FET devices

In the present work, the spatial distribution of the leakage current through Zr_xLa_1?xO_y thin films with different degrees of crystallinity temperatures was investigated. Zr_xLa_1?xO_y nanocrystallites were prepared by sol–gel method, in that Zr atomic fractions in the combined is at the range of x = 5–60 %. The nanocrystallite’s phases and properties were characterized with using X-ray diffraction, fourier transfer infrared radiation, scanning electron microscopy, atomic force microscopy and transmission electron microscopy techniques. Electrical property characterization was also performed with cyclic-voltameter (C-V) technique in TRIS solution (pH = 7.3, with the formula (HOCH₂)₃CNH₂). C-V measurements showed current flow through the TRIS reduces at higher temperatures. Moreover, elemental qualitative analysis was performed with map and energy dispersive X-ray spectra confirmed above claims.     

Optimization of biological synthesis of silver nanoparticles using Lactobacillus casei subsp. casei

BACKGROUND: The objectives of this study were optimization of silver nanoparticle synthesis using biotransformations by Lactobacillus casei subsp. casei, and studying the location of nanoparticles synthesis in this microorganism. RESULTS: The presence of AgNO₃ (0.1 mmol L^?1) in the culture as the enzyme inducer, and glucose (56 mmol L^?1) as the electron donor in the reaction mixture had positive effects on nanoparticle production. By gradually increasing the concentration of AgNO₃ (as the substrate) to 6 mmol L^?1, nanoparticle production was increased. By increasing biomass, nanoparticles production was also increased. Biosynthesized silver nanoparticles were almost spherical, single (25–50 nm) or in aggregates (100 nm), attached to the surface of biomass or were inside and outside of the cells. CONCLUSION: The present study demonstrated the bioreductive synthesis of silver nanoparticles using L. casei subsp. casei at room temperature. In this research, and due to experience in optimization of biotransformation reactions, the reaction conditions were successfully optimized to increase the yield of nanoparticles production and productivity of this biosynthetic approach. Copyright © 2012 Society of Chemical Industry     

Fabrication and modification of acrylonitrile–butadiene–styrene‐based heterogeneous ion‐exchange membranes by plasma treatment: Investigation of the nanolayer deposition rate and temperature effects

Our target in this study was the preparation of electrodialysis ion‐exchange membranes with appropriate properties for applications in water recovery and treatment. Composite mixed‐matrix, anion‐exchange membranes were prepared by a solution casting technique with acrylonitrile–butadiene–styrene as a base binder, resin powder as a functional group agent, activated carbon as an adsorptive filler, and an Ag nanolayer as a surface modifier. The Ag nanolayer was used with a magnetron sputtering method. The effect of the nanolayer deposition rate (R_q) and substrate and annealing temperatures on the physicochemical characteristics of the membranes were studied. The X‐ray diffraction results show that average grain size of the nanolayer and membrane crystallinity were improved with increasing R_q. The atomic force microscopy and scanning electron microscopy results show that the membrane roughness was enhanced with increasing R_q. The height distribution results also show the best height distribution for the modified membrane at low R_q. The selectivity and flux decreased with increasing nanolayer R_q in the membranes. The selectivity was also decreased initially with increases in the substrate and annealing temperatures from 300 to 325 K in the membranes and then showed an increasing trend. An opposite trend was found for flux with variations in the temperature. The modified membrane containing a 20‐nm Ag nanolayer at low R_q showed better performance compared to the other modified membranes and the pristine one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40025.     

Modeling of membrane bioreactor treating hypersaline oily wastewater by artificial neural network

A membrane sequencing batch reactor (MSBR) treating hypersaline oily wastewater was modeled by artificial neural network (ANN). The MSBR operated at different total dissolved solids (TDSs) (35,000; 50,000; 100,000; 150,000; 200,000; 250,000 mg/L), various organic loading rates (OLRs) (0.281, 0.563, 1.124, 2.248, and 3.372 kg COD/(m³ day)) and cyclic time (12, 24, and 48 h). A feed-forward neural network trained by batch back propagation algorithm was employed to model the MSBR. A set of 193 operational data from the wastewater treatment with the MSBR was used to train the network. The training, validating and testing procedures for the effluent COD, total organic carbon (TOC) and oil and grease (O&G) concentrations were successful and a good correlation was observed between the measured and predicted values. The results showed that at OLR of 2.44 kg COD/(m³ day), TDS of 78,000 mg/L and reaction time (RT) of 40 h, the average removal rate of COD was 98%. In these conditions, the average effluent COD concentration was less than 100 mg/L and met the discharge limits.     

Assessment quality of a nonuniform suspended sediment transport model under unsteady flow condition (case study: Aras River)

This study presents a one‐dimensional, fully coupled numerical model for nonequilibrium suspended sediment transport that can be applied to channels and alluvial rivers. The accuracy of calculations was enhanced using a nonuniform size distribution, and evaluating probability of hiding and exposure effect of particles. This model is also capable of calculating the flocculation and temperature effect on sediment transport. In addition, the BOD and its influence on suspended sediment transport have been discussed. The study was conducted on the Aras River, Iran's third major river with a relatively high sediment concentration. To verify the model, water depth and sediment concentration of measured field data are compared with simulated data. Comparisons show a regression coefficient of more than 95% and mean computational error is less than 5%. The agreement of the data shows that the model is capable of predicting flow and suspended sediment transport with a correlation coefficient higher than 98%.     

