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While new biodegradable materials are being rapidly introduced to address plastic pollution, their end-of-life impacts remain unclear. Biodegradable plastics typically comprise a biopolymer matrix with functional additives and/or solid fillers, which may be toxic. Here, using an established method for continuous biodegradation monitoring, we investigated the impact of a commonly used plasticizer, dibutyl phthalate (DBP), on the biodegradation of poly(3-hydroxybutyrate

The comprehensive study revealed a significant impact of the zeolite framework on the reactions involved in the polymers’ conversion, with multiple catalyst deactivation mechanisms being identified.

In the present paper, we describe how a robust and fundamental methodology was developed for extraction and determination of a principal natural toxin compound, simplexin, from a series of bulk biocomposites. These complex matrices were fabricated by direct encapsulating either ground plant particles or an ethanolic crude extract of the Australian toxic pasture plant Pimelea trichostachya in the biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Proton nuclear magnetic resonance spectroscopy was initially employed to examine the chemical compositions of these complicated systems. Then, a more sensitive strategy was developed and validated by combining solid-phase extraction and ultrahigh-performance liquid chromatography hyphenated with a quadrupole Orbitrap mass spectrometer for the quantification of simplexin embedded in different biocomposites. Satisfactory linearity (R2 > 0.99) and recovery ranges (86.8–116%) with precision (relative standard deviations) of between 0.2 and 13% (n = 3) were achieved from seven biocomposites. The established protocol was further shown to be accurate and reliable in confirming the homogeneous distribution of the simplexin in different biocomposite formulations. A limited mass transfer of simplexin (< 3.5%) from one of the biocomposites into a simulated but sterilized in vitro rumen environment after a 10-day incubation was also revealed by utilizing the method. This quantitative analysis of targeted natural product within plant material-integrated polymeric platforms has potential application when controlled release is required in the bovine rumen and other biological systems.

High-resolution micro-computed tomography (μ-CT) provides new insights into the release of water-soluble crystalline materials from hydrophobic polymer matrices. This technique was applied to investigate the complex pathways underpinning the release of the agrichemical dicyandiamide (DCD), a common crystalline, water-soluble nitrification inhibitor, following its encapsulation in a biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix at a loading of 250 g kg−1. Such a material allows controlled DCD delivery and improves its stability in tropical cropping systems. The insights gained from the use of this advanced 3-D imaging technique has led to a new understanding of the processes driving release of active agents and will aid the modelling and design of such tailored delivery formulations. These insights are broadly applicable and relevant to various soluble crystalline agrichemicals, drugs and medical implants. The release rate from DCD-PHBV pellets, fabricated through industrially relevant extrusion processing, was initially rapid, exponentially decaying over the first eight weeks. This was followed by a very gradual, linear release over the next 18 weeks. High-resolution μ-CT (0.5 μm) led to two important conclusions: i) the DCD that was rapidly mobilized existed within channels connected to the surface of the pellet, and ii) fine cracks present before and after release may explain the very slow mobilisation from the eighth week onward. Revealing the microstructure of this type of composite improves our current understanding of the mechanisms controlling the release of soluble crystalline materials encapsulated in a hydrophobic biodegradable polymer matrix.

Paunch is a fibrous solid residue consisting of partially digested feed from the stomachs of processed cattle. It is the largest untapped solid waste stream from animals at meat processing plants, and potentially a valuable source of fibres for the production of sustainable and potentially higher-value natural biocomposite materials. Paunch was obtained from the waste effluent of a red meat processing plant, and the fibre characteristics of the as-obtained material were studied and benchmarked against wood flour and ground buffel grass, with a view to evaluating the potential of paunch as a fibre for polymer composites. The ground paunch possessed a rough fibrous surface and fibre-like characteristics that were comparable to both wood flour and ground buffel grass, demonstrating their potential for use in composites. Without any pre-treatment or compatibilisation, composites of a representative biopolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and ground paunch were successfully produced for the first time via extrusion, with up to 50 wt% paunch content. Mechanical property analysis showed that, at 30 wt% content, PHBV/ground paunch composites yielded mechanical properties that were comparable to those of composites with ground buffel grass.

