Polylactic Acid-Based Polymer Blends for Durable Applications

There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of the material as a durable item: it has low ductility and impact strength in bulk applications, along with poor stability in the face of heat, humidity or liquid media. To combat these deficiencies, a number of techniques were investigated. Samples were annealed to create crystalline domains that would improve mechanical properties and reduce diffusion, blended with graphene to create barriers to diffusion throughout the material, or compounded with a polycarbonate (PC) polymer phase to protect the PLA phase and to enhance the mechanical properties of the blend. If a material containing biologically sourced components with good mechanical properties can be created, it would be desirable for durable uses such as electronics components or as an automotive grade resin.;Crystallization experiments were carried out in a differential scanning calorimeter to determine the effects of heat treatment and additives on the rather slow crystallization kinetics of PLA polymer. It was determined that the blending in of the PC phase did not significantly alter the kinetics or mechanism of crystal growth. The addition of graphene to any PC/PLA formulation served as a nucleating agent which speeded up the crystallization kinetics markedly, in some cases by several orders of magnitude. Results obtained from these experiments were internally consistent, showing that no matter the treatment or formulation, PLA achieved a maximum of 30-35 percent crystallinity.;Samples receiving no treatment as well as those with annealing, the addition of graphene, and in some cases annealing/graphene were subjected to both solvent and hydrolytic degradation in order to find the most stable blend or treatment. Both pellets and molded parts of varying thicknesses were investigated to evaluate the effect of diffusional resistance on long term durability. It was determined that while the addition of crystallinity or graphene platelets can provide a temporary barrier against diffusion of attacking species, PLA polymer itself is not dimensionally stable over the long lifecycle required for durable applications such as for automotive parts. In fact, PLA-only molded panels aged in distilled water at 50°C for 42 days experienced over 99% viscosity loss regardless of which treatment was applied, and nearly all mechanical strength was lost during this time. Furthermore, while the addition of graphene and the heat treatment produced diffusion barriers which could slightly enhance PLA\u27s degradation resistance, the treatments caused the already fragile polymer to become very brittle. Solvent degradation experiments also showed that molded parts containing more than 40% PLA loading lost in excess of 75% of the original viscosity no matter what treatment was used. This showed that these materials are likely to fail well before a sufficiently long lifecycle for durable goods is achieved.;Polycarbonate rich blends with less than 30% PLA as the dispersed phase showed excellent property retention after the accelerated aging tests. Formulations with up to 20% PLA content had degradation results that were nearly identical to those of 100% polycarbonate, which literature has shown to have useful lifecycles for durable applications of up to 20 years. By completely encapsulating the PLA in the polycarbonate matrix, which occurred at about 30% PLA by maximum, it was fully protected by the more stable phase.;Lastly, molded parts of differing thicknesses were hydrolytically degraded to examine the effects of diffusion resistance on the mechanical properties of untreated PC/PLA blends. It was determined that, similar to the droplet morphology study, the effect of PC content was the most dominating factor in the durability of the formulations. In fact, if molded parts reach a critical thickness, a transition from ductile to brittle failure modes can be observed. The rate of diffusion through the materials was also determined to be much faster than the rate of PLA hydrolysis.;It is concluded that the most effective way to create a durable material containing a significant bio-based content is to completely encapsulate PLA polymer with the more stable polycarbonate phase. Materials containing up to about 30% PLA at maximum were shown to be sufficiently durable so that they may be employed in similar automotive and electrical applications as for pure polycarbonate. (Abstract shortened by UMI.)

Some early recollections

Transcript of manuscripts, reference 'Finniss, Boyle Travers, 20-21', Borrow Collection, Flinders University LibraryBoyle Travers Finniss was Assistant Surveyor to Colonel William Light when the colony of South Australia was set up in 1836. He describes early encounters with the Aborigines, early settler life, the political and social life of the colony, the progress of surveying and building the city of Adelaide, and his own career which included a term as the first Premier of South Australia under responsible government

