A low-power multi-band CMOS RF receiver front-end for ubiquitous sensor network applications

This paper presents the design and experimental results of a low-power multi-band RF receiver including a multi-band low-noise amplifier (LNA) and a down-conversion mixer based on the IEEE 802.15.4 standard for sensor node applications. A multi-band LNA with two inputs is tuned to two resonant frequencies by controlling the voltage on a switched MOS. The implemented RF receiver front-end achieves a maximum voltage conversion gain of 38 and 30 dB, NF of 6.2 and 9.2 dB at the 868/915 MHz and the 2.45 GHz bands, respectively. The RF receiver front-end dissipates total 3.0 mA (including I/Q mixers) under supply voltage of 1.8 V at both operation bands.     

Preparation of chelating fabrics by radiation‐induced grafting of itaconic acid and acrylonitrile onto polypropylene nonwoven fabrics and subsequent amination of graft copolymer

A mixture of acrylonitrile (AN) and itaconic acid (IA) was cografted onto polypropylene (PP) nonwoven fabrics by preirradiation method. The effects of graft polymerization conditions such as temperature, reaction time, Mohr's salt concentration, solvent mixture ratio, and comonomer composition on the total grafting yield were investigated. The addition of AN as a comonomer increased the amount of IA that reacted with PP fabrics. An increase in the temperature from 40 to 60°C increased the grafting rate, but the final grafting yield decreased at high temperature. The addition of 0.01 wt % Mohr's salt to the reaction medium leaded to a sharp increase of grafting yield. The accelerative effect of solvent medium on the grating yield was higher in dimethylformamide (DMF) and methanol mixtures, when compared with DMF or methanol. Chelating fabrics was synthesized by subsequent amination of grafted fabric with ethylene diamine (EDA) and phenylhydrazine (PH). The conversion yield reached maximum value at about 90% for 80% PP‐g‐AN‐IA fabrics at 90°C. At same amination conditions, the conversion yield is higher when PP‐g‐AN‐IA fabrics react with EDA compared with PH. FT‐IR data indicate that amine groups were introduced onto PP‐g‐AN‐IA fabric through amide linkage between grafted AN or IA and EDA or PH. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microfabrication and characterization of spray-coated single-wall carbon nanotube film strain gauges

We present the design, fabrication, and characterization results of single-wall carbon nanotube (SWCNT) film strain gauges for potential applications as highly sensitive strain, weight, or pressure sensors on the macro-scale. A batch microfabrication process was developed for practical device construction and packaging using spray-coated SWCNTs and a conventional semiconductor process. The prototype was characterized using a commercial metal foil gauge with tensile and compressive testing on a binocular load cell. Our test results demonstrated that the proposed SWCNT film gauges have a linear relationship between resistance changes and externally applied strain. The gauge factor ranged from 7.0 to 16.4 for four different micro-grid configurations, indicating that the maximum strain sensitivity of the prototype was approximately eight times greater than that of commercial gauges.     

The potential antioxidant capacity and angiotensin I-converting enzyme inhibitory activity of Monascus-fermented soybean extracts: evaluation of Monascus-fermented soybean extracts as multifunctional food additives

ABSTRACT:  The potential antioxidant capacity and angiotensin I-converting enzyme (ACE) inhibitory activity of Monascus -fermented soybean extracts (MFSE) were investigated. The average antioxidant capacities of 70% ethanol extracts from soybean after fermenting for 15 d at 30 °C were increased by a 5.2 to 7.4-fold (0.26 mM trolox equivalent/g dry weight, 91.7% 1,1-diphenyl-2-picrylhydrazyl [DPPH] radical scavenging effect at 3 mg/mL) when compared with those of the unfermented soybean extracts ( P < 0.01). The potentially significant antioxidant properties of MFSE are associated with its content of bioactive mevinolins ( r = 0.85) and isoflavone aglycones ( r = 0.98), which were derived from the soybean during Monascus -fermentation. It was also found that the water extract having a molecular mass 1 to 3 kDa showed the highest ACE inhibitory activity (65.3%), which was remarkably greater (6.5 times) than the control.     

Effects of liquid‐type silane additives and organoclay on the morphology and thermal conductivity of rigid polyisocyanurate‐polyurethane foams