Polycyclic hydrocarbons are known to be efficient hydrogen carriers capable of yielding high purity H2 upon dehydrogenation. Due to their high hydrogen density, high boiling point, and stability, these compounds demonstrate the potential to be used as hydrogen donors under catalytic transfer hydrogenation (CTH) conditions. In this work, the potential of a suite of hydrogen carriers to donate hydrogen, as well as the mechanisms affecting their hydrogen transfer, are assessed through the CTH of guaiacol, on Pd/Al2O3, as a model system. The results indicated the following descending order of transfer hydrogenation rate: bicyclohexyl > tetralin » hydrogenated terphenyl (HTP) > cyclohexylbenzene. Among the products, cyclohexanone and phenol are the most abundant, directly resulting from CTH. Detailed analysis of the hydrogen carrier conversion and selectivity clearly shows that the potential for CTH is highly linked to the molecular structure of the donor, rather than the amount of hydrogen available for transfer. A density functional theory (DFT) study, supported by experimental data, reveals that when unsaturated hydrocarbons are utilized, such as tetralin, cyclohexylbenzene, and HTP, the effective CTH rate to guaiacol is limited, despite dehydrogenation being more favorable for those molecules than from fully saturated donors, such as bicyclohexyl.

Pimelea poisoning of cattle, historically known as St. George Disease or Marree Disease, is a prevailing issue in arid grazing regions of inland Australia. Ingestion of the toxic native Pimelea species that contain the secondary metabolite simplexin, a diterpene orthoester with potent protein kinase C activity, induces diarrhoea, characteristic oedema and potentially fatal right-sided heart failure in cattle. Outbreaks of toxic Pimelea in the grazing field depend on seasonal prevalence. However, all stages of the plant carry the toxin, from seeds, juvenile plants to dead plant material. Livestock generally avoid consuming green Pimelea plants and only consume toxic Pimelea when pasture is minimal or where Pimelea growing through grass tussocks results in inadvertent ingestion. Our knowledge base of Pimelea poisoning has greatly improved with past research, yet the health hazards for livestock grazing in Pimelea affected pastures remains a significant issue whilst the ongoing search to develop effective strategies to mitigate poisoning continues. The goal of this review is to collate historical and recent research giving an overview of the current understandings of Pimelea poisoning, the toxin, its toxic effects and progress made towards remedies to alleviate the effects of Pimelea intoxication.

A growing common public interest in a more sustainable society drives efforts into the development of bio-based and biodegradable polymers. Such renewable polymers can replace conventional non-degradable polymers as the matrix for wood plastic composites (WPCs). However, despite ongoing advancements towards the implementation of these biocomposites, experience with biocomposite mechanical durability is limited. This comparative study investigated the mechanical stability of biocomposites based on polyhydroxyalkanoate (PHA) and wood flour at 50 wt% wood content in real-life in-service conditions, including indoor, outdoor and in soil environments. Polylactic acid (PLA) and polyethylene (PE) wood composites served as comparative reference materials. Aging studies over a 12-month period showed that PHA composites were mechanically stable under indoor conditions. A reduction in mechanical stability was observed for outdoor exposure but the composite property deterioration was independent of the polymer type. In soil, the biocomposites steadily degraded towards a complete loss in mechanical properties, in contrast to the PLA and PE based composites. Overall, the rate of water absorption and the rate of polymer biodegradation are principal factors controlling mechanical stability over time. These factors promote the formation of cracks and voids which in turn weaken the material performance under mechanical loading. Without such crack formation, the composites retained mechanical properties over the aging time. The results provide a basis for consideration of strategic applications of PHA-based WPCs in cases where sustained or time-constrained mechanical performance is required.

