MC-MAC: a multi-channel based MAC scheme for interference mitigation in WBANs

Wireless body area networks (WBANs) support the inter-operability of biomedical sensors and medical institutions with convenience and high-efficiency, which makes it an appropriate solution for the pervasive healthcare. Typically, WBANs comprise in-body or around-body sensor nodes for collecting data of physiological feature. Therefore, the efficient medium access control (MAC) protocol is a crucial paramount to coordinate these devices and forward data to the medical center in an efficient and reliable way. However, the extensive use of wireless channel and coexistence of WBANs may result in inevitable interference which will cause performance degradation. Besides, contention-based access in single channel in WBANs is less efficient for dense medical traffic on account of large packet delay, energy consumption and low priority starvation. To address these issues above, we propose a multi-channel MAC (MC-MAC) scheme to obtain better network performance. Considering the characteristic and emergency degree of medical traffic, we introduce a novel channel mapping and selection mechanism, cooperating with conflict avoidance strategy, to organize nodes to access available channels without collisions. In addition, we have evaluated the performance of MC-MAC and the standard IEEE 802.15.6 via simulation and hardware test. The test is conducted by hardware platform based on prototype system of WBANs. Both of the analysis and simulation results show that MC-MAC outperforms the IEEE 802.15.6 in terms of packet delay, throughput, packet error rate and frame error rate.     

Comparison of mechanical properties of heat‐polymerized acrylic resin with silver nanoparticles added at different concentrations and sizes

The aim of this study was to investigate the effect of silver nanoparticles (AgNPs) incorporation on the flexural strength (FS) of poly(methyl methacrylate) (PMMA). PMMA specimens (65 mm × 10 mm × 3.3 mm for flexural test, 50 mm × 6 mm × 4 mm for impact test) containing different sizes (40, 50, 60 nm) and concentrations (0.05%, 0.2%) of AgNPs were prepared, along with a control group with no AgNP. Impact strength (IS) and FS of all specimens were measured, and one‐way ANOVA and Tukey–Kramer post hoc multiple comparisons tests were used to identify any statistical differences between groups. The addition of AgNPs has no effect on IS of PMMA. The incorporation of AgNPs affected the FS of PMMA depending on the concentration of nanoparticles. The addition of large‐sized nanoparticles to PMMA increases its FS. Accordingly, adding AgNP with proper concentrations to PMMA may enhance the mechanical properties of denture bases used in clinical practice. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45807.     

Power and Resource Allocation in Wireless Communication Network

Wireless Personal Communications - Present-day wireless methods are necessary to support a variety of higher-speed data communication facilities for its subscribers such as cloud-based video...     

VNS methods for home care routing and scheduling problem with temporal dependencies,and multiple structures and specialties

The need for optimization in the Home Care Service is becoming more and more legitimate in the face of the increase of demand and cost all over the world. Recently, many researchers in the Operation Research community have been attracted by this issue, which presents interesting aspects related to the vehicle routing problems. In this paper, we consider a new variant called the vehicle routing problem with time windows, temporal dependencies (synchronization, precedence, and disjunction), multi‐structures, and multispecialties problem (VRPTW‐TD‐2MS). This new variant is an extension of the vehicle routing problems with time windows and synchronization constraints (VRPTW‐S) that is well‐studied in literature. We present a Mixed Integer Programming method, and propose three Variable Neighborhood Search approaches. Extensive experiments show the effectiveness and efficiency of the General Variable Neighborhood Search with Ejection Chains‐based local search for solving VRPTW‐TD‐2MS and VRPTW‐S.     

Poly (vinyl alcohol)/poly (acrylamide‐ co ‐diallyldimethyl ammonium chloride) semi‐IPN hydrogels for ciprofloxacin hydrochloride drug delivery

Herein, the authors developed a new and potential semi‐interpenetrating polymer network (semi‐IPN) hydrogels of poly vinyl alcohol (PVA), acryl amide and diallyldimethyl ammonium chloride employing chemical cross‐linker N, N''‐methylene bisacrylamide (NNMBA) and ammonium persulphate as an initiator by radical polymerisation. To analyse the copolymer formation between two monomers and IPN cross‐linking reaction, the resulting hydrogel was characterised by Fourier transform infrared spectroscopy and the surface morphology was analysed using scanning electron microscopy. Differential scanning calorimetry and X‐ray diffraction studies were also carried out for investigating drug loading and distribution and swelling experiments were carried out for the uptake of water. In vitro release of ciprofloxacin hydrochloride from hydrogel was performed at intestinal conditions. The amount of PVA, NNMBA and total monomer concentration was found to strongly control the drug release behaviour from the hydrogels.Inspec keywords: hydrogels, polymer blends, biomedical materials, drug delivery systems, polymerisation, Fourier transform infrared spectra, surface morphology, scanning electron microscopy, differential scanning calorimetry, X‐ray diffraction, swelling, biological organs, ammonium compoundsOther keywords: PVA‐poly(acrylamide‐co‐diallyldimethyl ammonium chloride) semiIPN hydrogels, ciprofloxacin hydrochloride drug delivery, semiinterpenetrating polymer network hydrogels, polyvinyl alcohol, acryl amide, diallyldimethyl ammonium chloride, chemical crosslinker N,N''‐methylene bisacrylamide, ammonium persulphate, radical polymerisation initiator, NNMBA, copolymer formation, IPN crosslinking reaction, Fourier transform infrared spectroscopy, surface morphology, scanning electron microscopy, differential scanning calorimetry, X‐ray diffraction, drug loading, drug distribution, swelling, water uptake, in vitro ciprofloxacin hydrochloride release, intestinal conditions, total monomer concentration, drug release behaviour     

