some new macrocyclic dibenzotetraoxadiamides, tribenzotetraoxadimides, tribenzopentaoxadiamide, tribenzohexaoxadiamide, and tetrabenzoheptaoxadiamide 15-22 have been prepared. these compounds were obtained in the macrocyclization step by reacting the diamines 6 and 7 with appropriate dicarboxylic acid dichlorides 8-14. the cyclization does not require high dilution techniques or template effect...

Ultrafast superconductor digital microelectronic circuits operate at speeds up to 100 GHz, enabling true digital-RF architecture. This permits direct conversion between analog RF and digital baseband signals, replacing frequency and protocol-specific analog hardware with flexible, software-programmable digital processors. On the receive side, high sampling-speed (20 Gsamples/s) and linearity (>...

We demonstrate a new technique for selectively growing gold nanoparticles on a patterned three-dimensional (3D) polymer microstructure. The technique integrates 3D direct writing of heterogeneous microstructures with nanoparticle synthesis. A digital micromirror device is employed as a dynamic mask in the digital projection photopolymerization process to build the heterogeneous microstructure l...

Introdouction:The study aimed to compare the accuracy of proximal caries detection by dental practitioners using two different systems, direct digital system and conventional films, under routine environmental conditions. Materials and methods: Eleven extracted human posterior teeth were mounted on wax frames and were exposed using the direct digital system and conventional films. Seventy-four ...

Direct digital frequency synthesizers (DDSs) are of interest in modern digital communication systems and high-precision function generation. Wide frequency synthesis range, agile and continuous phase frequency switching, fine frequency resolution, and the ability to synthesize arbitrary waveforms as well as sinewaves are some of the important advantages of this family of frequency synthesizers....

Modulation is the technique in which carrier signal varies according to amplitude of modulating signal. A brilliant solution for realizing digital modulators is CORDIC (CO-ordinate Rotation Digital Computer) algorithm. Rotation mode and vector mode are two modes in which this algorithm is used. Here rotation mode is used to convert the coordinates from polar mode to rectangular mode. This paper...