Simulating the physiology of athletes during endurance sports events: modelling human energy conversion and metabolism

The human physiological system is stressed to its limits during endurance sports competition events. We describe a whole body computational model for energy conversion during bicycle racing. About 23 per cent of the metabolic energy is used for muscle work, the rest is converted to heat. We calculated heat transfer by conduction and blood flow inside the body, and heat transfer from the skin by radiation, convection and sweat evaporation, resulting in temperature changes in 25 body compartments. We simulated a mountain time trial to Alpe d'Huez during the Tour de France. To approach the time realized by Lance Armstrong in 2004, very high oxygen uptake must be sustained by the simulated cyclist. Temperature was predicted to reach 39°C in the brain, and 39.7°C in leg muscle. In addition to the macroscopic simulation, we analysed the buffering of bursts of high adenosine triphosphate hydrolysis by creatine kinase during cyclical muscle activity at the biochemical pathway level. To investigate the low oxygen to carbohydrate ratio for the brain, which takes up lactate during exercise, we calculated the flux distribution in cerebral energy metabolism. Computational modelling of the human body, describing heat exchange and energy metabolism, makes simulation of endurance sports events feasible.     

Conjugated-polyelectrolyte-grafted cotton fibers act as "micro flypaper" for the removal and destruction of bacteria

We demonstrate herein a method for chemically modifying cotton fibers and cotton-containing fabric with a light-activated, cationic phenylene-ethynylene (PPE-DABCO) conjugated polyelectrolyte biocide. When challenged with Pseudomonas aeruginosa and Bacillus atropheaus vegetative cells from liquid suspension, light-activated PPE-DABCO effects 1.2 and 8 log, respectively, losses in viability of the exposed bacteria. These results suggest that conjugated polyelectrolytes retain their activity when grafted to fabrics, showing promise for use in settings where antimicrobial textiles are needed.     

Physicochemical characterisation and biological evaluation of polyvinylpyrrolidone-iodine engineered polyurethane (Tecoflex<Superscript>®</Superscript>)

Bacterial adhesion and encrustation are the known causes for obstruction or blockage of urethral catheters and ureteral stents, which often hinders their effective use within the urinary tract. In this in vitro study, polyvinylpyrrolidone-iodine (PVP-I) complex modified polyurethane (Tecoflex^®) systems were created by physically entrapping the modifying species during the reversible swelling of the polymer surface region. The presence of the PVP-I molecules on this surfaces were verified by ATR-FTIR, AFM and SEM-EDAX analysis, while wettability of the films was investigated by water contact angle measurements. The modified surfaces were investigated for its suitability as a urinary tract biomaterial by comparing its lubricity and ability to resist bacterial adherence and encrustation with that of base polyurethane. The PVP-I modified polyurethane showed a nanopatterned surface topography and was highly hydrophilic and more lubricious than control polyurethane. Adherence of both the gram positive Staphylococcus aureus (by 86%; **P < 0.01) and gram-negative Pseudomonas aeruginosa (by 80%; *P < 0.05) was significantly reduced on the modified surfaces. The deposition of struvite and hydroxyapatite the major components of urinary tract encrustations were significantly less on PVP-I modified polyurethane as compared to base polyurethane, especially reduction in hydroxyapatite encrustation was particularly marked. These results demonstrated that the PVP-I entrapment process can be applied on polyurethane in order to reduce/lower complications associated with bacterial adhesion and deposition of encrustation on polyurethanes.     

Role of dopant concentration, crystal phase and particle size on microbial inactivation of Cu-doped TiO2 nanoparticles

The properties of Cu-doped TiO(2) nanoparticles (NPs) were independently controlled in a flame aerosol reactor by varying the molar feed ratios of the precursors, and by optimizing temperature and time history in the flame. The effect of the physico-chemical properties (dopant concentration, crystal phase and particle size) of Cu-doped TiO(2) nanoparticles on inactivation of Mycobacterium smegmatis (a model pathogenic bacterium) was investigated under three light conditions (complete dark, fluorescent light and UV light). The survival rate of M. smegmatis (in a minimal salt medium for 2 h) exposed to the NPs varied depending on the light irradiation conditions as well as the dopant concentrations. In dark conditions, pristine TiO(2) showed insignificant microbial inactivation, but inactivation increased with increasing dopant concentration. Under fluorescent light illumination, no significant effect was observed for TiO(2). However, when TiO(2) was doped with copper, inactivation increased with dopant concentration, reaching more than 90% (>3 wt% dopant). Enhanced microbial inactivation by TiO(2) NPs was observed only under UV light. When TiO(2) NPs were doped with copper, their inactivation potential was promoted and the UV-resistant cells were reduced by over 99%. In addition, the microbial inactivation potential of NPs was also crystal-phase-and size-dependent under all three light conditions. A lower ratio of anatase phase and smaller sizes of Cu-doped TiO(2) NPs resulted in decreased bacterial survival. The increased inactivation potential of doped TiO(2) NPs is possibly due to both enhanced photocatalytic reactions and leached copper ions.     

