The photonic crystal is investigated as a substrate material for planar antennas in the microwave and millimeter-wave bands. Experimental results are presented for a bow-tie antenna on a (111)-oriented face-centered-cubic photonic-crystal substrate with a band gap between approximately 13 and 16 GHz. When driven at 13.2 GHz, the antenna radiates predominantly into the air rather than into the substrate. This suggests that highly efficient planar antennas can be made on photonic-crystal regions fabricated in semiconductor substrates such as GaAs.
This paper describes the philosophy, application, and implementation of a collection of FORTRAN IV computer programs currently being used in a sophomore course on nonlinear circuit analysis at Purdue University. Since these programs were developed from the education rather than the user point of view, some of them were deliberately designed in the form of a series of subroutines, and were stored in a common disk file. These subroutines and programs are used to analyze a large class of nonlinear electronic circuits such as waveshaping networks, multivibrators, time-base generators, etc. Since the computer is used to take over only the nonconceptual but otherwise very time-consuming task, the students were found to be much more receptive and motivated in learning new concepts. The results reported in this paper are based on the experiences and reactions of approximately 150 students using the batch-processing mode. A short description, however, is also given on a forthcoming experiment to be conducted at Purdue University on the merits of using an on-line graphic display console.
We extend the notion of memristive systems to capacitive and inductive elements, namely capacitors and inductors whose properties depend on the state and history of the system. All these elements show pinched hysteretic loops in the two constitutive variables that define them: current-voltage for the memristor, charge-voltage for the memcapacitor, and current-flux for the meminductor. We argue that these devices are common at the nanoscale where the dynamical properties of electrons and ions are likely to depend on the history of the system, at least within certain time scales. These elements and their combination in circuits open up new functionalities in electronics and they are likely to find applications in neuromorphic devices to simulate learning, adaptive and spontaneous behavior.
This chapter contains sections titled: Introduction The Formation of Compounds Containing Transition-metal–Silicon Bonds Late Transition-metal Derivatives Methods Involving Oxidative Addition of SiH Bonds Methods Involving Oxidative Addition of Other SiX Bonds Methods Employing Transition-metal Anions Methods Employing Main-group Metal Silyl Compounds Miscellaneous Methods Transition-metal Silicon Clusters Early Transition-metal Derivatives Methods Employing Main-group Metal Silyl Compounds Methods Involving Cleavage of SiH Bonds Related F-element Derivatives Transition-metal Silylene Complexes Indirect Evidence for Coordinated Silylenes Attempted Preparations Transition-metal Silene Complexes Structure and Bonding Structural Information Metal–silicon Bond Distances Other Structural Features Information from NMR Studies Information from Infrared and Raman Studies Information from Mass Spectrometric Studies Reactions Involving MSi Bonds Cleavage of MSi Bonds by Nucleophiles Cleavage of MSi Bonds by Electrophiles Cleavage of MSi Bonds by Other Reagents Insertion Reactions Insertion of Alkenes Insertion of Alkynes Insertion of Nitriles Insertion of Organic Carbonyl Compounds Insertion of Carbon Monoxide and Isocyanides Catalytic Reactions Hydrosilylation Dehydrogenative Coupling Reactions Involving Hydrosilanes Redistribution on Silicon Other SiC Bond-forming Reactions Catalytic Reactions with Hydrosilanes and Carbon Monoxide References
ABSTRACT Synthetic biological pathways could enhance the development of novel processes to produce chemicals from renewable resources. On the basis of models that describe the evolution of metabolic pathways and enzymes in nature, we developed a framework to rationally identify enzymes able to catalyze reactions on new substrates that overcomes one of the major bottlenecks in the assembly of a synthetic biological pathway. We verified the framework by implementing a pathway with two novel enzymatic reactions to convert isopentenyl diphosphate into 3-methyl-3-butenol, 3-methyl-2-butenol, and 3-methylbutanol. To overcome competition with native pathways that share the same substrate, we engineered two bifunctional enzymes that redirect metabolic flux toward the synthetic pathway. Taken together, our work demonstrates a new approach to the engineering of novel synthetic pathways in the cell.
In this paper, we give a framework for synchronization of dynamical systems which unifies many results in synchronization and control of dynamical systems, in particular chaotic systems. We define concepts such as asymptotical synchronization, partial synchronization and synchronization error bounds. We show how asymptotical synchronization is related to asymptotical stability. The main tool we use to prove asymptotical stability and synchronization is Lyapunov stability theory. We illustrate how many previous results on synchronization and control of chaotic systems can be derived from this framework. We will also give a characterization of robustness of synchronization and show that master-slave asymptotical synchronization in Chua’s oscillator is robust.
