Bis[3‐(diethoxyphosphoryl)propyl]diallylammonium chloride: Synthesis and use of its cyclopolymer as an antiscalant

A new symmetrically substituted cationic monomer bis[3‐(diethoxyphosphoryl)propyl]diallylammonium chloride has been synthesized and cyclopolymerized to give the corresponding cationic polyelectrolyte (+) (CPE) bearing two identical (diethoxyphosphoryl)propyl penedents on the pyrrolidinium repeating units. The hydrolysis of the phosphonate ester in (+) (CPE) gave a pH‐responsive cationic polyacid (+) (CPA) bearing the motifs of a tetrabasic acid. The (+) (CPA) under pH‐induced transformation was converted into a water‐insoluble polyzwitterion acid (±) (PZA) or water‐soluble polyzwitterion/monoanion (± ?) (PZMAN) or polyzwitterion/dianion (± =) (PZDAN) or polyzwitterion/trianion (± ≡) (PZTAN), all having identical degree of polymerization. The interesting solubility and viscosity behaviors of the polymers have been investigated in some detail. The apparent protonation constants of the anionic centers in (± ≡) (PZTAN) and its corresponding monomer (± ≡) (ZTAN) have been determined. Evaluation of antiscaling properties of the PZA using supersaturated solutions of CaSO₄ revealed ≈100% scale inhibition efficiency at a meager concentration of 10 ppm for a duration over 71 h at 40°C. The PZA has the potential to be an effective antiscalant in Reverse Osmosis plants. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40615.     

Hybrid Josephson Junctions with Iron-based and Conventional Superconductor Electrodes

We investigate the iron-based superconductor Ba(Fe _1?x Co _x ) ₂As ₂ (Ba-122) regarding its superconducting properties and possible applications. Therefore, Ba-122 thin films are used as base electrode to prepare different kinds of hybrid Josephson junctions with a counter electrode of the conventional superconductor Pb. Additionally, we use both c-axis and a b-plane transport geometries and different kinds of barriers like interface-engineered surfaces, sputtered titanium oxide and gold layers. Temperature dependent I– V characteristics as well as magnetic field dependence and microwave response of the junctions are shown. The examined I– V characteristics and I _c R _n– T behaviours of each junction type are compared and described according to the electrical behaviour of the respective normal conducting or insulating barrier. While the I _c R _n product of the interface-engineered barrier junction was 12 μV and the planar junction with Au barrier showed 18 μV, we could increase the I _c R _n to 90 μV for planar TiO _x barrier junctions.     

Precipitation polymerization in mixed monomer–solvent droplets

This contribution reports the precipitation copolymerization of lauryl methacrylate–divinylbenzene (LMA–DVB) in stable isolated droplets dispersed in water. The droplets contain either n‐hexadecane (HD) or HD–toluene (HD–T) or toluene as a nonsolvent for the resulting P(LMA–DVB) copolymer. The polymerization proceeds smoothly with an appreciably high content of DVB without the formation of coagulum and thus proves the quite high stability of the droplet reactors. The differences in the interaction between the nonsolvent–copolymer combinations allow the variation of the internal morphology of the particles between core and shell type, highly porous, and solid sphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41881.     

Developing cation exchange capacity and soil index properties relationships using a neuro-fuzzy approach

Artificial intelligence methods are employed to predict cation exchange capacity (CEC) from five different soil index properties, namely specific surface area (SSA), liquid limit, plasticity index, activity (ACT), and clay fraction (CF). Artificial neural networks (ANNs) analyses were first employed to determine the most related index parameters with cation exchange capacity. For this purpose, 40 datasets were employed to train the network and 10 datasets were used to test it. The ANN analyses were conducted with 15 different input vector combinations using same datasets. As a result of this investigation, the ANN analyses revealed that SSA and ACT are the most effective parameters on the CEC. Next, based upon these most effective input parameters, the fuzzy logic (FL) model was developed for the CEC. In the developed FL model, triangular membership functions were employed for both the input (SSA and ACT) variables and the output variable (CEC). A total of nine Mamdani fuzzy rules were deduced from the datasets, used for the training of the ANN model. Minimization (min) inferencing, maximum (max) composition, and centroid defuzzification methods are employed for the constructed FL model. The developed FL model was then tested against the remaining datasets, which were also used for testing the ANN model. The prediction results are satisfactory with a determination coefficient, R ² = 0.94 and mean absolute error, (MAE) = 7.1.     

A novel CVM precoding scheme for PAPR reduction in OFDM transmissions

High peak-to-average power ratio (PAPR) is still one of the major problems in orthogonal frequency division multiplexing (OFDM). In this article, a new precoding method is proposed and analyzed based on complex Vandermonde matrix (CVM). The reduction in PAPR of the OFDM signal is obtained using the decorrelation property of CVM which removes any redundancy from the input sequence and can be a very effective for PAPR reduction. Also, the phase-rotation property of CVM takes an advantage of the fact that the PAPR is very sensitive to phase-shifts of the signal. It is shown that the proposed precoding outperforms most of the powerful precoding techniques and can achieve a PAPR gain up to 6.5 and 7.4 dB for IEEE 802.11a and DVB-T OFDM systems respectively. Moreover, CVM precoding does not change power spectral levels or error performances when compared with the normal OFDM systems, also it does not increase the computational complexity when compared with the existing precoding methods. It is shown that the performance of the proposed precoding is independent of modulation schemes and the number of subcarriers. The proposed CVM precoding also takes advantage of the frequency variations of the communication channel and can provide considerable performance gain in fading-multipath channels.     

