Exploiting path diversity in the link layer in wireless ad hoc networks

We develop an anycast mechanism at the link layer for wireless ad hoc networks. The goal is to exploit path diversity in the link layer by choosing the best next hop to forward packets when multiple next hop choices are available. Such choices can come from a multipath routing protocol, for example. This technique can reduce transmission retries and packet drop probabilities in the face of channel fading. We develop an anycast extension of the IEEE 802.11 MAC layer based on this idea. We implement the protocol in an experimental proof-of-concept testbed using the Berkeley motes platform and S-MAC protocol stack. We also implement it in the popular ns-2 simulator and experiment with the AOMDV multipath routing protocol and Ricean fading channels. We show that anycast performs significantly better than 802.11 in terms of packet delivery, particularly when the path length or effect of fading is large. Further we experiment with anycast in networks that use multiple channels and those that use directional antennas for transmission. In these networks, deafness and hidden terminal problems are the main source of packet loss. We implemented anycast as extension of 802.11 like protocols that were proposed for these special networks. We are able to show that anycast is capable of enhancing the performance of these protocols by simply making use of the path diversity whenever it is available.     

Thiazole derivatives‐functionalized polyvinyl chloride nanocomposites with photostability and antimicrobial properties

Polyvinyl chloride (PVC) was modified via substitution reaction with 2‐aminothiazole and ethyl 2‐aminothiazole‐4‐carboxylate separately in the absence and in presence of silver (AgNPs) or copper (CuNPs) nanoparticles, using metal salts as precursors, in 3% (w/w) with respect to PVC. The functionalized PVC‐nanocomposites have been characterized via FTIR, ¹HNMR spectroscopic analyses, in addition to the morphological investigation such as scanning (SEM) and transmission electron microscopy (TEM). Spectral data confirmed the introduction of the thiazole (ester) to the PVC backbone. TEM analysis showed that the sizes of the AgNPs and CuNPs have fallen in the range of 10–30 nm and 30–50 nm for the prepared nanocomposites, respectively. Evaluating the photostability of modified nanocomposites was estimated by following the extent of discoloration for UV‐irradiated samples colorimetrically in accordance with the irradiation time. The antimicrobial activity of the modified nanocomposites was explored against three Gram+ve bacteria (Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis), three Gram‐ve bacteria (Escherichia coli, Neisseria gonorrhoeae, and Pseudomonas aeruginosa), and two fungi (Candida albicans and Aspergillus flavus). Aminothiazole (ester)‐functionalized PVC exhibited significant antimicrobial efficiencies against the investigated pathogens. However, incorporation of AgNPs or CuNPs to the modified PVC enhanced their inhibitory effect against the microorganisms under investigation. J. VINYL ADDIT. TECHNOL., 25:E137–E146, 2019. © 2018 Society of Plastics Engineers     

Heavy Metal Residues in Some Fishes from Manzala Lake,Egypt, and Their Health‐Risk Assessment

A total of 600 freshly caught fish samples (200 each of Nile tilapia, flathead grey mullet, and African catfish) were collected from Manzala Lake, Egypt, and analyzed for determination of heavy metal residues using an atomic absorption spectrophotometer. Metal concentrations (µg/g wet weight) were detected in all examined samples in quantities of 0.045, 0.0145, and 0.017 µg/g for Hg; 0.511, 0.621, and 0.568 µg/g for As; 0.704, 0.635, and 0.64 µg/g for Pb; and 0.024, 0.006, and 0.020 µg/g for Cd in Nile tilapia, flathead grey mullet, and African catfish, respectively. The mean concentrations of Hg, Pb, and Cd among the three fish species tested followed the order Nile tilapia > African catfish > flathead grey mullet; meanwhile, As concentration followed the order flathead grey mullet > African catfish > Nile tilapia. The contamination levels of Hg and Cd showed significant differences between summer and winter in the three different fish species examined. Both the mullet and catfish tested revealed significant negative correlations between fish size and their residual levels of Hg, Pb, and Cd. Health‐risk assessment indices suggesting that consuming such fishes from Manzala Lake could have a potential health hazard to consumers.     

Antioxidant constituents from Lawsonia inermis leaves: Isolation,structure elucidation and antioxidative capacity

The antioxidant potential of different fractions of Lawsonia inermis (Lythraceae) was investigated. The n-butanolic fraction showed the highest yield of extraction; it also exhibited a strong antioxidant activity in the DPPH assay and a potent capacity in preventing linoleic acid oxidation. Five phenolic glycosides were identified in this fraction. The structure of a new compound was established as 1,2,4-trihydroxynaphthalene-1-Ο-β-d-glucopyranoside. In addition, the known 2,4,6-trihydroxyacetophenone-2-Ο-β-d-glucopyranoside was described for the first time in this species. The three other compounds, lalioside (2,3,4,6-tetrahydroxyacetophenone-2-Ο-β-d-glucopyranoside), lawsoniaside (1,2,4-trihydroxynaphthalene-1,4-di-Ο-β-d-glucopyranoside) and luteolin-7-Ο-β-d-glucopyranoside, have been previously reported in L. inermis. The antioxidant activity of these glycosides was evaluated by DPPH and β-carotene assays, and compared to those of commercial standards. 1,2,4-Trihydroxynaphthalene-1-Ο-β-d-glucopyranoside was the most active in the DPPH free-radical scavenging test (EC₅₀ = 6.5 μg/ml) and showed a moderate inhibition in the β-carotene bleaching assay. Chemical components of L. inermis have good antioxidant capacities and this species could be used as a potential source of new natural antioxidants.     

