High‐Performance Multifunctional Graphene‐PLGA Fibers: Toward Biomimetic and Conducting 3D Scaffolds

The development of electrically conducting fibers based on known cytocompatible materials is of interest to those engaged in tissue regeneration using electrical stimulation. Herein, it is demonstrated that with the aid of rheological insights, optimized formulations of graphene containing spinnable poly(lactic‐co‐glycolic acid) (PLGA) dopes can be made possible. This helps extend the general understanding of the mechanics involved in order to deliberately translate the intrinsic superior electrical and mechanical properties of solution‐processed graphene into the design process and practical fiber architectural engineering. The as‐produced fibers are found to exhibit excellent electrical conductivity and electrochemical performance, good mechanical properties, and cellular affinity. At the highest loading of graphene (24.3 wt%), the conductivity of as‐prepared fibers is as high as 150 S m^?1 (more than two orders of magnitude higher than the highest conductivity achieved for any type of nanocarbon‐PLGA composite fibers) reported previously. Moreover, the Young's modulus and tensile strength of the base fiber are enhanced 647‐ and 59‐folds, respectively, through addition of graphene.     

Cyclic response and modeling of saturated silty clay due to fluctuations in reservoir water level of the Three Gorges Dam,China

The deformation characteristics of soil obtained from landslides at the Three Gorges Dam Reservoir have been examined. Due to the annual fluctuation in the water level of the reservoir, landslides around the Three Gorges Dam Reservoir are subjected to cyclic loading. Laboratory triaxial tests have been carried out on silty clay specimens subjected to cyclic changes in pore water pressure. The test results indicate that when the soil is subjected to repeated unloading–reloading with constant deviatoric stress in an overconsolidated state, the silty clay material shows inelastic deformation with the accumulation of irrecoverable strain. To capture this behavior, a constitutive model has been developed to simulate the deformation induced by changes in pore water pressure. This model is based on a modification of Yao et al. (2009)’s model to include the effect of cyclic loading. The model has been used to calculate the shear strain during cyclic loading and for a comparison with the laboratory test results. It has been shown that the proposed model is capable of capturing the deformation response of landslide soil subjected to changes in pore water pressure caused by the fluctuating water level of the reservoir.     

Ultrasonic detection of the anisotropy of protein cross linking in myocardium at diagnostic frequencies

Increased myocardial stiffness in aging and diabetes that may result in pathologies such as diastolic dysfunction has been attributed, in part, to an increase in cross linking of extracellular matrix proteins such as collagen. With the development of new approaches to cardiovascular therapy, it becomes increasingly important to develop noninvasive approaches for monitoring changes in myocardial cross linking. The objective of this study was to use ultrasound at frequencies used in clinical echocardiography to measure changes in myocardial attenuation resulting from increased cross linking as a function of angle of insonification over a complete rotation. Through-transmission radiofrequency-based measurements were performed on 36 specimens from 12 freshly excised ovine hearts at room temperature, which were then fixed in formalin to induce protein cross linking prior to repeated measurements. For angles near perpendicular to the myofiber direction, the measured slope of attenuation increased from 0.52 +/- 0.07 dB/(cm MHz) (mean +/- one standard deviation) for freshly excised to 0.85 +/- 0.08 dB/(cm MHz) for formalin-fixed myocardium. In contrast, results for parallel insonification exhibit considerable overlap (1.88 +/- 0.17 for freshly excised and 1.75 +/- 0.19 dB/(cm MHz) for formalin-fixed myocardium). Results of this study suggest that the response of the extracellular collagenous matrix to changes in cross linking is directionally dependent. The anisotropy of ultrasonic attenuation thus may provide an approach for noninvasive monitoring of the extent and progression of myocardial disease associated with changes in protein cross linking. Accounting for effects due to anisotropy may be essential for the future detection of such changes using ultrasonic attenuation in vivo.     

Enhanced stability and fluidity in droplet on hydrogel bilayers for measuring membrane protein diffusion

We form artificial lipid bilayers suitable for single-molecule fluorescence microscopy by contacting an aqueous droplet with a hydrogel support immersed in a solution of lipid in oil. Our results show that droplet on hydrogel bilayers (DHBs) have high lipid mobilities, similar to those observed in unsupported lipid bilayers. DHBs are also stable over a period of several weeks. We examine membrane protein diffusion in these bilayers and report a decreased lateral mobility of the heptameric beta-barrel pore-forming toxin alpha-hemolysin versus that of its monomeric precursor. These results corroborate previous models of the alpha-hemolysin insertion mechanism where the monomer binds to the lipid bilayer without insertion.     

Electrodeposition and characterisation of polypyrroles containing sulfonated carbon nanotubes

Using facile diazonium chemistry, sulfonate groups have been covalently attached to single wall carbon nanotubes. The resulting sulfonated tubes form a stable aqueous dispersion in the presence of pyrrole monomer. Subsequent electropolymerisation results in a conductive, electroactive polypyrrole doped with sulfonated tubes being formed at unusually low potentials. The potential of this material as a host matrix for biomolecules has been demonstrated by entrapping horse-radish peroxidase directly in the polypyrrole during composite formation.     

Costs and benefits of smoking cessation aids: making a case for public reimbursement of nicotine replacement therapy in Australia

Background

Tobacco smoking is the leading preventable cause of morbidity and mortality in Australia and other developed countries. Of the pharmacological aids that are available for smoking cessation, bupropion (Zyban SR) is eligible for public reimbursement on the Australian Pharmaceutical Benefits Scheme (PBS), whereas nicotine replacement therapy (NRT) is not. Information on the cost‐effectiveness and financial impact of public reimbursement of these strategies can better inform debate about their inclusion or exclusion in public reimbursement schemes.

