Rheological prediction of sensory attributes for lotions – learning from toothpastes

Lotions and toothpastes are rheologically similar in that most of them are thixotropic yield stress materials, semi-solid under static conditions, but flowing when shaken or agitated . Some of their relevant sensory attributes are also similar although methods of their assessment are somewhat different. This presentation demonstrates what formulators of these seemingly different products may learn from each other. To this end, complex rheological behavior of commercial lotions from European and Latin American markets were investigated and compared to panelist assessment of their sensory attributes. Similar studies were performed on some commercial as well as prototype toothpastes. Various rheological procedures, such as stress ramps, creep-recovery, stepped-shear rates, dynamic oscillatory strain sweeps and extensional viscosity measurements are discussed in this presentation. Tribological measurements and some visualization techniques on custom-built instruments are also discussed. The main goal of this work was to identify correlations between such laboratory measurements and consumer perceived properties of these products. For toothpastes, squeezability, shape retention and stringiness are the main sensory properties of interest and can be successfully predicted based on rheological measurements. For lotions, the variety of sensory attributes is much wider, although shape retention and stringiness are also relevant and can be assessed by similar methods. In addition to that, it is shown that firmness, peaking, wetness and oiliness of lotions correlate with yield stress and instantaneous viscosity. For toothpaste, rheological analysis allowed to establish basic structure-property relationships and optimize many formulations in terms of their main structure-forming elements, i.e., optimization can occur through adjusting levels of polymers, thickeners and abrasives. For lotions, similar analysis is possible although appears to be more complicated due to larger variability of formulas

Annotating UI Architecture with Actual Use

Developing an appropriate user interface architecture for supporting a system's tasks is critical to the system's overall usability. While there are principles to guide architectural design, confirming that the correct decisions are made can involve the collection and analysis of lots of test data. We are developing a testing environment that will automatically compare and contrast the actual user interaction data against the existing user interface architectural models. This can help a designer more clearly understand how the actual tasks performed relate to the proposed architecture, and enhances feedback between different design artifacts

Linear viscoelastic behavior of aggregated colloidal dispersions

The viscoelastic behavior of a depletion-flocculated dispersion of colloidal spheres is investigated at different volume fractions of the spheres, using a controlled stress and a dynamic rheometer. Combining the results, we obtain the storage G′ and loss G′′ moduli over a frequency range of 0.02<ω<200rad/s. The measured G′ gradually increases with increasing frequency, while G′′ almost remains constant, indicating a broad spectrum of relaxation times. To describe and explain the observed behavior of the moduli as a function of frequency and volume fraction in terms of microscopic parameters, a microrheological model based on the fractal concept is proposed. Comparing experimental results with model calculations, we find a good agreement between the two, with physically plausible parameter values

Featherweight Generic Confinement

Existing approaches to object encapsulation either rely on ad hoc syntactic restrictions or require the use of specialised type systems. Syntactic restrictions are difficult to scale and to prove correct, while specialised type systems require extensive changes to programming languages. We demonstrate that confinement can be enforced cheaply in Featherweight Generic Java, with no essential change to the underlying language or type system. This result demonstrates that polymorphic type parameters can simultaneously act as ownership parameters and should facilitate the adoption of confinement and ownership type systems in general-purpose programming languages

A Capability-Based Module System for Authority Control (Artifact)

This artifact is intended to demonstrate the module system of the Wyvern programming language and consists of a Linux virtual machine with a snapshot of the Wyvern programming language\u27s codebase. The Wyvern codebase contains a test suite that corresponds to the code examples in the paper accompanying the artifact. In addition, the artifact contains a document describing how to compile and run Wyvern programs