Additively patterned ferroelectric thin films with vertical sidewalls

The functional properties of electroceramic thin films can be degraded by subtractive patterning techniques used for microelectromechanical (MEMS) applications. This work explores an alternative deposition technique, where lead zirconate titanate (PZT) liquid precursors are printed onto substrates in a desired geometry from stamp wells (rather than stamp protrusions). Printing from wells significantly increased sidewall angles (from ~1 to >35 degrees) relative to printing solutions from stamp protrusions. Arrays of PZT features were printed, characterized, and compared to continuous PZT thin films of similar thickness. Three‐hundred‐nanometer‐thick printed PZT features exhibit a permittivity of 730 and a loss tangent of 0.022. The features showed remanent polarizations of 26 μC/cm², and coercive fields of 95 kV/cm. The piezoelectric response of the features produced an e_31,f of ?5.2 C/m². This technique was also used to print directly atop prepatterned substrates. Optimization of printing parameters yielded patterned films with 90° sidewalls. Lateral feature sizes ranged from hundreds of micrometers down to one micrometer. In addition, several device designs were prepatterned onto silicon on insulator (SOI) wafers (Si/SiO₂/Si with thicknesses of 0.35/1/500 μm). The top patterned silicon was released from the underlying material, and PZT was directly printed and crystallized on the free‐standing structures.     

Architect as User

More than simply helping reshape the tools, methods, and sites of architectural practice, computer-aided design software programs have become a prime shaper of the architectural worker's self-imagination through the digital environments and knowledge practices these software programs demand of their users. Implicit in this shaping are socially and technically contingent value propositions regarding means of production and systems of labor that architectural workers operate within. To assert the value of architectural work and to make new value propositions, this essay examines the software-based techno-social structures that underwrite these existing conditions.     

Reflections on the virtues of modularity: a case study in linux security modules

Developing a modular system that properly supports a range of security models is challenging. The work presented here details our experiences with the modular Linux security framework called Linux Security Modules, or LSMs. Throughout our experiences we discovered that the developers of the LSM framework made certain tradeoffs for speed and simplicity during implementation, and consequently leaving the framework incomplete. Our experiences show at which points the theory of the LSM differs from reality, and details how these differences play out when developing and using a custom LSM. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluating model fit for growth curve models: Integration of fit indices from SEM and MLM frameworks.

Evaluating overall model fit for growth curve models involves 3 challenging issues. (a) Three types of longitudinal data with different implications for model fit may be distinguished: balanced on time with complete data, balanced on time with data missing at random, and unbalanced on time. (b) Traditional work on fit from the structural equation modeling (SEM) perspective has focused only on the covariance structure, but growth curve models have four potential sources of misspecification: within-individual covariance matrix, between-individuals covariance matrix, marginal mean structure, and conditional mean structure. (c) Growth curve models can be estimated in both the SEM and multilevel modeling (MLM) frameworks; these have different emphases for the evaluation of model fit. In this article, the authors discuss the challenges presented by these 3 issues in the calculation and interpretation of SEM- and MLM-based fit indices for growth curve models and conclude by identifying some lines for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elastomeric Electronic Skin for Prosthetic Tactile Sensation

This report demonstrates a wearable elastomer‐based electronic skin including resistive sensors for monitoring finger articulation and capacitive tactile pressure sensors that register distributed pressure along the entire length of the finger. Pressure sensitivity in the order of 0.001 to 0.01 kPa^?1 for pressures from 5 to 405 kPa, which includes much of the range of human physiological sensing, is achieved by implementing soft, compressible silicone foam as the dielectric and stretchable thin‐metal films. Integrating these sensors in a textile glove allows the decoupling of the strain and pressure cross‐sensitivity of the tactile sensors, enabling precise grasp analysis. The sensorized glove is implemented in a human‐in‐the‐loop system for controlling the grasp of objects, a critical step toward hand prosthesis with integrated sensing capabilities.     

