Experimental and Numerical Analysis of Initial Plasticity in P91 Steel Small Punch Creep Samples

To date, the complex behaviour of small punch creep test (SPCT) specimens has not been completely understood, making the test hard to numerically model and the data difficult to interpret. This paper presents a novel numerical model able to generate results that match the experimental findings. For the first time, pre-strained uniaxial creep test data of a P91 steel at 600 ^°C have been implemented in a conveniently modified Liu and Murakami creep damage model in order to simulate the effects of the initial localised plasticity on the subsequent creep response of a small punch creep test specimen. Finite element (FE) results, in terms of creep displacement rate and time to failure, obtained by the modified Liu and Murakami model are in good agreement with experimental small punch creep test data. The rupture times obtained by the FE calculations which make use of the non-modified creep damage model are one order of magnitude shorter than those obtained by using the modified constitutive model. Although further investigation is needed, this novel approach has confirmed that the effects of initial localised plasticity, taking place in the early stages of small punch creep test, cannot be neglected. The new results, obtained by using the modified constitutive model, show a significant improvement with respect to those obtained by a ’state of the art’ creep damage constitutive model (the Liu and Murakami constitutive model) both in terms of minimum load-line displacement rate and time to rupture. The new modelling method will potentially lead to improved capability for SPCT data interpretation.     

Environmental and ecological studies using proton activation analysis

Multielement analyses of environmental samples have been carried out using proton activation analysis. It has been shown that this technique is suitable for both the analysis of aerosol particulates collected on polystyrene filters and for the analysis of the roots of Eucalyptus trees. Aerosol particulates from around the eastern coast of Australia were found to contain S, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Ga, Se, Sr, Y, Zr, Ru, Pt and Hg ranging in concentration from <0.003 to over 3.0 μg per cubic metre of air. A comparison between the ashed roots of healthy and diseased Eucalyptus trees from the Brisbane Ranges in Victoria showed that the concentrations of Fe and Ti in the diseased tree were only 30% and 59% respectively of that in the healthy tree.     

Observation of cascaded two-photon-induced transitions between fluxoid states of a SQUID

We present evidence for transitions between fluxoid wells of a SQUID due to cascaded, two-photon processes. Such transitions are evidenced by an anomalous dependence on the transition rate from the one-photon resonant level within the initial well, which cannot be explained by previously observed macroscopic resonant tunneling. These two-photon processes may be a significant source of decoherence in SQUID qubits subject to microwave radiation.     

A linear dilution microfluidic device for cytotoxicity assays

A two-layer polymer microfluidic device is presented which creates nine linear dilutions from two input fluid streams mixed in varying volumetric proportions. The linearity of the nine dilutions is conserved when the flow rate is held constant at 1.0 microl min(-1) (R(2) = 0.9995) and when it is varied from 0.5-16 microl min(-1) (R(2) = 0.9998). An analytical expression is presented for designing microfluidic devices with arbitrary numbers of linear dilutions. To demonstrate the efficacy of this device, primary human epidermal keratinocytes (HEK) were stained with nine dilutions of calcein, resulting in a linear spread of fluorescent intensities (R(2) = 0.94). The operating principles of the device can be scaled up to incorporate any number of linear dilutions. This scalability, coupled with an intrinsic ability to create linear dilutions under a variety of operating conditions, makes the device applicable to high throughput screening applications such as combinatorial chemistry or cytotoxicity assays.     

Binding Studies of AICAR and Human Serum Albumin by Spectroscopic,Theoretical, and Computational Methodologies

The interactions of small molecule drugs with plasma serum albumin are important because of the influence of such interactions on the pharmacokinetics of these therapeutic agents. 5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) is one such drug candidate that has recently gained attention for its promising clinical applications as an anti-cancer agent. This study sheds light upon key aspects of AICAR’s pharmacokinetics, which are not well understood. We performed in-depth experimental and computational binding analyses of AICAR with human serum albumin (HSA) under simulated biochemical conditions, using ligand-dependent fluorescence sensitivity of HSA. This allowed us to characterize the strength and modes of binding, mechanism of fluorescence quenching, validation of FRET, and intermolecular interactions for the AICAR–HSA complexes. We determined that AICAR and HSA form two stable low-energy complexes, leading to conformational changes and quenching of protein fluorescence. Stern–Volmer analysis of the fluorescence data also revealed a collision-independent static mechanism for fluorescence quenching upon formation of the AICAR–HSA complex. Ligand-competitive displacement experiments, using known site-specific ligands for HSA’s binding sites (I, II, and III) suggest that AICAR is capable of binding to both HSA site I (warfarin binding site, subdomain IIA) and site II (flufenamic acid binding site, subdomain IIIA). Computational molecular docking experiments corroborated these site-competitive experiments, revealing key hydrogen bonding interactions involved in stabilization of both AICAR–HSA complexes, reaffirming that AICAR binds to both site I and site II.     

Equivalent standard DEA models to provide super-efficiency scores

DEA super-efficiency models were introduced originally with the objective of providing a tie-breaking procedure for ranking units rated as efficient in conventional DEA models. This objective has been expanded to include sensitivity analysis, outlier identification and inter-temporal analysis. However, not all units rated as efficient in conventional DEA models have feasible solutions in DEA super-efficiency models. We propose a new super-efficiency model that (a) generates the same super-efficiency scores as conventional super-efficiency models for all units having a feasible solution under the latter, and (b) generates a feasible solution for all units not having a feasible solution under the latter. Empirical examples are provided to compare the two super-efficiency models.     

Chemical and Biological Mechanisms of Pathogen Reduction Technologies

Within the last decade new technologies have been developed and implemented which employ light, often in the presence of a photosensitizer, to inactivate pathogens that reside in human blood products for the purpose of transfusion. These pathogen reduction technologies attempt to find the proper balance between pathogen kill and cell quality. Each system utilizes various chemistries that not only impact which pathogens they can inactivate and how, but also how the treatments affect the plasma and cellular proteins and to what degree. This paper aims to present the various chemical mechanisms for pathogen reduction in transfusion medicine that are currently practiced or in development.     

Twisted index theory for foliations

For any Lie groupoid with a twisting, we define an analytic index morphism using the Connes tangent groupoid. This morphism agrees with the one of the Lie groupoid when the twisting is trivial. We discuss a longitudinal index theorem, geometric cycles, push-forward maps and Baum–Connes assembly maps for foliations with a twisting on the space of leaves.     

Compounds with bridgehead nitrogen. 42—1H NMR and stereochemistry of isomeric 6a-methylperhydroindolo[3,2,1-i,j]benzoxazines and the position of conformational equilibrium in perhydropyrrolo[1,2-c][1,3]oxazine

The ¹H NMR parameters of the NCH₂O protons in the spectrum of perhydropyrrolo[1,2-c][1,3]oxazine show its existence in solution at room temperature in the O-inside cis-fused conformation. rel-(3aS,6aS,6bR,10aS,11aS)-6a-Methylperhydroindolo[3,2,1-i,j]benzoxazine and rel-(3aS,6aS,6bS,10aR,11aS)-6a-methylperhydroindolo[3,2,1-i,j]benzoxazine are shown to adopt cis- and trans-fused conformations, respectively, for the corresponding bicyclic moiety.