Healthcare waste is an unforeseen calamity around the world. The US health system produces a staggering 6 billion tons of waste annually. 1 Over 30% of total healthcare waste comes from the operating room (OR). 1 Between 50 and 80% of this OR waste is accumulated prior to the patient even entering the OR. 2 , 3 Therefore, the majority of OR waste is clean, uncontaminated, and much of it can be recycled. The absolute requirement for sterility during surgery has led to the custom practice of single-use equipment that is packaged in large volumes of sterile packaging, all of which is discarded after surgery. Plastic from packaging, single-use equipment, monitoring equipment, and many other sources contributes one quarter of total OR waste, and most of this can be recycled (see Table 1). 4 , 5

Coiled-coils with defined assembly properties are attractive materials for the manufacture of peptide-based hybrid nanomaterials. In tailoring such peptide assemblies, the incorporation of aromatic residues is increasingly being investigated due to their potential to deliver controllable functionalities, such as interaction with aromatic porphyrins, carbon nanotubes, or graphene. Aromatic residues have the potential to either destabilise or stabilise the α-helical peptide structure, depending on the quantity, type, combination, and position of these residues in the peptide chain. In this work, we used a known synthetic three heptad repeat peptide containing no aromatic residues as an α-helical template. We then substituted the aliphatic residues with two different types of aromatic residues (phenylalanine and tryptophan), varying their number, position, and combination in the peptide chain as a preliminary assessment of the impact on peptide architecture. Circular dichroism (CD) spectroscopy combined with coarse-grained (CG) and all-atom (AA) molecular dynamics (MD) simulation were used to analyse the peptide structure and assembly. Aromatic residues designed to be within the hydrophobic core were had impact on self-assembly than those placed on the outer face of the coil. Tryptophan was seen to destabilise α-helical structure more than phenylalanine, potentially due to steric hindrance and hydrogen-bonding interactions. Using atomic force microscopy (AFM) and supported by CG-MD simulation, substituting all phenylalanine residues with tryptophan appeared to completely destabilise fibril-formation propensity. Subsituting tryptophan into the first heptad repeat was seen to have a greater impact on fibril formation compared to subtitution into the third heptad repeat, suggesting the importance of sequence design. These results add to the body of knowledge used to inform the design of α-helical peptides when incorporating aromatic residues.

The production of polyhydroxyalkanoates (PHAs) from methane is limited to mesophiles and thus suffers from high energy requirements for cooling. To address this issue, the use of thermophilic processes is gaining interest, as this strategy may deliver improved economic feasibility for PHA production. This study reports the first thermophilic PHA-producing culture grown on methane at 55 °C in fill-and-draw batch reactors. Harvested cells were incubated with various combinations of methane, propionic acid and valeric acid to assess their capacity for the synthesis of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Only PHB was produced when fed with methane alone. The addition of odd-carbon-number fatty acids resulted in higher PHA content with 3 HV fractions in the range of 15–99 mol%, depending on the types of fatty acids added. Acetic acid addition enhanced the synthesis of 3HB monomer, but not of 3 HV. On increasing the temperature to 58 °C, PHA productivity was not significantly affected.

Understanding and engaging the public is key for ensuring the success of government and industry initiatives aimed at addressing the problem of plastic waste. However, there has been little focus on documenting the general public’s attitudes towards plastics. This study examines public beliefs and attitudes towards plastics in Australia and provides insight on a global level. The research was conducted using an online survey of a nationally representative sample (2518 respondents). Overall, the survey results indicate that the public view plastics as a serious environmental issue. Plastic in the ocean had the highest mean rating for seriousness out of nine environmental issues, followed by two other issues relating to plastic waste production and disposal. Whilst there was an association of plastics with food packaging and convenience, there was more of a negative association with the use of plastic overall. Eighty percent of respondents indicated a desire to reduce plastic use and the majority of respondents believe that paper and glass are more environmentally friendly packaging materials than plastics. However, the results showed that many respondents do not translate their aspiration to reduce plastic use into action. Overall, while a majority of the Australian public are concerned about plastics as an environmental issue, they place the bulk of the responsibility for reducing the use of disposable plastic on industry and government.

There is a reasonably extensive body of literature recording mass loss of polyhydroxyalkanoates (PHAs) (a class of biodegradable plastics) in the natural marine environment. However, to date, this research has been very disparate. Thus, it remains unclear what the timeframe for the biodegradation of such marine biodegradable plastics actually is. The aim of this work was to determine the rate of biodegradation of PHA in the marine environment and apply this to the lifetime estimation of PHA products. This provides the clarification required as to what ‘marine biodegradation of PHA’ means in practicality and allows the risks and benefits of using PHA to be transparently discussed. It was determined that the mean rate of biodegradation of PHA in the marine environment is 0.04–0.09 mg·day−1·cm−2 (p = 0.05) and that, for example, a PHA water bottle could be expected to take between 1.5 and 3.5 years to completely biodegrade.

