Rapid swelling and deswelling of semi‐interpenetrating network poly(acrylic acid)/poly(aspartic acid) hydrogels prepared by freezing polymerization

Hydrogels with semi‐interpenetrating networks composed of poly(acrylic acid) (PAAc) and poly(aspartic acid) (PASP) have great potential for pharmaceutical and biomedical applications. In this study, we aimed to synthesize semi‐interpenetrating PAAc/PASP hydrogels with improved swelling–deswelling properties via two‐step polymerization, in which the first step of polymerization was performed at 37 °C for 15 min and the second step, the freezing polymerization, was performed at ?20 °C for 24 h. The synthesized hydrogels were characterized with field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The swelling and deswelling behaviors of the hydrogels in response to the ionic strength of the buffer solution were investigated. The Schott's swelling kinetic model was used to elucidate the swelling behavior of the hydrogels. The swelling and deswelling rates of the hydrogels prepared via freezing polymerization were faster than those of the hydrogels prepared via conventional polymerization. This was attributed to the large mean pore size of the freeze‐polymerized hydrogels. The PAAc/PASP hydrogels that underwent freezing polymerization had better swelling–deswelling characteristics than the PAAc hydrogels. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43515.     

THR EFFECT OF OXIDE LAYER FORMATION ON THE ADHESION OF CONDUCTIVE POLYMER COATING TO A MILDSTEEL

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A Review of Analysis of Dynamic Response in Design of Experiments

Systems with dynamic characteristics have gained increasing attention of both researchers and engineers in industry in recent years. The purpose of this article is to provide an overview of investigations on what might be called dynamic response in experimental design, so as to facilitate further research in this area. We briefly review the development of research on dynamic problems in diverse fields such as statistical quality control, biostatistics, experimental design and repeated measurements. Discussions in the past are specially sorted out on the definition and classification of dynamic response problems as encountered in general experimental design and robust design, and various perspectives of system types and response types. Four categories of modelling techniques in classical experimental design are summarized from the literature according to distinct application conditions; this would provide a useful basis for future investigations. Copyright © 2014 John Wiley & Sons, Ltd.     

Stress of caregivers of dementia patients in the Singapore Chinese family

In a study of 50 family caregivers of elderly Chinese patients with dementia in Singapore, 28 (56%) scored five points or more on the 28-item General Health Questionnaire (GHQ). The GHQ scores correlated significantly with duration of care; presence of delusion, hallucination, depression, insomnia, incontinence and agitation; and the total score of the Behavioural Pathology in Alzheimer's Disease Rating Scale. On multiple regression analysis the only variables to achieve a significant relationship with the GHQ scores were duration of care, depression and the total behavioural score.     

Economic design of exponential charts for time between events monitoring

The occurrence of defects or non-conformities in manufacturing processes can usually be modeled by a homogeneous Poisson process. However, the process parameter may change over time and it can be monitored with statistical process control techniques. Control charts based on an exponential distribution, called exponential charts in this paper, can be developed to monitor the occurrence rate of such events. For manufacturers, the economic objective of production is very important and has to be optimized. An economic approach is developed in this paper for the design of exponential charts. We compare and contrast the performances of statistical design, economic design and economic–statistical design. The usefulness of the proposed economic design approach is justified. The relationships among these designs are illustrated through numerical examples. In particular, the economic–statistical design approach is interpreted from a multi-objective optimization viewpoint. The limitations of the approach as well as future research are also discussed.     

Audible Noise Reduction in Eigendomain for Speech Enhancement

A signal subspace scheme based on masking properties is proposed for enhancement of speech degraded by additive noise. Since the masking properties are related to the critical frequency band that is derived from the characteristics of human cochlea, the incorporation of masking threshold into a subspace technique requires the transformation between the frequency and eigen domains. We present and apply an invertible transformation between the frequency and eigen domains. In this paper, we use masking properties of the human auditory system to define the audible noise quantity in the eigendomain. We derive the eigen-decomposition of the estimated speech autocorrelation matrix with the assumption of white noise. Subsequently, an audible noise reduction scheme is developed based on a signal subspace technique, and the implementation of our proposed scheme is outlined. We further extend the scheme to the colored noise case. Simulation results show the superiority of our proposed scheme over other existing subspace methods in terms of segmental signal-to-noise ratio (SNR), perceptual evaluation of speech quality (PESQ), modified Bark spectral distortion (MBSD), spectrogram and informal listening tests.     

A new subaperture approach to high squint SAR processing

A high squint subaperture (HSS) algorithm was developed from the perspective of a strip map synthetic aperture radar (SAR) system and has the ability to focus SAR data at extremely high squint angle of 55° with less than 1.27% mainlobe expansion or even higher squint angles if larger mainlobe expansion can be tolerated. The unique characteristic of this algorithm is that the subapertures are formed by multiplying the received signal with a set of overlapped complex conjugated reference signals where the chirp rate varies in the azimuth direction. This is done to solve the range focus problem that arises after the azimuth input signal undergoes the range walk removal procedure. As the IISS algorithm only involves short fast Fourier transforms (FFTs) and avoids interpolation, it is computationally efficient and allows for small data buffers and facilitates hardware real-time implementation. The distinct feature of this algorithm is its simplicity of implementation, which is vital in real time processing and motion compensation when the squint angle may be changing continuously