RNA Protection is Effectively Achieved by Pullulan Film Formation

RNA is a functionally versatile polymer but suffers from susceptibility to spontaneous and RNase‐catalyzed degradation. This vulnerability makes it difficult to preserve RNA for extended periods of time, thus limiting its use in various contexts, including practical applications as functional nucleic acids. Here we present a simple method to preserve RNA by pullulan (a complex sugar produced by Aureobasidium pullulans fungus) film formation. This strategy can markedly suppress both spontaneous and RNase degradation. Importantly, the pullulan film readily dissolves in aqueous solution, thus allowing retrieval of fully functional RNA species. In order to illustrate the advantage of this protective method in a practical application, we engineered a simple paper sensor containing a bacteria‐detecting RNA‐cleaving DNAzyme. This detection capability of the device was unchanged after storage at room temperature for six months.     

Speech enhancement based on perceptual filter bank improvement

In this paper, a new denoising approach is presented based on perceptual analysis. The noisy signal is split by a gammatone filterbank with nonlinear frequency distributions according to ERB scale. The frequency masking threshold is calculated in each sub-band according to the Johnston model in the output of the Wiener filter. This threshold is then used in the gain function given by the perceptual filter. The evaluation tests are performed by using objective criterion including perceptual evaluation of speech quality as well as subjective criterion including mean opinion score. Obtained results show that the proposed method achieves best results in terms of quality and intelligibility of enhanced signal.     

A controlled release of antibiotics from calcium phosphate-coated poly(lactic-co-glycolic acid) particles and their in vitro efficacy against Staphylococcus aureus biofilm

Ceramic-polymer hybrid particles, intended for osteomyelitis treatment, were fabricated by preparing poly(lactic-co-glycolic acid) particles through an emulsion solvent evaporation technique, followed by calcium phosphate (CaP) coating via a surface adsorption-nucleation method. The presence of CaP coating on the surface of the particles was confirmed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Subsequently, two antibiotics for treating bone infection, nafcillin (hydrophilic) and levofloxacin (amphiphilic), were loaded into these hybrid particles and their in vitro drug release studies were investigated. The CaP coating was shown to reduce burst release, while providing sustained release of the antibiotics for up to 4 weeks. In vitro bacterial study against Staphylococcus aureus demonstrated the capability of these antibiotic-loaded hybrid particles to inhibit biofilm formation as well as deteriorate established biofilm, making this hybrid system a potential candidate for further investigation for osteomyelitis treatment.     

Breathing ontological knowledge into feature model synthesis: an empirical study

Feature Models (FMs) are a popular formalism for modeling and reasoning about the configurations of a software product line. As the manual construction of an FM is time-consuming and error-prone, management operations have been developed for reverse engineering, merging, slicing, or refactoring FMs from a set of configurations/dependencies. Yet the synthesis of meaningless ontological relations in the FM – as defined by its feature hierarchy and feature groups – may arise and cause severe difficulties when reading, maintaining or exploiting it. Numerous synthesis techniques and tools have been proposed, but only a few consider both configuration and ontological semantics of an FM. There are also few empirical studies investigating ontological aspects when synthesizing FMs. In this article, we define a generic, ontologic-aware synthesis procedure that computes the likely siblings or parent candidates for a given feature. We develop six heuristics for clustering and weighting the logical, syntactical and semantical relationships between feature names. We then perform an empirical evaluation on hundreds of FMs, coming from the SPLOT repository and Wikipedia. We provide evidence that a fully automated synthesis (i.e., without any user intervention) is likely to produce FMs far from the ground truths. As the role of the user is crucial, we empirically analyze the strengths and weaknesses of heuristics for computing ranking lists and different kinds of clusters. We show that a hybrid approach mixing logical and ontological techniques outperforms state-of-the-art solutions. We believe our approach, environment, and empirical results support researchers and practitioners working on reverse engineering and management of FMs.