On the performance of wireless ad hoc networks using bandwidth partitioning

Wireless Networks - We consider an hoc network where nodes are assumed to be distributed uniformly in space, according to a 2-D Poisson point process (PPP), and packets arrive at each transmitter...     

Cellulose-reinforced bioglass composite as flexible bioactive bandage to enhance bone healing

Low mechanical strength of cellulose nanofiber (CNF) and its lack of osseoconductivity in physiological media limit its application for bone tissue regeneration. To resolve these limitations, the densely packed cellulosic layers with thickness of ~50 μm impregnated by 58S bioglass (BG) nanoparticles was made-up (via the simple method of vacuum filtration) in this study. The developed fabrics showed uniform distribution of BG nanoparticles and effectively wrapped between CNF layers which caused sustained ion release into the SBF × 5 solution. The FTIR spectrum of the fabric after the SBF test was illustrated the presence of newly formed HA on the fabric. Also, no significant difference in the hydrophilicity of pure CNF and the developed fabric was presented by AFM results. Alkaline phosphatase activity (ALP) and cytotoxicity evaluation were performed to investigate cell treatment of the fabric which indicated its superior osteogenic potential of developed fabric compared with pure CNF. The increase in osseoconductivity of the developed fabric caused better cell attachment thanks to the interconnected CNFs network. Effective integration of BG nanoparticles between CNF interlayers increased Young's modulus of the developed fabric by 50% that mitigated swelling and enhanced structural stability of CNFs in the SBF × 5 solution. Thus, developed fabric could be considered as an appropriate biomaterial such as a bandage around cracked bone before metallic implantation with good mechanical integrity of the layered constructs obtained as well as strength and swelling.     

Complete mineralization of the antibiotic amoxicillin by electro-Fenton with a BDD anode

On April 30, 2014, the World Health Organization’s first global report on the presence of antibiotics in waters focused on their negative consequences, which may include the growth of microorganisms with antimicrobial resistance. The β-lactam antibiotic amoxicillin (AMX) is widely used in human and veterinary medicine, and it has been recently detected in sewage treatment plants and effluents. In this paper, the degradation of acidic aqueous solutions of AMX by electro-Fenton process has been studied at constant current. Experiments have been performed in an undivided cell equipped with a carbon-felt cathode and a Pt or boron-doped diamond (BDD) anode. In such systems, the organic molecules are mainly oxidized by hydroxyl radical (^?OH) simultaneously formed on the anode surface from water oxidation as well as in the bulk from Fenton’s reaction between Fe²⁺ catalyst and electrogenerated H₂O₂. The decay and mineralization of AMX was monitored by means of high performance liquid chromatography (HPLC) and TOC measurements. The evolution of the concentration of the final aliphatic carboxylic acids and inorganic ions like ammonium, nitrate and sulfate was assessed by HPLC and ion chromatography, respectively. The effect of the anode material, initial AMX concentration and current density was thoroughly studied. The AMX decay always followed a pseudo-first-order kinetics using either Pt or BDD, and the apparent rate constant increased with applied current. A quicker mineralization was reached with BDD because of the larger production of active ^?OH. The absolute rate constant between hydroxyl radical and AMX determined by the competition kinetics method using p-hydroxybenzoic acid as the reference compound was found to be (2.02 ± 0.01) × 10⁹ M^?1 s^?1.     

Effect of Impact Milling and Ball Milling on Microstructure of Lead Titanate Powders Synthesized by Solid-State Reaction

Single phase lead titanate （PbTiO3） was prepared by solid-state route using lead （1I） oxide （PbO） and titanium dioxide （TiO2） as precursors. The effects of using impact mill （IM） and ball mill （BM） in solid state reaction have been observed. X-ray diffraction （XRD） pattern was recorded at room temperature and analyzed by employing Rietveld method. X-ray diffraction （XRD） pattern shows that the PbTiO3 particles are tetragonal with tetragonality （c/a） ratio ranging from 1.058 to 1.063 and average crystallite size from 40.8 to 64.2 nm. It is found that the impact mill （IM） can be used to produce pure tetragonal perovskite with a lower tetragonality and average crystallite size.     