Evidence for surface states in pristine and Co-doped ZnO nanostructures: magnetization and nonlinear optical studies

An unexpected presence of ferromagnetic (FM) ordering in nanostructured ZnO has been reported previously. Recently, from our detailed magnetization studies and ab initio calculations, we attributed this FM ordering in nanostructured ZnO to the presence of surface states, and a direct correlation between the magnetic properties and crystallinity of ZnO was observed. In this study, through a systematic sample preparation of both pristine and Co-doped ZnO nanostructures, and detailed magnetization and nonlinear optical (NLO) measurements, we confirm that the observed FM ordering is due to the presence of surface states.     

Label-free electrochemical monitoring of concentration enrichment during bipolar electrode focusing

We show that a label-free electrochemical method can be used to monitor the position of an enriched analyte band during bipolar electrode focusing in a microfluidic device. The method relies on formation of a depleted buffer cation region, which is responsible for concentration enrichment of the charged analyte. However, this depletion region also leads to an increase in the local electric field in the solution near a bipolar electrode (BPE), and this in turn results in enhanced faradaic reactions (oxidation and reduction of water) at the BPE. Therefore, it is possible to detect the presence of the concentrated analyte band by measuring the current passing through the BPE used for concentration enrichment, or the concentrated band can be detected at a secondary BPE dedicated to that purpose. Both experiments and simulations are presented that fully elucidate the underlying phenomenon responsible for these observations.     

Rate control-based framework and algorithm for optimal provisioning

Ideally, networks should be designed to accommodate a variety of different traffic types, while at the same time maximizing its efficiency and utility. Network utility maximization (NUM) serves as an effective approach for solving the problem of network resource allocation (NRA) in network analysis and design. In existing literature, the NUM model has been used to achieve optimal network resource allocation such that the network utility is maximized. This is important, since network resources are at premium with the exponential increase in Internet traffic. However, most research work considering network resource allocation does not take into consideration key issues, such as routing and delay. A good routing policy is the key to efficient network utility, and without considering the delay requirements of the different traffic, the network will fail to meet the user’s quality of service (QoS) constraints. In this paper, we propose a new NUM framework that achieves improved network utility while taking into routing and delay requirements of the traffic. Then, we propose a decomposition technique-based algorithm, D-NUM, for solving this model efficiently. We compare our approach with existing approaches via simulations and show that our approach performs well.     

Lithium recycling behaviour of nano-phase-CuCo2O4 as anode for lithium-ion batteries

Nano-CuCo₂O₄ is synthesized by the low-temperature (400 °C) and cost-effective urea combustion method. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) studies establish that the compound possesses a spinel structure and nano-particle morphology (particle size (10–20 nm)). A slight amount of CuO is found as an impurity. Galvanostatic cycling of CuCo₂O₄ at 60 mA g⁻¹ in the voltage range 0.005–3.0 V versus Li metal exhibits reversible cycling performance between 2 and 50 cycles with a small capacity fading of 2 mAh g⁻¹ per cycle. Good rate capability is also found in the range 0.04–0.94C. Typical discharge and charge capacity values at the 20th cycle are 755(±10) mAh g⁻¹ (∼6.9 mol of Li per mole of CuCo₂O₄) and 745(±10) mAh g⁻¹ (∼6.8 mol of Li), respectively at a current of 60 mA g⁻¹. The average discharge and charge potentials are ∼1.2 and ∼2.1 V, respectively. The underlying reaction mechanism is the redox reaction: Co ↔ CoO ↔ Co₃O₄ and Cu ↔ CuO aided by Li₂O, after initial reaction with Li. The galvanostatic cycling studies are complemented by cyclic voltammetry (CV), ex situ TEM and SAED. The Li-cycling behaviour of nano-CuCo₂O₄ compares well with that of iso-structural nano-Co₃O₄ as reported in the literature.     

Study of magnetohydrodynamic convection between two rotating cylinders filled with casson fluid and the viscous dissipation effect

We have studied the forced convection of a viscous incompressible and electrically conducting non‐Newtonian Casson fluid between two rotating cylinders with viscous dissipation effect. An angular velocity and gives to inner and outer cylinders, respectively, and constant heat flux presented on the inner cylinder surface. Also, the outer cylinder is taken as insulated. Here, we have discussed three cases: (i) The inner cylinder is rotating with a constant angular velocity while the outer cylinder is at rest; (ii) Both the cylinders rotate in the identical direction with equal angular velocity; and (iii) Both the cylinders are rotating with equal angular speed but the outer cylinder rotates in the opposite direction of the inner cylinder. The governing equations are solved by numerical techniques using MATLAB Software and the results are obtained graphically.     

Cu/SBA-15 is an Efficient Solvent-Free and Acid-Free Catalyst for the Rearrangement of Benzaldoxime into Benzamide

Abstract  

Cu/SBA-15 catalysts with various Cu loadings in the range of 5–20 wt% were prepared by an impregnation method and characterized by N₂ adsorption, X-ray diffraction, temperature programmed reduction and X-Ray photoelectron spectroscopic techniques. Cu/SBA-15 catalysts are found to be highly active and selective for the Beckmann rearrangement of benzaldoxime into benzamide under solvent-free and acid-free conditions.