The crystallisation of a range of as-produced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer blends from a mixed culture polyhydroxyalkanoate production process, with low (15%), high (82%) and intermediate (62% and 50%) average 3-hydroxyvalerate (3HV) contents, was studied at different temperatures using polarised optical microscopy, differential scanning calorimetry and X-ray crystallography. The low-3HV content material had narrow compositional distribution and crystallised in the typical highly regular banded spherulite morphology, while the other materials displayed varying degrees of interpenetrating crystallisation of separate crystal phases comprising either the 3HV or 3-hydroxybutyrate (3HB) crystal lattice structure. Because of the differing and competing crystallisation kinetics of these phases coupled with diffusion effects, there was a very strong influence of crystallisation temperature on the resulting morphology. Thus manipulation of the final material properties of such copolymeric materials is dependent on understanding these effects and controlling their processing and crystallisation temperatures and conditions.

Significant efforts have recently been invested in assessing the physical and chemical properties of microbial nanowires for their promising role in developing alternative renewable sources of electricity, bioelectronic materials and implantable sensors. One of their outstanding properties, the ever-desirable conductivity has been the focus of numerous studies. However, the lack of a straightforward and reliable method for measuring it seems to be responsible for the broad variability of the reported data. Routinely employed methods tend to underestimate or overestimate conductivity by several orders of magnitude. In this work, synthetic peptide nanowires conductivity is interrogated employing a non-destructive measurement technique developed on a terahertz scanning near-field microscope to test if peptide aromaticity leads to higher electrical conductivity. Our novel peptide conductivity measurement technique, based on triple standards calibration method, shows that in the case of two biopolymer mimicking peptides, the sample incorporating aromatic residues (W6) is about six times more conductive than the negative control (L6). To the best of our knowledge, this is the first report of a quantitative nano-scale terahertz s-SNOM investigation of peptides. These results prove the suitability of the terahertz radiation-based non-destructive approach in tandem with the designer peptides choice as model test subjects. This approach requires only simple sample preparation, avoids many of the pitfalls of typical contact-based conductivity measurement techniques and could help understanding fundamental aspects of nature’s design of electron transfer in biopolymers.

In the present paper, we describe how a robust and fundamental methodology was developed for extraction and determination of a principal natural toxin compound, simplexin, from a series of bulk biocomposites. These complex matrices were fabricated by direct encapsulating either ground plant particles or an ethanolic crude extract of the Australian toxic pasture plant Pimelea trichostachya in the biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Proton nuclear magnetic resonance spectroscopy was initially employed to examine the chemical compositions of these complicated systems. Then, a more sensitive strategy was developed and validated by combining solid-phase extraction and ultrahigh-performance liquid chromatography hyphenated with a quadrupole Orbitrap mass spectrometer for the quantification of simplexin embedded in different biocomposites. Satisfactory linearity (R

This chapter focuses on the biodegradable subset of bioplastic alternatives, including thermoplastic starch, polylactic acid, and polyhydroxyalkanoate, which offer significant potential for tackling long-term plastic pollution. The majority of plastic ends up in landfills, but a considerable proportion also will escape into the environment, including the oceans. The volume of biodegradable bioplastics produced represents only a very small fraction of global plastics production. The fate of biodegradable bioplastics in natural and engineered environments is poorly understood and potentially problematic. Biodegradable bioplastics, as a “silver bullet” for plastic pollution, are not compatible with this agenda, as they are normally being designed from the outset to be disposed of after one use. A critical question when considering the use of biodegradable bioplastics is what happens to polymers in the environment. Starch-based mulch films have been shown to perform similarly to conventional plastic in terms of agronomic benefit, although control of lifetimes and mechanical properties can be a challenge.

