Multifunctional,pH‐responsive graft copolymer prepared from deproteinized natural rubber and 4‐vinylpyridine via emulsion polymerization

We investigated the synthesis of a pH‐responsive graft copolymer of natural rubber and 4‐vinylpyridine. The grafting reaction was carried out using deproteinized natural rubber (DPNR) latex, with potassium persulfate as a free radical initiator. The pH responsiveness of the graft copolymer was investigated using water swelling and contact angle measurements, and was compared with that of pure DPNR. The graft copolymer was found to become responsive in solution at a pH of around 4. Indigo carmine adsorption studies identified the Langmuir isotherm, suggesting monolayer coverage. The adsorbed indigo carmine, a model anionic drug, and carbon dots, an emerging nanosized fluorophore, could be released from the graft copolymer by lowering the pH of the solution. The graft copolymer was tested as a heavy metal adsorbent, and demonstrated selectivity to copper(II) ions. The graft copolymer of 4‐vinylpyridine and DPNR developed in this study is therefore a multifunctional, pH‐responsive material with a wide range of potential applications, including sensing and catalysis, as a biomedical material and as an adsorbent. © 2017 Society of Chemical Industry     

Control of Spin-Valley Current in Strain-Engineered Graphene Magnetic Junction

We investigate the spin-valley current in a strain-engineered graphene magnetic system, normal region (N)/strain region(S)/ferromagnetic region (F)/normal region (N) junction. Locally strained region S leads to valley-dependent current, and ferromagnetic region F leads to the spin-dependent current. We find that pure valley current can be created easily by applying the real-vector potential that is equal to the pseudo-vector potential caused by strains in the S-region. In this work, we focus on the spin current in each valley when exchange field is applied in the F-region, and find that the linear control of spin-valley polarization by gate potential is possible. It is also found that when the current is carried only by the carriers in one valley (pure valley current), pure spin-up current can be linearly altered to pure spin-down current by tuning the gate potential, in the case of very large-F-thickness junction. Our work is applicable for devising controllable spin-valley-current electronics circuits.     

Australia’s nutritional food balance: situation,outlook and policy implications

Australia is a food trading nation with a complex food system. Change can have important implications for rural communities, employment, trade, public health nutrition and food security. This study compares Australian food intake scenarios to 2050 with linear projections for Australian agricultural production. The study is distinguished by its nutritional perspective, characterising food balance in terms of basic foods rather than food energy or macronutrients, as well as its systems perspective, taking into account the transformations that occur in food processing and cooking, livestock feed requirements, as well as supply chain and kitchen losses. With Australia’s population projected to increase from around 23 million in 2015 to 37.5 million in 2050, substantial increases in domestic food supply will be required. Although the situation and outlook differ for each commodity, in most respects demand is projected to increase at a greater rate than local production. This suggests that the Australian food system is on a trajectory toward reduced net food exports and increased dependence on imports. This will have implications for Australia’s role in the global food system and presents a change in some of the determinants of national food security. The trajectory of the food system also appears to be at odds with the massive public health challenges associated with diet related disease. These and other implications of an enlarging and increasingly international food system are discussed.     

A hierarchy-based similarity measure for intuitionistic fuzzy sets

Due to some unreasonable results obtained from most current similarity measures for intuitionistic fuzzy sets (IFSs), we introduce a necessary condition to obtain a stronger definition of similarity measures for IFSs, and present a new similarity measure derived from a general idea of similarity measures for concepts on a lattice. In experiments, we focus our attention on two basic directions of performance evaluation: one is how much the proposed measure is reasonable and the other is how much accuracy the measure produces when it is applied to classification problems. The experimental results show that the proposed measure is reasonable and achieves a satisfactory performance on classification problems.     

