Templated Grain Growth in Macroporous Materials

We demonstrate a facile method to produce crystallographically textured, macroporous materials using a combination of modified ice templating and templated grain growth (TGG). The process is demonstrated on alumina and the lead‐free piezoelectric material sodium potassium niobate. The method provides macroporous materials with aligned, lamellar ceramic walls which are made up of crystallographically aligned grains. Each method showed that the ceramic walls present a long‐range order over the entire sample dimensions and have crystallographic texture as a result of the TGG process. We also present a modification of the March–Dollase equation to better characterize the overall texture of materials with textured but slightly misaligned walls. The controlled crystallographic and morphologic orientation at two different length scales demonstrated here can be the basis of multifunctional materials.     

Estimation of the long‐memory stochastic volatility model parameters that is robust to level shifts and deterministic trends

I provide conditions under which the trimmed FDQML estimator, advanced by McCloskey (2010) in the context of fully parametric short‐memory models, can be used to estimate the long‐memory stochastic volatility model parameters in the presence of additive low‐frequency contamination in log‐squared returns. The types of low‐frequency contamination covered include level shifts as well as deterministic trends. I establish consistency and asymptotic normality in the presence or absence of such low‐frequency contamination under certain conditions on the growth rate of the trimming parameter. I also provide theoretical guidance on the choice of trimming parameter by heuristically obtaining its asymptotic MSE‐optimal rate under certain types of low‐frequency contamination. A simulation study examines the finite sample properties of the robust estimator, showing substantial gains from its use in the presence of level shifts. The finite sample analysis also explores how different levels of trimming affect the parameter estimates in the presence and absence of low‐frequency contamination and long‐memory.     

Composite model of the shark's skeleton in bending: A novel architecture for biomimetic design of functional compression bias

Much of the skeleton of sharks, skate and rays (Elasmobranchii) is characterized by a tessellated structure, composed of a shell of small, mineralized plates (tesserae) joined by intertesseral ligaments overlaying a soft cartilage core. Although tessellated cartilage is a defining feature of this group of fishes and has been maintained for millions of years, the significance of this skeletal tissue type — particularly from a mechanical perspective — is unknown. A cross-sectional model, based on empirical material property and morphological data, was developed in the present work to analyze the function of intertesseral joints in regulating the stress distribution within the skeletal tissue during bending. The results indicate that this structure distributes more stress to the tesserae loaded in compression when compared to those loaded in tension. A functional bias towards compression has also been observed for bone, but with the formation of microcracks in the region under greatest tension. The present model demonstrates how functional compression bias can also be achieved in tessellated cartilage structures but in the absence of microcracking. This behavior provides possible advantages including increasing the resistance to fatigue damage as well as mitigating the risk of tearing under excessive bending loads.     

Contributions to advisory working alliance: Advisee attachment orientation and pairing methods.

Authors of the current study examined the contributions of four factors on the advisory working alliance from counseling psychology advisees' perspectives: (a) anxious attachment orientation, (b) avoidant attachment orientation, (c) frequency of advising meetings, and (d) method of pairing an advisee to a faculty advisor. Participants were 109 counseling psychology doctoral students who were enrolled in American Psychological Association-accredited programs. A mixed model analysis indicated that lower attachment-anxiety scores, lower attachment-avoidance scores, and advisees choosing advisors each contributed to higher advisory working alliance scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactive coupling between immiscible polymer chains: Acceleration by compressive flow

It is demonstrated that processing flow affects the kinetics of the interfacial coupling reaction between functional groups that are grafted to polymer chains. At melt temperatures the amine group on the end of nylon 6 chains reacts with maleic anhydride grafted polyethylene (PE‐MA) and forms graft copolymers. Bilayers were made by lamination and coextrusion and adhesion was measured using asymmetric dual cantilever beam (ADCB). The amount of graft copolymer in the interface was quantified by X‐ray photon spectroscopy (XPS). With quiescent lamination, adhesion increased with temperature and the concentration of PE‐MA. The adhesion metric, G_c (critical energy release rate), plotted as a function of Σ (interfacial copolymer density) fell on the same master curve, unifying reaction process, temperature and time. G_c was a linear function of Σ for low‐copolymer coverage and weak adhesion. For relatively high coverage and strong adhesion, G_c scaled with Σ. 2 Coextrusion with compressive flow resulted in a reaction rate strikingly two‐orders of magnitude faster than that without compressive flow. The rate in the noncompressive die was close to quiescent lamination. Even for lamination, when compressive flow was applied normal to the interface, the coupling reaction rate was also greatly accelerated. Several mechanisms are speculated for this remarkable acceleration in polymer chain coupling. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3391–3402, 2013     

Investigations of mass transfer with chemical reactions in two-phase liquid–liquid systems

A new method based on experimental determination of the product distribution of a set of complex test reactions has been introduced and applied to study mass transfer in liquid–liquid systems. The test reactions consist of two parallel reactions, one of them being instantaneous and the second fast relative to mass transfer. Two reactants are transferred from the dispersed, organic phase (phase volume 1% vol) to the continuous aqueous phase, where the third reactant is present. Experiments were carried out in a batch system agitated with either a six-blade paddle impeller or a high-shear rotor–stator LR4 Silverson mixer to disperse drops and increase the mass transfer rate. The product distribution and the drop size distribution were measured using gas chromatography–mass spectroscopy and Malvern MasterSizer, respectively with pH variation recorded during the process. The results show that the focused supply of energy in the Silverson mixer is effective for the short term irreversible drop break-up process producing smaller droplets than the six-blade paddle impeller. However for the long term mass transfer process the paddle impeller is more effective due to more uniform supply of energy and better mixing throughout the tank compared to the more localized mixing of the Silverson.     

Capital Gains,Homeownership and Economic Inequality

The paper examines the distribution of capital gains and the net benefits of homeownership in terms of the debate between Marxists and Weberians on how homeownership modifies class inequality. Capital gains and net benefits are measured using unit record data from valuation records of the 1980s and a survey carried out by the Australian Institute of Family Studies in 1991 of over 2500 families in Sydney and Melbourne. Higher socio-economic groups generally had significantly larger dollar gains than groups below them and, by this measure, homeownership adds to inequalities generated through the labour market. However, because they had commenced purchase with smaller deposits, the low socio-economic groups did as well or better than other groups when capital gains are expressed as a percentage return on deposits. Capital gains are one of the variables included in a measure of net housing benefits; an attempt to quantify all the major benefits and costs involved in purchase rather than renting. The net housing benefits accruing to different socio-economic groups since deregulation of finance markets are compared using survey data relating to the 1980s property boom, and estimates using the much lower rates of interest and capital gains in housing markets of the 1990s. Again, there is a strong association found between dollar benefits and socio-economic status. The paper concludes that, measured in dollar terms, the distribution of net housing benefits in Sydney and Melbourne has had a substantial class bias since deregulation, tending to create a more unequal society.