The agricultural sector faces looming challenges including dwindling fertiliser reserves, environmental impacts of conventional soil inputs, and increasingly difficult growing conditions wrought by climate change. Naturally-occurring rocks and minerals may help address these challenges. In this case, we explore opportunities through which the geosphere could support viable agricultural systems, primarily via a literature review supplemented by data analysis and preliminary-scale experimentation. Our objective is to focus on opportunities specifically relating to emerging agricultural challenges. Our findings reveal that a spectrum of common geological materials can assist across four key agricultural challenges: 1. Providing environmentally-sustainable fertiliser deposits especially for the two key elements in food production, nitrogen (via use of slow release N-rich clays), and phosphorus (via recovery of the biomineral struvite) as well as through development of formulations to tap into mineral nutrient reserves underlying croplands. 2. Reducing contamination from farms—using clays, zeolites, and hydroxides to intercept, and potentially recycle nutrients discharged from paddocks. 3. Embedding drought resilience into agricultural landscapes by increasing soil moisture retention (using high surface area minerals including zeolite and smectite), boosting plant availability of drought protective elements (using basalts, smectites, and zeolites), and decreasing soil surface temperature (using reflective smectites, zeolites, and pumices), and 4. mitigating emissions of all three major greenhouse gases—carbon dioxide (using fast-weathering basalts), methane (using iron oxides), and nitrous oxide (using nitrogen-sorbing clays). Drawbacks of increased geological inputs into agricultural systems include an increased mining footprint, potential increased loads of suspended sediments in high-rainfall catchments, changes to geo-ecological balances, and possible harmful health effects to practitioners extracting and land-applying the geological materials. Our review highlights potential for ‘geo-agriculture’ approaches to not only help meet several key emerging challenges that threaten sustainable food and fiber production, but also to contribute to achieving some of the United Nations Sustainable Development Goals—‘Zero Hunger,’ ‘Life on Land,’ and ‘Climate Action.’

Rapid and continuous ammonium adsorption from mainstream coupled with side-stream ammonium recovery and adsorbent regeneration could enable ammonium recovery from domestic wastewater. This study describes the use of tailored poly­(acrylic acid)-based (NaPAA) hydrogels as effective sorbents for ammonium removal from domestic wastewater. Modified NaPAA hydrogels having 60% ionization and 4.8 mol % N′,N′-methylenebisacrylamide as the cross-linker reduced the overall swelling by 92% from 407 to 31 g/g because of higher cross-linking density. At hydrogel loadings of 2.5–7.5 g/L, the NaPAA hydrogels achieved ammonium concentrations of 8.3 ± 0.6 to 10.1 ± 0.1 mg/L NH4–N, which corresponds to removal efficiencies of 53–77% after 10 min of contact time in real domestic wastewater. At the same hydrogel loadings, the ammonium removal efficiency of NaPAA hydrogels in synthetic wastewater was found to be comparable to that in real sewage (71% vs 69%, respectively), suggesting that the sorption performance is only marginally affected by organic constituents found in domestic wastewater. In addition, the NaPAA hydrogels removed 25–51% ammonium in 10 min from synthetic streams having 200–400% higher ionic strengths than those commonly observed in sewage. Furthermore, simulation studies showed that a discharge concentration of ∼1.9 mg/L NH4–N, well below the commonly applied discharge limits in most regions, can be achieved using mainstream ammonium removal by NaPAA hydrogels followed by biological assimilation from the growth of ordinary heterotrophic organisms.