Medicine’s inconvenient truth: The placebo/nocebo effect

Placebo and nocebo effects are often regarded by clinicians as either a quaint reminiscence from the pre-therapeutic era, or simply as a technique for establishing the efficacy of therapeutic interventions within the locus of evidence-based practice. However, neither of these explanations sufficiently account for their complexity or their persistence and impact in clinical medicine. Placebo and nocebo effects are embedded in the very fabric of therapeutic relationships and are both a manifestation and outcome of the rituals that characterise clinical practice. They are also a stark reminder of the many personal and environmental factors, including the attitudes, beliefs and expectations of both doctor and patient, that shape the outcomes of health professional-patient interactions. We describe how recent biological and neuropsychiatric data have clarified the operation of placebo and nocebo effects in clinical practice – demonstrating the ability of the therapeutic context to modulate endogenous biological processes in a targeted manner. This, in turn, illustrates the potent philosophical and sociocultural aspects of medical praxis. Keywords: placebo; nocebo; context effect; medical therapeutics; medical practice; medical ethic

Medicine’s inconvenient truth: The placebo/nocebo effect

Placebo and nocebo effects are often regarded by clinicians as either a quaint reminiscence from the pre-therapeutic era, or simply as a technique for establishing the efficacy of therapeutic interventions within the locus of evidence-based practice. However, neither of these explanations sufficiently account for their complexity or their persistence and impact in clinical medicine. Placebo and nocebo effects are embedded in the very fabric of therapeutic relationships and are both a manifestation and outcome of the rituals that characterise clinical practice. They are also a stark reminder of the many personal and environmental factors, including the attitudes, beliefs and expectations of both doctor and patient, that shape the outcomes of health professional-patient interactions. We describe how recent biological and neuropsychiatric data have clarified the operation of placebo and nocebo effects in clinical practice – demonstrating the ability of the therapeutic context to modulate endogenous biological processes in a targeted manner. This, in turn, illustrates the potent philosophical and sociocultural aspects of medical praxis. Keywords: placebo; nocebo; context effect; medical therapeutics; medical practice; medical ethic

Destigmatizing the placebo effect

Alfano’s reframing of the operationalization of the placebo effect (PE) in the context of informed consent (IC) has broader implications for clinical practice, particularly with regard to the employment of the concept of authorized libertarian paternalism (Alfano 2015). Stigmatization of people refers to the development of a value judgment declaring that a person with certain attributes is in some way of lesser status, diminished, or invalid, with resultant negative consequences for such individuals. Concepts may also be stigmatized, particularly those that are easily falsifiable, including, apropos of the subject of PEs, mesmerism, sugar pills, and sham procedures, and hence PEs have historically been regarded with great skepticism, exemplifying something dishonest, misleading, “unscientific,” or invalid (Gold and Lichtenberg 2014). While recent studies have revealed extraordinary insights into the placebo and nocebo effect (PNE), in many ways these insights have had only limited impact upon the practice of medicine or upon (negative) views of the PNE. There may be many reasons why this is so. It may be because of the inherent conservatism of medicine, the need for medicine to distinguish itself from nonconventional practices through its (scientific) method and its capacity to provide an account of mechanism, or the intransigence of firmly held views in any field of practice. Indeed, investigators have “long recognized that individuals tend to maintain rather than change their stereotypes, despite receiving evidence that counters them” (Lyons and Kashima 2003, 989). Enculturation in medicine, in particular, systematically reinforces that certain concepts and actions are “foreign” to valid practice through a process of stereotype maintenance. Conscious, deliberate, or incidental/unwitting utilization of the placebo effect is characterized as deceptive, unethical, unscientific, and unprofessional and hence an action that separates physicians from nonphysicians. However, as distinct from a modern correlate of mesmerism or purely charismatic practice, there is an extensive, well-validated evidence base demonstrating specific psychological and biological processes underpinning PNEs (Hall, Loscalzo, and Kaptchuk 2015). This emergent evidence base is not simply of passing interest but poses significant challenges to traditionally held beliefs about both the role of PNEs in medical practice and about medical practice more generally

Synthesis and complexation of bis(imino)aryl ligands: towards the generation of iridium based water oxidation catalysts

The C,C-trans bis-cyclometalation of 2,6-diphenylpyridine across an iridium center was investigated. Equally the synthesis and complexation of a series of bis(imino)aryl ligands was studied. Installing methyl and fluoro substituents in the backbone of the ligand prevented the C-H activation of the 4- and 6- positions and resulted in metalation of the 2- position..

