Impact of tripropyl borate on life and impedance of lithium-ion cells

Tripropyl borate was investigated as a low cost anion receptor to improve the performance of lithium-ion cells. The impact of tripropyl borate was examined using lithium-ion cells comprising a negative electrode of mesocarbon microbeads, a positive electrode of Li_1.1[Mn_1/3Ni_1/3Co_1/3]_0.9O₂ and an LiPF₆-based electrolyte. It was found that the performance of the cells was improved by adding a proper amount of tripropyl borate (≤0.1 wt%) to the LiPF₆-based electrolyte. However, a small amount of gas was observed from cells with high contents of tripropyl borate when cycled at 55 °C, and as a result, the performance of the cells deteriorated.     

Fatty Acids in Heterocyclic Synthesis Part XII: Synthesis of Surfactants from Pyrazole, Isoxazole, Pyrimidine and Triazine, Incorporating the 1,3,4-Thiadiazole Moiety Having Dyeing and Antimicrobial Activities

The titled compounds were prepared from 2-amino-5-heptadecyl[1,3,4]thiadiazole (1). Diazotization of (1) produced (2) which was coupled with active methylene compounds and gave azo ⇌ hydrazono derivatives (3A, 3B) _a–d . It was found that there is regio-specificity for addition of different nucleophiles to these tautomers; thus, nitrogen nucleophiles such as hydrazine hydrate, hydroxylamine hydrochloride and thiourea were reacted via Azo tautomer (3A) to yield pyrazole, isoxazole and pyrimidine respectively (5-7), while carbon nucleophiles as phenylisocyanate was reacted via the hydrazono tautomer (3B) and produced triazine derivatives (4). Additionally, the diazonium chloride (2) was coupled with alkaline 2-naphthol and produced 2-(5-heptadecyl-[1,3,4]thiadiazol-2-yl)-1,2-dihydro-3-oxa-1,2-diaza-cyclopenta[a]naphthalene (8). UV–visible spectra of the synthesized colored compounds (2-8) showed λ _max at 374–398 nm, while screening these compounds in vitro against micro-organisms (including structure-activity relationship SAR study) revealed high antibacterial and moderate antifungal activities. Propoxylation of compounds 1, 3, 5, 6, 7 and 8 with 3, 5, 7 mol of propylene oxide produced nonionic surfactants I(a–c)–IX(a–c) having surface active properties so, it is clear that the tested surfactants can be used in the manufacture of dyes, drugs, cosmetics, emulsifiers, pesticides, luminphores for optical applications and many other industries with low toxicity to human beings and the environment owing to their high solubility and good biodegradability.     

A hybrid multiagent routing approach for wireless ad hoc networks

Wireless ad-hoc networks are infrastructureless networks that comprise wireless mobile nodes able to communicate each other outside wireless transmission range. Due to frequent network topology changes in one hand and the limited underlying bandwidth in the other hand, routing becomes a challenging task. In this paper we present a novel routing algorithm devoted for mobile ad hoc networks. It entails both reactive and proactive components. More precisely, the algorithm is based on ant general behavior, but differs from the classic ant methods inspired from Ant-Colony-Optimization algorithm [1]. We do not use, during the reactive phase, a broadcasting technique that exponentially increases the routing overhead, but we introduce a new reactive route discovery technique that considerably reduces the communication overhead. In the simulation results, we show that our protocol can outperform both Ad hoc On-demand Distance Vector (AODV) protocol [2], one of the most important current state-of-the-art algorithms, and AntHocNet protocol [5], one of the most important ant-based routing algorithms, in terms of end-to-end delay, packet delivery ratio and the communication overhead.     

