Flow characteristics of surfactant stabilized water-in-oil emulsions

In this paper, an investigation was carried out to study the effect of water fraction and flow conditions on the flow characteristics of surfactant stabilized water-in-oil emulsion. Pressure drop measurements were conducted in 2.54-cm and 1.27-cm horizontal pipes. The influence of water fraction and the flow conditions on emulsion stability, type, conductivity, droplet size distribution, viscosity and pressure drop were reported. The results showed a significant increase in the emulsion stability, viscosity and pressure drop with increasing water fraction up to 70%. In addition, shear thinning behavior was observed for the emulsions especially at high water fractions. Furthermore, pressure drop measurements of high concentrated emulsions showed pipe diameter dependency especially at high Reynolds (Re) numbers. Moreover, drag reduction was observed with decreasing water fraction. The viscosity of surfactant-stabilized water-in-oil emulsions was modeled with a modified fluidity-additivity model.     

Influence of molecular structure on the rheology and thermorheology of metallocene polyethylenes

The rheology of linear and branched metallocene polyethylenes (m‐PEs) was investigated. The linear metallocenes were prepared by gas‐phase polymerization, while the branched PEs were commercial resins. Molecular parameters such as M_w, branch type, and molecular weight distribution have influenced the viscoelastic behavior of both linear and branched PEs, whereas branch content (BC) had little influence on viscoelastic properties. Plots of log G′ versus log G″ revealed the effect of comonomer type on the viscoelastic behavior of m‐PEs. Flow activation energy (E) was found to be sensitive to both M_w and BC. Also, E for ethylene‐octene copolymers was observed to be always higher than the butene counterparts, which have been caused by the increase in molar volume of the repeating unit. For the effect of BC on E, different trends were observed for octene and butene m‐LLDPEs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1717–1728, 2006     

Synthesis and characterization of crosslinked chitosan immobilized on bentonite and its grafted products with polyaniline

Chitosan immobilized bentonite (CIB) namely chitosan‐coated bentonite (5% chitosan content) was synthesized in 2% acetic acid solution, followed by crosslinking, using epichlorohydrien (ECH). The so‐obtained crosslinked chitosan immobilized on bentonite (CIB‐ECH) and CIB composites were grafted with polyaniline (PANI) through oxidative‐radical copolymerization using ammonium peroxydisulfate in acidic medium to produce PANI‐grafted crosslinked chitosan immobilized on bentonite (PANI‐g‐CIB‐ECH) and PANI‐grafted‐chitosan immobilized on bentonite (PANI‐g‐CIB) composites, respectively. The resultant composites were characterized by using X‐ray diffraction (XRD), thermo gravimetric analysis/differential scanning calorimetry, scanning electron microscopy, Fourier transform infrared (FTIR), and electrical conductivity. XRD and FTIR analyses indicate that chitosan was not intercalated into the silicate layer. Also the electrical conductivity elucidates that the grafted composites fall in the range required for the application as electrostatic dissipation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41078.     

Controlled-release formulation of perindopril erbumine loaded PEG-coated magnetite nanoparticles for biomedical applications

Iron oxide nanoparticles (FNPs) were synthesized due to low toxicity and their ability to immobilize biological materials on their surfaces by the coprecipitation of iron salts in ammonia hydroxide followed by coating it with polyethylene glycol (PEG) to minimize the aggregation of iron oxide nanoparticles and enhance the effect of nanoparticles for biological applications. Then, the FNPs–PEG was loaded with perindopril erbumine (PE), an antihypertensive compound to form a new nanocomposite (FPEGPE). Transmission electron microscopy results showed that there are no significant differences between the sizes of FNPs and FPEGPE nanocomposite. The existence of PEG–PE was supported by the FTIR and TGA analyses. The PE loading (10.3 %) and the release profiles from FPEGPE nanocomposite were estimated using ultraviolet–visible spectroscopy which showed that up to 60.8 and 83.1 % of the adsorbed drug was released in 4223 and 1231 min at pH 7.4 and 4.8, respectively. However, the release of PE was completed very fast from a physical mixture (FNPs–PEG–PE) after 5 and 7 min at pH 4.8 and 7.4, respectively, which reveals that the release of PE from the physical mixture is not in the sustained-release manner. Cytotoxicity study showed that free PE presented slightly higher toxicity than the FNPs and FPEGPE nanocomposite. Therefore, the decrease toxicity against mouse normal fibroblast (3T3) cell lines prospective of this nanocomposite together with controlled-release behavior provided evidence of the possible beneficial biological activities of this new nanocomposite for nanopharmaceutical applications for both oral and non-oral routes.     

