Experimental study of on-body radio channel performance of a compact ultra wideband antenna

In this paper, on-body radio channel performance of a compact ultra wideband (UWB) antenna is investigated for body-centric wireless communications. Measurement campaigns were first done in the chamber and then repeated in an indoor environment for comparison. The path loss parameter for eight different on-body radio channels has been characterized and analyzed. In addition, the path loss was modeled as a function of distance for 34 different receiver locations for propagation along the front part of the body. Results and analysis show that, compared with anechoic chamber, a reduction of 16.34% path loss exponent is noticed in indoor environment. The antenna shows very good on-body radio channel performance and will be a suitable candidate for future efficient and reliable body-centric wireless communications

Design, Synthesis and Evaluation of DNA Interactive Small Molecules

Most non-covalently binding DNA-interactive molecules based on pyrrole-type building blocks (e.g., polyamides such as netropsin) have a preference for AT-rich sequences. One objective of this project was to develop a set of novel biaryl building blocks with the potential to recognise GC sequences. Using solution phase combinatorial chemistry, a library of 135 novel polyamides was initially designed and synthesized containing a biaryl unit as a key feature. A Fluorescent Intercalator Displacement assay indicated that library members containing a 4-(1-methyl-1H-pyrrol-3-yl)benzenamine (MPB) motif switched to a GC preference. Further evaluation using HPLC/MS, DNA thermal denaturation and footprinting assays confirmed this strong GC preference. Unexpectedly, the biaryl polyamides were also found to be highly selective for some G-quadruplex DNA structures, with related selective cytotoxicity in relevant cancer cell lines. The MPB biaryl motifs were conjugated to pyrrolobenzodiazepine (PBD) molecules to produce covalently-binding agents with extended GC-selectivity within duplex DNA. Many of these MPB-PBD conjugates exhibited potent bactericidal activity against MRSA and VRE clinical isolates, and PBD-Py-MPB and PBD-Im-MPB conjugates showed significant selective in vitro cytotoxicity in a number of tumour cell lines. Finally, the HPLC/MS methodology was further developed to evaluate interaction of the PBD dimer SJG-136 with duplex oligonucleotides of varying length and sequence. In addition to the previously known interstrand cross-link at Pu-GATC-Py sequences, SJG-136 was shown to form a longer interstrand cross-link at Pu-GAATC-Py sequences, an intrastrand cross-link at both shorter Pu-GATG-Py and longer Pu-GAATG-Py sequences and, in addition, monoalkylated adducts at suitable PBD binding sites where neither intra-or interstrand cross-links are feasible. These observations impact on the proposed mechanism of action of SJG-136 both in vitro and in vivo, on the repair of its adducts and mechanism of resistance in cells, and potentially on the type of pharmacodynamic assay used in clinical trials. The HPLC assay was also used to assess the impact of microwave radiation on PBD-DNA interaction where it was found that microwave levels of insufficient power to cause heating led to a significant increase in the rate of reaction between PBDs and DNA. The HPLC method was also used to observe a dynamic equilibrium between covalent 1:1 hairpin and 2:1 duplex PBD-DNA adducts, and to study the reversibility of PBD-DNA adducts

Computational Study Reveals the Molecular Mechanism of the Interaction between the Efflux Inhibitor PAβN and the AdeB Transporter from Acinetobacter baumannii

Phenylalanine-arginine β-naphthylamide (PAβN) is a broad-spectrum efflux pump inhibitor that has shown to potentiate the activity of antibiotics in Gram-negative bacteria. AdeB is a part of the AdeABC tripartite pump that plays a pivotal role in conferring efflux-mediated resistance in Acinetobacter baumannii. To understand the molecular mechanism of efflux pump inhibition by PAβN, we investigated the interaction of PAβN with AdeB using different computational methods. We observed that PAβN does not have specific binding interactions with the proximal binding site and interacts strongly with the distal binding pocket. The Phe loop located between the proximal and distal binding pockets plays a key role in the PAβN-mediated inhibition and acts as a gate between the binding pockets. Molecular dynamics simulations suggested that PAβN behaved like a climber as we observed switching of the interaction energies between the ligand and the key Phe residues of the binding site during the course of the simulation. PAβN uses the hydrophobic microenvironment formed by Phe residues in the distal binding pocket to keep the binding monomer in the binding conformation. The simulation data suggests that this binding event should result in the inhibition of the peristaltic mechanism and prevent the exporter from extruding any other substrates leading to the inhibition of the tripartite pump

Smart Antenna Arrays for Advanced WLAN: Performance analysis of Linear and square array approach for adaptivity through phase shifting in antenna feed

The WLAN is operated in some high traffic area where the radiation beam produced by the antenna is to be utilized with optimum efficiency. The aim of those antennas is to produce some directive and switched beams rather than producing Omni-directional pattern since these beam patterns are considered to be wastage in some non-used or low traffic areas. Hence, the antenna systems producing the directive and switched beams should be highly preferred for the WLAN application. A smart antenna array system performs the adaptive beam forming by focusing the beam in the desired direction and creating nulls in other directions to avoid the interference and the wasting of the beams. This is performed by operating the phase shifting in its feed network and different ports. This paper investigates the performance of the different array patterns with different phase shifting for the optimum performance of the WLAN applications in a highly congested indoor environment