Australia and European Union: conflict, competition or engagement in agricultural and agri-food trade

Many scholars have mounted convincing cases that the engagement of Australia and the European Union (EU) has been characterised by skirmishes regarding the Common Agricultural Policy and its distortion of world markets, and lack of Australian access to EU markets. This article illustrates that agricultural and agri-food trade constitutes a relatively small portion of Australia -EU trade flows; that Australia exports more goods to the EU than in the past; and that, in some agri-food sectors, it exports more goods to the EU than the EU does to Australia. Further, it argues that conflict and competition regarding the Common Agricultural Policy need to be understood in the broader context of world trade, particularly with Asia, and in the context of anew and deeper engagement between the two interlocutors

Gelation Kinetics and Viscoelastic Properties of Pluronic and α‑Cyclodextrin-Based Pseudopolyrotaxane Hydrogels

The results of a systematic investigation into the gelation behavior of α-cyclodextrin (α-CD) and Pluronic (poly­(ethylene oxide)-poly­(propylene oxide)-poly­(ethylene oxide) block copolymers) pseudopolyrotaxane (PPR) hydrogels are reported here in terms of the effects of temperature, α-CD concentration, and Pluronic type (Pluronic F68 and Pluronic F127). It was found that α-CD significantly modifies the gelation behavior of Pluronic solutions and that the PPR hydrogels are highly sensitive to changes in the α-CD concentration. In some cases, the addition of α-CD was found to be detrimental to the gelation process, leading to slower gelation kinetics and weaker gels than with Pluronic alone. However, in other cases, the hydrogels formed in the presence of the α-CDs reached higher moduli and showed faster gelation kinetics than with Pluronic alone and in some instances α-CD allowed the formation of hydrogels from Pluronic solutions that would normally not undergo gelation. Depending on composition and ratio of α-CD/Pluronic, these highly viscoelastic hydrogels displayed elastic shear modulus values ranging from 2 kPa to 7 MPa, gelation times ranging from a few seconds to a few hours and self-healing behaviors post failure. Using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS), we probed the resident structure of these systems, and from these insights we have proposed a new molecular mechanism that accounts for the macroscopic properties observed

Tailorable Cell Culture Platforms from Enzymatically Cross-Linked Multifunctional Poly(ethylene glycol)-Based Hydrogels

As stem-cell-based therapies rapidly advance toward clinical applications, there is a need for cheap, easily manufactured, injectable gels that can be tailored to carry stem cells and impart function to such cells. Herein we describe a process for making hydrogels composed of hydroxyphenyl propionic acid (HPA) conjugated, branched poly­(ethylene glycol) (PEG) via an enzyme mediated, oxidative cross-linking method. Functionalization of the branched PEG with HPA at varying degrees of substitution was confirmed via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and ¹H NMR. The versatility of this hydrogel system was exemplified through variations in the degree of HPA substitution, polymer concentration, and the concentration of cross-linking reagents (horseradish peroxidase and H₂O₂), which resulted in a range of mechanical properties and gelation kinetics for these gels. Cross-linking of the PEG–HPA conjugate with a recombinantly produced Fibronectin fragment (Type III domains 7–10) encouraged attachment and spreading of human mesenchymal stem cells (hMSCs) when assessed in both two-dimensional and three-dimensional formats. Interestingly, when encapsulated in both nonfunctionalized and functionalized cross-linked PEG–HPA gels, MSCs showed good viability over all time periods assessed. With tunable gelation kinetics and mechanical properties, these hydrogels provide a flexible in vitro cell culture platform that will likely have significant utility in tissue engineering as an injectable delivery platform for cells to sites of tissue damage

Surface Modification and Characterization of Polycarbonate Microdevices for Capture of Circulating Biomarkers, Both in Vitro and in Vivo

Herein, we report the fabrication, characterization, and testing of a polymer microprojection array, for the direct and selective capture of circulating biomarkers from the skin of live mice. First, we modified polycarbonate wafers using an electrophilic aromatic substitution reaction with nitric acid to insert aromatic nitro-groups into the benzene rings, followed by treatment with sodium borohydride to reduce the nitro-groups to primary amines. Initial characterization by ultraviolet–visible (UV–vis) spectroscopy suggested that increasing acid concentration led to increased depth of material modification and that this was associated with decreased surface hardness and slight changes in surface roughness. Chemical analysis with X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy showed nitrogen species present at the surface for all acid concentrations used, but subsurface nitrogen species were only observed at acid concentrations >35%. The nitrogen species were identified as a mixture of nitro, imine, and amine groups, and following reduction, there was sufficient amounts of primary amine groups for covalent attachment of a polyethylene glycol antifouling layer and protein capture probes, as determined by colorimetric and radiometric assays. Finally, the modification scheme was applied to polycarbonate microprojection arrays, and we show that these devices achieve flank skin penetration depths and biomarker yields comparable with our previously reported gold-coated silicon arrays, with very low nonspecific binding even in 10% mouse serum (in vitro) or directly in mouse skin (in vivo). This study is the first demonstration showing the potential utility of polymer microprojections in immunodiagnostics applications