Time Dependent Ambient Oxidation of AA6061-T6 Alloy at the Temperature of 580°C

Protection of Metals and Physical Chemistry of Surfaces - The AA6061-T6 alloy is used in many industrial applications such as hydraulic pistons, aerospace and marine vehicle fittings, including the...     

A geometrically nonlinear size-dependent hypothesis for porous functionally graded micro-plate

The static bending behavior of porous functionally graded (PFG) micro-plate under the geometrically nonlinear analysis is studied in this article. A small-scale nonlinear solution is established using the Von-Kármán hypothesis and the modified couple stress theory (MCST). To obtain the deflection of the plate, the Reddy higher-order plate theory coupled with isogeometric analysis (IGA) is utilized. The distribution of porosities is assumed to be even and uneven across the plate’s thickness and the effective material properties of porous functionally graded micro-plate are calculated using the refined rule-of-mixture hypothesis. The influence of power index, porosity parameter and material length scale parameter on the nonlinear behaviors of static bending of porous FGM micro-plates are also investigated using several numerical examples.

     

New Peptide-Conjugated Chlorin-Type Photosensitizer Targeting Neuropilin-1 for Anti-Vascular Targeted Photodynamic Therapy

Photodynamic therapy (PDT) is a cancer treatment modality that requires three components, namely light, dioxygen and a photosensitizing agent. After light excitation, the photosensitizer (PS) in its excited state transfers its energy to oxygen, which leads to photooxidation reactions. In order to improve the selectivity of the treatment, research has focused on the design of PS covalently attached to a tumor-targeting moiety. In this paper, we describe the synthesis and the physico-chemical and photophysical properties of six new peptide-conjugated photosensitizers designed for targeting the neuropilin-1 (NRP-1) receptor. We chose a TPC (5-(4-carboxyphenyl)-10,15, 20-triphenyl chlorine as photosensitizer, coupled via three different spacers (aminohexanoic acid, 1-amino-3,6-dioxaoctanoic acid, and 1-amino-9-aza-3,6,12,15-tetraoxa-10-on-heptadecanoic acid) to two different peptides (DKPPR and TKPRR). The affinity towards the NRP-1 receptor of the conjugated chlorins was evaluated along with in vitro and in vivo stability levels. The tissue concentration of the TPC-conjugates in animal model shows good distribution, especially for the DKPPR conjugates. The novel peptide–PS conjugates proposed in this study were proven to have potential to be further developed as future NRP-1 targeting photodynamic therapy agent.     

Efficient recursive least squares parameter estimation algorithm for accurate nanoCMOS variable gain amplifier performances

ABSTRACT

With the aggressive scaling of integrated circuit technology, parametric estimation is a critical task for designers who looked for solutions to the challenges of some Nanoscale CMOS parameters. This paper presented the prediction of primary parameters of CMOS transistor for 16 nm to 10 nm process nodes using both of Bisquare Weights (BW) method and a novel recursive least squares (RLS) parameter estimation algorithm. The proposed RLS algorithm consists of the minimisation of a quadratic criterion relating to the prediction error in order to attain the best estimated parameters of the developed mathematical model. The obtained results thanks to the proposed RLS algorithm were better than those reached using the BW method. Comparisons between Predictive Technology Model (PTM) data and parameters estimated with RLS algorithm were made to check the validity and the consistency of the proposed algorithm. These predicted primary parameters were helpful to estimate and to optimise the performances of the Variable Gain Amplifier (VGA) which was a basic circuit element with a key role in the design of new upcoming receivers.     

Spectrum harvesting for heterogeneous wireless networks integration

Massive capacity demand is a major impetus behind the advances, in various ways, of today and near future wireless communication networks. To face this challenge, more wireless spectrum is needed, efficient usage of this spectrum is necessary, and adequate architectures are required. In this paper, we present a conceptual solution based on a cognitive-radio-inspired cellular network, for integrating idle spectrum resources of different wireless networks into a single mobile heterogeneous wireless network. We describe the conceptual architecture of this integrating network, referred to as Integrating cognitive-radio-inspired cellular network (I-CRICNet), and present a cooperative spectrum-harvesting scheme that keeps the former supplied with spectrum resources. In the latter scheme, we make extensive use of cross-correlated sequences (CSSs), for events signaling purposes. This choice is motived by the particularly interesting characteristics of the CSSs, namely, duration shortness, robustness to bad radio conditions, detection rather than decoding, and low probability of collision. As an illustration, we propose a reporting and detection scheme, in the context of OFDMA systems, and provide performance results from simulations to validate our proposal.

     

Image feature based high capacity steganographic algorithm

Multimedia Tools and Applications - Steganography is the growing field of research, where hiding techniques are used to secure the communicative elements (e.g., images). In this paper, the message...