Objective

To estimate the cost‐effectiveness of bupropion and NRT, and the potential financial impact of public reimbursement of NRT in Australia.

Design

A cost‐effectiveness analysis using a deterministic Markov model, and cost per disability‐adjusted life year (DALY) averted over a lifetime as the outcome measure.

Population

Current smokers, motivated to quit, in Australia in 2000.

Interventions

(1) NRT; (2) bupropion; and (3) a combined strategy using bupropion as the first‐line treatment and NRT in those who fail to quit smoking or have adverse reactions to bupropion.

Results

Quitting smoking can increase life expectancy of current smokers by 1–7.6 years depending on age at cessation and sex. Providing bupropion to current smokers who are motivated to quit would cost A$7900 (95% uncertainty interval A$6000 to A$10 500) for each DALY averted; NRT patches would cost A$17 000 (A$9000 to A$28 000) for each DALY averted, with similar results even if used as a second‐line treatment following initial failure to quit using bupropion. If 6% of current smokers were to use NRT following inclusion on the PBS, this would result in an annual cost of A$40–110 million to the PBS depending on the listed price.

Conclusions

Compared with other drugs included on the PBS, bupropion and NRT are both highly cost‐effective smoking cessation interventions, and including NRT on the PBS would have a moderate financial impact. Given the sizeable health burden of smoking, and the large individual benefits of quitting smoking, increasing the availability of alternative aids and uptake of these strategies through public reimbursement would be a positive and rational step towards further reducing tobacco‐related disease burden in Australia and other countries where NRT is currently not subsidised.Tobacco smoking is the largest preventable cause of morbidity and mortality in Australia and other developed countries. Despite projected declines in tobacco‐related diseases in line with decreasing prevalence, tobacco is still expected to be among the leading causes of disease burden in 2016.¹ Worldwide, it is the second highest cause of death and fourth highest cause of disease burden.Effective policies to control tobacco use are crucial. Although preventing individuals from starting smoking is an important aim of tobacco control, cessation in current smokers is also critical. As nicotine is highly addictive, smokers often require assistance to maintain abstinence. Modestly effective cessation aids are available, including pharmacological agents, such as bupropion (Zyban SR) and nicotine replacement therapy (NRT).^2,3Australia has implemented many strong tobacco control policies. The retail price of tobacco in Australia is among the top three worldwide.⁴ Advertising and promoting tobacco products has been totally banned, pictorial pack warnings have recently been implemented, opportunities to smoke cigarettes in public places are severely limited and there is legislation in place forcing an upcoming ban of smoking in bars and hotels.^5,6,7 Despite these measures, nearly one in five Australian adults still smoke daily, indicating the need for further strategies to encourage cessation.⁸In 1995, the Australian government rejected a recommendation by the Pharmaceutical Benefits Advisory Committee to include NRT on the public reimbursement scheme—the Pharmaceutical Benefits Scheme (PBS).⁹ By contrast, bupropion was made available on the PBS in February 2001.¹⁰ The continued exclusion of NRT and inclusion of bupropion may or may not be a rational decision. Valid and comparable information on the cost‐effectiveness and financial implications of including these interventions on the PBS are important inputs into this debate.The cost‐effectiveness of both NRT and bupropion has been studied previously.² A lack of consistency in the methods of these studies, however, makes comparisons difficult, and the context‐specific nature of inputs into cost‐effectiveness analyses such as disease outcomes means that these results may not be applicable to the Australian setting.^2,11 This study aims to evaluate the cost‐effectiveness of NRT and bupropion in the Australian context, as well as the potential financial impact of including NRT on the PBS.     

A high-resolution Navier–Stokes solver for direct numerical simulation of free shear flow

Abstract

A high-resolution, Navier–Stokes solver is developed for direct numerical simulation (DNS) of free shear flow. All terms in Navier–Stokes equations are discretized using higher order methods. Diffusion term is discretized using fourth order central difference scheme while second order Adams–Bashforth is used for time derivative. Advecting velocity is approximated using fourth order Lagrangian interpolation. For the approximation of advected velocity, a blended fifth order-upwind scheme is proposed. Developed high resolution solver is used for DNS of round jet in transitional and turbulent regimes. A novel open outlet boundary condition (OOBC) is proposed which has the ability to dynamically adjust according to prevailing local condition at the outlet thereby minimizing reflections from outlet. Ability of blended fifth order upwind scheme and fifth order WENO is assessed in terms of algorithmic efficiency as well as fidelity of simulations. It is demonstrated that the proposed blended fifth order upwind scheme outperforms the WENO scheme in terms of algorithmic efficiency. Assessment of fidelity of simulations reveals that WENO displays a tendency to over-predict momentum advection in transitional as well as fully turbulent regime of the round jet. In contrast, the proposed advection scheme is not faced with such limitation.     

Integration of CATHENA Thermal-Hydraulic Model with CANDU 6 Analytical Simulator Controller

This paper introduces a powerful design and analysis tool named SIMCAT, that is developed to support applications to license a CANDU nuclear reactor, refurbish projects, and support the existing CANDU stations. It consists of the CATHENA （Canadian Algorithm for Thermo-Hydraulic Network Analysis）, the control logics from C6SIM （CANDU 6 Analytical Simulator）, and a communication protocol, PVM （parallel virtual machine）. This is the first time that CATHENA has been successfully coupled directly with a program written in another language. The independence of CATHENA and the C6SIM controllers allows the development of both CATHENA and C6SIM controller to proceed independently.