Miscibility, crystallization κinetics and real-time small-Angle x-ray scattering investigation of the semicrystalline morphology in thermosetting polymer blends of epoxy resin and poly(ethylene oxide)

Thermosetting polymer blends of poly(ethylene oxide) (PEO) and bisphenol-A-type epoxy resin (ER) were prepared using 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) as curing agent. The miscibility and crystallization behavior of MCDEA-cured ER/PEO blends were investigated by differential scanning calorimetry (DSC). The existence of a single composition-dependent glass transition temperature (Tg) indicates that PEO is completely miscible with MCDEA-cured ER in the melt and in the amorphous state over the entire composition range. Fourier-transform infrared (FTIR) investigations indicated hydrogen-bonding interaction between the hydroxyl groups of MCDEA-cured ER and the ether oxygens of PEO in the blends, which is an important driving force for the miscibility of the blends. The average strength of the hydrogen bond in the cured ER/PEO blends is higher than in the pure MCDEA-cured ER. Crystallization kinetics of PEO from the melt is strongly influenced by the blend composition and the crystallization temperature. At high conversion, the time dependence of the relative degree of crystallinity deviated from the Avrami equation. The addition of a non-crystallizable ER component into PEO causes a depression of both the overall crystallization rate and the melting temperature. The surface free energy of folding σe displays a minimum with variation of composition. The spherulitic morphology of PEO in the ER/PEO blends exhibits typical characteristics of miscible crystalline/amorphous blends, and the PEO spherulites in the blends are always completely volume-filling. Real-time small-angle X-ray scattering (SAXS) experiments reveal that the long period L increases drastically with increasing ER content at the same temperatures. The amorphous cured ER component segregates interlamellarly during the crystallization process of PEO because of the low chain mobility of the cured ER. A model describing the semicrystalline morphology of MCDEA-cured ER/PEO blends is proposed based on the SAXS results. The semicrystalline morphology is a stack of crystalline lamellae; the amorphous fraction of PEO, the branched ER chains and imperfect ER network are located between PEO lamellae.

Modeling of light propagation through biological tissues : a novel approach

An efficient numerical technique for modeling biological tissues using the radiative transfer equation is presented. Time dependence of the transient radiative transfer equation is approximated using Laguerre expansion. Azimuthal angle is discretized using the discrete ordinates method and the resulting set of ordinary differential equations is solved using the Runge-Kutta-Felhberg method.

Optical phase change at the interface between mica and thin silver film

We describe a simple experiment which allows unequivocal determination of optical phase change upon reflection of light at the mica-silver interface. While the physical origin of such a phase change at the dielectric-metal interface is well understood to lie in absorption of electromagnetic energy by the metal, inconsistency and ambiguity has persisted as to what its sign and magnitude should be in the field of thin film optics. Most commonly, it has been assigned to be negative for mathematical convenience or just arbitrarily. Our finding shows that with the convention exp(-iωt) for time dependence of the electromagnetic wave, the phase change at the interface between mica and the thin silver film is necessarily positive and its magnitude falls between π and 3π/2 for silver thicknesses down to nanometres. This gives a physically reasonable correspondence to an increased equivalent thickness of the dielectric material, and it clarifies the assignment of interference orders in the harmonic series in a spectrum.

Applicability and accuracy of the initially dry and initially wet contact filter paper tests for matric suction measurement of geosynthetic clay liners.

An initially wet contact filter paper test (IW-CFPT) and an initially dry contact filter paper test (ID-CFPT) were used to examine the wetting paths of geosynthetic clay liners, including non-contact filter paper tests for comparative purposes. The CFPTs were applied to both geosynthetic clay liner faces to examine the effect of geotextile type on capillary contact. The non-woven geotextile face was found to be more likely to cause capillary breaks than the woven geotextile face. Both IW- and ID-CFPTs were found to be applicable to geosynthetic clay liners within their accurate upper matric suction measurement limits of 146 kPa and 66 kPa, respectively.

Time-varying dependence in the intraday AUS/USD spot market

Using a high-frequency data set of the spot Australian dollar/US dollar this study examines the distribution of quotes and returns across the 24 hour trading "day". Employing statistical methods for measuring long-tenn dependence in time-series we find evidence of time-varying dependence and volatility that aligns with the opening and closing of markets. This variation is attributed to the effects of liquidity and the price-discovery actions of dealers.

Time-budget and feeding behaviour of the squirrel glider (petaurus norfolcensis) in remnant linear habitat

The squirrel glider (Petaurus norfolcensis) occurs in forests and woodlands in eastern Australia. In Victoria it is now largely restricted to small, fragmented areas and is considered endangered. In this study, the time-budget, feeding behaviour and related habitat use of the squirrel glider were investigated in a linear remnant of roadside vegetation near Euroa, Victoria. Timed observations of three males and three females, fitted with radio-collars, were made in each of four seasons. Gliders were observed for a total of 53.2 h, during which they devoted 72% of time to foraging activities. Grooming accounted for 16% of observation time. Exudates associated with homopterous insects were the primary food items consumed throughout the year. Arthropods, nectar and pollen, and Acacia gum formed the remainder of the diet. The proportion of time devoted to harvesting these food items showed marked seasonal variation. The primary dependence on homopterous insect exudates in this study area contrasts with other investigations at sites of greater floristic diversity where nectar and pollen were the most important dietary resources. This highlights the need to obtain ecological information from the range of habitats occupied by a species. Large trees are a vital habitat component of remnant linear vegetation in this study area, providing gliders with critical foraging resources. Retention of such trees is essential for the longevity of glider populations.