The in vitro therapeutic activity of betulinic acid nanocomposite on breast cancer cells (MCF-7) and normal fibroblast cell (3T3)

In the present study, magnetic nanoparticles (MNPs) were coated with chitosan (CS) polymer to form CS–MNP nanoparticles. The CS–MNP were loaded with an anticancer drug, betulinic acid (BA) to form a BA–CS–MNP nanocomposite. The prepared nanocomposite was characterized using XRD, FTIR, TGA, VSM, SEM, TEM, and zeta potential techniques. The release behavior of the BA from the nanocomposite was investigated at pH 7.4, and the study found that the release of BA followed a pseudo-second-order kinetic model. The potential cytotoxicity of free BA, MNPs, CS–MNP, and the BA–CS–MNP nanocomposite was evaluated using normal mouse fibroblast cells (3T3) and breast cancer cells (MCF-7). BA and the nanocomposite at concentrations in the range 0.781–50 μg mL^?1 did not affect the viability of normal cells during 72 h of incubation. The BA and BA–CS–MNP nanocomposite exhibited cytotoxicity in MCF-7 cells in a dose-dependent manner with IC₅₀ values of 2 and 3.6 μg mL^?1, respectively.     

Bluetooth scatternet formation from a time-efficiency perspective

The Bluetooth Scatternet Formation (BSF) problem consists of interconnecting piconets in order to form a multi-hop topology. While a large number of BSF algorithms have been proposed, only few address time as a key parameter, and when doing so, virtually none of the solutions were tested under realistic settings. In particular, the baseband and link layers of Bluetooth are highly specific and known to have crucial impacts on performance. In this paper, we revisit performance studies for a number of time-efficient BSF algorithms, focusing on BlueStars, BlueMesh, and BlueMIS. We also introduce a novel time-efficient BSF algorithm called BSF-UED (for BSF based on Unnecessary-Edges Deletion), which forms connected scatternets deterministically and limits the outdegree of nodes to 7 heuristically. The performance of the algorithm is evaluated through detailed simulation experiments that take into account the low-level specificities of Bluetooth. We show that BSF-UED compares favorably against BlueMesh while requiring only 1/3 of its execution time. Only BlueStars is faster than BSF-UED, but at the cost of a very large number of slaves per master (much more than 7), which makes it impractical in many scenarios.     

Modified Wilkinson power divider with harmonics suppression and compact size for GSM applications

In this article, a modified microstrip Wilkinson power divider with harmonics suppression for GSM communications applications is presented. For low‐pass filter designing, one open stub, one radial resonator, and two rectangular resonators are used. According to results related to insertion losses (|S₂₁| and |S₃₁|), stopband is wide and equal to 7.5 GHz (3.4‐10.9 GHz), under the condition of 20 dB harmonic suppression level. The results show that at the designed frequency of 1.8 GHz, the input return loss (|S₁₁|) and output return losses (|S₂₂| and |S₃₃|) are better than 22 dB, and the isolation between of output ports (|S₃₂|) is better than 30 dB. The size of the proposed power divider is compact and equal to 10.6 × 14.6 mm². Finally, the proposed power divider was fabricated and the measurement results illustrate a good agreement with simulation results.     

Radiation pattern control of core shell nanoantenna by manipulation of nonlinear properties

Microsystem Technologies - In this article, a new structure of core–shell spherical nanoparticle as nanoantenna has been evaluated in which the main lobe direction of its radiation pattern is...     

Automatic COVID-19 detection mechanisms and approaches from medical images: a systematic review

Multimedia Tools and Applications - Since early 2020, Coronavirus Disease 2019 (COVID-19) has spread widely around the world. COVID-19 infects the lungs, leading to breathing difficulties. Early...     

High performing multimedia transmission approach based on QoS support and admission control over IEEE 802.11e networks

Hybrid coordination function controlled channel access (HCCA) is a medium to enhance quality of service (QoS) via the IEEE 802.11e standard. The main limitation of HCAA is that it is only efficient for constant bit rate (CBR) applications. This is due to the nature of its scheduler that allocates transmission opportunities (TXOPs) based on traffic stream (TS) specifications (TSPECs) that are determined during the traffic setup time. Variable bit rate (VBR) traffics used in HCCA have nondeterministic profile, making it not optimally and efficiently supported by HCCA. The result of this inefficiency is a deterioration of the transmission performance of multimedia data as well as a drop in the number of served QoS video traffics. We propose a novel approach to deal with this issue, which is the feedback‐based admission control unit (FACU). FACU works by optimizing the usage of extra bandwidth to ensure optimal transmission performance of multimedia data. FACU achieves this by exploiting piggybacked information concerning sequential video frames in order to accurately assign the TXOP. The proposed approach is evaluated by utilizing various video sequences. It is demonstrated that FACU maximizes the overall number of video streams and optimizes the overall usage of the network without having any adverse effects on the QoS constraints determined.