Immobilisation of redox active molecules as precursors for nanowire self-assembly

Spontaneously adsorbed monolayers of [Co(ttp-CH2-SH)2](PF6)2 have been formed on platinum microelectrodes by exposure to micromolar solutions of the complex in 0.1 M TBABF4 in acetonitrile, ttp-CH2-SH is 4'-(p-(thiolmethyl)-phenyl)-2,2':6',2''- terpyridine. Resonance Raman spectroscopy on roughened polycrystalline platinum macro electrodes show that the molecule undergoes adsorption by sulphur atom onto the platinum surface. The monolayers show reversible and well defined cyclic voltammetry when switched between Co2+ and Co3+ forms, with a peak to peak splitting of 0.040±0.005 V up to 200Vs'' and an FWHM of 0.138±0.010 V. Adsorption is irreversible leadi* ng to the maximum surface coverage, 6.3±0.3xl0‘ 1 m1 olc2m' for 2.5<[Co(ttp-Ctf2-SH)2]<10 (o,M. The rate of monolayer formation appears to be controlled not by mass transport or interfacial binding but by surface diffusion of the complex. The surface diffusion coefficient is 5 .5± l.lx l0 '7 cm V indicating that prior to formation of an equilibrated monolayer, the adsorbates have significant mobility on the surface. The electron transfer process across the monolayer-electrode interface has been probed by high speed chronoamperometry and the standard heterogeneous electron transfer rate constant, k°, is approximately 3.06±0.03xl04 s '1. The reorganization energy is. 18.5 kJmol'1. Self-assembled monolayers of pentanethiol-beta-cyclodextrins have been immobilised on gold polycrystalline macroelectrodes and electrochemically and spectroscopically characterised. The adsorption dynamics was followed by monitoring the change in capacitance during time and a surface diffusion process was found to be the rate determining step. The layers appear to have a mixed structure most likely between a hexagonal close-packed monolayer and a brick configuration. Blocking behaviour depends on the hydrophobicity of the solution phase redox active probe. Scan rate dependent cyclic voltammetry has been used to characterise the defect density within the assemblies. In general, the layers are stable enough in time and potential window to probe the host-guest properties of the immobilized cyclodextrin cavities. The modified gold electrodes were exposed to micromolar solutions of cobalt biphenylterpyridine, in order to electrochemically and spectroscopically characterise the inclusion process. The host-guest reaction occurred for the in-situ experiments and it was characterised in terms of equilibrium constant, 2.78±0.7><104 M'1, and free Gibbs energy of inclusion, 25 kJ m ol1. Finally, control experiments of the adsorption of the redox active probe onto the bare gold electrodes further confirmed the occurring of the inclusion

Experimental Investigation on Thermal Conductivity and Thermal Diffusivity of Water-Agar Gel from Room Temperature to –60℃

From a thermal point of view, water-agar gel can reproduce the behavior of human soft tissues with a good approximation. For this reason, agar gel is widely used to mimic the thermal diffusion inside the latter, in order to study the effect on human tissues of new techniques and probes used to solve various health diseases. Cryoablation is part of these techniques and its effectiveness strongly depends on the biological response of the tissues to the freezing action and heat diffusion and therefore on their thermo-physical properties. This study presents the values of thermal conductivity and thermal diffusivity, measured on water-agar gel samples, using the transient plane source method, forward and backward from room temperature down to −60℃. The freezing transient and the temperature at which the phase transition begins are highlighted, as well as the temperature dependence of both thermal conductivity and diffusivity

Influence of Turbulence Modeling on Velocity Profiles for Cyclone Separators

Newer aircraft engines are designed in order to obtain both the best performances and the lowest environmental impact, reducing the amount of polluting elements emitted in the atmosphere. The improvement of engine lubricating circuits is related to this task, aiming to a more efficient lubricant recycling when flowing into filtering devices. Cyclonic separators constitute one stage of the filtering phase. They are simple devices whose working principle consists in using centrifugal forces to separate two phases from one another, e.g. solid particles from a fluid or two fluids having different densities. The present work focuses on the impact of the turbulence models in the simulations of cyclone separators. The objective is to provide guidelines for future numerical analyses, paying special attention to the correct simulation of velocity profiles, which play a very important role in the particle separation process