Immunomagnetic capture PCR to detect viable Cryptosporidium parvum oocysts from environmental samples

A method to detect viable Cryptosporidium parvum oocysts was developed. Polyclonal immunoglobulin G against C. parvum oocyst and sporozoite surface antigens was purified from rabbit immune serum, biotinylated, and bound to streptoavidin-coated magnetic particles. C. parvum oocysts were captured by a specific antigen-antibody reaction and magnetic separation. The oocysts were then induced to excyst, and DNA was extracted by heating at 95 degrees C for 10 min. A 452-bp fragment of C. parvum DNA was amplified by using a pair of C. parvum-specific primers in PCR. The method detected as few as 10 oocysts in purified preparations and from 30 to 100 oocysts inoculated in fecal samples. The immunomagnetic capture PCR (IC-PCR) product was identified and characterized by a nested PCR that amplified a 210-bp fragment, followed by restriction endonuclease digestion of the IC-PCR and nested-PCR products at the StyI site and a nonradioactive hybridization using an internal oligonucleotide probe labeled with biotin. PCR specificity was also tested, by using DNAs from other organisms as templates. In the control experiments, inactivated oocysts were undetectable, indicating the ability of this method to differentiate between viable and nonviable oocysts. Thus, this system can be used to specifically detect viable C. parvum oocysts in environmental samples with great sensitivity, providing an efficient way to monitor the environment for C. parvum contamination.     

Covalently linked Au nanoparticles to a viral vector: potential for combined photothermal and gene cancer therapy

Hyperthermia can be produced by near-infrared laser irradiation of gold nanoparticles present in tumors and thus induce tumor cell killing via a bystander effect. To be clinically relevant, however, several problems still need to be resolved. In particular, selective delivery and physical targeting of gold nanoparticles to tumor cells are necessary to improve therapeutic selectivity. Considerable progress has been made with respect to retargeting adenoviral vectors for cancer gene therapy. We therefore hypothesized that covalent coupling of gold nanoparticles to retargeted adenoviral vectors would allow selective delivery of the nanoparticles to tumor cells, thus feasibilizing hyperthermia and gene therapy as a combinatorial therapeutic approach. For this, sulfo-N-hydroxysuccinimide labeled gold nanoparticles were reacted to adenoviral vectors encoding a luciferase reporter gene driven by the cytomegalovirus promoter (AdCMVLuc). We herein demonstrate that covalent coupling could be achieved, while retaining virus infectivity and ability to retarget tumor-associated antigens. These results indicate the possibility of using adenoviral vectors as carriers for gold nanoparticles.     

Vapor sensing performances of PVDF nanocomposites containing titanium dioxide nanotubes decorated multi-walled carbon nanotubes

Inorganic nanocarbon hybrid materials are good alternatives for superior electrochemical performance and specific capacitance to their traditional counterparts. Nanocarbons act as a good template for the growth of metal nanoparticles on it and their hybrid combinations enhance the charge transport and rate capability of electrochemical materials without sacrificing the specific capacity. In this study, titanium dioxide nanotubes (TNT) are synthesized hydrothermally in the presence of multi-walled carbon nanotubes (MWCNT) where the latter acts as base template material for the metal oxide nanotube growth. The MWCNT–TNT hybrid material possesses very high dielectric strength and this is used to enhance the dielectric property of the polymer polyvinyledene fluoride (PVDF). Solution mixing was used to prepare the PVDF/MWCNT–TNT nanocomposites by varying the filler concentrations from 0.5 to 2.5 wt%. Excellent vapor sensing was noticed for the PVDF nanocomposites with different rate of response towards commonly used laboratory solvents. The composites and the fillers were characterized for its morphology and structural properties using scanning and transmission electron microscopy, X-ray diffraction studies and infrared spectroscopy. Vapor sensing was measured as relative resistance variations against the solvent vapors, and the dielectric properties of the composites were measured at room temperature during the frequency 10²–10⁷ Hz. Experimental results revealed the influence of filler synergy on the properties of PVDF and the enhancement in the solvent vapor detectability and dielectric properties reflects the ability of these composite films in flexible vapor sensors and in energy storage.     

Conceivable security risks and authentication techniques for smart devices: A comparative evaluation of security practices

With the rapidly escalating use of smart devices and fraudulent transaction of users data from their devices, efficient and reliable techniques for authentication of the smart devices have become an obligatory issue. This paper reviews the security risks for mobile devices and studies several authentication techniques available for smart devices. The results from field studies enable a comparative evaluation of user-preferred authentication mechanisms and their opinions about reliability, biometric authentication and visual authentication techniques.