Oxygen-dependence of metabolic rate in the muscles of craniates

We present evidence that oxygen consumption (V_O2 ) is oxygen partial pressure (P_O2) dependent in striated muscles and P_O2 -independent in the vasculature in representatives of three craniate taxa: two teleost fish, a hagfish and a rat. Blood vessel V_O2 displayed varying degrees of independence in a P_O2 range of 15–95 mmHg, while V_O2 by striated muscle tissue slices from all species related linearly to P_O2 between 0 and 125 mmHg, despite V_O2 rates varying greatly between species and muscle type. In salmon red muscle, lactate concentrations fell in slices incubated at a P_O2 of either 30 or 100 mmHg, suggesting aerobic rather than anaerobic metabolism. Consistent with this finding, potential energy, a proxy of ATP turnover, was P_O2 -dependent. Our data suggest that the reduction in V_O2 with falling P_O2 results in a decrease in ATP demand, suggesting that the hypoxic signal is sensed and cellular changes effected. Viability and diffusion limitation of the preparations were investigated using salmon cardiac and skeletal muscles. Following the initial P_O2 depletion, reoxygenation of the Ringer bathing salmon cardiac muscle resulted in V_O2^s that was unchanged from the first run. V_O2 increased in all muscles uncoupled with p-trifluoromethoxylphenyl-hydrazone (FCCP) and 2,4-dinitrophenol (DNP). Mitochondrial succinate dehydrogenase activity, quantified by reduction of 3-(4,5-dimethylthiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan, was constant over the course of the experiment. These three findings indicate that the tissues remained viable over time and ruled out diffusion-limitation as a constraint on V_O2.

Mutually assured destruction or co-dependence? The G20 and the UN

The G20 forum has acted to crystallise important changes in the architecture of global governance emerging since the 1970s. This has seen the locus of power shift away from the United Nations (UN) System as smaller and poorer states become increasingly adept at exercising their power within UN structures. Yet it is too simple to set the G20 against the UN, for example as minilateralism versus multilateralism. While the UN seems increasingly constrained and less relevant, it is not about to disappear. Moreover, we argue there are two significant obstacles to the G20 claiming the mantle of dominant global governance institution. First, that minilateralism is still a form of multilateralism, and ultimately subject to the same problems with the generation of consensus if extended, as in the G20, to include sufficiently diverse state members for a claim of legitimacy. Second, its emergence from the Global Financial Crisis and historical focus on financial governance means its agenda is excessively narrow at a time when food and environmental crises command similar global political significance. We conclude by considering some of the different elements of the emerging G20/UN dynamic, and whether this emerging dialectic can enhance prospects for wide ranging reforms to global trade, finance and economic structures that are currently incapable of functioning sustainably or preventing wide scale famine.

Modifying the risk associated with an impulsive temperament: a prospective study of drug dependence treatment

The evidence linking the personality trait of impulsivity and substance misuse is well established. Importantly, impulsivity not only predicts substance misuse problems but has an association with duration in treatment, likelihood of completing treatment and time to relapse. Treatment that focuses on increasing awareness and acceptance of thoughts and emotions may potentially address impulsive behaviour and in this respect improve treatment outcomes for substance misuse. The current paper investigated the relationship between the facet of impulsivity that taps into poor inhibitory control and treatment outcome. In addition, there was a specific focus on ascertaining the impact of an increase in awareness and attentional control measured in 144 adult substance users receiving treatment in a residential therapeutic community. Impulsivity predicted poorer treatment outcome (measured as drug use severity). Increases in awareness and acceptance of emotions and thoughts during treatment were related to better outcome although this was not associated with baseline levels of impulsivity. Clinical and theoretical implications are discussed.

Some properties of finite-time stable stochastic nonlinear systems

In this paper we study some properties of finite-time stable stochastic nonlinear systems. We begin by showing several continuous dependence theorems of solutions on initial values under some conditions on the coefficients of stochastic systems. We then derive some regular properties of its stochastic settling time for a finite-time stable stochastic nonlinear system. We show continuity, positive definiteness and boundedness of the expected stochastic settling time under appropriate conditions. Finally, a Lyapunov function is constructed by making use of the expectation of the stochastic settling time, and the infinitesimal generator of the stochastic system defined on the Lyapunov function is also given, and hence resulting in a converse Lyapunov theorem of finite-time stochastic stability.

Temperature and grain orientation dependence of mechanical twinning in a high manganese TWIP steel

 This thesis contains fundamental studies of the deformation mechanisms of the third generation steel at different deformation temperatures. To analyse the microstructure of the steel a unique characterisation technique was implemented for the first time. These analyses provided with vital parameters for modelling the stress-strain behaviour of the steel at different deformation temperatures.