Synergistic effect of multi walled carbon nanotubes and reduced graphene oxides in natural rubber for sensing application

Utilizing the electrical properties of polymer nanocomposites is an important strategy to develop high performance solvent sensors. Here we report the synergistic effect of multi walled carbon nanotubes (MWCNTs) and reduced graphene oxide (RGO) in regulating the sensitivity of the naturally occurring elastomer, natural rubber (NR). Composites were fabricated by dispersing CNTs alone and together with exfoliated RGO sheets (thermally reduced at temperatures of 200 and 600 °C) in NR by a solution blending method. RGO exfoliation and the uniform distribution of fillers in the composites were studied by atomic force microscopy, Fourier transformation infrared spectroscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The solvent sensitivity of the composite samples was noted from the sudden variation in electrical conductivity which was due to the breakdown of the filler networks during swelling in different solvents. It was found that the synergy between CNTs and RGO exfoliated at 200 °C imparts maximum sensitivity to NR in recognizing the usually used aromatic laboratory solvents. Mechanical and dynamic mechanical studies reveal efficient filler reinforcement, depending strongly on the nature of filler-elastomer interactions and supports the sensing mechanism. Such interactions were quantitatively determined using the Maier and Göritz model from Payne effect experiments. It is concluded that the polarity induced by RGO addition reduces the interactions between CNTs and ultimately results in the solvent sensitivity. © 2013 The Royal Society of Chemistry.

Retention of the original LLC structure in a cross-linked poly(ethylene glycol) diacrylate hydrogel with reinforcement from a silica network

Cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogels with uniformly controlled nanoporous structures templated from hexagonal lyotropic liquid crystals (LLC) represent separation membrane materials with potentially high permeability and selectivity due to their high pore density and narrow pore size distribution. However, retaining LLC templated nanostructures is a challenge as the polymer gels are not strong enough to sustain the surface tension during the drying process. In the current study, cross-linked PEGDA gels were reinforced with a silica network synthesized via an in situ sol-gel method, which assists in the retention of the hexagonal LLC structure. The silica precursor does not obstruct the formation of hexagonal phases. After surfactant removal and drying, these hexagonal structures in samples with a certain amount of tetraethoxysilane (TEOS) loading are well retained while the nanostructures are collapsed in samples without silica reinforcement, leading to the hypothesis that the reinforcement provided by the silica network stabilizes the LLC structure. The study examines the conditions necessary for a sufficient and well dispersed silica network in PEGDA gels that contributes to the retention of original LLC structures, which potentially enables broad applications of these gels as biomedical and membrane materials.

Does dynamic vulcanization induce phase separation?

Immiscible and miscible blends of poly(vinylidene fluoride) (PVDF) and acrylic rubber (ACM) were subjected to dynamic vulcanization to investigate the effect of crosslinking on phase separation. As a result of different processability, mixing torque behavior of miscible and immiscible blends was significantly different from one another. Scanning electron microscopy (SEM) was used to investigate the morphology of the system. After dynamic vulcanization, submicron ACM droplets were observed in the samples near the binodal curve of the system under mixing conditions. Small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) analysis were used to investigate the effect of dynamic vulcanization on the lamellar structure of the system. It was shown that for samples near the boundary of phase separation, increasing the crosslink density led to a decrease in the lamellar long period (L) as a sign of increment of crosslink density induced phase decomposition. Effects of shear rate on the final morphology of the system were investigated by changing the mixing temperature and by comparing the results of dynamic vulcanization at one phase and two phase regions.

An amoeboid algorithm for solving linear transportation problem

Transportation Problem (TP) is one of the basic operational research problems, which plays an important role in many practical applications. In this paper, a bio-inspired mathematical model is proposed to handle the Linear Transportation Problem (LTP) in directed networks by modifying the original amoeba model Physarum Solver. Several examples are used to prove that the provided model can effectively solve Balanced Transportation Problem (BTP), Unbalanced Transportation Problem (UTP), especially the Generalized Transportation Problem (GTP), in a nondiscrete way. © 2013 Elsevier B.V. All rights reserved.

Shear-free perfect fluids with a γ-law equation of state

 We investigate all shear-free perfect fluid solutions of the Einstein field equations where the pressure and energy density satisfy a (Formula presented.)-law equation of state with (Formula presented.). We prove that such a fluid is either non rotating or non expanding. As a consequence, it follows by combining our result with those of Collins and Wainwright that any such shear-free perfect fluid which models either an expand universe or a collapsing star must in fact be a Friedmann–Robertson–Walker spacetime.

A robust and reproducible procedure for cross-linking thermoset polymers using molecular simulation

Molecular simulation can provide valuable guidance in establishing clear links between structure and function to enable the design of new polymer-based materials. However, molecular simulation of thermoset polymers in particular, such as epoxies, present specific challenges, chiefly in the credible preparation of polymerised samples. Despite this need, a comprehensive, reproducible and robust process for accomplishing this using molecular simulation is still lacking. Here, we introduce a clear and reproducible cross-linking protocol to reliably generate three dimensional epoxy cross-linked polymer structures for use in molecular simulations. This protocol is sufficiently detailed to allow complete reproduction of our results, and is applicable to any general thermoset polymer. Amongst our developments, key features include a reproducible procedure for calculation of partial atomic charges, a reliable process for generating and validating an equilibrated liquid precursor mixture, and establishment of a novel, robust and reproducible protocol for generating the three-dimensional cross-linked solid polymer. We use these structures as input to subsequent molecular dynamics simulations to calculate a range thermo-mechanical properties, which compare favourably with experimental data. Our general protocol provides a benchmark for the process of simulating epoxy polymers, and can be readily translated to prepare and model epoxy samples that are dynamically cross-linked in the presence of surfaces and nanostructures.

