Fast piezoelectric actuation of an elastomeric micropore

A viscoelastic membrane unit fabricated from thermoplastic polyurethane, with a formed single micropore, was interfaced to a piezoelectric actuator to demonstrate rapid actuation of the pore. Changes in through-pore conductance were measured as a function of the voltage applied to the actuator. The pore was opened and closed either in a stepwise fashion, or else made to oscillate between more and less open positions at up to 200 Hz. The step-driven response exhibited both a fast (<100 ms) majority component and a slow (∼1 s) minority component. The oscillatory method indicated that the majority component reached 95% of the low frequency (5 Hz) conductance amplitude in ∼5 ms, fast enough for a pore to close upon a particle driven by a 50 Pa pressure head. This advance in the rapid control of very small pores was achieved by reducing the amount of viscoelastic material between the pore and the source of actuation. This technique has potential for measurement and manipulation of micro- and nano-particles.     

Education and human environment

The rapid growth of population, extensive urbanization and considerable advances in technologies have brought about at the present time a host of human and environmental consequences on a global scale. There is an urgent need for reviewing the aims, methods and organization of these changes. One of the approaches suggested to achieve this is by instituting courses in human environmental studies of a truly multidisciplinary character. A scheme is put forward as a basis for discussion.     

Doing more with fewer people: Human Factors contributions on the road to efficiency and productivity

Cognition, Technology & Work -     

Measuring the stability of scientific collaboration

Stability has long been regarded as an important characteristic of many natural and social processes. In regards to scientific collaborations, we define stability to reflect the consistent investment of a certain amount of effort into a relationship. In this paper, we provide an explicit definition of a new indicator of stability, based on the year-to-year publication output of collaborations. We conduct a large-scale analysis of stability among collaborations between authors publishing in the field of computer science. Collaborations with medium–high degree of stability tend to occur most frequently, and on average, have the highest average scientific impact. We explore other “circumstances”, reflecting the composition of collaborators, that may interact with the relationship between stability and impact, and show that (1) Transdisciplinary collaborations with low stability leads to high impact publications; (2) Stable collaboration with the collaborative author pairs showing greater difference in scientific age or career impact can produce high impact publications; and (3) Highly-cited collaborators whose publications have a large number of co-authors do not keep stable collaborations. We also demonstrate how our indicator for stability can be used alongside other similar indicators, such as persistence, to better understand the nature of scientific collaboration, and outline a new taxonomy of collaborations.     

A novel co-processing method to manufacture an API for extended release formulation via formation of agglomerates of active ingredient and hydroxypropyl methylcellulose during crystallization

A novel process for generating agglomerates of active pharmaceutical ingredient (API) and polymer by swelling the polymer in a water/organic mixture has been developed to address formulation issues resulting from a water sensitive, high drug load API with poor powder properties. Initially, the API is dissolved in water, following which hydroxypropyl methylcellulose (HPMC) is added, resulting in the imbibing of water, along with the dissolved API, into the HPMC matrix. The addition of acetone and isopropyl acetate (anti-solvents) then causes the API to crystallize inside and on the surface of HPMC agglomerates. The process was scaled up to 20?kg scale. The agglomerates of API and HPMC generated by this process are ～350?µm diameter, robust, and have significantly better flow than the API as measured by Erweka flow testing. These agglomerates exhibit improved bulk density, acceptable chemical stability, and high compressibility. The agglomerates process well through roller compaction and tableting, with no flow or sticking issues. This process is potentially adaptable to other APIs with similar attributes.