Assessment Of Impacts Of A Fossil Fuel Based Power Plant

Prediction of air pollution impacts of a proposed fossil fuel-based power plant has been made using meteorological data, information on stack characteristics and emission rate, baseline air quality and validated model condition. It is observed that under normal operation, the emission rate of SO 2 and NO 2 is significant, while under a worst case scenario, the SPM emission rate is significant. It has been predicted that 24-hr average SO 2 , NO 2 and SPM concentrations due to proposed plant in normal operation would be around 38 w g/m 3 , 40 w g/m 3 and less than 1 w g/m 3 , respectively, beyond the site boundary. The total 24-hr average SPM concentration under the worst case beyond site boundary would be below the national air quality standard for SPM in a mixed industrial area. Therefore, the impact of proposed power plant on local air quality would be acceptable. However, the implementation of a green belt comprising various tree spacies which will act as dust attenuators around the site boundary alongwith efficient control measures at source would efficiently mitigate and minimised pollution impacts from the proposed power plant.     

Effect of prior compression treatment on the deformation behavior of Zr based bulk metallic glass

In the present work, the plasticity of Zr_64.2Cu_11.2 Ni_14.6Al₁₀ bulk metallic glass was enhanced through prior compression treatment. A considerably large compressive plastic deformation (over 6.5%) was achieved by pressing Zr_64.2Cu_11.2 Ni_14.6Al₁₀ bulk metallic glass laterally in specially designed tool steel die before compression test. Numerical analysis was also carried out to investigate the stress distribution under same mechanical conditions. It was revealed that the lateral pressing induced structural heterogeneity and high stress gradients facilitate large plastic strains through the generation of dense multiple shear band network.     

A New PAPR Reduction Technique in OFDM Systems Using Linear Predictive Coding

High peak-to-average power ratio (PAPR) has always been as a major problem in orthogonal frequency division multiplexing (OFDM) that leads to a severe nonlinear distortion in practical hardware implementations of high power amplifier. In this article, a new PAPR reduction method is proposed based on linear predictive coding (LPC). This method proposes the use of signal whitening property of LPC as a preprocessing step in OFDM systems. Error filtering of the proposed method removes the predictable content of stationary stochastic processes which can reduce the autocorrelation of input data sequences and is shown to be very effective solution for PAPR problem in OFDM transmissions. It is shown that the proposed method can achieve a significant reduction in PAPR without degrading the power spectral level, error performance or computational complexity of the systems. It is also shown that the proposed method is independent of modulation schemes and can be applied to any number of subcarriers under both additive white gaussian noise and wireless Rayleigh fading channel.     

Efficient Hardware-Based Image Compression Schemes for Wireless Sensor Networks: A Survey

Multidimensional sensors, such as digital camera sensors in the visual sensor networks VSNs generate a huge amount of information compared with the scalar sensors in the wireless sensor networks WSNs. Processing and transmitting such data from low power sensor nodes is a challenging issue through their limited computational and restricted bandwidth requirements in a hardware constrained environment. Source coding can be used to reduce the size of vision data collected by the sensor nodes before sending it to its destination. With image compression, a more efficient method of processing and transmission can be obtained by removing the redundant information from the captured image raw data. In this paper, a survey of the main types of the conventional state of the art image compression standards such as JPEG and JPEG2000 is provided. A literature review of their advantages and shortcomings of the application of these algorithms in the VSN hardware environment is specified. Moreover, the main factors influencing the design of compression algorithms in the context of VSN are presented. The selected compression algorithm may have some hardware-oriented properties such as; simplicity in coding, low memory need, low computational load, and high-compression rate. In this survey paper, an energy efficient hardware based image compression is highly requested to counter the severe hardware constraints in the WSNs.     

Functional near-infrared neuroimaging.

Functional near-infrared spectroscopy (fNIR) is a neroimaging modality that enables continuous, noninvasive, and portable monitoring of changes in blood oxygenation and blood volume related to human brain function. Over the last decade, studies in the laboratory have established that fNIR spectroscopy provides a veridical measure of oxygenation and blood flow in the brain. Our recent findings indicate that fNIR can effectively monitor cognitive tasks such as attention, working memory, target categorization, and problem solving. These experimental outcomes compare favorably with functional magnetic resonance imaging (fMRI) studies, and in particular, with the blood oxygenation level dependent signal. Since fNIR can be implemented in the form of a wearable and minimally intrusive device, it has the capacity to monitor brain activity under real life conditions and in everyday environments. Moreover, the fNIR system is amenable to integration with other established physiological and neurobehavioral measures, including electroencephalogram, eye tracking, pupil reflex, heart rate variability, respiration, and electrodermal activity.