Wood fibre reinforced polyhydroxyalkanoate (PHA) composites have attracted significant interest as promising new sustainable biocomposites. However, their manufacture can be challenging due to PHA's relatively low thermal stability and melt viscosity. There is currently a lack of understanding of the effect of extrusion processing parameters on the molecular weight of the PHA matrix and, ultimately, on the mechanical properties of the composites. In this study, we show that commercially-relevant mechanical properties of a wood-poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) composite can be achieved through extrusion processing, even at temperatures as high as 190 °C, by adjusting screw speed and feeding rate, and consequently the induced shear rate and residence time. Moreover, the mechanical properties of 40 wt% wood-PHBV were found to be superior to properties previously reported in the literature. Relative to neat PHBV, a 73% increase in modulus and 80% retention of tensile strength was achieved. A Taguchi approach to experimental design was adopted to systematically investigate the effect of extrusion parameters (temperature profile, screw speed, feeding rate, and fibre mixing) on the processing of neat PHBV biopolymer and wood-PHBV composites with wood contents of 10, 20, 30, and 40 wt%. Evaluation of the mechanical performance was conducted through testing of tensile strength, tensile modulus and strain at maximum load. Changes in molecular weight were analysed via gel permeation chromatography (GPC). For both neat PHBV and wood-PHBV composites, molecular weight Mw was found to decrease under high shear stress and long residence time from 550-650 kDa to 350–550 kDa. However, Mw reductions were not enough to result in a decrease of mechanical performance. This discovery is significant for industrial-scale production as it shows that the processing window for wood-PHBV composites is not as narrow as expected, because thermal degradation can be limited by optimising a combination of processing parameters.

BACKGROUND Various active chemical agents, such as soil microbial inhibitors, are commonly applied to agricultural landscapes to optimise plant yields or minimise unwanted chemical transformations. Dicyandiamide (DCD) is a common nitrification inhibitor. However, it rapidly decomposes under warm and wet conditions, losing effectiveness in the process. Blending DCD with an encapsulating polymer matrix could help overcome this challenge and slow its release. Here, we encapsulated DCD in a biodegradable matrix of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and investigated the effects of DCD crystal size and loading rates on release rates. RESULTS Three DCD crystal size fractions (0–106, 106–250 and 250-44 μm) were blended with PHBV at 200, 400, 600 and 800 g.kg−1 loadings through extrusion processing and release kinetics were studied in water over eight weeks. For loadings ≥600 g.kg−1, more than 95% release was reached within the first seven days. By contrast, at 200 g.kg−1 loading only 10%, 36% and 57% of the DCD was mobilized after eight weeks in water for 0–106 μm, 106–250 μm and 250–420 μm crystal size fractions, respectively. CONCLUSION The lower percolation threshold for this combination of materials lies between 200 and 400 g.kg−1 DCD loading. The grind size fraction of DCD significantly affects the quantity of burst release from the surface of the pellet, particularly below the lower percolation threshold. The results presented here are likely translatable to the encapsulation and release of other crystalline materials from hydrophobic polymer matrixes used in controlled release formulations, such as fertilisers, herbicides and pesticides. This article is protected by copyright. All rights reserved.

Cattle grazing the pastures of inland Australia can be poisoned by ingestion of certain native Pimelea plant species, particularly Pimelea trichostachya and Pimelea simplex. The Pimelea toxin, simplexin, causes often fatal restriction of the pulmonary venules, with resultant heart impacts and characteristic fluid accumulation (oedema) of the jaw and brisket regions. In certain years heavy livestock losses can occur. Currently, there is no effective vaccine or antidote for Pimelea poisoning and the only management strategy is to reduce contact between toxic plants and susceptible stock, for beef producers to avoid potentially devastating poisoning events. Nevertheless, previous research has demonstrated that prolonged low dose feeding diminished the effect in animals. It was postulated that the animal exposed to prolonged low doses developed a mechanism for detoxifying simplexin, possibly through adaptation of the rumen microbial environment. The present study seeks to investigate the use of a biopolymer/toxin composite to foster toxin-degrading microbe populations. The objectives are to manufacture biopolymer composites based on biodegradable polylactic acid (PLA), polyhydroxyalkanoates (PHAs) and/or polycaprolactone (PCL), as toxin slow-release systems for the rumen that would have broad utility across a range of plant toxins and other beneficial rumen compounds. The poster covers the manufacturing, characterisation and performance of the biopolymers in a simulated rumen environment. Preliminary results of different biopolymers/composites containing Pimelea material and toxin extracts in an in vitro simulated rumen environment for up to 30 days are presented. It was found that the release rate could be tailored by choosing the right type of biopolymer.

