Broadband bowtie belt nanoantennas

In this article, we study a linear array of bowtie nanoantennas placed between two metallic strips that can work from 800 to 1420 nm (600 nm linewidth), with an electric field enhancement factor close to 20. We study the dynamical change of the position of the electric field enhancement amongst different elements in the array and, at the same time, the effects of dispersion on the scalability of the array elements. A systematic analysis and methodology to produce an array that can operate over a large bandwidth whilst maintaining the electric field enhancement without significant variation is provided.     

Prediction of phosphorus content of electroless nickel–phosphorous coatings using artificial neural network modeling

A multilayer feedforward neural network with two hidden layers was designed and developed for prediction of the phosphorus content of electroless Ni–P coatings. The input parameters of the network were the pH, metal turnover, and loading of an electroless bath. The output parameter was the phosphorus content of the electroless Ni–P coatings. The temperature and molar rate of the bath were constant ( 91^° \textC, 0.4 \textNi^{\text + +} /\textH₂ \textPO₂ ^{- -} 91^\circ {\text{C}},\:0.4\,{\text{Ni}}^{{{\text{ + + }}}} /{\text{H}}_{2} {\text{PO}}_{2}^{{ - - }} ). The network was trained and tested using the data gathered from our own experiments. The goal of the study was to estimate the accuracy of this type of neural network in prediction of the phosphorus content. The study result shows that this type of network has high accuracy even when the number of hidden neurons is very low. Some comparison between the network’s predictions and own experimental data are given.     

Sequency Domain Signal Processing Using Complex Hadamard Transform

Signal processing can be performed in time domain as well as intransform domain. Frequency domain is perhaps the most widely used domain for transform domain signal processing. In this paper we analyze sequency domain (SD) signal processing as an alternate to the conventional frequency domain signal processing. We perform signal processing in sequency domain using conjugate-symmetric sequency-ordered complex Hadamard transform and compare the results with those of discrete Fourier transform. We observe that in comparison with frequency spectrum, spectral energy of sequency spectrum is spread over the entire spectrum. We performed signal and image denoising in SD and found that our designed SD filters effectively denoise the signals.     

Do ‘passive’ medical titanium surfaces deteriorate in service in the absence of wear?

Globally, more than 1000 tonnes of titanium (Ti) is implanted into patients in the form of biomedical devices on an annual basis. Ti is perceived to be ‘biocompatible’ owing to the presence of a robust passive oxide film (approx. 4 nm thick) at the metal surface. However, surface deterioration can lead to the release of Ti ions, and particles can arise as the result of wear and/or corrosion processes. This surface deterioration can result in peri-implant inflammation, leading to the premature loss of the implanted device or the requirement for surgical revision. Soft tissues surrounding commercially pure cranial anchorage devices (bone-anchored hearing aid) were investigated using synchrotron X-ray micro-fluorescence spectroscopy and X-ray absorption near edge structure. Here, we present the first experimental evidence that minimal load-bearing Ti implants, which are not subjected to macroscopic wear processes, can release Ti debris into the surrounding soft tissue. As such debris has been shown to be pro-inflammatory, we propose that such distributions of Ti are likely to effect to the service life of the device.     

New calix[4]arenedimethacrylate derivatives for dental composites

Calix[4]arenes were double alkylated with various alkylhalogenides and the residual OH functions were subsequently dimethacrylated with methacryloyl chloride. The successful synthesis of polymerizable calixarenes was proved using ¹H NMR spectroscopy, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry and differential scanning calorimetry. The polymerization behaviour was confirmed by copolymerization with methacrylic acid methyl ester. Furthermore, the flexural strength, the flexural modulus of elasticity, the exothermic course of the photo‐curing reaction and the polymerization shrinkage of experimental dental filling composites containing the modified calixarenes were evaluated. Copyright © 2012 Society of Chemical Industry     

Methacrylated calix[4]arene phosphonic acids as functionalized crosslinker for radical polymerization

We describe the synthesis of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dioxypropylphosphonic acid‐26,28‐dimethacryloyloxy‐calix [4]arene and 5,11,17,23‐tetra‐tert‐butyl‐25‐oxypropylphosphonic acid‐27‐hydroxy‐26,28‐dimethacryloyloxy‐calix[4]arene starting from para‐tert‐butyl‐calix[4]arene. The complete reaction was proved by matrix‐assisted laser desorption ionization time of flight mass spectrometry and nuclear magnetic resonance spectroscopy. The influence of these compounds on the kinetics of the radical polymerization of methyl methacrylate was shown by dilatometry. Furthermore, the adhesive properties of dental adhesives containing these calix[4]arene derivatives were investigated. Copyright © 2012 Society of Chemical Industry     

Approximate methods in Bayesian point process spatial models

A range of point process models which are commonly used in spatial epidemiology applications for the increased incidence of disease are compared. The models considered vary from approximate methods to an exact method. The approximate methods include the Poisson process model and methods that are based on discretization of the study window. The exact method includes a marked point process model, i.e., the conditional logistic model. Apart from analyzing a real dataset (Lancashire larynx cancer data), a small simulation study is also carried out to examine the ability of these methods to recover known parameter values. The main results are as follows. In estimating the distance effect of larynx cancer incidences from the incinerator, the conditional logistic model and the binomial model for the discretized window perform relatively well. In explaining the spatial heterogeneity, the Poisson model (or the log Gaussian Cox process model) for the discretized window produces the best estimate.     

Copper(II)‐Catalyzed Aerobic Oxidative Coupling between Chalcone and 2‐Aminopyridine via C?H Amination: An Expedient Synthesis of 3‐Aroylimidazo[1,2‐a]pyridines

A simple and efficient protocol has been developed for the synthesis of 3‐aroylimidazopyridines via copper(II) acetate‐catalyzed aerobic oxidative amination. A library of 3‐aroylimidazopyridines was synthesized from readily accessible chalcones and 2‐aminopyridines with high yields and regioselectivity. The reaction proceeds through a tandem Michael addition followed by an intramolecular oxidative amination. The successful application of this methodology for a gram‐scale reaction indicates its potential for bulk synthesis.

     

Enhanced Hydrogen Generation from Empty Fruit Bunches by Charcoal Addition into a Downdraft Gasifier

Hydrogen production by co-gasification of empty fruit bunches of palm oil could be enhanced by adding charcoal. Physiochemical characterization of raw feedstocks was performed to determine their exergy potentiality. The raw feedstocks, gasified charcoal, and the end product of produced gas were analyzed by different techniques. Gasification experiments were performed using a pilot-scale downdraft gasifier. The heating value, composition of product gas, yield of hydrogen, and exergy efficiency were used to verify the improvement of hydrogen production during the co-gasification process. Charcoal with empty fruit bunches of palm oil leads to a much higher yield of hydrogen than lower charcoal ratios or solely empty fruit bunches. This enhanced hydrogen fuel can contribute to future energy demand.