Preparation of pH‐responsive crosslinked materials from natural rubber and poly(4‐vinylpyridine)

Stimuli‐responsive elastomers are smart materials for sensing applications. Natural rubber (NR) is a renewable elastomer with excellent elasticity and fatigue resistance. In this work, a straightforward method for the preparation of pH‐responsive crosslinked materials from NR and poly(4‐vinylpyridine) (P4VP) via free radical crosslinking reaction using benzoyl peroxide (BPO) as an initiator is described. The effects of P4VP and BPO concentrations, reaction time and reaction temperature on immobilization percentage were investigated. It was found that the immobilization percentage reached 90% when using a P4VP concentration of 150 phr and a BPO concentration of 10 phr for 24 h at 90 °C. The pH responsiveness of the crosslinked materials was studied via water swelling, water contact angle and dye release measurements. Unlike unmodified rubber, the P4VP‐crosslinked NR was found to be pH‐responsive in acidic solution. Indigo carmine adsorption studies showed the Langmuir isotherm suggesting monolayer coverage of dye on the rubber surface. The dye could also be released upon increasing the pH of solution above 4. Based on these results, the introduction of pH responsiveness to NR will lead to novel responsive rubber‐based materials that can be used in biomedical and sensing applications. © 2016 Society of Chemical Industry     

Production,iron analysis and consumer perception of functional Thai Sinlek iron rice (Oryza sativa) drink

We produced the iron rice (IR) drink, determined the relevant chemical composition and antioxidant activity and tested the consumers’ degree of satisfaction. IR grains were digested with α-amylase and analysed chemical composition and antioxidant activity, while the hydrolysate (pH 4.0) and flavouring agents were added for final preparation of the IR drink. The IR hydrolysate contained a total iron content of 13.9 mg g⁻¹, a total phenolic content of 1.33 ± 0.07 mg gallic acid equivalent g⁻¹ and γ-oryzanol of 70.12 ± 2.7 mg kg⁻¹ rice grain, all of which inhibited the generation of free radicals in a concentration-dependent manner. The IR drink was composed of flavonoids and phenolic acids for which kaempferol was predominant. The members of all three groups of elderly subjects who consumed the low-dose IR (1.47 mg iron/100 mL), high-dose IR (2.74 mg iron/100 mL) and white rice (WR; 0.5 mg iron/100 mL) drinks expressed satisfaction and interest with the beverages at 91.2%, 100% and 88.9%, respectively. In terms of sensory evaluation, the low-dose IR drink revealed a higher acceptance rating than high-dose IR and WR (P < 0.05). Notably, the Sinlek rice drink was abundant with iron, anti-oxidative phenolics and γ-oryzanol, for which consumers expressed an overall degree of acceptance (8.1 ± 1.1).     

Advances in innovative processing technologies for microbial inactivation and enhancement of food safety – pulsed electric field and low-temperature plasma

The need for enhancing microbial food safety and quality, without compromising the nutritional, functional and sensory characteristics of foods, has created an increasing world-wide interest in low-temperature innovative processes for food preservation. In contrast, to the traditional thermal processes, these emerging technologies are predominantly reliant on physical processes, including high hydrostatic pressures, pulsed electric fields and low-temperature plasmas that inactivate microorganisms at ambient or moderately elevated temperatures and short treatment times. The current review presents the latest developments in the two most recent of these technologies, pulsed electric field and low-temperature plasma treatments for food preservation and disinfection of food contact surfaces.     

Highly efficient interpenetrating polymerization of styrene and 4‐vinylpyridine with poly(ethylene terephthalate) using benzoyl peroxide

A polymerization method for the preparation of an interpenetrating network polymer with poly(ethylene terephthalate) is reported. Two types of monomer, styrene and 4‐vinylpyridine, were chosen as hydrophobic and hydrophilic representatives, respectively, in order to show the versatility of this polymerization method. The polymer‐immobilized poly(ethylene terephthalate) samples were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and X‐ray photoelectron spectroscopy. The immobilization efficiency of styrene as a function of reaction temperature, monomer‐to‐initiator molar ratio, reaction time, addition of solvent, surface hydrophilicity and immersion in initiator was studied. The maximum immobilization percentage of styrene reaches 111%. The immobilization efficiency is proportional to polymer molecular weight and sample thickness. Based on these results, this strategy is shown to be an efficient, versatile method for preparing interpenetrating network polymers and can be used as a means to modify the structures and properties of polymeric substrates. © 2013 Society of Chemical Industry