Pimelea poisoning in grazing cattle, also known as St George or Marree Disease, has been a long-time pestilence for the pastoral industry throughout arid regions of inland Australia. The causative species Pimelea (Thymelaeaceae), native to Queensland, New South Wales and South Australia, have been confirmed, with the secondary metabolite simplexin, a daphnane orthoester, being extracted and identified as the principal toxin. Despite the lack of effective prevention or treatment for Pimelea poisoning, naïve calves have previously been demonstrated to develop detoxification capability following prolonged low-dose simplexin intake. A variety of composites are being fabricated by encapsulating Pimelea plant material or a crude extract in biodegradable and biocompatible polyesters, aiming to develop a sustained toxin release mechanism. Studies on screening potential rumen microflora able to decompose simplexin during rumen-fluid fermentation are being conducted simultaneously. In this project, a quantification method for simplexin within these biocomposites was developed and validated utilising solid-phase extraction combined with UHPLC-Q-Orbitrap MS/MS. Reliable simplexin measurement in matrices will allow investigations into the material composition, geometry and rumen microorganism’s effects on the controlled release kinetics of simplexin in vitro. The degradation patterns of toxin delivery systems when exposed to simulated rumen environments will also be thoroughly assessed on both microscopic and chemical scales. Mathematical models of the underlying mass transport mechanisms will ultimately be established through approaches ranging from simple empirical correlations to stochastic simulations, which hold the potential to facilitate future design, optimisation, and prediction of other intra-ruminal devices based on biodegradable polymers.

Delivering nutrients from mineral or organic fertilizers out of synchrony with crop uptake causes inefficiencies and pollution. We explore methodologies for evaluating sorbents as additives to organic agricultural wastes to retain nitrogen in an exchangeable form and deliver at rates that approximate the uptake capacity of roots. Focussing on ammonium (NH4+) as the main inorganic nitrogen form in the studied wastes (sugarcane mill mud, poultry litter), we tested geo-sorbents and biochar for their ability to retain NH4+. Sorption capacity was ranked palagonite

The photooxidative stability of an aromatic segmented poly(urethane-urea) (PUU) elastomer, stabilised with a range of carbon black fillers, was assessed after very low UVA doses as a means to identify components that are highly susceptible to UV degradation, and suggest better design of such materials. Fourier-transform infrared (FTIR) analysis indicated rapid degradation of the urea bonds in the hard segments, followed by chain scission and photo-Fries reaction of the urethane linkages. In the soft segments, the oxidation of the original ether groups resulted in the formation of large amounts of ester groups, while some crosslinking of the ether groups was also evident. Carbon black provided moderate protection against degradation, with the smallest-sized particles being the most effective. Protection was evidenced by reduced surface cracking as well as an increased resistance to chemical changes in both the soft segments and hard segments. Even so, significant degradation was still evident at low UV doses suggesting that further stabilisation is required to increase the UV durability of these elastomers and improve their long-term performance.\ud \ud

Lignin, an inexpensive renewable biopolymer that offers both aliphatic and aromatic hydroxyl ( OH) functional groups, is a potential raw material for the polyurethane industry. Contemporary approaches for incorporating lignin in rigid polyurethane foam (RPUF) involve mechanical mixing of microscale lignin powder under ambient conditions or at high loading levels, resulting in the RPUF with inferior compressive mechanical and thermal conductivity properties compared to petrochemical-based controls. Herein, we demonstrate a significant improvement in the dispersion of an industrial grade kraft lignin in a polyol mixture (96% sucrose/glycerine initiated polyether polyol and 4% glycerol) by dispersing at high-temperature (120 °C, 12 h) resulting in RPUF with enhanced performance. Through this methodology, the polyol/lignin dispersion with 5 wt.% lignin has afforded a simultaneous improvement in thermal insulation (by 5%) and compressive strength (by 4%) of RPUF compared to the control and such a property profile, to the best of our knowledge, has not yet been achieved in lignin substituted RPUF systems.

