High-speed high-resolution gas-phase Raman spectroscopy

A new Raman spectrometer has been developed that can produce a complete high-resolution gas-phase vibrational spectrum during the time period of a single laser pulse. Conventional gas-phase Raman spectroscopy uses a single narrow-band laser to produce signals that are weak, requiring relatively long collection times. This spectrometer uses a degenerate OPO as a broad-band source that covers a continuous range of >3000 cm(-1). When a beam from this broad-band source is added to a narrow-band laser beam, the intensity of the Raman signal is amplified by the nonlinear optical effect. The resulting instrument can generate spectra with high-spectral (<1 cm(-1)), spatial (<0.05 mm2), and temporal resolution (<1 s).     

Production and characterization of α-linolenic acid enriched structured lipids from lipase-catalyzed interesterification

The purpose of this study was to enrich α-linolenic acid (ALA) on the triacylglycerol (TAG) molecules of the selected vegetable oils (soybean and corn oil) in order to synthesized structural lipid (SL) with low ω6 to ω3 ratio. SLs were synthesized by lipase-catalyzed interesterification of soybean (SO) and corn oil (CO) with perilla oil (PO). Lipozyme RM IM from Rhizomucor miehei (5% by weight of total substrate) was used for the reaction. The reaction was performed during 24 hr at 55°C in the stirred-batch type reactor with solvent free system. After 24 hr reaction the ratio of ω6 to ω3 in SL products dramatically decreased comparing to that of substrates (SO and CO) before the reaction. At sn-2 position, the contents of ALA were 25.99% in soybean-SL and 23.25% in corn-SL, respectively. According to the equivalent carbon number (ECN) of TAG profile, newly produced SLs were separated by reverse-phase high performance liquid chromatography (HPLC). These results indicated that lipase-catalyzed interesterification is effective to produce SL with low ω6 to ω3 ratio which might be used as health beneficial oil.     

Computer‐aided design methodology for linearity enhancement of multiwatt GaN HEMT amplifiers using multiple parallel devices

This article presents a design methodology for linearizing GaN HEMT amplifiers based on splitting a large FET into multiple parallel FETs with same total gate periphery and by biasing them individually. By varying the biases, the magnitude and the phase of the IMD3 components at the output of FET changes. A detailed simulation methodology using commercial microwave CAD software is presented. Simulation results show that by biasing one device in Class AB and other(s) in deep Class AB mode, IMD3 components of parallel FETs can be made out of phase to each other leading to cancellation and improvement in linearity. Three prototype circuits were simulated using (a) a single 5 mm FET (1 × 5 mm), (b) two parallel 2.5 mm FETs (2 × 2.5 mm), and (c) four parallel 1.25 mm FETs (4 × 1.25 mm), for a total gate periphery of 5 mm, over the frequency range of 0.8 to 1.0 GHz. IMD3 improvement up to 20 dBc was achieved with the 4 × 1.25 mm circuit when the FET biases were optimized. Measurement results show improvement in linearity up to 20 dBc for 4 × 1.25 mm circuit. The proposed method improves linearity without a substantial penalty on the power consumption and is straightforward to implement.     

Energy efficient compression sensing-based clustering framework for IoT-based heterogeneous WSN

Telecommunication Systems - Compressive Sensing (CS) has proved to be a promising approach for the Internet of things (IoT) due to the fact that CS can abate the magnitude of raw data which is to...     

Design of a novel CMOS/MTJ-based multibit SRAM cell with low store energy for IoT applications

ABSTRACT

With rapid growth of Internet of Things, more and more devices are getting connected, which results in generation of large amount of data. To convert this collected raw data into useful information, it needs to be processed. However, during processing a significant amount of energy is spent in bringing data from off-chip non-volatile memory to on-chip memory. In addition, these devices are generally operated in ‘Normally OFF’ mode, which requires energy intensive boot process for waking up. Addressing these issues, Magnetic Tunnel Junction offers features like non-volatility and high integration density, which allows storage of data and instruction closer to the core. Therefore, this work proposes a hybrid multibit SRAM cell, which integrates MTJ with conventional 6T SRAM cell. The proposed SRAM cell supports multiple bit storage within a single cell. However, one of the critical issues with the MTJ is high-energy consumption while storing data. Hence, we also propose a store assist circuit for multibit SRAM cell, which asynchronously terminates the store operation after its completion to reduce the power consumption. Our simulation results show that the store assist circuit results in reduction of store energy by 35% and 72% when compared with existing multibit non-volatile SRAM.     

Production tactic and physiochemical properties of low ω6/ω3 ratio structured lipid synthesised from perilla and soybean oil

Structured lipid (SL) was synthesised by enzymatic interesterification of soybean oil and perilla oil. Response surface methodology (RSM) was used to determine the effects of three variables on the lipase‐catalysed interesterification. Based on ridge analysis, combination of reaction time (X₁; 18 h), reaction temperature (X₂; 60 °C), and substrate mole ratio (X₃; 1:1) were optimised for higher incorporation of ω3 (alpha (α) linolenic acid (ALA)) (Y). The predictive model was found to be adequate due to no significant lack of fit and satisfactory level of coefficient of determination (R² = 0.97). Experiments were conducted under optimised conditions which were predicted by the model equations, obtained from RSM yielded SL with linoleic (44.01%) and ALA (35.82%) were detected at sn‐2 position. The effects of antioxidants such as catechin, butylated hydroxytoluene (BHT) BHT and rosemary extracted on the oxidative stability in SL were investigated. Among all antioxidants, the highest stability was obtained from catechin.