Fentanyl buccal soluble film (FBSF) for breakthrough pain in patients with cancer: a randomized, double-blind, placebo-controlled study

Background: Fentanyl buccal soluble film (FBSF) has been developed as a treatment of breakthrough pain in opioid-tolerant patients with cancer. The objective of this study was to evaluate the efficacy of FBSF at doses of 200–1200 μg in the management of breakthrough pain in patients with cancer receiving ongoing opioid therapy

Scalable desktop visualisation of very large radio astronomy data cubes

Observation data from radio telescopes is typically stored in three (or higher) dimensional data cubes, the resolution, coverage and size of which continues to grow as ever larger radio telescopes come online. The Square Kilometre Array, tabled to be the largest radio telescope in the world, will generate multi-terabyte data cubes – several orders of magnitude larger than the current norm. Despite this imminent data deluge, scalable approaches to file access in Astronomical visualisation software are rare: most current software packages cannot read astronomical data cubes that do not fit into computer system memory, or else provide access only at a serious performance cost. In addition, there is little support for interactive exploration of 3D data. We describe a scalable, hierarchical approach to 3D visualisation of very large spectral data cubes to enable rapid visualisation of large data files on standard desktop hardware. Our hierarchical approach, embodied in the AstroVis prototype, aims to provide a means of viewing large datasets that do not fit into system memory. The focus is on rapid initial response: our system initially rapidly presents a reduced, coarse-grained 3D view of the data cube selected, which is gradually refined. The user may select subregions of the cube to be explored in more detail, or extracted for use in applications that do not support large files. We thus shift the focus from data analysis informed by narrow slices of detailed information, to analysis informed by overview information, with details on demand. Our hierarchical solution to the rendering of large data cubes reduces the overall time to complete file reading, provides user feedback during file processing and is memory efficient. This solution does not require high performance computing hardware and can be implemented on any platform supporting the OpenGL rendering library

RTVP-1 regulates glioma cell migration and invasion via interaction with N-WASP and hnRNPK

Glioblastoma (GBM) are characterized by increased invasion into the surrounding normal brain tissue. RTVP-1 is highly expressed in GBM and regulates the migration and invasion of glioma cells. To further study RTVP-1 effects we performed a pull-down assay using His-tagged RTVP-1 followed by mass spectrometry and found that RTVP-1 was associated with the actin polymerization regulator, N-WASP. This association was further validated by co-immunoprecipitation and FRET analysis. We found that RTVP-1 increased cell spreading, migration and invasion and these effects were at least partly mediated by N-WASP. Another protein which was found by the pull-down assay to interact with RTVP-1 is hnRNPK. This protein has been recently reported to associate with and to inhibit the effect of N-WASP on cell spreading. hnRNPK decreased cell migration, spreading and invasion in glioma cells. Using co-immunoprecipitation we validated the interactions of hnRNPK with N-WASP and RTVP-1 in glioma cells. In addition, we found that overexpression of RTVP-1 decreased the association of N-WASP and hnRNPK. In summary, we report that RTVP-1 regulates glioma cell spreading, migration and invasion and that these effects are mediated via interaction with N-WASP and by interfering with the inhibitory effect of hnRNPK on the function of this protein

Problematic placebos in physical therapy trials

The placebo controlled, randomised controlled trial is widely recognised as the gold standard design for providing evidence in health care. Yet controversies surrounding placebos persist, which include issues regarding ethics, legality, mechanisms, and even whether there should be such a thing as placebo at all. Here, we intend to highlight some of the difficulties in the design and use of placebo controls within physical therapy trials. Unlike placebo tablets, which can be constructed simply by removing the active or‘characteristic’ingredient, physical therapy treatments are often more complex, with many active features that cannot be easily separated. Based on the challenges of isolating the characteristic feature(s) of treatments, we explore the problem with constructing placebos in trials of physical therapies, drawing on philosophy of science as a basis for defining what a placebo is and is not. After pointing out common problems, we outline potential solutions using alternative designs that allow trials to remain rigorous, while at the same time avoiding the pitfalls introduced when using inadequate placebos