From a waste management perspective, high-barrier, multi-layer, biodegradable food packaging could be a useful replacement for current multi-layered packaging that is non-recyclable and non-degradable. Whilst there is still technical research required, it is envisioned that a biodegradable thermoplastic starch (TPS) and polyhydroxyalkanoate (PHA) layered material could be a promising target. However, there is currently limited research identifying what environmental trade-offs are associated with using such a material meaning there is no guidance regarding what design characteristics are important to consider during development of such packaging. The aim of this study was to quantify the greenhouse gas (GHG) trade-offs associated with using the proposed biodegradable packaging and identify the important design considerations. To our knowledge this is the first study to discuss the implications of including food wastage when assessing biodegradable food packaging materials. It also considers the impacts of landfill methane capture efficiency, which is an important aspect as biodegradable packaging may release methane when disposed of in a landfill whereas non-biodegradable packaging is inert. However, a key result is that when food waste is included in the system boundaries, it contributes over 50% of the GHG emissions associated with the system, regardless of whether the package is biodegradable or not. This shows that even for biodegradable packaging, reducing food waste is a key design consideration. In fact, the negative environmental impacts associated with disposal of a PHA-TPS packaging in landfill with low gas capture rates can actually be offset if the package reduces food wastage (beef) by approximately 6%. The overarching result is that a PHA-TPS food packaging only delivers positive GHG outcomes if it reduces food wastage or increases the viability of biological food waste processing. (C) 2018 Elsevier Ltd. All rights reserved.

Electron transfer is central to cellular life, from photosynthesis to respiration. In the case of anaerobic respiration, some microbes have extracellular appendages that can be utilised to transport electrons over great distances. Two model organisms heavily studied in this arena are Shewanella oneidensis and Geobacter sulfurreducens. There is some debate over how, in particular, the Geobacter sulfurreducens nanowires (formed from pilin nanofilaments) are capable of achieving the impressive feats of natural conductivity that they display. In this article, we outline the mechanisms of electron transfer through delocalised electron transport, quantum tunnelling, and hopping as they pertain to biomaterials. These are described along with existing examples of the different types of conductivity observed in natural systems such as DNA and proteins in order to provide context for understanding the complexities involved in studying the electron transport properties of these unique nanowires. We then introduce some synthetic analogues, made using peptides, which may assist in resolving this debate. Microbial nanowires and the synthetic analogues thereof are of particular interest, not just for biogeochemistry, but also for the exciting potential bioelectronic and clinical applications as covered in the final section of the review. Statement of Significance Some microbes have extracellular appendages that transport electrons over vast distances in order to respire, such as the dissimilatory metal-reducing bacteria Geobacter sulfurreducens. There is significant debate over how G. sulfurreducens nanowires are capable of achieving the impressive feats of natural conductivity that they display: This mechanism is a fundamental scientific challenge, with important environmental and technological implications. Through outlining the techniques and outcomes of investigations into the mechanisms of such protein-based nanofibrils, we provide a platform for the general study of the electronic properties of biomaterials. The implications are broad-reaching, with fundamental investigations into electron transfer processes in natural and biomimetic materials underway. From these studies, applications in the medical, energy, and IT industries can be developed utilising bioelectronics.

This study aims to understand the material properties and long-term indoor stability of a biocomposite based on pine wood flour and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) modified by a nucleating agent, boron nitride (BN), and an inorganic filler, talc, and to develop knowledge of the linkage between the microscale-structure and mechanical properties. Both BN, at a loading of 1 wt% and talc, at 5 wt%, had a nucleating effect on polymer crystallisation, with BN being more effective as evidenced by Avrami kinetic analysis. The addition of 5 and 10 wt% of talc enhanced the tensile strength of the PHBV/wood flour (50/50 wt%) composite from 22.3 ± 1.3 MPa (mean ± 95% confidence interval) to 24.3 ± 0.6 MPa and 24.7 ± 0.9 MPa respectively. The tensile modulus was also improved from 5.6 ± 0.6 GPa to 6.9 ± 0.4 GPa and 8.1 ± 0.7 GPa respectively. The micron-sized talc may fill voids within the composite matrix and/or act as an alternate filler, altering the deformation mechanism. However, the level of improvement in modulus was reduced after 1 year of conditioned ageing under a controlled environment (20 °C, 50% humidity). It is proposed that the combined effects of the swelling of wood through moisture uptake, the shrinkage of PHBV through secondary crystallisation, and the localised stress around talc particles led to weakened talc-PHBV interfaces.