Characterization of indoor time reversal UWB communication systems: Spatial,temporal and frequency properties

In this paper, an indoor UWB communications system that applies time reversal (TR) for transmitting the desired signal is proposed. First we define equivalent channel model of TR‐UWB, which is the convolution of channel impulse response and its complex conjugate time‐reversed version. Then spatial, temporal and frequency characteristics of equivalent channel are analyzed and the analytical or semi‐analytical results are validated by comparing measurements with simulation. (Semi) analytical expression of equivalent channel transfer function, TR UWB power delay profile (PDP), focusing gain, spatial correlation and power azimuth spectrum (PAS) is performed. Also probability density function (PDF) of TR‐UWB amplitude and path‐gain is derived. Analysis and simulation results of different distributions, such as uniform, Laplacian and Gaussian for PAS, are considered and presented. It is shown that uniform and truncated Laplacian distributions are appropriate fits to the measurement results for power azimuth spectrum of TR‐UWB. It is seen that for distances greater than λ/2 from the authorized receiver, received signal decreases 10 dB, where λ is the wavelength of the central frequency. Finally, PDF of TR‐UWB path‐gain is described. Measurement results show that for small time windows, the densities of the path‐gain are highly non‐Gaussian. But for starting time of 10T_w or more, and window size of 2T_w or more the densities are nearly Gaussian, where T_w is the transmitted pulse duration. Copyright © 2010 John Wiley & Sons, Ltd.     

Application of computer vision for determining viscoelastic characteristics of date fruits

Date fruits are subjected to different environmental conditions from harvest to consumption. Since the rheological behavior of fruits are important for any processing operation, the viscoelastic characteristics of date fruits were studied at six moisture content, and four temperature levels of product, using a computer vision method. The whole date fruits were subjected to uniaxial compression for relaxing the stress during 300 s. As a new approach, a probe that equipped with a camera was used to measure the samples true contact area simultaneously. Three famous viscoelastic models were used to fit on experimental data. It was found that Generalized Maxwell and Nussinovitch models describe viscoelastic characteristics of date fruits appropriately, as compared to Peleg model. Furthermore, it was observed that moisture content of the product has dominant effect on viscoelastic characteristics of the fruits than temperature.     

Improvement of a Novel SOI- MESFET with an Embedded GaN Layer for High-Frequency Operations

Silicon - In this paper, we propose a novel Silicon on Insulator (SOI) Metal Semiconductor Field Effect Transistor (MESFET) with an embedded GaN layer (GL-SOI-MESFET) for modifying the electric...     

Common FABP4 Genetic Variants and Plasma Levels of Fatty Acid Binding Protein 4 in Older Adults

We examined common variants in the fatty acid binding protein 4 gene (FABP4) and plasma levels of FABP4 in adults aged 65 and older from the Cardiovascular Health Study. We genotyped rs16909187, rs1054135, rs16909192, rs10808846, rs7018409, rs2290201, and rs6992708 and measured circulating FABP4 levels among 3190 European Americans and 660 African Americans. Among European Americans, the minor alleles of six single nucleotide polymorphisms (SNP) were associated with lower FABP4 levels (all p ≤ 0.01). Among African Americans, the SNP with the lowest minor allele frequency was associated with lower FABP4 levels (p = 0.015). The C-A haplotype of rs16909192 and rs2290201 was associated with lower FABP4 levels in both European Americans (frequency = 16 %; p = 0.001) and African Americans (frequency = 8 %; p = 0.04). The haplotype combined a SNP in the first intron with one in the 3′untranslated region. However, the alleles associated with lower FABP4 levels were associated with higher fasting glucose in meta-analyses from the MAGIC consortium. These results demonstrate associations of common SNP and haplotypes in the FABP4 gene with lower plasma FABP4 but higher fasting glucose levels.     

Controlled release of protein from magnetite–chitosan nanoparticles exposed to an alternating magnetic field

In this research, the controlled release of proteins from magnetite (Fe₃O₄)–chitosan (CS) nanoparticles exposed to an alternating magnetic field is reported. Fe₃O₄–CS nanoparticles were synthesized with sodium tripolyphosphate (TPP) molecules as a crosslinking reagent. Bovine serum albumin (BSA) was used as a model protein, and its controlled release studied through the variation of the frequency of an alternating magnetic field. The results show the successful coating of CS and BSA on the Fe₃O₄ nanoparticles with an average diameter of 50 nm. Intermolecular interactions of TPP with CS and BSA were confirmed by Fourier transform infrared spectroscopy. The application of low‐frequency alternating magnetic fields to such magnetic CS nanoparticles enhanced the protein release properties, in which the external magnetic fields could switch on the unloading of these nanoparticles. We concluded that enhanced BSA release from nanoparticles exposed to an alternating magnetic field is a promising method for achieving both the targeted delivery and controlled release of proteins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43335.     

Dual responsive polymeric bionanocomposite gel beads for controlled drug release systems

Scientists are searching potential solutions for cancer treatments as well as ways to avoid the side effects of anti‐cancer agents, via targeted drug delivery. The aim of this research is to propose dual responsive beads based on sodium alginate (SA), methylcellulose (MC), and magnetic iron oxide nanoparticles (MIONs) for controlled release of 5‐Fluorouracil (5‐FU) as model drug. The beads were prepared by the dual crosslinking of SA and MC in the presence of MIONs. The structural, thermal, morphological, magnetic characteristics as well as the release profile of 5‐FU were studied. The characterization results showed that the drug molecules and MIONs were well dispersed in the polymeric matrix. The cumulative release percentage was ca. 80% at pH = 4.2 and 40% at pH = 7.2 after 6 h. Thus, the sensitivity of beads on the pH value was verified. Moreover, the release profile exhibited reduction with an increase in the concentration of MIONs under an external magnetic field. The obtained results confirmed the dual sensitive release of 5‐FU (i.e., PH/magnetic) that can be used for the targeted and controlled drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45143.