"A continuous awaking movement". Note sul choreocinema di Maya Deren

Maya Deren ha prodotto tra gli anni quaranta e la metà degli anni cinquanta del secolo scorso un cinema visionario in cui la danza e i danzatori diventano i protagonisti della trasfigurazione del reale in arte, del viaggio dal mondo visibile a quello invisibile delle forme sottili dell’inconscio e della mente. Il saggio si incentra sul ciclo di film di Maya Deren che John Martin, critico di danza del New York Times e teorico di punta della modern dance, definì come choreocinema: >, soffermandosi principalmente su A Study in Choreography for Camera del 1945 che Deren creò collaborando con il danzatore afro-americano Talley Beatty

Analysis of Electrowetting of a Conducting Droplet on a Dielectric Layer

Electrowetting has been used to actuate and control the motion of droplets on solid surfaces. An analysis based on the theories of thermodynamics and thermal activation processes is presented for the electrowetting of a conducting droplet on a dielectric layer. The concept of release rate of electric energy is proposed. The release rate of electric energy is proportional to the square of the applied electric voltage and the derivative of electric capacitance with respect to the surface area of the corresponding electric system. The velocity of a contact line under the action of an electric voltage is a hyperbolic sine function of the release rate of electric energy. Using the release rate of electric energy and introducing line tension in the analysis, the contact angle of a droplet at a stationary state under the action of a constant electric voltage is found to be a linear function of the release rate of electric energy and the line tension. The line tension introduces the droplet-size effect on the contact angle. A critical contact angle as a function of the applied electric voltage, the thickness of the dielectric layer, and the radius of the contact area is obtained. There exist stable and unstable zones, depending on the relative value of the contact angle and the critical contact angle. There exists an upper bound of electric voltage with the corresponding contact angle of 65.89° between 60 and 70° of the saturated contact angle reported for electrowetting of conducting droplets. This result suggests that the saturation of contact angle likely is related to the condition determining the field-induced stability of the contact line

Dynamic polygonal spreading of a droplet on a lyophilic pillar-arrayed surface

<p>We experimentally investigated the dynamic polygonal spreading of droplets on lyophilic pillar-arrayed substrates. When deposited on lyophilic rough surfaces, droplets adopt dynamic evolutions of projected shapes from initial circles to final bilayer polygons. These dynamic processes are distinguished in two regimes on the varied substrates. The bilayer structure of a droplet, induced by micropillars on the surface, was explained by the interaction between the fringe (liquid in the space among the micropillars) and the bulk (upper liquid). The evolution of polygonal shapes, following the symmetry of the pillar-arrayed surface, was analysed by the competition effects of excess driving energy and resistance which were induced by micropillars with increasing solid surface area fraction. Though the anisotropic droplets spread in different regimes, they obey the same scaling law <i>S</i> ~ <i>t</i>^2/3 (<i>S</i> being the wetted area and <i>t</i> being the spreading time), which is derived from the molecular kinetic theory. These results may expand our knowledge of the liquid dynamics on patterned surfaces and assist surface design in practical applications.</p

Tuning Structural and Mechanical Properties of Two-Dimensional Molecular Crystals: The Roles of Carbon Side Chains

A key requirement for the future applicability of molecular electronics devices is a resilience of their properties to mechanical deformation. At present, however, there is no fundamental understanding of the origins of mechanical properties of molecular films. Here we use quinacridone, which possesses flexible carbon side chains, as a model molecular system to address this issue. Eight molecular configurations with different molecular coverage are identified by scanning tunneling microscopy. Theoretical calculations reveal quantitatively the roles of different molecule–molecule and molecule–substrate interactions and predict the observed sequence of configurations. Remarkably, we find that a single Young’s modulus applies for all configurations, the magnitude of which is controlled by side chain length, suggesting a versatile avenue for tuning not only the physical and chemical properties of molecular films but also their elastic properties