Modeling of filtration through multiple layers of dual scale fibrous porous media

Functionally graded composites exhibit properties within the material that vary gradually without a recognizable boundary. One technique to manufacture functionally graded polymer composites is by liquid composite molding process. In this process, structural fabric layers are stacked in a closed mold and resin is injected into the mold. Particles may be added to the resin to tailor the properties of the final product. The structural fabrics typically consist of yarns or bundles of thousands of micron size fibers woven, stitched, or knitted together, which gives rise to a bimodal distribution of pore sizes; the larger pores in between the bundles and smaller ones within the bundles. The filtration process that takes place during infusion alters the flow resistance of the porous media and complicates the impregnation process. In this study, a vacuum‐assisted resin transfer molding (VARTM) process‐based approach is presented that enables functional grading in composites to obtain a desired distribution in properties. A model of the filtration phenomenon is proposed to predict the concentration distribution of particles within the dual scale fibrous porous media infused under a constant pressure drop. The approach uses Darcy's law and accounts for lowering of the permeability value due to the particle entrapment in the available pores. Experiments are conducted and the concentration of the particles in the fabric is measured. The results compare well with the predictions despite many assumptions made in the model. Nondimensional analysis and parametric study reveals the influence of critical parameters on the final particles concentration gradient. POLYM. COMPOS. 27:570–581, 2006. © 2006 Society of Plastics Engineers     

The food preservative potential of essential oils: is lemongrass the answer?

Several essential oils of medicinal plants possess proven antimicrobial activity and are suitable for applications on the food industry. The oil from Cymbopogon citratus (lemongrass) has been reported to have a wide range of biological activities. However, there are few controlled studies confirming its antimicrobial activity. The aim of our study was to assess the antimicrobial potential of lemongrass oil against a wide spectrum of food spoilage and pathogenic bacteria and yeast in liquid and vapour phase. The chemical composition of the oil was analyzed by gas chromatography; 14 components were identified and geranial (28.93 %), neral (24.30 %) and myrcene (23.92 %) were the most abundant constituents. Lemongrass oil showed potent antimicrobial activity against Gram positive bacteria and exhibited the strongest antifungal effect against Candida albicans and C. parapsilosis. Minimum inhibitory concentration varied from 0.019 to 1.25 mg mL^?1 for Gram positive bacteria and yeasts, indicating Staphylococcus aureus, S. epidermidis and C. albicans as the most susceptible strains. Moreover, the diameter of inhibition zone (DIZ) increased with increasing essential oil (EO) volume. Considerably superior antimicrobial activity was observed in the vapour phase. The DIZ resulting from the exposure to EO vapour was significantly larger than that from the same volume in the liquid phase. The DIZ varied from 22 to 90 mm for Candida strains. There is growing evidence that EO in vapour phase are effective antimicrobial systems and that they do have advantages over the use of oil in liquid phase. Our results imply that lemongrass oil could be useful for the development of novel types of natural preservatives for food control.     

Authentication schemes for smart mobile devices: threat models,countermeasures, and open research issues

Telecommunication Systems - This paper presents a comprehensive investigation of authentication schemes for smart mobile devices. We start by providing an overview of existing survey articles...     

On the modeling of the annual corrosion rate in main cables of suspension bridges using combined soft computing model and a novel nature-inspired algorithm

Neural Computing and Applications - Suspension bridges are critical components of transport infrastructure around the world. Therefore, their operating conditions should be effectively monitored to...     

On the effective conductivity and the apparent viscosity of a thin rough polymer interface using PGD-based separated representations

Composite manufacturing processes usually proceed from preimpregnated preforms that are consolidated by simultaneously applying heat and pressure, so as to ensure a perfect contact compulsory for making molecular diffusion possible. However, in practice, the contact is rarely perfect. This results in a rough interface where air could remain entrapped, thus affecting the effective thermal conductivity. Moreover, the interfacial melted polymer is squeezed flowing in the rough gap created by the fibers located on the prepreg surfaces. Because of the typical dimensions of a composite prepreg, with thickness orders of magnitude smaller than its other in-plane dimensions, and its surface roughness having a characteristic size orders of magnitude smaller than the prepreg thickness, high-fidelity numerical simulations for elucidating the impact of surface and interface roughness remain today, despite the impressive advances in computational availabilities, unattainable. This work aims at elucidating roughness impact on heat conduction and the effective viscosity of the interfacial polymer squeeze flow by using an advanced numerical strategy able to reach resolutions never attained until now, a sort of numerical microscope able to attain the scale of the smallest geometrical detail.