Artificially designed molecular systems with programmable behaviors have become a valuable tool in chemistry, biology, material science, and medicine. Although information processing in biological regulatory pathways is remarkably robust to error, it remains a challenge to design molecular systems that are similarly robust. With functionality determined entirely by secondary structure of DNA, strand displacement has emerged as a uniquely versatile building block for cell-free biochemical networks. Here, we experimentally investigate a design principle to reduce undesired triggering in the absence of input (leak), a side reaction that critically reduces sensitivity and disrupts the behavior of strand displacement cascades. Inspired by error correction methods exploiting redundancy in electrical engineering, we ensure a higher-energy penalty to leak via logical redundancy. Our design strategy is, in principle, capable of reducing leak to arbitrarily low levels, and we experimentally test two levels of leak reduction for a core "translator" component that converts a signal of one sequence into that of another. We show that the leak was not measurable in the high-redundancy scheme, even for concentrations that are up to 100 times larger than typical. Beyond a single translator, we constructed a fast and low-leak translator cascade of nine strand displacement steps and a logic OR gate circuit consisting of 10 translators, showing that our design principle can be used to effectively reduce leak in more complex chemical systems.
Chirality is a geometrical property by which an object is not superimposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature-from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research. If the magnetic dipoles were replaced by their electrical counterparts, then electrically controllable chiral devices could be designed. Complex oxide BaTiO3/SrTiO3 nanocomposites and PbTiO3/SrTiO3 superlattices are perfect candidates, since "polar vortices," in which a continuous rotation of ferroelectric polarization spontaneously forms, have been recently discovered. Using resonant soft X-ray diffraction, we report the observation of a strong circular dichroism from the interaction between circularly polarized light and the chiral electric polarization texture that emerges in PbTiO3/SrTiO3 superlattices. This hallmark of chirality is explained by a helical rotation of electric polarization that second-principles simulations predict to reside within complex 3D polarization textures comprising ordered topological line defects. The handedness of the texture can be topologically characterized by the sign of the helicity number of the chiral line defects. This coupling between the optical and novel polar properties could be exploited to encode chiral signatures into photon or electron beams for information processing.
Design and diversity are the two great challenges in the study of life. Microbial Life History draws on the latest advances in microbiology to describe the fundamental forces of biological design and apply these evolutionary processes to a broad diversity of traits in microbial metabolism and biochemistry.Emphasizing how to formulate and test hypotheses of adaptation, Steven Frank provides a new foundation for exploring the evolutionary forces of design. He discusses the economic principles of marginal valuations, trade-offs, and payoffs in risky and random environments; the social aspects of conflict and cooperation; the demographic aspects of age and spatial heterogeneity; and the engineering control theory principles by which systems adjust to environments. Frank then applies these evolutionary principles to the biochemistry of microbial metabolism, providing the first comprehensive link between the forces that shape biological design and cellular energetics.Tracing how natural selection sculpts metabolism, Microbial Life History provides new perspectives on the life histories of organisms, from growth rate and survival to dispersal and defense against attack. Along the way, this incisive book addresses the conceptual and philosophical challenges confronting evolutionary biologists and other practitioners who study biological design and seek to apply its lessons.
Abstract:Renewable energy sources are increasingly being integrated into small-scale production systems, so plants with multiple supply sources are becoming more common. This improvement in technology added to a greater social awareness of energy saving and resource usage, which makes flexible systems to manage these facilities necessary. Modern energy management can be more accessible to the interested public if it is located in universities, making it available to teachers and students alike. Furthermore, as it is a developing field of study, its location on campus facilitates research, maintenance, and financing. In this scenario, a SCADA system is proposed, capable of monitoring and centrally storing the values of the most important production and consumption parameters. In addition, by using this system, it is possible to control the state of the different energy sources in a centralized way, as well as their distribution in the plant where it is implemented. This study focuses on the management of a flexible, modern, and accessible solution to the advances in electrical systems because of technological development in this field, which broadens the experience of university teachers and students in their engineering careers. The systems have been put into practice in the facilities of a research and teaching laboratory at the University of Almeria, which integrates renewable and conventional energy resources.Keywords: energy monitoring; renewable energy; sustainability; electrical engineering; online learning; virtual laboratories 2b1af7f3a8