The advancing science by enhancing learning in the laboratory (ASELL) project : the first Australian multidisciplinary workshop

Most science educators and researchers will agree that the laboratory experience ranks as a major factor that influences students’ attitudes to their science courses. Consequently, good laboratory programs should play a major role in influencing student learning and performance. The laboratory program can be pivotal in defining a student's experience in the sciences, and if done poorly, can be a major contributing factor in causing disengagement from the subject area. The challenge remains to provide students with laboratory activities that are relevant, engaging and offer effective learning opportunities.

The Advancing Science by Enhancing Learning in the Laboratory (ASELL) project has developed over the last 10 years with the aim of improving the quality of learning in undergraduate laboratories, providing a validated means of evaluating the laboratory experience of students and effective professional development for academic staff. After successful development in chemistry and trials using the developed principles in physics and biology, the project has now expanded to include those disciplines. This paper will discuss the activities of ASELL and provide a report about the first ASELL science workshop held at the University of Adelaide in April 2010, present some views of academic and student delegates, and make comparisons with other workshops.
Introduction

Ethnography and the Australian drug field: emaciation, appropriation and multidisciplinary myopia

In this paper, I provide a critical commentary on the current state of drug ethnography in Australia. I identify and discuss funding problems and the appropriation of ethnography by qualitative and quantitative researchers, both of which undermine the credibility and potential contribution of ethnography to the Australian drug field. I also interrogate the much-heralded but little-scrutinised idea of ‘multidisciplinary drug research’, drawing on examples of non-drug multidisciplinary research to argue that, while multidisciplinary drug research is a worthy goal, the research vision offered by advocates of such research is frequently an intellectually impoverished one. I conclude by suggesting possible ways to strengthen Australia's capacity to conduct both stand-alone ethnographic drug research and high-quality multidisciplinary drug research involving ethnography.

Evaluation of advanced breast cancer multidisciplinary team meatings

Background: Multidisciplinary team meetings (MDMs) have become an important decision-making forum in oncology. These meetings bring together expertise from each relevant field to improve continuity of care and health care outcomes for cancer patients. However there is a lack of evidence demonstrating the effectiveness of MDT meetings in improving cancer patient outcomes. The aim of this study was to explore the perceived value and potential usefulness of multidisciplinary team meetings for patients with advanced breast cancer (ABC).

Methods: ABC MDMs have been conducted since 2002 at two sites of Eastern Health, the second largest health service in Melbourne. Attendees were invited to complete a confidential questionnaire in November 2007 that comprised seven areas aimed to assess their judgment of how well the MDMs have improved patient management, including medical recommendations, psychosocial care, palliative care, community care, and team development. Average scores were calculated for improvement of each area.

Results: A total of 16 (69%) health practitioners participated in the survey, with main representation from nursing (37%), allied health (25%) and medicine (19%). Preliminary results indicate that the broad areas members reported the meeting had improved patient outcomes were in palliative care and medical management. Specific areas of perceived improvement were medical outcomes for patients; early referral to palliative care services; confirmation of diagnosis; referral to supportive care; and appropriateness of palliative care referrals. Conversely, the area that had least improved was community care, as there was no input from GPs or community services other than palliative care. Attendance by GPs and radiologists were considered important for further improving medical outcomes for patients.

Conclusions: This study demonstrates the perceived value of the MDT approach in the care of ABC patients, particularly in improving patient outcomes. The next stage of this research is to conduct a survey of ABC patient satisfaction level.

Knowledge-in-practice in the caring professions : multidisciplinary perspectives

Contents:  Ideas of knowledge in practice / Struan Jacobs -- Information, knowledge, and wisdom in medical practice / P. B. Greenberg -- The practice of the psychiatrist / Alex Holmes -- Social work knowledge-in-practice / Heather D'Cruz -- Disability : a personal approach / Lisa Chaffey -- Knowledge in the making : an analytical psychology perspective / Joy Norton -- Knowledge to action in the practice of nursing / Alison Hutchinson, Tracey Bucknall -- The risky business of birth / Frances Sheean and Jennifer M. Cameron -- Skills for person-centred care : health professionals supporting chronic condition prevention and self-management / Sharon Lawn and Malcolm Battersby -- Knowledge and reasoning in practice : an example from physiotherapy and occupational therapy / Megan Smith ... [et al.] -- Using knowledge in the practice of dealing with addiction : an ideal worth aiming for / Peter Miller.

Avian color vision and coloration : multidisciplinary evolutionary biology

A fundamental issue in biology is explaining the diversity of coloration found in nature. Birds provide some of the best-studied examples of the evolution and causes of color variation and some of the most arresting color displays in the natural world. They possess perhaps the most richly endowed visual system of any vertebrate, including UV-A sensitivity and tetrachromatic color vision over the 300-700-nm waveband. Birds provide model systems for the multidisciplinary study of animal coloration and color vision. Recent advances in understanding avian coloration and color vision are due to recognition that birds see colors in a different way than humans do and to the ready availability of small spectrometers. We summarize the state of the current field, recent trends, and likely future directions.