Innately adaptive robotics through embodied evolution

Autonomous adaptation in robots has become recognised as crucial for devices deployed in remote or inhospitable environments. The aim of this work is to investigate autonomous robot adaptation, focussing on damage recovery and adaptation to unknown environments. An embodied evolutionary algorithm is introduced and its capabilities demonstrated with experimental results. This algorithm is shown to be able to control the motion of a robot snake effectively; this same algorithm inherently recovers the snake’s motion after damage. Another experiment shows that the algorithm is capable of contorting a shape-changing antenna in such a way as to minimise the affect of background noise on it, thus allowing the antenna to achieve a better signal.     

Paddy Fields as Electrically Dense Media: Theoretical Modeling and Measurement Comparisons

Early models for paddy fields consist of a single-layered medium in which coherent effects within clusters of leaves are considered but multiple volume scattering is not. In this paper, the paddy canopy is modeled as a multilayered dense discrete random medium consisting of cylindrical and needle-shaped scatterers. Consideration is given to the coherent and near-field effects of the closely spaced scatterers through the Dense Medium Phase and Amplitude Correction Theory and Fresnel corrections, respectively, in the phase matrix. Then, this dense medium phase matrix is applied in the radiative transfer equations and solved up to the second order to consider double-volume scattering. Ground truth measurements of paddy fields were acquired at Sungai Burung, Selangor, Malaysia, for an entire season from the early vegetative stage of the plants to their reproductive stage. Measured parameters are used in the theoretical model to calculate the backscattering coefficients of paddy fields. Theoretical analysis of the simulation results shows in particular that second-order effects are important for cross-polarized backscatter data and that coherent effects need to be considered at lower frequencies. However, the use of needles to represent paddy leaves tends to underestimate the HH-polarized backscattering coefficients especially at the latter stages of plant growth, i.e., when the leaves are broader. The results are also used for comparisons with the backscattering coefficients obtained from RADARSAT images as well as that of earlier models to test the validity of the dense medium model with promising results.     

Effect of Global Warming on Intensity and Frequency Curves of Precipitation, Case Study of Northwestern Iran

Predicting natural phenomena like flood and drought and consequently presenting an appropriate solution for fighting such natural hazards in northwestern Iran is considered in this study through clustering the precipitation regime. To compare the reference period (past) with the simulated data, the statistics of daily precipitation in six stations of Ardebil, Ghazvin, Hamedan, Kermanshah, Sanandaj, and Tabriz, have been provided for a 30-year period (1961–1990) and compared with the simulated data of 2021–2050. The simulated data was generated by general atmosphere circulation model HADCM3, A1scenario and was downscaled using the LARS-WG model. The method for comparing precipitations was done based on clustering in the form of 5 clusters for all the stations and study periods. One of the results of this research is the greater concentration of precipitation for the cold periods of the year (winter and fall) and the increase of annual precipitation by the amount of 20.62 mm for future period. Furthermore, the normality of two coordinates of precipitation and cluster frequency percentage was evaluated. The outputs of this section demonstrate that the precipitations of cluster 3 which have the features of light rain with average intensity, fall on this normal line for most of the stations and study periods. On the other hand, precipitations of cluster 1 indicating very heavy and intense precipitations, have the most distance to the normal line in most cases. Therefore, the precipitations of the third cluster need optimal exploitation management while those of the first cluster need required risk and crisis management.     

Novel natural and biomimetic ligands to enhance selectivity of membrane processes for solute‐solute separations: beyond nature's logistic legacy

The integration of natural or biomimetic ligands in membrane processes was explored, focusing on simplicity and originality, with an eye to increasing the often moderate selectivity. Due to their simple structure, selection and manufacturing procedure, aptamers could dramatically increase the cost effectiveness of ligand‐based membrane processes. Proteins are distinctly more complex than aptamers, but many excel in organizing selective transmembrane transport. The channel geometry of aquaporins was also found to be tailored for high fluxes by minimizing vortex formation. Incorporation of bacterial porins could tremendously increase the performance of nanofiltration membranes by increasing the rejection of apolar often more toxic compounds. Sugar‐selective porins on the other hand, could be used to manufacture the first chemical‐free membrane adsorber. Ultimately, bacterial strains could be selected, through multiple evolution cycles, which express porins tailored to recognize specific molecules. Lectins are definitely better suited than porins for high resolution carbohydrate purification. Lectins could be used to effectively separate different sugar isomers in one bind and elution step. The potential of Concanavalin A for the purification of the natural sweetener stevioside was explored. A discrimination factor in dissociation constant of a factor 6 and 23 was obtained in silico relative to glucose and mannose respectively. Finally, a new method was discussed from the field of drug design that can determine the selectivity in silico, independent of other competing ligands or targets. The intrinsic selectivity ratio seems to solve an age‐old problem and another possible impediment to swift industrial application of ligand‐based membrane processes. © 2013 Society of Chemical Industry