liquid_crystals   6

Self-organized dynamics and the transition to turbulence of confined active nematics | PNAS
"We study how confinement transforms the chaotic dynamics of bulk microtubule-based active nematics into regular spatiotemporal patterns. For weak confinements in disks, multiple continuously nucleating and annihilating topological defects self-organize into persistent circular flows of either handedness. Increasing confinement strength leads to the emergence of distinct dynamics, in which the slow periodic nucleation of topological defects at the boundary is superimposed onto a fast procession of a pair of defects. A defect pair migrates toward the confinement core over multiple rotation cycles, while the associated nematic director field evolves from a distinct double spiral toward a nearly circularly symmetric configuration. The collapse of the defect orbits is punctuated by another boundary-localized nucleation event, that sets up long-term doubly periodic dynamics. Comparing experimental data to a theoretical model of an active nematic reveals that theory captures the fast procession of a pair of +1/2+1/2 defects, but not the slow spiral transformation nor the periodic nucleation of defect pairs. Theory also fails to predict the emergence of circular flows in the weak confinement regime. The developed confinement methods are generalized to more complex geometries, providing a robust microfluidic platform for rationally engineering 2D autonomous flows."
to:NB  self-organization  turbulence  liquid_crystals  physics 
march 2019 by cshalizi
The TVs of Tomorrow: How RCA’s Flat-Screen Dreams Led to the First LCDs, Gross
"In 1968 a team of scientists and engineers from RCA announced the creation of a new form of electronic display that relied upon an obscure set of materials known as liquid crystals. At a time when televisions utilized bulky cathode ray tubes to produce an image, these researchers demonstrated how liquid crystals could electronically control the passage of light. One day, they predicted, liquid crystal displays would find a home in clocks, calculators—and maybe even a television that could hang on the wall.
"Half a century later, RCA’s dreams have become a reality, and liquid crystals are the basis of a multibillion-dollar global industry. Yet the company responsible for producing the first LCDs was unable to capitalize upon its invention. In The TVs of Tomorrow, Benjamin Gross explains this contradiction by examining the history of flat-panel display research at RCA from the perspective of the chemists, physicists, electrical engineers, and technicians at the company’s central laboratory in Princeton, New Jersey.
"Drawing upon laboratory notebooks, internal reports, and interviews with key participants, Gross reconstructs the development of the LCD and situates it alongside other efforts to create a thin, lightweight replacement for the television picture tube. He shows how RCA researchers mobilized their technical expertise to secure support for their projects. He also highlights the challenges associated with the commercialization of liquid crystals at RCA and Optel—the RCA spin-off that ultimately manufactured the first LCD wristwatch. The TVs of Tomorrow is a detailed portrait of American innovation during the Cold War, which confirms that success in the electronics industry hinges upon input from both the laboratory and the boardroom."
to:NB  books:noted  history_of_technology  20th_century_history  liquid_crystals  the_present_before_it_was_widely_distributed 
april 2018 by cshalizi
Liquid Crystals: The Science and Art of a Fluid Form, Leslie
"While it is responsible for today’s abundance of flat screens—on televisions, computers, and mobile devices—most of us have only heard of it in the ubiquitous acronym, LCD, with little thought as to exactly what it is: liquid crystal. In this book, Esther Leslie enlightens us, offering an accessible and fascinating look at—not a substance, not a technology—but a wholly different phase of matter."
            As she explains, liquid crystal is a curious material phase that organizes a substance’s molecules in a crystalline form yet allows them to move fluidly like water. Observed since the nineteenth century, this phase has been a deep curiosity to science and, in more recent times, the key to a new era of media technology. In between that time, as Leslie shows, it has figured in cultural forms from Romantic landscape painting to snow globes, from mountaineering to eco-disasters, and from touchscreen devices to DNA. Expertly written but accessible, Liquid Crystals recounts the unheralded but hugely significant emergence of this unique form of matter.
to:NB  books:noted  liquid_crystals  physics  popular_science  condensed_matter 
june 2017 by cshalizi
Liquid Crystals: The Science and Art of a Fluid Form, Leslie
"While it is responsible for today’s abundance of flat screens—on televisions, computers, and mobile devices—most of us have only heard of it in the ubiquitous acronym, LCD, with little thought as to exactly what it is: liquid crystal. In this book, Esther Leslie enlightens us, offering an accessible and fascinating look at—not a substance, not a technology—but a wholly different phase of matter.
"As she explains, liquid crystal is a curious material phase that organizes a substance’s molecules in a crystalline form yet allows them to move fluidly like water. Observed since the nineteenth century, this phase has been a deep curiosity to science and, in more recent times, the key to a new era of media technology. In between that time, as Leslie shows, it has figured in cultural forms from Romantic landscape painting to snow globes, from mountaineering to eco-disasters, and from touchscreen devices to DNA. Expertly written but accessible, Liquid Crystals recounts the unheralded but hugely significant emergence of this unique form of matter."
to:NB  books:noted  condensed_matter  liquid_crystals  physics  popular_science 
january 2017 by cshalizi
Rev. Mod. Phys. 84, 497 (2012): Colloquium: Disclination loops, point defects, and all that in nematic liquid crystals
"The homotopy theory of topological defects is a powerful tool for organizing and unifying many ideas across a broad range of physical systems. Recently, experimental progress was made in controlling and measuring colloidal inclusions in liquid crystalline phases. The topological structure of these systems is quite rich but, at the same time, subtle. Motivated by experiment and the power of topological reasoning, the classification of defects in uniaxial nematic liquid crystals was reviewed and expounded upon. Particular attention was paid to the ambiguities that arise in these systems, which have no counterpart in the much-storied XY model or the Heisenberg ferromagnet."
to:NB  pattern_formation  statistical_mechanics  liquid_crystals  topological_defects  phys 
april 2012 by cshalizi

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20th_century_history  books:noted  condensed-matter_physics  condensed_matter  history_of_technology  pattern_formation  phys  physics  popular_science  self-organization  statistical_mechanics  the_present_before_it_was_widely_distributed  to:nb  topological_defects  turbulence 

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