Rapid detection of biologically active natural products plays a strategic role in the phytochemical investigation of crude plant extracts. In order to perform an efficient screening of the extracts, both biological assays and HPLC analysis with various detection methods are used. Combined techniques such as HPLC coupled to UV photodiode array detection (LC/UV) and to mass spectrometry (LC/MS or...

The photoaligned vertical aligned nematic (VAN) mode in liquid crystals (LC) was developed using the photosensitive polyimide (PI) JALC 2021-R2, illuminated by obliquely incident nonpolarized light. It has been found that the combination of PI with water soluble sulfonic azo-dye (SD) yields a perfect electro-optical performance of a liquid crystal in the VAN mode. The polar and the azimuthal an...

We report the operation of a Bloch oscillator. The active medium was a staticvoltage driven, doped GaAs/AlAs superlattice which was electromagnetically coupled to a resonator. The oscillator produced tuneable microwave radiation (frequency ~ 60 GHz; power ~ 0.5 mW; efficiency ~ 4 %). The gain (~ 10 cm) was due to the nonlinearity mediated by miniband electrons. We also present a theory of the o...

A novel varactor using single PMOS is proposed. By utilizing the capacitance difference between saturation and linear region, the proposed varactor can improve frequency resolution of a LC-tank based digitally controlled oscillator without introducing extra fixed loading capacitance. A digitally controlled oscillator with the proposed varactor is designed using 0.13μm CMOS technology for verifi...

A new CMOS LC Voltage Controlled Oscillator (VCO) for IEEE 802.11a application with low phase noise and consumed power less than 1mW is presented. This circuit was taped out by TSMC 0.18um 1P6M process. The measured phase noise is -115-88dBc/Hz at 1MHz offset at the operation frequency of 5.815GHz. And the dc core current consumption is 0.71mA at a supply voltage of 1.4 V. Its figure of merit (...

A phase-locked clock and data recovery circuit incorporates a multiphase LC oscillator and a quarter-rate bang-bang phase detector. The oscillator is based on differential excitation of a closed-loop transmission line at evenly spaced points, providing half-quadrature phases. The phase detector employs eight flip-flops to sample the input every 12.5 ps, detecting data transitions while retiming...

Synchronization of many coupled oscillators is widely found in nature and has the potential to revolutionize timing technologies. Here, we demonstrate synchronization in arrays of silicon nitride micromechanical oscillators coupled in an all-to-all configuration purely through an optical radiation field. We show that the phase noise of the synchronized oscillators can be improved by almost 10 d...

Synchronization of many coupled oscillators is widely found in nature and has the potential to revolutionize timing technologies. Here we demonstrate synchronization in arrays of silicon nitride micromechanical oscillators coupled purely through optical radiation field. We show that the phase noise of the synchronized oscillators can be improved by almost 10 dB below the phase noise limit for e...