Transformations for early reply and forward message passing mechanisms

Message passing notations (language, package, etc.) typically include some form of asynchronous or synchronous invocation. In a synchronous invocation, the invoker waits for the invocation's servicer to pass back results. Some message passing notations also include early reply or deferred reply (including forwarding), which alters how and when the servicer passes back its results; this additional flexibility is useful in realistic applications. It is well known how to transform a synchronous invocation into only asynchronous invocations. This paper extends such transformations to early reply and forward. This paper also describes the use of these transformations within the implementations of programming notations. Using the transformation simplifies the implementation without significantly affecting run‐time costs. Copyright © 2015 John Wiley & Sons, Ltd.     

Metabolic versatility in full-scale wastewater treatment plants performing enhanced biological phosphorus removal

This study analysed the enhanced biological phosphorus removal (EBPR) microbial community and metabolic performance of five full-scale EBPR systems by using fluorescence in situ hybridisation combined with off-line batch tests fed with acetate under anaerobic–aerobic conditions. The phosphorus accumulating organisms (PAOs) in all systems were stable and showed little variability between each plant, while glycogen accumulating organisms (GAOs) were present in two of the plants. The metabolic activity of each sludge showed the frequent involvement of the anaerobic tricarboxylic acid cycle (TCA) in PAO metabolism for the anaerobic generation of reducing equivalents, in addition to the more frequently reported glycolysis pathway. Metabolic variability in the use of the two pathways was also observed, between different systems and in the same system over time. The metabolic dynamics was linked to the availability of glycogen, where a higher utilisation of the glycolysis pathway was observed in the two systems employing side-stream hydrolysis, and the TCA cycle was more active in the A²O systems. Full-scale plants that showed higher glycolysis activity also exhibited superior P removal performance, suggesting that promotion of the glycolysis pathway over the TCA cycle could be beneficial towards the optimisation of EBPR systems.     

Role of salt on adhesion of an epoxy/aluminum (oxide) interface in aqueous environments

Joints held by polymeric adhesives are commonplace in many engineered products, but normal service can require exposure to environmental conditions that present a significant challenge for maintaining the structural integrity of the interface. In particular, aqueous environments can wreak havoc on the joint strength. Here, a mechanistic approach is used to understand the difference in the debonding behavior of an epoxy/aluminum (oxide) interface when exposed to deionized (DI) water and aqueous sodium chloride by correlating macroscopic failure with the sorption of salt and water into the adhesive and its nanoscale distribution. For the epoxy‐aluminum system examined here, the presence of sodium chloride increases the resistance to crack growth in comparison to DI water. The debonding appears to be controlled by water near the buried interface. Salt water decreases the solubility of water in the epoxy and decreases the concentration of water near the buried interface, but the concentration of salt that enters the epoxy is below the detection limit. Thus, even if ions cannot penetrate or sorb into the adhesive, the presence of salt can significantly alter the water distribution within the adhesive and ultimately the strength of the joint. POLYM. ENG. SCI., 56:18–26, 2016. © 2015 Society of Plastics Engineers     

Polyester composite water uptake and organic contaminant release affected by carbon nanofiber reinforcements

The incorporation of carbon nanofiber (CNF) into glass fiber (GF) composites is a potential route to extend polymer composite service‐life and enhance mechanical properties. Under nonstatic conditions, only limited information concerning water uptake and contaminant release properties of nanocomposite materials is currently available. Polyester composites containing GF and oxidized CNF were immersed in water for 30 days under nominal pressure at 23 °C, below the polymer's glass‐transition temperature. Water was analyzed and changed every three days to simulate water chemistry regeneration similar to exposures in flowing systems. Composites with oxidized CNF had greater water sorption capacity and leaching rates than CNF‐free composites. The total mass of organic contaminant released correlated with the amount of water sorbed by each composite (r² = 0.91), although CNF dispersion was found to vary greatly within composites. The greatest and least contaminant release rates were found for the polyester‐CNF and the polyester‐GF composites, respectively. While volatile aromatic resin solvents and stabilizer compounds were detected, their concentrations declined over the 30 day exposure period. We hypothesize that the hydrophilic nature of the oxidized CNF increased the water sorption capacity of the polyester composites. Additional studies are warranted that examine the impact of this phenomenon on composite mechanical and long‐term durability properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43724.