A Mass Balance-Based Method for the Anaerobic Digestion of Rice Straw

Current rice straw disposal practices have serious repercussions on the environment and, in addition, do not consider its energy potential. On the contrary, the anaerobic digestion of rice straw makes it possible to produce renewable energy and to reintroduce into the soil the nutrients present in the digestate, at the same time, reducing greenhouse gas emissions from paddies. For rice straw of different geographical origin, by applying a mass balance method to the digester, the minimum requirements in terms of conditioners (nitrogen, phosphorus and potassium) and water, which allow obtaining the maximum production of methane, were calculated. The results obtained show that after the first 30 days (hydraulic retention time) for each ton of rice straw digested, the daily water consumption varies considerably from one country to another, from a minimum value of 1.5 m3/d to a maximum of 4.3 m3/d. After the same time, the addition of nitrogen and phosphorus is only required for the optimal anaerobic digestion of Indian rice straw. The low presence of these elements in Indian straw requires an addition of 3 kg/d of urea and 1.5 kg/d of superphosphate to compensate for the lack of nitrogen and phosphorus, respectively. In all the examined cases, the concentration of potassium, even if higher than the optimal value, does not reach levels that can significantly affect the methane production

Rice Straw: A Waste with a Remarkable Green Energy Potential

With reference to the province of Novara in northwest Italy, this study aims to raise awareness about the environmental benefits that can derive from the use of alternative rice straw management practices to those currently in use, also highlighting how the use of these straws for energy purposes can be a valid alternative to the use of non-renewable resources. Using the LCA (Life Cycle Assessment) method, the two rice straw management practices currently in place (open field combustion and straw incorporation) were compared with an alternative strategy consisting in their collection and removal. The results show that removal of straw allows reducing the emissions of pollutants significantly: about one-hundredth of the PM (Particulate Matter) formation compared to the open-field burning and about one-tenth of the ozone depletion (CFCs, HCFCs, halons, etc.) compared to both the other two practices. Moreover, the LCA results show how the use of rice straw to produce energy as an alternative to conventional fuels helps to reduce the global warming potential of rice cultivatio

transferrin and structural anomalies of chromosome 3 in the blastic phase of chronic myelocytic leukemia

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Effect of Ligament Mapping from Different Magnetic Resonance Image Quality on Joint Stability in a Personalized Dynamic Model of the Human Ankle Complex

Background. Mechanical models of the human ankle complex are used to study the stabilizing role of ligaments. Identification of ligament function may be improved via image-based personalized approach. The aim of this study is to compare the effect of the ligament origin and insertion site definitions obtained with different magnetic resonance imaging (MRI) modalities on the mechanical behaviour of a dynamic model of the ankle complex. Methods. MRI scans, both via 1.5 T and 3.0 T, were performed on a lower-limb specimen, free from anatomical defects, to obtain morphological information on ligament-to-bone attachment sites. This specimen was used previously to develop the dynamic model. A third ligament attachment site mapping scheme was based on anatomical dissection of the scanned specimen. Following morphological comparison of the ligament attachment sites, their effect on the mechanical behaviour of the ankle complex, expressed by three-dimensional load&ndash;displacement properties, was assessed through the model. Results. Large differences were observed in the subtalar ligament attachment sites between those obtained through the two MRI scanning modalities. The 3.0 T MRI mapping was more consistent with dissection than the 1.5 T MRI. Load&ndash;displacement curves showed similar mechanical behaviours between the three mappings in the frontal plane, but those obtained from the 3.0 T MRI mapping were closer to those obtained from dissection. Conclusions. The state-of-the-art 3.0 T MRI image analysis resulted in more realistic mapping of ligament fibre origin and insertion site definitions; corresponding load&ndash;displacement predictions from a subject-specific model of the ankle complex showed a mechanical behaviour more similar to that using direct ligament attachment observations