THE MAGNIFICATION FACTOR IN SPINNING DROP INTERFACIAL TENSIOMETRY

The accuracy with which the interfacial tension between two immiscible fluid phases can be determined by the spinning drop method is limited by the accuracy with which the spinning drop diameter can be found. Thus, it is important to know the factor by which the cylindrical sample tube and its content magnifies the on-axis drop or bubble. Here, we analyze the image formation and magnification factor of the spinning drop by a non-paraxial ray tracing method of geometric optics. Our analysis shows that when the drop and the walls of the lube are concentric, the magnification factor is exactly the refractive index of the denser fluid surrounding the drop and is independent of the refractive index and wall thickness of the sample tube. Our analysis also reveals that the image, a virtual one, is formed concentric with the drop.     

Neoliberalism and changing regional policy in Australia

This paper examines the role of neoliberalism in shaping Australian federal regional development policy over the past three decades. As in other parts of the world, since the 1980s Australian federal governments have tended to favour the role of market forces, as opposed to direct intervention in regional development. By the 1990s, however, the negative social and economic impacts of neoliberal approaches, together with a widespread electoral backlash, contributed to an adjustment in the direction of regional development policy. We argue that this transition is reflective of a wider shift in neoliberal politics, whereby limited government intervention and institution building are increasingly seen as appropriate policy responses. While in part this is linked to the shortcomings of previous policy approaches, it is also apparent that political opportunism is an important element of this shift.     

The Effect of Nanotube Content and Orientation on the Mechanical Properties of Polymer–Nanotube Composite Fibers: Separating Intrinsic Reinforcement from Orientational Effects

We have measured the mechanical properties of coagulation‐spun polymer–nanotube composite fibers. Both the fiber modulus, Y, and strength, σ_B, scale linearly with volume fraction, V_f, up to V_f ～10%, after which these properties remain constant. We measured dY/dV_f = 254 GPa and dσ_B/dV_f = 2.8 GPa in the linear region. By drawing fibers with V_f < 10% to a draw ratio of ～60%, we can increase these values to dY/dV_f = 600 GPa and dσ_B/dV_f = 7 GPa. Raman measurements show the Herman's orientation parameter, S, to increase with drawing, indicating that significant nanotube alignment occurs. Raman spectroscopy also shows that the nanotube effective modulus, Y_Eff, also increases with drawing. We have calculated an empirical relationship between the nanotube orientation efficiency factor, η_o, and S. This allows us to fit the data for Y_Eff versus η_o, showing that the fiber modulus scales linearly with η_o, as predicted theoretically by Krenchel. From the fit, we estimate the nanotube modulus to be; Y_NT = 480 GPa. Finally, we show that the fiber strength also scales linearly with η_o, giving an effective interfacial stress transfer of τ = 40 MPa and a nanotube critical length of l_c=1250 nm. This work demonstrates the validity of the Cox‐Krenchel rule of mixtures and shows that continuum theory still applies at the near‐molecular level.     

A lead isotopic study of the human bioaccessibility of lead in urban soils from Glasgow, Scotland

The human bioaccessibility of lead (Pb) in Pb-contaminated soils from the Glasgow area was determined by the Unified Bioaccessibility Research Group of Europe (BARGE) Method (UBM), an in vitro physiologically based extraction scheme that mimics the chemical environment of the human gastrointestinal system and contains both stomach and intestine compartments. For 27 soils ranging in total Pb concentration from 126 to 2160 mg kg^− 1 (median 539 mg kg^− 1), bioaccessibility as determined by the ‘stomach’ simulation (pH ~ 1.5) was 46-1580 mg kg^− 1, equivalent to 23-77% (mean 52%) of soil total Pb concentration. The corresponding bioaccessibility data for the ‘stomach + intestine’ simulation (pH ~ 6.3) were 6-623 mg kg^− 1 and 2-42% (mean 22%) of soil Pb concentration. The soil ²⁰⁶Pb/²⁰⁷Pb ratios ranged from 1.057 to 1.175. Three-isotope plots of ²⁰⁸Pb/²⁰⁶Pb against ²⁰⁶Pb/²⁰⁷Pb demonstrated that ²⁰⁶Pb/²⁰⁷Pb ratios were intermediate between values for source end-member extremes of imported Australian Pb ore (1.04) - used in the manufacture of alkyl Pb compounds (1.06-1.10) formerly added to petrol - and indigenous Pb ores/coal (1.17-1.19). The ²⁰⁶Pb/²⁰⁷Pb ratios of the UBM ‘stomach’ extracts were similar (< 0.01 difference) to those of the soil for 26 of the 27 samples (r = 0.993, p < 0.001) and lower in 24 of them. A slight preference for lower ²⁰⁶Pb/²⁰⁷Pb ratio was discernible in the UBM. However, the source of Pb appeared to be less important in determining the extent of UBM-bioaccessible Pb than the overall soil total Pb concentration and the soil phases with which the Pb was associated. The significant phases identified in a subset of samples were carbonates, manganese oxides, iron-aluminium oxyhydroxides and clays.     