This article investigates the effects of liquid‐type silane additives and organoclay as a solid‐type additive on the morphological, mechanical and thermal insulating properties of polyisocyanurate‐polyurethane (PIR‐PUR) foams. The organoclay likely acted as nucleating agents during the formation of PIR‐PUR foams. When the liquid silane additives and organoclay were added, the cell size and thermal conductivity of the PIR‐PUR foams appeared to be decreased. However, organoclay did not contribute to reduce the cell size distribution of the foam. PIR‐PUR foams synthesized with tetramethylsilane as a liquid‐type additive showed a smaller average cell size and lower thermal conductivity than that of PIR‐PUR foams synthesized with the other silane additives or with organoclay as a solid‐type additive. For the PIR‐PUR foam with organoclay/TEMS (1.5/1.5 php) mixture, cell size and thermal conductivity of the foam showed similar to the foam with TEMS. These results suggest that smaller cell size appears to be one of the major factors in the improvement of thermal insulation properties of the PIR‐PUR foams. Silane additives did not seem to have a strong effect on the flammability of the PIR‐PUR foams. However, heat resistance was more dominant for the foam with the organoclay at the higher temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Disposable Plastic-Silicon Micro PCR Chip Using Flexible Printed Circuit Board Protocols and Its Application to Genomic DNA Amplification

This paper describes a novel disposable and portable plastic-silicon polymerase chain reaction (PCR) system using microfabrication technologies for the realization of miniaturized nucleic acid analyses. The system consists of a polyimide-based film microheating system, embedding with a microheater and a temperature sensor made entirely with flexible printed circuit board (FPCB) process protocols, and a bulk-micromachined silicon reaction chamber. Reduction of the thermal mass by employing a 25 mum-thick polyimide film substrate, which has chemical and thermal resistance suitable for photolithography processes, and integration of a temperature sensor as well as a heater on the film facilitates rapid and precise temperature control. The microfabricated PCR chip demonstrated precise heat control and rapid thermal response in the chip. In addition, the chip successfully amplified a genomic DNA template (breast cancer suppressor gene, BRCA 1 127 base pairs), extracted from the human whole blood containing approximately 100 copies in a 3 muL-volume chamber within 18 min. Thus, it is applicable to a portable system for precise, fast, efficient and cost-effective nucleic analysis, and can be utilized with microscale biochemical analysis and sensing systems as well.     

Desorption of Fructose from a Packed Column to an Oleic Acid/Fructose Oleate Mixture for Employment in a Bioreactor System

Adsorption isotherms for a packed column consisting of fructose and silica gel in contact with a liquid phase consisting of oleic acid and fructose mono- and di-oleate at 65 °C were determined to assist the column’s utilization in a bioreactor system for the solvent-free lipase-catalyzed synthesis of saccharide ester biosurfactants. The liquid-phase fructose content was very low, ranging from 0.005 to 0.1% (w/w), with the higher values obtained for a higher fructose concentration in the column and a higher ester content in the liquid phase. The desorption behavior of fructose followed the Freundlich isotherm. An increase in the liquid phase space velocity increased the initial rate of fructose desorption linearly. Dynamic light scattering measurements demonstrate solutions obtained by mechanical stirring of crystalline fructose and oleic acid/fructose oleate contained 50–250 μm sized aggregates, even after centrifugation at 12,000 rpm, but that the aggregates were absent from the desorption column effluent stream. Therefore, employment of a desorption column will lead to a low saccharide concentration in the liquid phase, but will reduce suspension-induced fouling of lipase in a bioreactor downstream of the column, which could improve the retention of lipase activity.     

Hybrid determination of mixed-mode stress intensity factors on discontinuous finite-width plate by finite element and photoelasticity

For isotropic material structure, the stress in the vicinity of crack tip is generally much higher than the stress far away from it. This phenomenon usually leads to stress concentration and fracture of structure. Previous researches and studies show that the stress intensity factor is one of most important parameter for crack growth and propagation. This paper provides a convenient numerical method, which is called hybrid photoelasticity method, to accurately determine the stress field distribution in the vicinity of crack tip and mixed-mode stress intensity factors. The model was simulated by finite element method and isochromatic data along straight lines far away from the crack tip were calculated. By using the isochromatic data obtained from finite element method and a conformal mapping procedure, stress components and photoelastic fringes in the hybrid region were calculated. To easily compare calculated photoelastic fringes with experiment results, the fringe patterns were reconstructed, doubled and sharpened. Good agreement shows that the method presented in this paper is reliable and convenient. This method can then directly be applied to obtain mixed mode stress intensity factors from the experimentally measured isochromatic data along the straight lines.     

Characterization of AMOLED pixel circuit without power line

We fabricated and evaluated the simple active matrix organic light emitting diode (AMOLED) pixel circuits without power line and proved that it is useful for the AMOLED display. Without power line in the pixel circuit we got higher-aperture ratio of emission area than the pixel with power line and the pixel with high aperture ratio can give a long life time due to lower current density of organic light emitting diode. However, the lack of power line requires the verification of the driving scheme of the pixel circuit. After fabrication of two types of AMOLED with and without power line in the pixel, we evaluated the pixel currents under various conditions. The operation of the pixel circuit without power line gave similar characteristics to that of the pixel circuit with power line. By the comparison, we verified that the pixel without power line is acceptable for the application to the AMOLED display combined with feedback compensation scheme for the uniform brightness.