An efficient fully bio‐based reactive diluent for epoxy thermosets: 2‐[(Oxiran‐2‐ylmethoxy) methyl] furan versus a petroleum‐based counterpart

Furfuryl alcohol and bio‐based epichlorohydrin were used to prepare a fully bio‐based reactive diluent, 2‐[(oxiran‐2‐ylmethoxy) methyl] furan (FOM). After spectral characterization, FOM was blended with epoxy resin, diglycidylether bisphenol A (DGEBA), at different ratios for reducing the viscosity. For a comparison, Cardura (one of the most common commercial reactive diluents), was separately incorporated to DGEBA. Amine‐curing process of the blends was recorded by FTIR and DSC. Similar trends of curing progression for DGEBA containing the reactive diluents were observed. Thermogravimetric analysis and dynamic mechanical thermal analysis, mechanical (hardness, adhesion, and stress–strain) and morphological properties were also investigated to study characteristics of the epoxy matrices formulated with FOM or Cardura. It was concluded that FOM could be considered as an efficient reactive diluent in formulations of polymer composites, structural adhesives and surface coatings based on epoxy resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44957.     

Wavelets and statistical analysis of functional magnetic resonance images of the human brain

Wavelets provide an orthonormal basis for multiresolution analysis and decorrelation or 'whitening' of nonstationary time series and spatial processes. Wavelets are particularly well suited to analysis of biological signals and images, such as human brain imaging data, which often have fractal or scale-invariant properties. We briefly define some key properties of the discrete wavelet transform (DWT) and review its applications to statistical analysis of functional magnetic resonance imaging (fMRI) data. We focus on time series resampling by 'wavestrapping' of wavelet coefficients, methods for efficient linear model estimation in the wavelet domain, and wavelet-based methods for multiple hypothesis testing, all of which are somewhat simplified by the decorrelating property of the DWT.     

A framework for background modelling and shadow suppression for moving object detection in complex wavelet domain

This paper describes a simple, robust and efficient framework for background subtraction and cast shadow suppression in complex wavelet domain. A background subtraction approach exploiting noise resilience capability of wavelet domain combined with local spatial coherence and median filter in the training stage is proposed. A novel shadow suppression scheme based on directional coefficients of Daubechies complex wavelet transform is introduced. The effectiveness of the proposed approach is demonstrated via qualitative and quantitative evaluation measures on both indoor and outdoor video sequences. The experimental results show that the proposed approach outperforms state-of-the-art methods.     

Functionalized poly (vinyl alcohol) polymer as chemodosimeter material for the colorimetric sensing of cyanide in pure water

New poly (vinyl alcohol) (PVA) derivative containing pendant chemoselective functionality is prepared for the cyanide detection in pure water. Particularly, incorporation of the chemodosimeter 4 on PVA is performed by direct coupling of the hydroxyl group of the dye 4 and PVA hydroxyl groups via ethereal linkage using di-bromoalkane as a cross-linking agent. The chemosensory capacity of the polymeric material for the colorimetric sensing of cyanide in water is based on the reactivity of this anion toward the chemodosimeter, and its water solubility is given by PVA moiety. The chemodosimeter is developed on the basis of the trifluoroacetyl group as electrophile receptor of the cyanide anions. The final water soluble functionalized polymer presents a sensible selectivity toward cyanide anions in pure water.     

Photodegradation of CL-20: insights into the mechanisms of initial reactions and environmental fate

Hexanitrohexaazaisowurtzitane (HNIW) or CL-20 is a caged structure polycyclic nitramine that may replace RDX and HMX as a common use energetic chemical. To provide insight into the environmental fate of CL-20 we photolyzed the chemical in a Rayonet photoreactor (254-350 nm) and with sunlight in aqueous solutions. Previously, we found that initial photodenitration of the monocyclic nitramine RDX leads to ring cleavage and decomposition. Presently, we found that photolysis of the rigid molecule CL-20 produced NO2-, NO3-, NH3, HCOOH, N2 and N2O. Using LC/MS (ES-) we detected several key intermediates carrying important information on the initial steps involved in the degradation of CL-20. The identities of the intermediates were confirmed using a uniformly ring labeled 15N-[CL-20]. When CL-20 was photolyzed in the presence of H2(18)O, D2O or 18O2 we obtained a product distribution suggesting that the energetic chemical degraded via at least two initial routes; one involved sequential homolysis of N-NO2 bond(s) and another involved photorearrangement prior to hydrolytic ring cleavage and decomposition in water.     

Performance evaluation of Wi‐Fi and WiMAX over OFDM physical layer

Orthogonal frequency division multiplexing (OFDM) is an alternative technology that is constrained to keep up with the increasingly high data transmission rate due to its robustness against selective frequency fading and its resistance to intersymbol interference (ISI). This paper aims to study and optimize its performance, namely, its probability of communication failure and signal‐to‐interference‐plus‐noise ratio (SINR) metrics. The mathematical tool used to perform OFDM evaluation and analysis is the Fourier transform and its properties. The obtained results of those equations led to the demonstration of the probability of communication outage and to notice that the cutoff time occurs after the 10th iteration for values of λ less than or equal to 1. It could also be checked that this period is small if λ exceeds 1 by considering the sensitivity factor. Moreover, for the obtained results, in terms of bit error rate (BER) and SINR, the influence of the modulation on the error vector magnitude (EVM) shows the sensitivity factor Ω presents a key role in the transmission chain.     

A unified short-channel compact model for cylindrical surrounding-gate MOSFET

For the first time, a continuous and explicit model valid in all operating regions, for undoped short-channel cylindrical gate-all-around (GAA) MOSFETs, is presented in this study. From a two-dimensional analysis, the threshold voltage roll-off, the drain-induced barrier lowering (DIBL) and the subthreshold swing are explicitly modeled. Short-channel effects are then implemented into a continuous drain-current model based on an effective surface potential approach using the gradual channel approximation. Improving the model behavior in the saturation operating region by accounting the channel pinch-off displacement, channel length modulation is studied and implemented as well. Analytical results are compared to TCAD-Atlas numerical simulations and validate the short-channel model in all operating modes making it suitable for circuit design simulations.     

Characterization of β-lactamase- and efflux pump-mediated multiple antibiotic resistance in Salmonella Typhimurium

Food Science and Biotechnology - This study aimed to assess the β-lactamase- and efflux pump-mediated antibiotic resistance in Salmonella Typhimurium (WT-ST), ciprofloxacin-induced...     

The undecimated wavelet decomposition and its reconstruction.

This paper describes the undecimated wavelet transform and its reconstruction. In the first part, we show the relation between two well known undecimated wavelet transforms, the standard undecimated wavelet transform and the isotropic undecimated wavelet transform. Then we present new filter banks specially designed for undecimated wavelet decompositions which have some useful properties such as being robust to ringing artifacts which appear generally in wavelet-based denoising methods. A range of examples illustrates the results.