Carfilzomib Promotes the Unfolded Protein Response and Apoptosis in Cetuximab-Resistant Colorectal Cancer

Cetuximab is a common treatment option for patients with wild-type K-Ras colorectal carcinoma. However, patients often display intrinsic resistance or acquire resistance to cetuximab following treatment. Here we generate two human CRC cells with acquired resistance to cetuximab that are derived from cetuximab-sensitive parental cell lines. These cetuximab-resistant cells display greater in vitro proliferation, colony formation and migration, and in vivo tumour growth compared with their parental counterparts. To evaluate potential alternative therapeutics to cetuximab-acquired-resistant cells, we tested the efficacy of 38 current FDA-approved agents against our cetuximab-acquired-resistant clones. We identified carfilzomib, a selective proteosome inhibitor to be most effective against our cell lines. Carfilzomib displayed potent antiproliferative effects, induced the unfolded protein response as determined by enhanced CHOP expression and ATF6 activity, and enhanced apoptosis as determined by enhanced caspase-3/7 activity. Overall, our results indicate a potentially novel indication for carfilzomib: that of a potential alternative agent to treat cetuximab-resistant colorectal cancer.     

COMPETING DRYING AND REACTION MECHANISMS IN THE FORMATION OF SOL-TO-GEL FILMS, FIBERS, AND SPHERES

Drying of films, fibers, and spheres undergoing sol-to-gel transformation is greatly affected by the strong dependence of the diffusion coefficients on composition, molecular weight, and temperature. This dependence is probed by solving the equations of mass and heat transfer by diffusion or conduction and associated convection, along with chemical reaction. A one-dimensional analysis is used that encompasses the planar, cylindrical, and spherical configurations. The solutions are obtained by Galerkin's method with finite element basis functions and entail large-scale computation.

Skinning and solidification phenomena in silica sol-to-gel systems are greatly affected not only by falling diffusion coefficients, but also by the competition between drying and reaction. The kinetics of silica reactions are modeled with the statistical scheme of Kay and Assink (1988). Gelation is predicted by the recursive technique of Bailey et al. (1990). Results show that at intermediate reaction rates, high molecular weight silica polymers are formed first near the evaporating free surface and gelation proceeds from that surface inwards, but at high or low reaction rates, gelation occurs before or after drying, respectively. These results help predict conditions in which uniform films can be cast, uniform fibers can be drawn, and uniform microspheres can be formed by spray drying.     

On the dynamics of phase growth : L. E. Scriven, Chem. Engng. Sci. 10: 1–13, 1959

This paper laid out fundamentals of convection and diffusion around a sphere of one phase growing from another, whether pure material or binary solution, e.g., bubbles in boiling.     

On the dynamics of phase growth

The equations governing spherically symmetric phase growth in an infinite medium are first formulated for the general case and are then simplified to describe growth controlled by the transport of heat and matter. All assumptions and restrictions are recounted. Exact solutions of the equations are obtained for conditions typical of bubble growth in the nucleate boiling of (a) pure materials and (b) binary mixtures. The effect of radial convection resulting from unequal phase densities is established and the regions of applicability of previously reported approximate solutions are determined.     

Measurement of liquid film profiles by Moiré topography

Area-wide surface topography is continuously monitored with the moiré technique, i.e. measurement of patterns formed by superposition of the warped image of a line grating on a similar reference grating. A simple method for reconstructing liquid film profiles from moir$\text{\$}\text{?}$fringe patterns is developed. The method is tested with a known specimen, a convex lens. Leveling of an uneven liquid film by gravity and capillary force is followed and film profiles are measured at intervals of time. Waves flowing down an inclined plate and disturbances in a liquid curtain are viewed, as are small disturbances caused by the impingement of tiny surface-active particles. Possible application to control of coating operations is pointed out.