CRN++ : molecular programming language

Synthetic biology is a rapidly emerging research area, with expected wide-ranging impact in biology, nanofabrication, and medicine. A key technical challenge lies in embedding computation in molecular contexts where electronic micro-controllers cannot be inserted. This necessitates effective representation of computation using molecular components. While previous work established the Turing-completeness of chemical reactions, defining representations that are faithful, efficient, and practical remains challenging. This work introduces CRN++, a new language for programming deterministic (mass-action) chemical kinetics to perform computation. We present its syntax and semantics, and build a compiler translating CRN++ programs into chemical reactions, thereby laying the foundation of a comprehensive framework for molecular programming. Our language addresses the key challenge of embedding familiar imperative constructs into a set of chemical reactions happening simultaneously and manipulating real-valued concentrations. Although some deviation from ideal output value cannot be avoided, we develop methods to minimize the error, and implement error analysis tools. We demonstrate the feasibility of using CRN++ on a suite of well-known algorithms for discrete and real-valued computation. CRN++ can be easily extended to support new commands or chemical reaction implementations, and thus provides a foundation for developing more robust and practical molecular programs.Electrical and Computer Engineerin

Conception d’un pont en béton

L’objectif du projet est la conception et le dimensionnement d’un pont en béton armé en précontrainte. Plus précisément, le sujet est le pont de Tiguelet, un nouvel ouvrage, qui a pour but de joindre deux routes séparées par des voies de chemin de fer. Pour améliorer l’esthétique de l’ouvrage on vise à réduire le plus possible la hauteur du tablier, en augmentant au maximum son élancement. La construction a une longueur totale de 274 mètres. La travée principale mesure 50 mètres (40 mètres si l’on considère la réduction par les piles obliques) et les autres 7 travées d’environ 30 mètres. Le pont est constitué d’une section bipoutre de hauteur variable, variant entre 1.20 et 1.60 mètres et a donc un élancement de h/l = 1/25. Le tablier a une largeur de 10.30 mètres et permet le transit bidirectionnel des véhicules motorisés. En vue d’un éventuel changement d’utilisation dans le futur, le pont a été dimensionné pour deux variantes différentes: la première avec deux voies de circulation et des trottoirs des deux côtés, la deuxième avec trois voies de circulation. L’orientation des piles et de la culée nord est de 30° par rapport à l’axe du pont, elle est faite pour avoir les lames parallèles à la voie de chemin de fer. Cette inclinaison augmente graduellement jusqu’à devenir perpendiculaire au tablier sur la culée sud. Le terrain n’a pas une grande dénivellation et l’ouvrage reste assez bas. La hauteur des piles arrive jusqu’à 9 mètres, ainsi il est important d’avoir un bon élancement. Les piles sont en forme de lames et sont soutenues par des fondations à pieux d’une longueur de 12 mètres. Elles sont disposées en « V » au nord pour réduire la portée principale du tablier et mettre en évidence la zone du chemin de fer. Les piles de la zone sud, sont verticales. La culée nord et les piles en « V » sont monolithiques au tablier, Les autres soutènements ont des appuis mécaniques qui permettent les déplacements horizontaux dans l’axe du pont. Le pont peut donc se dilater vers la culée sud, où on trouve le joint de dilatation qui reprend ces déplacements

CRNs Exposed: A Method for the Systematic Exploration of Chemical Reaction Networks

Formal methods have enabled breakthroughs in many fields, such as in hardware verification, machine learning and biological systems. The key object of interest in systems biology, synthetic biology, and molecular programming is chemical reaction networks (CRNs) which formalizes coupled chemical reactions in a well-mixed solution. CRNs are pivotal for our understanding of biological regulatory and metabolic networks, as well as for programming engineered molecular behavior. Although it is clear that small CRNs are capable of complex dynamics and computational behavior, it remains difficult to explore the space of CRNs in search for desired functionality. We use Alloy, a tool for expressing structural constraints and behavior in software systems, to enumerate CRNs with declaratively specified properties. We show how this framework can enumerate CRNs with a variety of structural constraints including biologically motivated catalytic networks and metabolic networks, and seesaw networks motivated by DNA nanotechnology. We also use the framework to explore analog function computation in rate-independent CRNs. By computing the desired output value with stoichiometry rather than with reaction rates (in the sense that X ? Y+Y computes multiplication by 2), such CRNs are completely robust to the choice of reaction rates or rate law. We find the smallest CRNs computing the max, minmax, abs and ReLU (rectified linear unit) functions in a natural subclass of rate-independent CRNs where rate-independence follows from structural network properties

Comparative Structural and Optical Properties of Different Ceria Nanoparticles

Herein a comparative study of five nanocrystalline cerium oxides (CeO2-delta) synthesised by different methods and calcined at 500 degrees C is reported. XRPD analysis showed that stoichiometry parameter delta, crystallite size/strain and lattice constant were only slightly affected by the method utilized. All ceria nanoparticles are nearly spherical in shape with faceted morphology, free of defects and with a relatively uniform size distribution. The average microstrain was found to be approximately 10 times higher than that of bulk counterpart. The absorption edge of nanocrystalline materials was shifted towards a higher wavelengths (red shift) in comparison with bulk counterpart, and band gap values were in the range 2.7-3.24 eV (3.33 eV for bulk counterpart)

Application and modeling of GaN FET in 1MHz large signal bandwidth power supply for radio frequency power amplifier

In this paper, implementation and testing of non- commercial GaN HEMT in a simple buck converter for envelope amplifier in ET and EER transmission techn iques has been done. Comparing to the prototypes with commercially available EPC1014 and 1015 GaN HEMTs, experimentally demonstrated power supply provided better thermal management and increased the switching frequency up to 25MHz. 64QAM signal with 1MHz of large signal bandw idth and 10.5dB of Peak to Average Power Ratio was gener ated, using the switching frequency of 20MHz. The obtaine defficiency was 38% including the driving circuit an d the total losses breakdown showed that switching power losses in the HEMT are the dominant ones. In addition to this, some basic physical modeling has been done, in order to provide an insight on the correlation between the electrical characteristics of the GaN HEMT and physical design parameters. This is the first step in the optimization of the HEMT design for this particular application